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gecko/layout/generic/nsFlexContainerFrame.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 et sw=2 tw=80: */
/* This Source Code is subject to the terms of the Mozilla Public License
* version 2.0 (the "License"). You can obtain a copy of the License at
* http://mozilla.org/MPL/2.0/. */
/* rendering object for CSS display: -moz-flex */
#include "nsFlexContainerFrame.h"
#include "nsLayoutUtils.h"
#include "nsPresContext.h"
#include "nsStyleContext.h"
#include "prlog.h"
using namespace mozilla::css;
#ifdef PR_LOGGING
static PRLogModuleInfo* nsFlexContainerFrameLM = PR_NewLogModule("nsFlexContainerFrame");
#endif /* PR_LOGGING */
// XXXdholbert Some of this helper-stuff should be separated out into a general
// "LogicalAxisUtils.h" helper. Should that be a class, or a namespace (under
// what super-namespace?), or what?
// Helper enums
// ============
// Represents a physical orientation for an axis.
// The directional suffix indicates the direction in which the axis *grows*.
// So e.g. eAxis_LR means a horizontal left-to-right axis, whereas eAxis_BT
// means a vertical bottom-to-top axis.
// NOTE: The order here is important -- these values are used as indices into
// the static array 'kAxisOrientationToSidesMap', defined below.
enum AxisOrientationType {
eAxis_LR,
eAxis_RL,
eAxis_TB,
eAxis_BT,
eNumAxisOrientationTypes // For sizing arrays that use these values as indices
};
// Represents one or the other extreme of an axis (e.g. for the main axis, the
// main-start vs. main-end edge.
// NOTE: The order here is important -- these values are used as indices into
// the sub-arrays in 'kAxisOrientationToSidesMap', defined below.
enum AxisEdgeType {
eAxisEdge_Start,
eAxisEdge_End,
eNumAxisEdges // For sizing arrays that use these values as indices
};
// This array maps each axis orientation to a pair of corresponding
// [start, end] physical mozilla::css::Side values.
static const Side
kAxisOrientationToSidesMap[eNumAxisOrientationTypes][eNumAxisEdges] = {
{ eSideLeft, eSideRight }, // eAxis_LR
{ eSideRight, eSideLeft }, // eAxis_RL
{ eSideTop, eSideBottom }, // eAxis_TB
{ eSideBottom, eSideTop } // eAxis_BT
};
// Helper structs / classes / methods
// ==================================
// Indicates whether advancing along the given axis is equivalent to
// increasing our X or Y position (as opposed to decreasing it).
static inline bool
AxisGrowsInPositiveDirection(AxisOrientationType aAxis)
{
return eAxis_LR == aAxis || eAxis_TB == aAxis;
}
// Indicates whether the given axis is horizontal.
static inline bool
IsAxisHorizontal(AxisOrientationType aAxis)
{
return eAxis_LR == aAxis || eAxis_RL == aAxis;
}
// Given an AxisOrientationType, returns the "reverse" AxisOrientationType
// (in the same dimension, but the opposite direction)
static inline AxisOrientationType
GetReverseAxis(AxisOrientationType aAxis)
{
AxisOrientationType reversedAxis;
if (aAxis % 2 == 0) {
// even enum value. Add 1 to reverse.
reversedAxis = AxisOrientationType(aAxis + 1);
} else {
// odd enum value. Subtract 1 to reverse.
reversedAxis = AxisOrientationType(aAxis - 1);
}
// Check that we're still in the enum's valid range
MOZ_ASSERT(reversedAxis >= eAxis_LR &&
reversedAxis <= eAxis_BT);
return reversedAxis;
}
// Returns aFrame's computed value for 'height' or 'width' -- whichever is in
// the same dimension as aAxis.
static inline const nsStyleCoord&
GetSizePropertyForAxis(const nsIFrame* aFrame, AxisOrientationType aAxis)
{
const nsStylePosition* stylePos = aFrame->GetStylePosition();
return IsAxisHorizontal(aAxis) ?
stylePos->mWidth :
stylePos->mHeight;
}
static nscoord
MarginComponentForSide(const nsMargin& aMargin, Side aSide)
{
switch (aSide) {
case eSideLeft:
return aMargin.left;
case eSideRight:
return aMargin.right;
case eSideTop:
return aMargin.top;
case eSideBottom:
return aMargin.bottom;
}
NS_NOTREACHED("unexpected Side enum");
return aMargin.left; // have to return something
// (but something's busted if we got here)
}
static nscoord&
MarginComponentForSide(nsMargin& aMargin, Side aSide)
{
switch (aSide) {
case eSideLeft:
return aMargin.left;
case eSideRight:
return aMargin.right;
case eSideTop:
return aMargin.top;
case eSideBottom:
return aMargin.bottom;
}
NS_NOTREACHED("unexpected Side enum");
return aMargin.left; // have to return something
// (but something's busted if we got here)
}
// Encapsulates our flex container's main & cross axes.
NS_STACK_CLASS class FlexboxAxisTracker {
public:
FlexboxAxisTracker(nsFlexContainerFrame* aFlexContainerFrame);
// Accessors:
AxisOrientationType GetMainAxis() const { return mMainAxis; }
AxisOrientationType GetCrossAxis() const { return mCrossAxis; }
nscoord GetMainComponent(const nsSize& aSize) const {
return IsAxisHorizontal(mMainAxis) ?
aSize.width : aSize.height;
}
int32_t GetMainComponent(const nsIntSize& aIntSize) const {
return IsAxisHorizontal(mMainAxis) ?
aIntSize.width : aIntSize.height;
}
nscoord GetMainComponent(const nsHTMLReflowMetrics& aMetrics) const {
return IsAxisHorizontal(mMainAxis) ?
aMetrics.width : aMetrics.height;
}
nscoord GetCrossComponent(const nsSize& aSize) const {
return IsAxisHorizontal(mCrossAxis) ?
aSize.width : aSize.height;
}
int32_t GetCrossComponent(const nsIntSize& aIntSize) const {
return IsAxisHorizontal(mCrossAxis) ?
aIntSize.width : aIntSize.height;
}
nscoord GetCrossComponent(const nsHTMLReflowMetrics& aMetrics) const {
return IsAxisHorizontal(mCrossAxis) ?
aMetrics.width : aMetrics.height;
}
nscoord GetMarginSizeInMainAxis(const nsMargin& aMargin) const {
return IsAxisHorizontal(mMainAxis) ?
aMargin.LeftRight() :
aMargin.TopBottom();
}
nscoord GetMarginSizeInCrossAxis(const nsMargin& aMargin) const {
return IsAxisHorizontal(mCrossAxis) ?
aMargin.LeftRight() :
aMargin.TopBottom();
}
nsPoint PhysicalPositionFromLogicalPosition(nscoord aMainPosn,
nscoord aCrossPosn) const {
return IsAxisHorizontal(mMainAxis) ?
nsPoint(aMainPosn, aCrossPosn) :
nsPoint(aCrossPosn, aMainPosn);
}
nsSize PhysicalSizeFromLogicalSizes(nscoord aMainSize,
nscoord aCrossSize) const {
return IsAxisHorizontal(mMainAxis) ?
nsSize(aMainSize, aCrossSize) :
nsSize(aCrossSize, aMainSize);
}
private:
AxisOrientationType mMainAxis;
AxisOrientationType mCrossAxis;
};
// Encapsulates a frame for a flex item, with enough information for us to
// sort by 'order' (and by the frame's actual index inside the parent's
// child-frames array, among frames with the same 'order').
class SortableFrame {
public:
SortableFrame(nsIFrame* aFrame,
int32_t aOrderValue,
uint32_t aIndexInFrameList)
: mFrame(aFrame),
mOrderValue(aOrderValue),
mIndexInFrameList(aIndexInFrameList)
{
MOZ_ASSERT(aFrame, "expecting a non-null child frame");
}
// Implement operator== and operator< so that we can use nsDefaultComparator
bool operator==(const SortableFrame& rhs) const {
MOZ_ASSERT(mFrame != rhs.mFrame ||
(mOrderValue == rhs.mOrderValue &&
mIndexInFrameList == rhs.mIndexInFrameList),
"if frames are equal, the other member data should be too");
return mFrame == rhs.mFrame;
}
bool operator<(const SortableFrame& rhs) const {
if (mOrderValue == rhs.mOrderValue) {
return mIndexInFrameList < rhs.mIndexInFrameList;
}
return mOrderValue < rhs.mOrderValue;
}
// Accessor for the frame
inline nsIFrame* Frame() const { return mFrame; }
protected:
nsIFrame* const mFrame; // The flex item's frame
int32_t const mOrderValue; // mFrame's computed value of 'order' property
uint32_t const mIndexInFrameList; // mFrame's idx in parent's child frames
};
// Represents a flex item.
// Includes the various pieces of input that the Flexbox Layout Algorithm uses
// to resolve a flexible width.
class FlexItem {
public:
FlexItem(nsIFrame* aChildFrame,
float aFlexGrow, float aFlexShrink, nscoord aMainBaseSize,
nscoord aMainMinSize, nscoord aMainMaxSize,
nscoord aCrossMinSize, nscoord aCrossMaxSize,
nsMargin aMargin, nsMargin aBorderPadding,
const FlexboxAxisTracker& aAxisTracker);
// Accessors
nsIFrame* Frame() const { return mFrame; }
nscoord GetFlexBaseSize() const { return mFlexBaseSize; }
nscoord GetMainMinSize() const { return mMainMinSize; }
nscoord GetMainMaxSize() const { return mMainMaxSize; }
// Note: These return the main-axis position and size of our *content box*.
nscoord GetMainSize() const { return mMainSize; }
nscoord GetMainPosition() const { return mMainPosn; }
nscoord GetCrossMinSize() const { return mCrossMinSize; }
nscoord GetCrossMaxSize() const { return mCrossMaxSize; }
// Note: These return the cross-axis position and size of our *content box*.
nscoord GetCrossSize() const { return mCrossSize; }
nscoord GetCrossPosition() const { return mCrossPosn; }
nscoord GetAscent() const { return mAscent; }
float GetShareOfFlexWeightSoFar() const { return mShareOfFlexWeightSoFar; }
bool IsFrozen() const { return mIsFrozen; }
bool HadMinViolation() const { return mHadMinViolation; }
bool HadMaxViolation() const { return mHadMaxViolation; }
// Indicates whether this item's cross-size has been stretched (from having
// "align-self: stretch" with an auto cross-size and no auto margins in the
// cross axis).
bool IsStretched() const { return mIsStretched; }
uint8_t GetAlignSelf() const { return mAlignSelf; }
// Returns the flex weight that we should use in the "resolving flexible
// lengths" algorithm. If we've got a positive amount of free space, we use
// the flex-grow weight; otherwise, we use the "scaled flex shrink weight"
// (scaled by our flex base size)
float GetFlexWeightToUse(bool aHavePositiveFreeSpace)
{
if (IsFrozen()) {
return 0.0f;
}
return aHavePositiveFreeSpace ?
