gecko/layout/generic/nsFloatManager.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2012-05-21 04:12:37 -07:00
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* class that manages rules for positioning floats */
#include "nsFloatManager.h"
#include "nsIPresShell.h"
#include "nsMemory.h"
#include "nsHTMLReflowState.h"
#include "nsBlockDebugFlags.h"
#include "nsError.h"
using namespace mozilla;
PRInt32 nsFloatManager::sCachedFloatManagerCount = 0;
void* nsFloatManager::sCachedFloatManagers[NS_FLOAT_MANAGER_CACHE_SIZE];
/////////////////////////////////////////////////////////////////////////////
// PresShell Arena allocate callback (for nsIntervalSet use below)
static void*
PSArenaAllocCB(size_t aSize, void* aClosure)
{
return static_cast<nsIPresShell*>(aClosure)->AllocateMisc(aSize);
}
// PresShell Arena free callback (for nsIntervalSet use below)
static void
PSArenaFreeCB(size_t aSize, void* aPtr, void* aClosure)
{
static_cast<nsIPresShell*>(aClosure)->FreeMisc(aSize, aPtr);
}
/////////////////////////////////////////////////////////////////////////////
// nsFloatManager
nsFloatManager::nsFloatManager(nsIPresShell* aPresShell)
: mX(0), mY(0),
mFloatDamage(PSArenaAllocCB, PSArenaFreeCB, aPresShell),
mPushedLeftFloatPastBreak(false),
mPushedRightFloatPastBreak(false),
mSplitLeftFloatAcrossBreak(false),
mSplitRightFloatAcrossBreak(false)
{
MOZ_COUNT_CTOR(nsFloatManager);
}
nsFloatManager::~nsFloatManager()
{
MOZ_COUNT_DTOR(nsFloatManager);
}
// static
void* nsFloatManager::operator new(size_t aSize) CPP_THROW_NEW
{
if (sCachedFloatManagerCount > 0) {
// We have cached unused instances of this class, return a cached
// instance in stead of always creating a new one.
return sCachedFloatManagers[--sCachedFloatManagerCount];
}
// The cache is empty, this means we haveto create a new instance using
// the global |operator new|.
return nsMemory::Alloc(aSize);
}
void
nsFloatManager::operator delete(void* aPtr, size_t aSize)
{
if (!aPtr)
return;
// This float manager is no longer used, if there's still room in
// the cache we'll cache this float manager, unless the layout
// module was already shut down.
if (sCachedFloatManagerCount < NS_FLOAT_MANAGER_CACHE_SIZE &&
sCachedFloatManagerCount >= 0) {
// There's still space in the cache for more instances, put this
// instance in the cache in stead of deleting it.
sCachedFloatManagers[sCachedFloatManagerCount++] = aPtr;
return;
}
// The cache is full, or the layout module has been shut down,
// delete this float manager.
nsMemory::Free(aPtr);
}
/* static */
void nsFloatManager::Shutdown()
{
// The layout module is being shut down, clean up the cache and
// disable further caching.
PRInt32 i;
for (i = 0; i < sCachedFloatManagerCount; i++) {
void* floatManager = sCachedFloatManagers[i];
if (floatManager)
nsMemory::Free(floatManager);
}
// Disable further caching.
sCachedFloatManagerCount = -1;
}
nsFlowAreaRect
nsFloatManager::GetFlowArea(nscoord aYOffset, BandInfoType aInfoType,
nscoord aHeight, nsRect aContentArea,
SavedState* aState) const
{
NS_ASSERTION(aHeight >= 0, "unexpected max height");
NS_ASSERTION(aContentArea.width >= 0, "unexpected content area width");
nscoord top = aYOffset + mY;
if (top < nscoord_MIN) {
NS_WARNING("bad value");
top = nscoord_MIN;
}
// Determine the last float that we should consider.