mFlexGrow :
mFlexShrink * mFlexBaseSize;
}
// Getters for margin:
// ===================
const nsMargin& GetMargin() const { return mMargin; }
// Returns the margin component for a given mozilla::css::Side
nscoord GetMarginComponentForSide(Side aSide) const
{ return MarginComponentForSide(mMargin, aSide); }
// Returns the total space occupied by this item's margins in the given axis
nscoord GetMarginSizeInAxis(AxisOrientationType aAxis) const
{
Side startSide = kAxisOrientationToSidesMap[aAxis][eAxisEdge_Start];
Side endSide = kAxisOrientationToSidesMap[aAxis][eAxisEdge_End];
return GetMarginComponentForSide(startSide) +
GetMarginComponentForSide(endSide);
}
// Getters for border/padding
// ==========================
// Returns the border+padding component for a given mozilla::css::Side
nscoord GetBorderPaddingComponentForSide(Side aSide) const
{ return MarginComponentForSide(mBorderPadding, aSide); }
// Returns the total space occupied by this item's borders and padding in
// the given axis
nscoord GetBorderPaddingSizeInAxis(AxisOrientationType aAxis) const
{
Side startSide = kAxisOrientationToSidesMap[aAxis][eAxisEdge_Start];
Side endSide = kAxisOrientationToSidesMap[aAxis][eAxisEdge_End];
return GetBorderPaddingComponentForSide(startSide) +
GetBorderPaddingComponentForSide(endSide);
}
// Getter for combined margin/border/padding
// =========================================
// Returns the total space occupied by this item's margins, borders and
// padding in the given axis
nscoord GetMarginBorderPaddingSizeInAxis(AxisOrientationType aAxis) const
{
return GetMarginSizeInAxis(aAxis) + GetBorderPaddingSizeInAxis(aAxis);
}
// Setters
// =======
// Setters used while we're resolving flexible lengths
// ---------------------------------------------------
// Sets the main-size of our flex item's content-box.
void SetMainSize(nscoord aNewMainSize)
{
MOZ_ASSERT(!mIsFrozen, "main size shouldn't change after we're frozen");
mMainSize = aNewMainSize;
}
void SetShareOfFlexWeightSoFar(float aNewShare)
{
MOZ_ASSERT(!mIsFrozen || aNewShare == 0.0f,
"shouldn't be giving this item any share of the weight "
"after it's frozen");
mShareOfFlexWeightSoFar = aNewShare;
}
void Freeze() { mIsFrozen = true; }
void SetHadMinViolation()
{
MOZ_ASSERT(!mIsFrozen,
"shouldn't be changing main size & having violations "
"after we're frozen");
mHadMinViolation = true;
}
void SetHadMaxViolation()
{
MOZ_ASSERT(!mIsFrozen,
"shouldn't be changing main size & having violations "
"after we're frozen");
mHadMaxViolation = true;
}
void ClearViolationFlags()
{ mHadMinViolation = mHadMaxViolation = false; }
// Setters for values that are determined after we've resolved our main size
// -------------------------------------------------------------------------
// Sets the main-axis position of our flex item's content-box.
// (This is the distance between the main-start edge of the flex container
// and the main-start edge of the flex item's content-box.)
void SetMainPosition(nscoord aPosn) {
MOZ_ASSERT(mIsFrozen, "main size should be resolved before this");
mMainPosn = aPosn;
}
// Sets the cross-size of our flex item's content-box.
void SetCrossSize(nscoord aCrossSize) {
MOZ_ASSERT(mIsFrozen, "main size should be resolved before this");
mCrossSize = aCrossSize;
}
// Sets the cross-axis position of our flex item's content-box.
// (This is the distance between the cross-start edge of the flex container
// and the cross-start edge of the flex item.)
void SetCrossPosition(nscoord aPosn) {
MOZ_ASSERT(mIsFrozen, "main size should be resolved before this");
mCrossPosn = aPosn;
}
void SetAscent(nscoord aAscent) {
mAscent = aAscent;
}
void SetIsStretched() {
MOZ_ASSERT(mIsFrozen, "main size should be resolved before this");
mIsStretched = true;
}
// Setter for margin components (for resolving "auto" margins)
void SetMarginComponentForSide(Side aSide, nscoord aLength)
{
MOZ_ASSERT(mIsFrozen, "main size should be resolved before this");
MarginComponentForSide(mMargin, aSide) = aLength;
}
uint32_t GetNumAutoMarginsInAxis(AxisOrientationType aAxis) const;
protected:
// Our frame:
nsIFrame* const mFrame;
// Values that we already know in constructor: (and are hence mostly 'const')
const float mFlexGrow;
const float mFlexShrink;
const nsMargin mBorderPadding;
nsMargin mMargin; // non-const because we need to resolve auto margins
const nscoord mFlexBaseSize;
const nscoord mMainMinSize;
const nscoord mMainMaxSize;
const nscoord mCrossMinSize;
const nscoord mCrossMaxSize;
// Values that we compute after constructor:
nscoord mMainSize;
nscoord mMainPosn;
nscoord mCrossSize;
nscoord mCrossPosn;
nscoord mAscent;
// Temporary state, while we're resolving flexible widths (for our main size)
// XXXdholbert To save space, we could use a union to make these variables
// overlay the same memory as some other member vars that aren't touched
// until after main-size has been resolved. In particular, these could share
// memory with mMainPosn through mAscent, and mIsStretched.
float mShareOfFlexWeightSoFar;
bool mIsFrozen;
bool mHadMinViolation;
bool mHadMaxViolation;
// Misc:
bool mIsStretched; // See IsStretched() documentation
uint8_t mAlignSelf; // My "align-self" computed value (with "auto"
// swapped out for parent"s "align-items" value,
// in our constructor).
};
bool
nsFlexContainerFrame::IsHorizontal()
{
const FlexboxAxisTracker axisTracker(this);
return IsAxisHorizontal(axisTracker.GetMainAxis());
}
nsresult
nsFlexContainerFrame::AppendFlexItemForChild(
nsPresContext* aPresContext,
nsIFrame* aChildFrame,
const nsHTMLReflowState& aParentReflowState,
const FlexboxAxisTracker& aAxisTracker,
nsTArray<FlexItem>& aFlexItems)
{
// Create temporary reflow state just for sizing -- to get hypothetical
// main-size and the computed values of min / max main-size property.
// (This reflow state will _not_ be used for reflow.)
nsHTMLReflowState childRS(aPresContext, aParentReflowState, aChildFrame,
nsSize(aParentReflowState.ComputedWidth(),
aParentReflowState.ComputedHeight()));
// MAIN SIZES (flex base size, min/max size)
// -----------------------------------------
nscoord flexBaseSize =
aAxisTracker.GetMainComponent(nsSize(childRS.ComputedWidth(),
childRS.ComputedHeight()));
nscoord mainMinSize =
aAxisTracker.GetMainComponent(nsSize(childRS.mComputedMinWidth,
childRS.mComputedMinHeight));
nscoord mainMaxSize =
aAxisTracker.GetMainComponent(nsSize(childRS.mComputedMaxWidth,
childRS.mComputedMaxHeight));
// This is enforced by the nsHTMLReflowState where these values come from:
MOZ_ASSERT(mainMinSize <= mainMaxSize, "min size is larger than max size");
// SPECIAL MAIN-SIZING FOR VERTICAL FLEX CONTAINERS
// If we're vertical and our main size ended up being unconstrained
// (e.g. because we had height:auto), we need to instead use our
// "max-content" height, which is what we get from reflowing into our
// available width. This is the same as our "min-content" height --
// so if we have "min-height:auto", we need to use this value as our
// min-height.
if (!IsAxisHorizontal(aAxisTracker.GetMainAxis())) {
bool isMainSizeAuto = (NS_UNCONSTRAINEDSIZE == flexBaseSize);
bool isMainMinSizeAuto =
(eStyleUnit_Auto ==
aChildFrame->GetStylePosition()->mMinHeight.GetUnit());
if (isMainSizeAuto || isMainMinSizeAuto) {
// Give the item a special reflow with "mIsFlexContainerMeasuringHeight"
// set. This tells it to behave as if it had "height: auto", regardless
// of what the "height" property is actually set to.
nsHTMLReflowState
childRSForMeasuringHeight(aPresContext, aParentReflowState,
aChildFrame,
nsSize(aParentReflowState.ComputedWidth(),
NS_UNCONSTRAINEDSIZE),
-1, -1, false);
childRSForMeasuringHeight.mFlags.mIsFlexContainerMeasuringHeight = true;
childRSForMeasuringHeight.Init(aPresContext);
nsHTMLReflowMetrics childDesiredSize;
nsReflowStatus childReflowStatus;
nsresult rv = ReflowChild(aChildFrame, aPresContext,
childDesiredSize, childRSForMeasuringHeight,
0, 0, NS_FRAME_NO_MOVE_FRAME,
childReflowStatus);
NS_ENSURE_SUCCESS(rv, rv);
MOZ_ASSERT(NS_FRAME_IS_COMPLETE(childReflowStatus),
"We gave flex item unconstrained available height, so it "
"should be complete");
// Subtract border/padding in vertical axis, to get _just_
// the effective computed value of the "height" property.
nscoord childDesiredHeight = childDesiredSize.height -
childRS.mComputedBorderPadding.TopBottom();
childDesiredHeight = NS_MAX(0, childDesiredHeight);
if (isMainSizeAuto) {
flexBaseSize = childDesiredHeight;
}
if (isMainMinSizeAuto) {
mainMinSize = childDesiredHeight;
mainMaxSize = NS_MAX(mainMaxSize, mainMinSize);
}
}
}
// CROSS MIN/MAX SIZE
// ------------------
nscoord crossMinSize =
aAxisTracker.GetCrossComponent(nsSize(childRS.mComputedMinWidth,
childRS.mComputedMinHeight));
nscoord crossMaxSize =
aAxisTracker.GetCrossComponent(nsSize(childRS.mComputedMaxWidth,
childRS.mComputedMaxHeight));
// SPECIAL-CASE FOR WIDGET-IMPOSED SIZES
// Check if we're a themed widget, in which case we might have a minimum
// main & cross size imposed by our widget (which we can't go below), or
// (more severe) our widget might have only a single valid size.
bool isFixedSizeWidget = false;
const nsStyleDisplay* disp = aChildFrame->GetStyleDisplay();
if (aChildFrame->IsThemed(disp)) {
nsIntSize widgetMinSize(0, 0);
bool canOverride = true;
aPresContext->GetTheme()->
GetMinimumWidgetSize(childRS.rendContext, aChildFrame,
disp->mAppearance,
&widgetMinSize, &canOverride);
nscoord widgetMainMinSize =
aPresContext->DevPixelsToAppUnits(
aAxisTracker.GetMainComponent(widgetMinSize));
nscoord widgetCrossMinSize =
aPresContext->DevPixelsToAppUnits(
aAxisTracker.GetCrossComponent(widgetMinSize));
// GMWS() returns border-box; we need content-box
widgetMainMinSize -=
aAxisTracker.GetMarginSizeInMainAxis(childRS.mComputedBorderPadding);
widgetCrossMinSize -=
aAxisTracker.GetMarginSizeInCrossAxis(childRS.mComputedBorderPadding);
if (!canOverride) {
// Fixed-size widget: freeze our main-size at the widget's mandated size.
// (Set min and max main-sizes to that size, too, to keep us from
// clamping to any other size later on.)
flexBaseSize = mainMinSize = mainMaxSize = widgetMainMinSize;
crossMinSize = crossMaxSize = widgetCrossMinSize;
isFixedSizeWidget = true;
} else {
// Variable-size widget: ensure our min/max sizes are at least as large
// as the widget's mandated minimum size, so we don't flex below that.
mainMinSize = NS_MAX(mainMinSize, widgetMainMinSize);
mainMaxSize = NS_MAX(mainMaxSize, widgetMainMinSize);
crossMinSize = NS_MAX(crossMinSize, widgetCrossMinSize);
crossMaxSize = NS_MAX(crossMaxSize, widgetCrossMinSize);
}
}
// FLEX GROW & SHRINK WEIGHTS
const nsStylePosition* stylePos = aChildFrame->GetStylePosition();
float flexGrow = stylePos->mFlexGrow;
float flexShrink = stylePos->mFlexShrink;
aFlexItems.AppendElement(FlexItem(aChildFrame,
flexGrow, flexShrink, flexBaseSize,
mainMinSize, mainMaxSize,
crossMinSize, crossMaxSize,
childRS.mComputedMargin,
childRS.mComputedBorderPadding,
aAxisTracker));
// If we're inflexible, we can just freeze to our hypothetical main-size
// up-front. Similarly, if we're a fixed-size widget, we only have one
// valid size, so we freeze to keep ourselves from flexing.
if (isFixedSizeWidget || (flexGrow == 0.0f && flexShrink == 0.0f)) {
aFlexItems.LastElement().Freeze();
}
return NS_OK;
}
FlexItem::FlexItem(nsIFrame* aChildFrame,
float aFlexGrow, float aFlexShrink, nscoord aFlexBaseSize,
nscoord aMainMinSize, nscoord aMainMaxSize,
nscoord aCrossMinSize, nscoord aCrossMaxSize,
nsMargin aMargin, nsMargin aBorderPadding,
const FlexboxAxisTracker& aAxisTracker)
: mFrame(aChildFrame),
mFlexGrow(aFlexGrow),
mFlexShrink(aFlexShrink),
mBorderPadding(aBorderPadding),
mMargin(aMargin),
mFlexBaseSize(aFlexBaseSize),
mMainMinSize(aMainMinSize),
mMainMaxSize(aMainMaxSize),
mCrossMinSize(aCrossMinSize),
mCrossMaxSize(aCrossMaxSize),
// Init main-size to 'hypothetical main size', which is flex base size
// clamped to [min,max] range:
mMainSize(NS_CSS_MINMAX(aFlexBaseSize, aMainMinSize, aMainMaxSize)),
mMainPosn(0),
mCrossSize(0),
mCrossPosn(0),
mAscent(0),
mShareOfFlexWeightSoFar(0.0f),
mIsFrozen(false),
mHadMinViolation(false),
mHadMaxViolation(false),
mIsStretched(false),
mAlignSelf(aChildFrame->GetStylePosition()->mAlignSelf)
{
MOZ_ASSERT(aChildFrame, "expecting a non-null child frame");
// Assert that any "auto" margin components are set to 0.
// (We'll resolve them later; until then, we want to treat them as 0-sized.)
#ifdef DEBUG
{
const nsStyleSides& styleMargin = mFrame->GetStyleMargin()->mMargin;
NS_FOR_CSS_SIDES(side) {
if (styleMargin.GetUnit(side) == eStyleUnit_Auto) {
MOZ_ASSERT(GetMarginComponentForSide(side) == 0,
"Someone else tried to resolve our auto margin");
}
}
}
#endif // DEBUG
// Resolve "align-self: auto" to parent's "align-items" value.
if (mAlignSelf == NS_STYLE_ALIGN_SELF_AUTO) {
mAlignSelf = mFrame->GetParent()->GetStylePosition()->mAlignItems;
}
// If the flex item's inline axis is the same as the cross axis, then
// 'align-self:baseline' is identical to 'flex-start'. If that's the case, we
// just directly convert our align-self value here, so that we don't have to
// handle this with special cases elsewhere.
// Moreover: for the time being (until we support writing-modes),
// all inline axes are horizontal -- so we can just check if the cross axis
// is horizontal.
// FIXME: Once we support writing-mode (vertical text), this IsAxisHorizontal
// check won't be sufficient anymore -- we'll actually need to compare our
// inline axis vs. the cross axis.
if (mAlignSelf == NS_STYLE_ALIGN_ITEMS_BASELINE &&
IsAxisHorizontal(aAxisTracker.GetCrossAxis())) {
mAlignSelf = NS_STYLE_ALIGN_ITEMS_FLEX_START;
}
}
uint32_t
FlexItem::GetNumAutoMarginsInAxis(AxisOrientationType aAxis) const
{
uint32_t numAutoMargins = 0;
const nsStyleSides& styleMargin = mFrame->GetStyleMargin()->mMargin;
for (uint32_t i = 0; i < eNumAxisEdges; i++) {
Side side = kAxisOrientationToSidesMap[aAxis][i];
if (styleMargin.GetUnit(side) == eStyleUnit_Auto) {
numAutoMargins++;
}
}
// Mostly for clarity:
MOZ_ASSERT(numAutoMargins <= 2,
"We're just looking at one item along one dimension, so we "
"should only have examined 2 margins");
return numAutoMargins;
}
// Keeps track of our position along a particular axis (where a '0' position
// corresponds to the 'start' edge of that axis).
// This class shouldn't be instantiated directly -- rather, it should only be
// instantiated via its subclasses defined below.
NS_STACK_CLASS
class PositionTracker {
public:
// Accessor for the current value of the position that we're tracking.
inline nscoord GetPosition() const { return mPosition; }
inline AxisOrientationType GetAxis() const { return mAxis; }
// Advances our position across the start edge of the given margin, in the
// axis we're tracking.
void EnterMargin(const nsMargin& aMargin)
{
Side side = kAxisOrientationToSidesMap[mAxis][eAxisEdge_Start];
mPosition += MarginComponentForSide(aMargin, side);
}
// Advances our position across the end edge of the given margin, in the axis
// we're tracking.
void ExitMargin(const nsMargin& aMargin)
{
Side side = kAxisOrientationToSidesMap[mAxis][eAxisEdge_End];
mPosition += MarginComponentForSide(aMargin, side);
}
// Advances our current position from the start side of a child frame's
// border-box to the frame's upper or left edge (depending on our axis).
// (Note that this is a no-op if our axis grows in positive direction.)
void EnterChildFrame(nscoord aChildFrameSize)
{
if (!AxisGrowsInPositiveDirection(mAxis))
mPosition += aChildFrameSize;
}
// Advances our current position from a frame's upper or left border-box edge
// (whichever is in the axis we're tracking) to the 'end' side of the frame
// in the axis that we're tracking. (Note that this is a no-op if our axis
// grows in the negative direction.)
void ExitChildFrame(nscoord aChildFrameSize)
{
if (AxisGrowsInPositiveDirection(mAxis))
mPosition += aChildFrameSize;
}
protected:
// Protected constructor, to be sure we're only instantiated via a subclass.
PositionTracker(AxisOrientationType aAxis)
: mPosition(0),
mAxis(aAxis)
{}
private:
// Private copy-constructor, since we don't want any instances of our
// subclasses to be accidentally copied.
PositionTracker(const PositionTracker& aOther)
: mPosition(aOther.mPosition),
mAxis(aOther.mAxis)
{}
protected:
// Member data:
nscoord mPosition; // The position we're tracking
const AxisOrientationType mAxis; // The axis along which we're moving
};
// Tracks our position in the main axis, when we're laying out flex items.
NS_STACK_CLASS
class MainAxisPositionTracker : public PositionTracker {
public:
MainAxisPositionTracker(nsFlexContainerFrame* aFlexContainerFrame,
const FlexboxAxisTracker& aAxisTracker,
const nsHTMLReflowState& aReflowState,
const nsTArray<FlexItem>& aItems);
~MainAxisPositionTracker() {
MOZ_ASSERT(mNumPackingSpacesRemaining == 0,
"miscounted the number of packing spaces");
MOZ_ASSERT(mNumAutoMarginsInMainAxis == 0,
"miscounted the number of auto margins");
}
// Advances past the packing space (if any) between two flex items
void TraversePackingSpace();
// If aItem has any 'auto' margins in the main axis, this method updates the
// corresponding values in its margin.
void ResolveAutoMarginsInMainAxis(FlexItem& aItem);
private:
nscoord mPackingSpaceRemaining;
uint32_t mNumAutoMarginsInMainAxis;
uint32_t mNumPackingSpacesRemaining;
uint8_t mJustifyContent;
};
// Utility class for managing our position along the cross axis along
// the whole flex container (at a higher level than a single line)
class SingleLineCrossAxisPositionTracker;
NS_STACK_CLASS
class CrossAxisPositionTracker : public PositionTracker {
public:
CrossAxisPositionTracker(nsFlexContainerFrame* aFlexContainerFrame,
const FlexboxAxisTracker& aAxisTracker,
const nsHTMLReflowState& aReflowState);
// XXXdholbert This probably needs a ResolveStretchedLines() method,
// (which takes an array of SingleLineCrossAxisPositionTracker objects
// and distributes an equal amount of space to each one).
// For now, we just have Reflow directly call
// SingleLineCrossAxisPositionTracker::SetLineCrossSize().
};
// Utility class for managing our position along the cross axis, *within* a
// single flex line.
NS_STACK_CLASS
class SingleLineCrossAxisPositionTracker : public PositionTracker {
public:
SingleLineCrossAxisPositionTracker(nsFlexContainerFrame* aFlexContainerFrame,
const FlexboxAxisTracker& aAxisTracker,
const nsTArray<FlexItem>& aItems);
void ComputeLineCrossSize(const nsTArray<FlexItem>& aItems);
inline nscoord GetLineCrossSize() const { return mLineCrossSize; }
// Used to override the flex line's size, for cases when the flex container is
// single-line and has a fixed size, and also in cases where
// "align-self: stretch" triggers some space-distribution between lines
// (when we support that property).
inline void SetLineCrossSize(nscoord aNewLineCrossSize) {
mLineCrossSize = aNewLineCrossSize;
}
void ResolveStretchedCrossSize(FlexItem& aItem);
void ResolveAutoMarginsInCrossAxis(FlexItem& aItem);
void EnterAlignPackingSpace(const FlexItem& aItem);
// Resets our position to the cross-start edge of this line.
inline void ResetPosition() { mPosition = 0; }
private:
// Returns the distance from the cross-start side of the given flex item's
// margin-box to its baseline. (Used in baseline alignment.)
nscoord GetBaselineOffsetFromCrossStart(const FlexItem& aItem) const;
nscoord mLineCrossSize;
// Largest distance from an item's cross-start margin-box edge to its
// baseline. Computed in ComputeLineCrossSize, and used for alignment of any
// "align-self: baseline" items in this line (and possibly used for computing
// the baseline of the flex container, as well).
nscoord mCrossStartToFurthestBaseline;
};
//----------------------------------------------------------------------
// Frame class boilerplate
// =======================
NS_QUERYFRAME_HEAD(nsFlexContainerFrame)
NS_QUERYFRAME_ENTRY(nsFlexContainerFrame)
NS_QUERYFRAME_TAIL_INHERITING(nsFlexContainerFrameSuper)
NS_IMPL_FRAMEARENA_HELPERS(nsFlexContainerFrame)
nsIFrame*
NS_NewFlexContainerFrame(nsIPresShell* aPresShell,
nsStyleContext* aContext)
{
return new (aPresShell) nsFlexContainerFrame(aContext);
}
//----------------------------------------------------------------------
// nsFlexContainerFrame Method Implementations
// ===========================================
/* virtual */
nsFlexContainerFrame::~nsFlexContainerFrame()
{
}
/* virtual */
void
nsFlexContainerFrame::DestroyFrom(nsIFrame* aDestructRoot)
{
DestroyAbsoluteFrames(aDestructRoot);
nsFlexContainerFrameSuper::DestroyFrom(aDestructRoot);
}
/* virtual */
nsIAtom*
nsFlexContainerFrame::GetType() const
{
return nsGkAtoms::flexContainerFrame;
}
#ifdef DEBUG
NS_IMETHODIMP
nsFlexContainerFrame::GetFrameName(nsAString& aResult) const
{
return MakeFrameName(NS_LITERAL_STRING("FlexContainer"), aResult);
}
#endif // DEBUG
NS_IMETHODIMP
nsFlexContainerFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
const nsRect& aDirtyRect,
const nsDisplayListSet& aLists)
{
nsresult rv = DisplayBorderBackgroundOutline(aBuilder, aLists);
NS_ENSURE_SUCCESS(rv, rv);
for (nsFrameList::Enumerator e(mFrames); !e.AtEnd(); e.Next()) {
rv = BuildDisplayListForChild(aBuilder, e.get(), aDirtyRect, aLists);
NS_ENSURE_SUCCESS(rv, rv);
}
return NS_OK;
}
#ifdef DEBUG
// helper for the debugging method below
bool
FrameWantsToBeInAnonymousFlexItem(nsIFrame* aFrame)
{
// Note: This needs to match the logic in
// nsCSSFrameConstructor::FrameConstructionItem::NeedsAnonFlexItem()
return (aFrame->IsFrameOfType(nsIFrame::eLineParticipant) ||
nsGkAtoms::placeholderFrame == aFrame->GetType());
}
// Debugging method, to let us assert that our anonymous flex items are
// set up correctly -- in particular, we assert:
// (1) we don't have any inline non-replaced children
// (2) we don't have any consecutive anonymous flex items
// (3) we don't have any empty anonymous flex items
//
// XXXdholbert This matches what nsCSSFrameConstructor currently does, and what
// the spec used to say. However, the spec has now changed regarding what
// types of content get wrapped in an anonymous flexbox item. The patch that
// implements those changes (in nsCSSFrameConstructor) will need to change
// this method as well.
void
nsFlexContainerFrame::SanityCheckAnonymousFlexItems() const
{
bool prevChildWasAnonFlexItem = false;
for (nsIFrame* child = mFrames.FirstChild(); child;
child = child->GetNextSibling()) {
MOZ_ASSERT(!FrameWantsToBeInAnonymousFlexItem(child),
"frame wants to be inside an anonymous flex item, "
"but it isn't");
if (child->GetStyleContext()->GetPseudo() ==
nsCSSAnonBoxes::anonymousFlexItem) {
MOZ_ASSERT(!prevChildWasAnonFlexItem,
"two anon flex items in a row (shouldn't happen)");
nsIFrame* firstWrappedChild = child->GetFirstPrincipalChild();
MOZ_ASSERT(firstWrappedChild,
"anonymous flex item is empty (shouldn't happen)");
prevChildWasAnonFlexItem = true;
} else {
prevChildWasAnonFlexItem = false;
}
}
}
#endif // DEBUG
// Based on the sign of aTotalViolation, this function freezes a subset of our
// flexible sizes, and restores the remaining ones to their initial pref sizes.
static void
FreezeOrRestoreEachFlexibleSize(
const nscoord aTotalViolation,
nsTArray<FlexItem>& aItems)
{
enum FreezeType {
eFreezeEverything,
eFreezeMinViolations,
eFreezeMaxViolations
};
FreezeType freezeType;
if (aTotalViolation == 0) {
freezeType = eFreezeEverything;
} else if (aTotalViolation > 0) {
freezeType = eFreezeMinViolations;
} else { // aTotalViolation < 0
freezeType = eFreezeMaxViolations;
}
for (uint32_t i = 0; i < aItems.Length(); i++) {
FlexItem& item = aItems[i];
MOZ_ASSERT(!item.HadMinViolation() || !item.HadMaxViolation(),
"Can have either min or max violation, but not both");
if (!item.IsFrozen()) {
if (eFreezeEverything == freezeType ||
(eFreezeMinViolations == freezeType && item.HadMinViolation()) ||
(eFreezeMaxViolations == freezeType && item.HadMaxViolation())) {
MOZ_ASSERT(item.GetMainSize() >= item.GetMainMinSize(),
"Freezing item at a size below its minimum");
MOZ_ASSERT(item.GetMainSize() <= item.GetMainMaxSize(),
"Freezing item at a size above its maximum");
item.Freeze();
} // else, we'll reset this item's main size to its flex base size on the
// next iteration of this algorithm.
// Clear this item's violation(s), now that we've dealt with them
item.ClearViolationFlags();
}
}
}
// Implementation of flexbox spec's "Determine sign of flexibility" step.
// NOTE: aTotalFreeSpace should already have the flex items' margin, border,
// & padding values subtracted out.
static bool
ShouldUseFlexGrow(nscoord aTotalFreeSpace,
nsTArray<FlexItem>& aItems)
{
// NOTE: The FlexItem constructor sets its main-size to the
// *hypothetical main size*, which is the flex base size, clamped
// to the min/max range. That's what we want here. Good.
for (uint32_t i = 0; i < aItems.Length(); i++) {
aTotalFreeSpace -= aItems[i].GetMainSize();
if (aTotalFreeSpace <= 0) {
return false;
}
}
MOZ_ASSERT(aTotalFreeSpace > 0,
"if we used up all the space, should've already returned");
return true;
}
// Implementation of flexbox spec's "resolve the flexible lengths" algorithm.
// NOTE: aTotalFreeSpace should already have the flex items' margin, border,
// & padding values subtracted out, so that all we need to do is distribute the
// remaining free space among content-box sizes. (The spec deals with
// margin-box sizes, but we can have fewer values in play & a simpler algorithm
// if we subtract margin/border/padding up front.)
void
nsFlexContainerFrame::ResolveFlexibleLengths(
const FlexboxAxisTracker& aAxisTracker,
nscoord aFlexContainerMainSize,
nsTArray<FlexItem>& aItems)
{
PR_LOG(nsFlexContainerFrameLM, PR_LOG_DEBUG, ("ResolveFlexibleLengths\n"));
if (aItems.IsEmpty()) {
return;
}
// Subtract space occupied by our items' margins/borders/padding, so we can
// just be dealing with the space available for our flex items' content
// boxes.
nscoord spaceAvailableForFlexItemsContentBoxes = aFlexContainerMainSize;
for (uint32_t i = 0; i < aItems.Length(); i++) {
spaceAvailableForFlexItemsContentBoxes -=
aItems[i].GetMarginBorderPaddingSizeInAxis(aAxisTracker.GetMainAxis());
}
// Determine whether we're going to be growing or shrinking items.
bool havePositiveFreeSpace =
ShouldUseFlexGrow(spaceAvailableForFlexItemsContentBoxes, aItems);
// NOTE: I claim that this chunk of the algorithm (the looping part) needs to
// run the loop at MOST aItems.Length() times. This claim should hold up
// because we'll freeze at least one item on each loop iteration, and once
// we've run out of items to freeze, there's nothing left to do. However,
// in most cases, we'll break out of this loop long before we hit that many
// iterations.
for (uint32_t iterationCounter = 0;
iterationCounter < aItems.Length(); iterationCounter++) {
// Set every not-yet-frozen item's used main size to its
// flex base size, and subtract all the used main sizes from our
// total amount of space to determine the 'available free space'
// (positive or negative) to be distributed among our flexible items.
nscoord availableFreeSpace = spaceAvailableForFlexItemsContentBoxes;
for (uint32_t i = 0; i < aItems.Length(); i++) {
FlexItem& item = aItems[i];
if (!item.IsFrozen()) {
item.SetMainSize(item.GetFlexBaseSize());
}
availableFreeSpace -= item.GetMainSize();
}
PR_LOG(nsFlexContainerFrameLM, PR_LOG_DEBUG,
(" available free space = %d\n", availableFreeSpace));
// If sign of free space matches flexType, give each flexible
// item a portion of availableFreeSpace.
if ((availableFreeSpace > 0 && havePositiveFreeSpace) ||
(availableFreeSpace < 0 && !havePositiveFreeSpace)) {
// STRATEGY: On each item, we compute & store its "share" of the total
// flex weight that we've seen so far:
// curFlexWeight / runningFlexWeightSum
//
// Then, when we go to actually distribute the space (in the next loop),
// we can simply walk backwards through the elements and give each item
// its "share" multiplied by the remaining available space.
//
// SPECIAL CASE: If the sum of the flex weights is larger than the
// maximum representable float (overflowing to infinity), then we can't
// sensibly divide out proportional shares anymore. In that case, we
// simply treat the flex item(s) with the largest flex weights as if
// their weights were infinite (dwarfing all the others), and we
// distribute all of the available space among them.
float runningFlexWeightSum = 0.0f;
float largestFlexWeight = 0.0f;
uint32_t numItemsWithLargestFlexWeight = 0;
for (uint32_t i = 0; i < aItems.Length(); i++) {
FlexItem& item = aItems[i];
float curFlexWeight = item.GetFlexWeightToUse(havePositiveFreeSpace);
MOZ_ASSERT(curFlexWeight >= 0.0f, "weights are non-negative");
runningFlexWeightSum += curFlexWeight;
if (NS_finite(runningFlexWeightSum)) {
if (curFlexWeight == 0.0f) {
item.SetShareOfFlexWeightSoFar(0.0f);
} else {
item.SetShareOfFlexWeightSoFar(curFlexWeight /
runningFlexWeightSum);
}
} // else, the sum of weights overflows to infinity, in which
// case we don't bother with "SetShareOfFlexWeightSoFar" since
// we know we won't use it. (instead, we'll just give every
// item with the largest flex weight an equal share of space.)
// Update our largest-flex-weight tracking vars
if (curFlexWeight > largestFlexWeight) {
largestFlexWeight = curFlexWeight;
numItemsWithLargestFlexWeight = 1;
} else if (curFlexWeight == largestFlexWeight) {
numItemsWithLargestFlexWeight++;
}
}
if (runningFlexWeightSum != 0.0f) { // no distribution if no flexibility
PR_LOG(nsFlexContainerFrameLM, PR_LOG_DEBUG,
(" Distributing available space:"));
for (uint32_t i = aItems.Length() - 1; i < aItems.Length(); --i) {
FlexItem& item = aItems[i];
if (!item.IsFrozen()) {
// To avoid rounding issues, we compute the change in size for this
// item, and then subtract it from the remaining available space.
nscoord sizeDelta = 0;
if (NS_finite(runningFlexWeightSum)) {
float myShareOfRemainingSpace =
item.GetShareOfFlexWeightSoFar();
MOZ_ASSERT(myShareOfRemainingSpace >= 0.0f &&
myShareOfRemainingSpace <= 1.0f,
"my share should be nonnegative fractional amount");
if (myShareOfRemainingSpace == 1.0f) {
// (We special-case 1.0f to avoid float error from converting
// availableFreeSpace from integer*1.0f --> float --> integer)
sizeDelta = availableFreeSpace;
} else if (myShareOfRemainingSpace > 0.0f) {
sizeDelta = NSToCoordRound(availableFreeSpace *
myShareOfRemainingSpace);
}
} else if (item.GetFlexWeightToUse(havePositiveFreeSpace) ==
largestFlexWeight) {
// Total flexibility is infinite, so we're just distributing
// the available space equally among the items that are tied for
// having the largest weight (and this is one of those items).
sizeDelta =
NSToCoordRound(availableFreeSpace /
float(numItemsWithLargestFlexWeight));
numItemsWithLargestFlexWeight--;
}
availableFreeSpace -= sizeDelta;
item.SetMainSize(item.GetMainSize() + sizeDelta);
PR_LOG(nsFlexContainerFrameLM, PR_LOG_DEBUG,
(" child %d receives %d, for a total of %d\n",
i, sizeDelta, item.GetMainSize()));
}
}
}
}
// Fix min/max violations:
nscoord totalViolation = 0; // keeps track of adjustments for min/max
PR_LOG(nsFlexContainerFrameLM, PR_LOG_DEBUG,
(" Checking for violations:"));
for (uint32_t i = 0; i < aItems.Length(); i++) {
FlexItem& item = aItems[i];
if (!item.IsFrozen()) {
if (item.GetMainSize() < item.GetMainMinSize()) {
// min violation
totalViolation += item.GetMainMinSize() - item.GetMainSize();
item.SetMainSize(item.GetMainMinSize());
item.SetHadMinViolation();
} else if (item.GetMainSize() > item.GetMainMaxSize()) {
// max violation
totalViolation += item.GetMainMaxSize() - item.GetMainSize();
item.SetMainSize(item.GetMainMaxSize());
item.SetHadMaxViolation();
}
}
}
FreezeOrRestoreEachFlexibleSize(totalViolation, aItems);
PR_LOG(nsFlexContainerFrameLM, PR_LOG_DEBUG,
(" Total violation: %d\n", totalViolation));
if (totalViolation == 0) {
break;
}
}
// Post-condition: all lengths should've been frozen.
#ifdef DEBUG
for (uint32_t i = 0; i < aItems.Length(); ++i) {
MOZ_ASSERT(aItems[i].IsFrozen(),
"All flexible lengths should've been resolved");
}
#endif // DEBUG
}
const nsTArray<SortableFrame>
BuildSortedChildArray(const nsFrameList& aChildren)
{
// NOTE: To benefit from Return Value Optimization, we must only return
// this value:
nsTArray<SortableFrame> sortedChildArray(aChildren.GetLength());
// Throw all our children in the array...
uint32_t indexInFrameList = 0;
for (nsFrameList::Enumerator e(aChildren); !e.AtEnd(); e.Next()) {
int32_t orderValue = e.get()->GetStylePosition()->mOrder;
sortedChildArray.AppendElement(SortableFrame(e.get(), orderValue,
indexInFrameList));
indexInFrameList++;
}
// ... and sort (by 'order' property)
sortedChildArray.Sort();
return sortedChildArray;
}
MainAxisPositionTracker::
MainAxisPositionTracker(nsFlexContainerFrame* aFlexContainerFrame,
const FlexboxAxisTracker& aAxisTracker,
const nsHTMLReflowState& aReflowState,
const nsTArray<FlexItem>& aItems)
: PositionTracker(aAxisTracker.GetMainAxis()),
mNumAutoMarginsInMainAxis(0),
mNumPackingSpacesRemaining(0)
{
MOZ_ASSERT(aReflowState.frame == aFlexContainerFrame,
"Expecting the reflow state for the flex container frame");
// Step over flex container's own main-start border/padding.
// XXXdholbert Check GetSkipSides() here when we support pagination.
EnterMargin(aReflowState.mComputedBorderPadding);
// Set up our state for managing packing space & auto margins.
// * If our main-size is unconstrained, then we just shrinkwrap our
// contents, and we don't have any packing space.
// * Otherwise, we subtract our items' margin-box main-sizes from our
// computed main-size to get our available packing space.
mPackingSpaceRemaining =
aAxisTracker.GetMainComponent(nsSize(aReflowState.ComputedWidth(),
aReflowState.ComputedHeight()));
if (mPackingSpaceRemaining == NS_UNCONSTRAINEDSIZE) {
mPackingSpaceRemaining = 0;
} else {
for (uint32_t i = 0; i < aItems.Length(); i++) {
nscoord itemMarginBoxMainSize =
aItems[i].GetMainSize() +
aItems[i].GetMarginBorderPaddingSizeInAxis(aAxisTracker.GetMainAxis());
mPackingSpaceRemaining -= itemMarginBoxMainSize;
}
}
if (mPackingSpaceRemaining > 0) {
for (uint32_t i = 0; i < aItems.Length(); i++) {
mNumAutoMarginsInMainAxis += aItems[i].GetNumAutoMarginsInAxis(mAxis);
}
}
mJustifyContent = aFlexContainerFrame->GetStylePosition()->mJustifyContent;
// If packing space is negative, 'justify' behaves like 'start', and
// 'distribute' behaves like 'center'. In those cases, it's simplest to
// just pretend we have a different 'justify-content' value and share code.
if (mPackingSpaceRemaining < 0) {
if (mJustifyContent == NS_STYLE_JUSTIFY_CONTENT_SPACE_BETWEEN) {
mJustifyContent = NS_STYLE_JUSTIFY_CONTENT_FLEX_START;
} else if (mJustifyContent == NS_STYLE_JUSTIFY_CONTENT_SPACE_AROUND) {
mJustifyContent = NS_STYLE_JUSTIFY_CONTENT_CENTER;
}
}
// Figure out how much space we'll set aside for auto margins or
// packing spaces, and advance past any leading packing-space.
if (mNumAutoMarginsInMainAxis == 0 &&
mPackingSpaceRemaining != 0 &&
!aItems.IsEmpty()) {
switch (mJustifyContent) {
case NS_STYLE_JUSTIFY_CONTENT_FLEX_START:
// All packing space should go at the end --> nothing to do here.
break;
case NS_STYLE_JUSTIFY_CONTENT_FLEX_END:
// All packing space goes at the beginning
mPosition += mPackingSpaceRemaining;
break;
case NS_STYLE_JUSTIFY_CONTENT_CENTER:
// Half the packing space goes at the beginning
mPosition += mPackingSpaceRemaining / 2;
break;
case NS_STYLE_JUSTIFY_CONTENT_SPACE_BETWEEN:
MOZ_ASSERT(mPackingSpaceRemaining >= 0,
"negative packing space should make us use 'flex-start' "
"instead of 'space-between'");
// 1 packing space between each flex item, no packing space at ends.
mNumPackingSpacesRemaining = aItems.Length() - 1;
break;
case NS_STYLE_JUSTIFY_CONTENT_SPACE_AROUND:
MOZ_ASSERT(mPackingSpaceRemaining >= 0,
"negative packing space should make us use 'center' "
"instead of 'space-around'");
// 1 packing space between each flex item, plus half a packing space
// at beginning & end. So our number of full packing-spaces is equal
// to the number of flex items.
mNumPackingSpacesRemaining = aItems.Length();
if (mNumPackingSpacesRemaining > 0) {
// The edges (start/end) share one full packing space
nscoord totalEdgePackingSpace =
mPackingSpaceRemaining / mNumPackingSpacesRemaining;
// ...and we'll use half of that right now, at the start
mPosition += totalEdgePackingSpace / 2;
// ...but we need to subtract all of it right away, so that we won't
// hand out any of it to intermediate packing spaces.
mPackingSpaceRemaining -= totalEdgePackingSpace;
mNumPackingSpacesRemaining--;
}
break;
default:
MOZ_NOT_REACHED("Unexpected justify-content value");
}
}
MOZ_ASSERT(mNumPackingSpacesRemaining == 0 ||
mNumAutoMarginsInMainAxis == 0,
"extra space should either go to packing space or to "
"auto margins, but not to both");
}
void
MainAxisPositionTracker::ResolveAutoMarginsInMainAxis(FlexItem& aItem)
{
if (mNumAutoMarginsInMainAxis) {
const nsStyleSides& styleMargin = aItem.Frame()->GetStyleMargin()->mMargin;
for (uint32_t i = 0; i < eNumAxisEdges; i++) {
Side side = kAxisOrientationToSidesMap[mAxis][i];
if (styleMargin.GetUnit(side) == eStyleUnit_Auto) {
// NOTE: This integer math will skew the distribution of remainder
// app-units towards the end, which is fine.
nscoord curAutoMarginSize =
mPackingSpaceRemaining / mNumAutoMarginsInMainAxis;
MOZ_ASSERT(aItem.GetMarginComponentForSide(side) == 0,
"Expecting auto margins to have value '0' before we "
"resolve them");
aItem.SetMarginComponentForSide(side, curAutoMarginSize);
mNumAutoMarginsInMainAxis--;
mPackingSpaceRemaining -= curAutoMarginSize;
}
}
}
}
void
MainAxisPositionTracker::TraversePackingSpace()
{
if (mNumPackingSpacesRemaining) {
MOZ_ASSERT(mJustifyContent == NS_STYLE_JUSTIFY_CONTENT_SPACE_BETWEEN ||
mJustifyContent == NS_STYLE_JUSTIFY_CONTENT_SPACE_AROUND,
"mNumPackingSpacesRemaining only applies for "
"space-between/space-around");
MOZ_ASSERT(mPackingSpaceRemaining >= 0,
"ran out of packing space earlier than we expected");
// NOTE: This integer math will skew the distribution of remainder
// app-units towards the end, which is fine.
nscoord curPackingSpace =
mPackingSpaceRemaining / mNumPackingSpacesRemaining;
mPosition += curPackingSpace;
mNumPackingSpacesRemaining--;
mPackingSpaceRemaining -= curPackingSpace;
}
}
CrossAxisPositionTracker::
CrossAxisPositionTracker(nsFlexContainerFrame* aFlexContainerFrame,
const FlexboxAxisTracker& aAxisTracker,
const nsHTMLReflowState& aReflowState)
: PositionTracker(aAxisTracker.GetCrossAxis())
{
// Step over flex container's cross-start border/padding.
EnterMargin(aReflowState.mComputedBorderPadding);
}
SingleLineCrossAxisPositionTracker::
SingleLineCrossAxisPositionTracker(nsFlexContainerFrame* aFlexContainerFrame,
const FlexboxAxisTracker& aAxisTracker,
const nsTArray<FlexItem>& aItems)
: PositionTracker(aAxisTracker.GetCrossAxis()),
mLineCrossSize(0),
mCrossStartToFurthestBaseline(nscoord_MIN) // Starts at -infinity, and then
// we progressively increase it.
{
}
void
SingleLineCrossAxisPositionTracker::
ComputeLineCrossSize(const nsTArray<FlexItem>& aItems)
{
// NOTE: mCrossStartToFurthestBaseline is a member var rather than a local
// var, because we'll need it when we're baseline-aligning our children, and
// we'd prefer to not have to recompute it.
MOZ_ASSERT(mCrossStartToFurthestBaseline == nscoord_MIN,
"Computing largest baseline offset more than once");
nscoord crossEndToFurthestBaseline = nscoord_MIN;
nscoord largestOuterCrossSize = 0;
for (uint32_t i = 0; i < aItems.Length(); ++i) {
const FlexItem& curItem = aItems[i];
nscoord curOuterCrossSize = curItem.GetCrossSize() +
curItem.GetMarginBorderPaddingSizeInAxis(mAxis);
if (curItem.GetAlignSelf() == NS_STYLE_ALIGN_ITEMS_BASELINE &&
curItem.GetNumAutoMarginsInAxis(mAxis) == 0) {
// FIXME: Once we support multi-line flexbox with "wrap-reverse", that'll
// give us bottom-to-top cross axes. (But for now, we assume eAxis_TB.)
// FIXME: Once we support "writing-mode", we'll have to do baseline
// alignment in vertical flex containers here (w/ horizontal cross-axes).
MOZ_ASSERT(mAxis == eAxis_TB,
"Only expecting to do baseline-alignment in horizontal "
"flex containers, with top-to-bottom cross axis");
// Find distance from our item's cross-start and cross-end margin-box
// edges to its baseline.
//
// Here's a diagram of a flex-item that we might be doing this on.
// "mmm" is the margin-box, "bbb" is the border-box. The bottom of
// the text "BASE" is the baseline.
//
// ---(cross-start)---
// ___ ___ ___
// mmmmmmmmmmmm | |margin-start |
// m m | _|_ ___ |
// m bbbbbbbb m |curOuterCrossSize | |crossStartToBaseline
// m b b m | |ascent |
// m b BASE b m | _|_ _|_
// m b b m | |
// m bbbbbbbb m | |crossEndToBaseline
// m m | |
// mmmmmmmmmmmm _|_ _|_
//
// ---(cross-end)---
//
// We already have the curOuterCrossSize, margin-start, and the ascent.
// * We can get crossStartToBaseline by adding margin-start + ascent.
// * If we subtract that from the curOuterCrossSize, we get
// crossEndToBaseline.
nscoord crossStartToBaseline = GetBaselineOffsetFromCrossStart(curItem);
nscoord crossEndToBaseline = curOuterCrossSize - crossStartToBaseline;
// Now, update our "largest" values for these (across all the flex items
// in this flex line), so we can use them in computing mLineCrossSize
// below:
mCrossStartToFurthestBaseline = NS_MAX(mCrossStartToFurthestBaseline,
crossStartToBaseline);
crossEndToFurthestBaseline = NS_MAX(crossEndToFurthestBaseline,
crossEndToBaseline);
} else {
largestOuterCrossSize = NS_MAX(largestOuterCrossSize, curOuterCrossSize);
}
}
// The line's cross-size is the larger of:
// (a) [largest cross-start-to-baseline + largest baseline-to-cross-end] of
// all baseline-aligned items with no cross-axis auto margins...
// and
// (b) largest cross-size of all other children.
mLineCrossSize = NS_MAX(mCrossStartToFurthestBaseline +
crossEndToFurthestBaseline,
largestOuterCrossSize);
}
nscoord
SingleLineCrossAxisPositionTracker::
GetBaselineOffsetFromCrossStart(const FlexItem& aItem) const
{
Side crossStartSide = kAxisOrientationToSidesMap[mAxis][eAxisEdge_Start];
// XXXdholbert This assumes cross axis is Top-To-Bottom.
// For bottom-to-top support, probably want to make this depend on
// AxisGrowsInPositiveDirection(mAxis)
return aItem.GetAscent() + aItem.GetMarginComponentForSide(crossStartSide);
}
void
SingleLineCrossAxisPositionTracker::
ResolveStretchedCrossSize(FlexItem& aItem)
{
// We stretch IFF we are align-self:stretch, have no auto margins in
// cross axis, and have cross-axis size property == "auto". If any of those
// conditions don't hold up, we can just return.
if (aItem.GetAlignSelf() != NS_STYLE_ALIGN_ITEMS_STRETCH ||
aItem.GetNumAutoMarginsInAxis(mAxis) != 0 ||
GetSizePropertyForAxis(aItem.Frame(), mAxis).GetUnit() !=
eStyleUnit_Auto) {
return;
}
// Reserve space for margins & border & padding, and then use whatever
// remains as our item's cross-size (clamped to its min/max range).
nscoord stretchedSize = mLineCrossSize -
aItem.GetMarginBorderPaddingSizeInAxis(mAxis);
stretchedSize = NS_CSS_MINMAX(stretchedSize,
aItem.GetCrossMinSize(),
aItem.GetCrossMaxSize());
// Update the cross-size & make a note that it's stretched, so we know to
// override the reflow state's computed cross-size in our final reflow.
aItem.SetCrossSize(stretchedSize);
aItem.SetIsStretched();
}
void
SingleLineCrossAxisPositionTracker::
ResolveAutoMarginsInCrossAxis(FlexItem& aItem)
{
// Subtract the space that our item is already occupying, to see how much
// space (if any) is available for its auto margins.
nscoord spaceForAutoMargins = mLineCrossSize -
(aItem.GetCrossSize() + aItem.GetMarginBorderPaddingSizeInAxis(mAxis));
if (spaceForAutoMargins <= 0) {
return; // No available space --> nothing to do
}
uint32_t numAutoMargins = aItem.GetNumAutoMarginsInAxis(mAxis);
if (numAutoMargins == 0) {
return; // No auto margins --> nothing to do.
}
// OK, we have at least one auto margin and we have some available space.
// Give each auto margin a share of the space.
const nsStyleSides& styleMargin = aItem.Frame()->GetStyleMargin()->mMargin;
for (uint32_t i = 0; i < eNumAxisEdges; i++) {
Side side = kAxisOrientationToSidesMap[mAxis][i];
if (styleMargin.GetUnit(side) == eStyleUnit_Auto) {
MOZ_ASSERT(aItem.GetMarginComponentForSide(side) == 0,
"Expecting auto margins to have value '0' before we "
"update them");
// NOTE: integer divison is fine here; numAutoMargins is either 1 or 2.
// If it's 2 & spaceForAutoMargins is odd, 1st margin gets smaller half.
nscoord curAutoMarginSize = spaceForAutoMargins / numAutoMargins;
aItem.SetMarginComponentForSide(side, curAutoMarginSize);
numAutoMargins--;
spaceForAutoMargins -= curAutoMarginSize;
}
}
}
void
SingleLineCrossAxisPositionTracker::
EnterAlignPackingSpace(const FlexItem& aItem)
{
// We don't do align-self alignment on items that have auto margins
// in the cross axis.
if (aItem.GetNumAutoMarginsInAxis(mAxis)) {
return;
}
switch (aItem.GetAlignSelf()) {
case NS_STYLE_ALIGN_ITEMS_FLEX_START:
case NS_STYLE_ALIGN_ITEMS_STRETCH:
// No space to skip over -- we're done.
// NOTE: 'stretch' behaves like 'start' once we've stretched any
// auto-sized items (which we've already done).
break;
case NS_STYLE_ALIGN_ITEMS_FLEX_END:
mPosition +=
mLineCrossSize -
(aItem.GetCrossSize() +
aItem.GetMarginBorderPaddingSizeInAxis(mAxis));
break;
case NS_STYLE_ALIGN_ITEMS_CENTER:
// Note: If cross-size is odd, the "after" space will get the extra unit.
mPosition +=
(mLineCrossSize -
(aItem.GetCrossSize() +
aItem.GetMarginBorderPaddingSizeInAxis(mAxis))) / 2;
break;
case NS_STYLE_ALIGN_ITEMS_BASELINE:
MOZ_ASSERT(mCrossStartToFurthestBaseline != nscoord_MIN,
"using uninitialized baseline offset");
MOZ_ASSERT(mCrossStartToFurthestBaseline >=
GetBaselineOffsetFromCrossStart(aItem),
"failed at finding largest ascent");
// Advance so that aItem's baseline is aligned with
// largest baseline offset.
mPosition += (mCrossStartToFurthestBaseline -
GetBaselineOffsetFromCrossStart(aItem));
break;
default:
NS_NOTREACHED("Unexpected align-self value");
break;
}
}
FlexboxAxisTracker::FlexboxAxisTracker(nsFlexContainerFrame* aFlexContainerFrame)
{
uint32_t flexDirection =
aFlexContainerFrame->GetStylePosition()->mFlexDirection;
uint32_t cssDirection =
aFlexContainerFrame->GetStyleVisibility()->mDirection;
MOZ_ASSERT(cssDirection == NS_STYLE_DIRECTION_LTR ||
cssDirection == NS_STYLE_DIRECTION_RTL,
"Unexpected computed value for 'direction' property");
// (Not asserting for flexDirection here; it's checked by the switch below.)
// These are defined according to writing-modes' definitions of
// start/end (for the inline dimension) and before/after (for the block
// dimension), here:
// http://www.w3.org/TR/css3-writing-modes/#logical-directions
// (NOTE: I'm intentionally not calling this "inlineAxis"/"blockAxis", since
// those terms have explicit definition in the writing-modes spec, which are
// the opposite of how I'd be using them here.)
// XXXdholbert Once we support the 'writing-mode' property, use its value
// here to further customize inlineDimension & blockDimension.
// Inline dimension ("start-to-end"):
AxisOrientationType inlineDimension =
cssDirection == NS_STYLE_DIRECTION_RTL ? eAxis_RL : eAxis_LR;
// Block dimension ("before-to-after"):
AxisOrientationType blockDimension = eAxis_TB;
// Determine main axis:
switch (flexDirection) {
case NS_STYLE_FLEX_DIRECTION_ROW:
mMainAxis = inlineDimension;
break;
case NS_STYLE_FLEX_DIRECTION_ROW_REVERSE:
mMainAxis = GetReverseAxis(inlineDimension);
break;
case NS_STYLE_FLEX_DIRECTION_COLUMN:
mMainAxis = blockDimension;
break;
case NS_STYLE_FLEX_DIRECTION_COLUMN_REVERSE:
mMainAxis = GetReverseAxis(blockDimension);
break;
default:
MOZ_NOT_REACHED("Unexpected computed value for 'flex-flow' property");
mMainAxis = inlineDimension;
break;
}
// Determine cross axis:
// (This is set up so that a bogus |flexDirection| value will
// give us blockDimension.
if (flexDirection == NS_STYLE_FLEX_DIRECTION_COLUMN ||
flexDirection == NS_STYLE_FLEX_DIRECTION_COLUMN_REVERSE) {
mCrossAxis = inlineDimension;
} else {
mCrossAxis = blockDimension;
}
// FIXME: Once we support "flex-wrap", check if it's "wrap-reverse"
// here to determine whether we should reverse mCrossAxis.
MOZ_ASSERT(IsAxisHorizontal(mMainAxis) != IsAxisHorizontal(mCrossAxis),
"main & cross axes should be in different dimensions");
// NOTE: Right now, cross axis is never bottom-to-top.
// The only way for it to be different would be if we used a vertical
// "writing-mode" or if we had "flex-wrap: wrap-reverse" -- but we don't
// support either of those yet, so that can't happen right now.
// (When we add support for either of those properties, this assert will
// no longer hold.)
MOZ_ASSERT(mCrossAxis != eAxis_BT, "Not expecting bottom-to-top cross axis");
}
nsresult
nsFlexContainerFrame::GenerateFlexItems(
nsPresContext* aPresContext,
const nsHTMLReflowState& aReflowState,
const FlexboxAxisTracker& aAxisTracker,
nsTArray<FlexItem>& aFlexItems)
{
MOZ_ASSERT(aFlexItems.IsEmpty(), "Expecting outparam to start out empty");
// Sort by 'order' property:
const nsTArray<SortableFrame> sortedChildren = BuildSortedChildArray(mFrames);
// Build list of unresolved flex items:
// XXXdholbert When we support multi-line, we might want this to be a linked
// list, so we can easily split into multiple lines.
aFlexItems.SetCapacity(sortedChildren.Length());
for (uint32_t i = 0; i < sortedChildren.Length(); ++i) {
nsresult rv = AppendFlexItemForChild(aPresContext,
sortedChildren[i].Frame(),
aReflowState, aAxisTracker,
aFlexItems);
NS_ENSURE_SUCCESS(rv,rv);
}
return NS_OK;
}
// Computes the content-box main-size of our flex container.
nscoord
nsFlexContainerFrame::ComputeFlexContainerMainSize(
const nsHTMLReflowState& aReflowState,
const FlexboxAxisTracker& aAxisTracker,
const nsTArray<FlexItem>& aItems)
{
// If we've got a finite computed main-size, use that.
nscoord mainSize =
aAxisTracker.GetMainComponent(nsSize(aReflowState.ComputedWidth(),
aReflowState.ComputedHeight()));
if (mainSize != NS_UNCONSTRAINEDSIZE) {
return mainSize;
}
MOZ_ASSERT(!IsAxisHorizontal(aAxisTracker.GetMainAxis()),
"Computed width should always be constrained, so horizontal "
"flex containers should always have a constrained main-size");
// Otherwise, use the sum of our items' hypothetical main sizes, clamped
// to our computed min/max main-size properties.
mainSize = 0;
for (uint32_t i = 0; i < aItems.Length(); ++i) {
mainSize +=
aItems[i].GetMainSize() +
aItems[i].GetMarginBorderPaddingSizeInAxis(aAxisTracker.GetMainAxis());
}
nscoord minMainSize =
aAxisTracker.GetMainComponent(nsSize(aReflowState.mComputedMinWidth,
aReflowState.mComputedMinHeight));
nscoord maxMainSize =
aAxisTracker.GetMainComponent(nsSize(aReflowState.mComputedMaxWidth,
aReflowState.mComputedMaxHeight));
return NS_CSS_MINMAX(mainSize, minMainSize, maxMainSize);
}
void
nsFlexContainerFrame::PositionItemInMainAxis(
MainAxisPositionTracker& aMainAxisPosnTracker,
FlexItem& aItem)
{
nscoord itemMainBorderBoxSize =
aItem.GetMainSize() +
aItem.GetBorderPaddingSizeInAxis(aMainAxisPosnTracker.GetAxis());
// Resolve any main-axis 'auto' margins on aChild to an actual value.
aMainAxisPosnTracker.ResolveAutoMarginsInMainAxis(aItem);
// Advance our position tracker to child's upper-left content-box corner,
// and use that as its position in the main axis.
aMainAxisPosnTracker.EnterMargin(aItem.GetMargin());
aMainAxisPosnTracker.EnterChildFrame(itemMainBorderBoxSize);
aItem.SetMainPosition(aMainAxisPosnTracker.GetPosition());
aMainAxisPosnTracker.ExitChildFrame(itemMainBorderBoxSize);
aMainAxisPosnTracker.ExitMargin(aItem.GetMargin());
aMainAxisPosnTracker.TraversePackingSpace();
}
nsresult
nsFlexContainerFrame::SizeItemInCrossAxis(
nsPresContext* aPresContext,
const FlexboxAxisTracker& aAxisTracker,
const nsHTMLReflowState& aChildReflowState,
FlexItem& aItem)
{
// In vertical flexbox (with horizontal cross-axis), we can just trust the
// reflow state's computed-width as our cross-size. We also don't need to
// record the baseline because we'll have converted any "align-self:baseline"
// items to be "align-self:flex-start" in the FlexItem constructor.
// FIXME: Once we support writing-mode (vertical text), we will be able to
// have baseline-aligned items in a vertical flexbox, and we'll need to
// record baseline information here.
if (IsAxisHorizontal(aAxisTracker.GetCrossAxis())) {
MOZ_ASSERT(aItem.GetAlignSelf() != NS_STYLE_ALIGN_ITEMS_BASELINE,
"In vert flex container, we depend on FlexItem constructor to "
"convert 'align-self: baseline' to 'align-self: flex-start'");
aItem.SetCrossSize(aChildReflowState.ComputedWidth());
return NS_OK;
}
nsHTMLReflowMetrics childDesiredSize;
nsReflowStatus childReflowStatus;
nsresult rv = ReflowChild(aItem.Frame(), aPresContext,
childDesiredSize, aChildReflowState,
0, 0, NS_FRAME_NO_MOVE_FRAME,
childReflowStatus);
NS_ENSURE_SUCCESS(rv, rv);
// XXXdholbert Once we do pagination / splitting, we'll need to actually
// handle incomplete childReflowStatuses. But for now, we give our kids
// unconstrained available height, which means they should always complete.
MOZ_ASSERT(NS_FRAME_IS_COMPLETE(childReflowStatus),
"We gave flex item unconstrained available height, so it "
"should be complete");
// Tell the child we're done with its initial reflow.
// (Necessary for e.g. GetBaseline() to work below w/out asserting)
rv = FinishReflowChild(aItem.Frame(), aPresContext,
&aChildReflowState, childDesiredSize, 0, 0, 0);
NS_ENSURE_SUCCESS(rv, rv);
// Save the sizing info that we learned from this reflow
// -----------------------------------------------------
// Tentatively accept the child's desired size, minus border/padding, as its
// cross-size:
MOZ_ASSERT(childDesiredSize.height >=
aItem.GetBorderPaddingSizeInAxis(aAxisTracker.GetCrossAxis()),
"Child should ask for at least enough space for border/padding");
nscoord crossSize =
aAxisTracker.GetCrossComponent(childDesiredSize) -
aItem.GetBorderPaddingSizeInAxis(aAxisTracker.GetCrossAxis());
aItem.SetCrossSize(crossSize);
// If we need to do baseline-alignment, store the child's ascent.
if (aItem.GetAlignSelf() == NS_STYLE_ALIGN_ITEMS_BASELINE) {
if (childDesiredSize.ascent == nsHTMLReflowMetrics::ASK_FOR_BASELINE) {
// Use GetFirstLineBaseline(), or just GetBaseline() if that fails.
if (!nsLayoutUtils::GetFirstLineBaseline(aItem.Frame(),
&childDesiredSize.ascent)) {
childDesiredSize.ascent = aItem.Frame()->GetBaseline();
}
}
aItem.SetAscent(childDesiredSize.ascent);
}
return NS_OK;
}
void
nsFlexContainerFrame::PositionItemInCrossAxis(
nscoord aLineStartPosition,
SingleLineCrossAxisPositionTracker& aLineCrossAxisPosnTracker,
FlexItem& aItem)
{
MOZ_ASSERT(aLineCrossAxisPosnTracker.GetPosition() == 0,
"per-line cross-axis position tracker wasn't correctly reset");
// Resolve any to-be-stretched cross-sizes & auto margins in cross axis.
aLineCrossAxisPosnTracker.ResolveStretchedCrossSize(aItem);
aLineCrossAxisPosnTracker.ResolveAutoMarginsInCrossAxis(aItem);
// Compute the cross-axis position of this item
nscoord itemCrossBorderBoxSize =
aItem.GetCrossSize() +
aItem.GetBorderPaddingSizeInAxis(aLineCrossAxisPosnTracker.GetAxis());
aLineCrossAxisPosnTracker.EnterAlignPackingSpace(aItem);
aLineCrossAxisPosnTracker.EnterMargin(aItem.GetMargin());
aLineCrossAxisPosnTracker.EnterChildFrame(itemCrossBorderBoxSize);
aItem.SetCrossPosition(aLineStartPosition +
aLineCrossAxisPosnTracker.GetPosition());
// Back out to cross-axis edge of the line.
aLineCrossAxisPosnTracker.ResetPosition();
}
NS_IMETHODIMP
nsFlexContainerFrame::Reflow(nsPresContext* aPresContext,
nsHTMLReflowMetrics& aDesiredSize,
const nsHTMLReflowState& aReflowState,
nsReflowStatus& aStatus)
{
DO_GLOBAL_REFLOW_COUNT("nsFlexContainerFrame");
DISPLAY_REFLOW(aPresContext, this, aReflowState, aDesiredSize, aStatus);
PR_LOG(nsFlexContainerFrameLM, PR_LOG_DEBUG,
("Reflow() for nsFlexContainerFrame %p\n", this));
// We (and our children) can only depend on our ancestor's height if we have
// a percent-height. (There are actually other cases, too -- e.g. if our
// parent is itself a vertical flex container and we're flexible -- but we'll
// let our ancestors handle those sorts of cases.)
if (GetStylePosition()->mHeight.HasPercent()) {
AddStateBits(NS_FRAME_CONTAINS_RELATIVE_HEIGHT);
}
#ifdef DEBUG
SanityCheckAnonymousFlexItems();
#endif // DEBUG
// If our subtree is dirty (i.e. some of our descendants have changed), we
// reflow _all_ of our children. We have to do this -- we can't just reflow
// select children, as we would in other frame classes. This is because flex
// items' sizes (in both axes) are highly dependent on their siblings' sizes.
bool shouldReflowChildren =
NS_SUBTREE_DIRTY(this) || aReflowState.ShouldReflowAllKids();
const FlexboxAxisTracker axisTracker(this);
// Generate a list of our flex items (already sorted), and get our main
// size (which may depend on those items).
nsTArray<FlexItem> items;
nsresult rv = GenerateFlexItems(aPresContext, aReflowState,
axisTracker, items);
NS_ENSURE_SUCCESS(rv, rv);
// XXXdholbert FOR MULTI-LINE FLEX CONTAINERS: Do line-breaking here.
// This would produce an array of arrays, or a list of arrays,
// or something like that. (one list/array per line)
nscoord flexContainerMainSize =
ComputeFlexContainerMainSize(aReflowState, axisTracker, items);
ResolveFlexibleLengths(axisTracker, flexContainerMainSize, items);
// Our frame's main-size is the content-box size plus border and padding.
nscoord frameMainSize = flexContainerMainSize +
axisTracker.GetMarginSizeInMainAxis(aReflowState.mComputedBorderPadding);
nscoord frameCrossSize;
if (!shouldReflowChildren) {
// Children don't need reflow --> assume our content-box size is the same
// since our last reflow.
frameCrossSize = mCachedContentBoxCrossSize +
axisTracker.GetMarginSizeInCrossAxis(aReflowState.mComputedBorderPadding);
} else {
MainAxisPositionTracker mainAxisPosnTracker(this, axisTracker,
aReflowState, items);
// First loop: Compute main axis position & cross-axis size of each item
for (uint32_t i = 0; i < items.Length(); ++i) {
FlexItem& curItem = items[i];
nsHTMLReflowState childReflowState(aPresContext, aReflowState,
curItem.Frame(),
nsSize(aReflowState.ComputedWidth(),
NS_UNCONSTRAINEDSIZE));
// Override computed main-size
if (IsAxisHorizontal(axisTracker.GetMainAxis())) {
childReflowState.SetComputedWidth(curItem.GetMainSize());
} else {
childReflowState.SetComputedHeight(curItem.GetMainSize());
}
PositionItemInMainAxis(mainAxisPosnTracker, curItem);
nsresult rv =
SizeItemInCrossAxis(aPresContext, axisTracker,
childReflowState, curItem);
NS_ENSURE_SUCCESS(rv, rv);
}
// SIZE & POSITION THE FLEX LINE (IN CROSS AXIS)
// Set up state for cross-axis alignment, at a high level (outside the
// scope of a particular flex line)
CrossAxisPositionTracker
crossAxisPosnTracker(this, axisTracker, aReflowState);
// Set up state for cross-axis-positioning of children _within_ a single
// flex line.
SingleLineCrossAxisPositionTracker
lineCrossAxisPosnTracker(this, axisTracker, items);
lineCrossAxisPosnTracker.ComputeLineCrossSize(items);
// XXXdholbert Once we've got multi-line flexbox support: here, after we've
// computed the cross size of all lines, we need to check if if
// 'align-content' is 'stretch' -- if it is, we need to give each line an
// additional share of our flex container's desired cross-size. (if it's
// not NS_AUTOHEIGHT and there's any cross-size left over to distribute)
// Figure out our flex container's cross size
mCachedContentBoxCrossSize =
axisTracker.GetCrossComponent(nsSize(aReflowState.ComputedWidth(),
aReflowState.ComputedHeight()));
if (mCachedContentBoxCrossSize == NS_AUTOHEIGHT) {
// unconstrained 'auto' cross-size: shrink-wrap our line(s)
mCachedContentBoxCrossSize =
lineCrossAxisPosnTracker.GetLineCrossSize();
} else {
// XXXdholbert When we support multi-line flex containers, we should
// distribute any extra space among or between our lines here according
// to 'align-content'. For now, we do the single-line special behavior:
// "If the flex container has only a single line (even if it's a
// multi-line flex container), the cross size of the flex line is the
// flex container's inner cross size."
lineCrossAxisPosnTracker.SetLineCrossSize(mCachedContentBoxCrossSize);
}
frameCrossSize = mCachedContentBoxCrossSize +
axisTracker.GetMarginSizeInCrossAxis(aReflowState.mComputedBorderPadding);
// XXXdholbert FOLLOW ACTUAL RULES FOR FLEX CONTAINER BASELINE
// If we have any baseline-aligned items on first line, use their baseline.
// ...ELSE if we have at least one flex item and our first flex item's
// baseline is parallel to main axis, then use that baseline.
// ...ELSE use "after" edge of content box.
// Default baseline: the "after" edge of content box. (Note: if we have any
// flex items, they'll override this.)
mCachedAscent = mCachedContentBoxCrossSize +
aReflowState.mComputedBorderPadding.top;
// Position the items in cross axis, within their line
for (uint32_t i = 0; i < items.Length(); ++i) {
PositionItemInCrossAxis(crossAxisPosnTracker.GetPosition(),
lineCrossAxisPosnTracker, items[i]);
}
// FINAL REFLOW: Give each child frame another chance to reflow, now that
// we know its final size and position.
for (uint32_t i = 0; i < items.Length(); ++i) {
FlexItem& curItem = items[i];
nsHTMLReflowState childReflowState(aPresContext, aReflowState,
curItem.Frame(),
nsSize(aReflowState.ComputedWidth(),
NS_UNCONSTRAINEDSIZE));
// Override computed main-size
if (IsAxisHorizontal(axisTracker.GetMainAxis())) {
childReflowState.SetComputedWidth(curItem.GetMainSize());
} else {
childReflowState.SetComputedHeight(curItem.GetMainSize());
}
// Override reflow state's computed cross-size, for stretched items.
if (curItem.IsStretched()) {
MOZ_ASSERT(curItem.GetAlignSelf() == NS_STYLE_ALIGN_ITEMS_STRETCH,
"stretched item w/o 'align-self: stretch'?");
if (IsAxisHorizontal(axisTracker.GetCrossAxis())) {
childReflowState.SetComputedWidth(curItem.GetCrossSize());
} else {
childReflowState.SetComputedHeight(curItem.GetCrossSize());
}
}
// XXXdholbert Might need to actually set the correct margins in the
// reflow state at some point, so that they can be saved on the frame for
// UsedMarginPropeorty(). Maybe doesn't matter though...?
// XXXdholbert Assuming horizontal
nscoord mainPosn = curItem.GetMainPosition();
nscoord crossPosn = curItem.GetCrossPosition();
if (!AxisGrowsInPositiveDirection(axisTracker.GetMainAxis())) {
mainPosn = frameMainSize - mainPosn;
}
if (!AxisGrowsInPositiveDirection(axisTracker.GetCrossAxis())) {
crossPosn = frameCrossSize - crossPosn;
}
nsPoint physicalPosn =
axisTracker.PhysicalPositionFromLogicalPosition(mainPosn, crossPosn);
nsHTMLReflowMetrics childDesiredSize;
nsReflowStatus childReflowStatus;
nsresult rv = ReflowChild(curItem.Frame(), aPresContext,
childDesiredSize, childReflowState,
physicalPosn.x, physicalPosn.y,
0, childReflowStatus);
NS_ENSURE_SUCCESS(rv, rv);
// XXXdholbert Once we do pagination / splitting, we'll need to actually
// handle incomplete childReflowStatuses. But for now, we give our kids
// unconstrained available height, which means they should always
// complete.
MOZ_ASSERT(NS_FRAME_IS_COMPLETE(childReflowStatus),
"We gave flex item unconstrained available height, so it "
"should be complete");
// Apply CSS relative positioning
const nsStyleDisplay* styleDisp = curItem.Frame()->GetStyleDisplay();
if (NS_STYLE_POSITION_RELATIVE == styleDisp->mPosition) {
physicalPosn.x += childReflowState.mComputedOffsets.left;
physicalPosn.y += childReflowState.mComputedOffsets.top;
}
rv = FinishReflowChild(curItem.Frame(), aPresContext,
&childReflowState, childDesiredSize,
physicalPosn.x, physicalPosn.y, 0);
NS_ENSURE_SUCCESS(rv, rv);
}
}
// XXXdholbert This could be more elegant
aDesiredSize.width =
IsAxisHorizontal(axisTracker.GetMainAxis()) ?
frameMainSize : frameCrossSize;
aDesiredSize.height =
IsAxisHorizontal(axisTracker.GetCrossAxis()) ?
frameMainSize : frameCrossSize;
aDesiredSize.ascent = mCachedAscent;
// Overflow area = union(my overflow area, kids' overflow areas)
aDesiredSize.SetOverflowAreasToDesiredBounds();
for (nsFrameList::Enumerator e(mFrames); !e.AtEnd(); e.Next()) {
ConsiderChildOverflow(aDesiredSize.mOverflowAreas, e.get());
}
NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aDesiredSize)
aStatus = NS_FRAME_COMPLETE;
FinishReflowWithAbsoluteFrames(aPresContext, aDesiredSize,
aReflowState, aStatus);
return NS_OK;
}
/* virtual */ nscoord
nsFlexContainerFrame::GetMinWidth(nsRenderingContext* aRenderingContext)
{
FlexboxAxisTracker axisTracker(this);
nscoord minWidth = 0;
for (nsFrameList::Enumerator e(mFrames); !e.AtEnd(); e.Next()) {
nscoord childMinWidth =
nsLayoutUtils::IntrinsicForContainer(aRenderingContext, e.get(),
nsLayoutUtils::MIN_WIDTH);
if (IsAxisHorizontal(axisTracker.GetMainAxis())) {
minWidth += childMinWidth;
} else {
minWidth = NS_MAX(minWidth, childMinWidth);
}
}
return minWidth;
}
/* virtual */ nscoord
nsFlexContainerFrame::GetPrefWidth(nsRenderingContext* aRenderingContext)
{
// XXXdholbert Optimization: We could cache our intrinsic widths like
// nsBlockFrame does (and return it early from this function if it's set).
// Whenever anything happens that might change it, set it to
// NS_INTRINSIC_WIDTH_UNKNOWN (like nsBlockFrame::MarkIntrinsicWidthsDirty
// does)
FlexboxAxisTracker axisTracker(this);
nscoord prefWidth = 0;
for (nsFrameList::Enumerator e(mFrames); !e.AtEnd(); e.Next()) {
nscoord childPrefWidth =
nsLayoutUtils::IntrinsicForContainer(aRenderingContext, e.get(),
nsLayoutUtils::PREF_WIDTH);
if (IsAxisHorizontal(axisTracker.GetMainAxis())) {
prefWidth += childPrefWidth;
} else {
prefWidth = NS_MAX(prefWidth, childPrefWidth);
}
}
return prefWidth;
}
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