PRUint32 floatCount;
if (aState) {
// Use the provided state.
floatCount = aState->mFloatInfoCount;
NS_ABORT_IF_FALSE(floatCount <= mFloats.Length(), "bad state");
} else {
// Use our current state.
floatCount = mFloats.Length();
}
// If there are no floats at all, or we're below the last one, return
// quickly.
if (floatCount == 0 ||
(mFloats[floatCount-1].mLeftYMost <= top &&
mFloats[floatCount-1].mRightYMost <= top)) {
return nsFlowAreaRect(aContentArea.x, aYOffset, aContentArea.width,
aHeight, false);
}
nscoord bottom;
if (aHeight == nscoord_MAX) {
// This warning (and the two below) are possible to hit on pages
// with really large objects.
NS_WARN_IF_FALSE(aInfoType == BAND_FROM_POINT,
"bad height");
bottom = nscoord_MAX;
} else {
bottom = top + aHeight;
if (bottom < top || bottom > nscoord_MAX) {
NS_WARNING("bad value");
bottom = nscoord_MAX;
}
}
nscoord left = mX + aContentArea.x;
nscoord right = mX + aContentArea.XMost();
if (right < left) {
NS_WARNING("bad value");
right = left;
}
// Walk backwards through the floats until we either hit the front of
// the list or we're above |top|.
bool haveFloats = false;
for (PRUint32 i = floatCount; i > 0; --i) {
const FloatInfo &fi = mFloats[i-1];
if (fi.mLeftYMost <= top && fi.mRightYMost <= top) {
// There aren't any more floats that could intersect this band.
break;
}
if (fi.mRect.IsEmpty()) {
// For compatibility, ignore floats with empty rects, even though it
// disagrees with the spec. (We might want to fix this in the
// future, though.)
continue;
}
nscoord floatTop = fi.mRect.y, floatBottom = fi.mRect.YMost();
if (top < floatTop && aInfoType == BAND_FROM_POINT) {
// This float is below our band. Shrink our band's height if needed.
if (floatTop < bottom) {
bottom = floatTop;
}
}
// If top == bottom (which happens only with WIDTH_WITHIN_HEIGHT),
// we include floats that begin at our 0-height vertical area. We
// need to to this to satisfy the invariant that a
// WIDTH_WITHIN_HEIGHT call is at least as narrow on both sides as a
// BAND_WITHIN_POINT call beginning at its top.
else if (top < floatBottom &&
(floatTop < bottom || (floatTop == bottom && top == bottom))) {
// This float is in our band.
// Shrink our band's height if needed.
if (floatBottom < bottom && aInfoType == BAND_FROM_POINT) {
bottom = floatBottom;
}
// Shrink our band's width if needed.
if (fi.mFrame->GetStyleDisplay()->mFloats == NS_STYLE_FLOAT_LEFT) {
// A left float.
nscoord rightEdge = fi.mRect.XMost();
if (rightEdge > left) {
left = rightEdge;
// Only set haveFloats to true if the float is inside our
// containing block. This matches the spec for what some
// callers want and disagrees for other callers, so we should
// probably provide better information at some point.
haveFloats = true;
}
} else {
// A right float.
nscoord leftEdge = fi.mRect.x;
if (leftEdge < right) {
right = leftEdge;
// See above.
haveFloats = true;
}
}
}
}
nscoord height = (bottom == nscoord_MAX) ? nscoord_MAX : (bottom - top);
return nsFlowAreaRect(left - mX, top - mY, right - left, height, haveFloats);
}
nsresult
nsFloatManager::AddFloat(nsIFrame* aFloatFrame, const nsRect& aMarginRect)
{
NS_ASSERTION(aMarginRect.width >= 0, "negative width!");
NS_ASSERTION(aMarginRect.height >= 0, "negative height!");
FloatInfo info(aFloatFrame, aMarginRect + nsPoint(mX, mY));
// Set mLeftYMost and mRightYMost.
if (HasAnyFloats()) {
FloatInfo &tail = mFloats[mFloats.Length() - 1];
info.mLeftYMost = tail.mLeftYMost;
info.mRightYMost = tail.mRightYMost;
} else {
info.mLeftYMost = nscoord_MIN;
info.mRightYMost = nscoord_MIN;
}
PRUint8 floatStyle = aFloatFrame->GetStyleDisplay()->mFloats;
NS_ASSERTION(floatStyle == NS_STYLE_FLOAT_LEFT ||
floatStyle == NS_STYLE_FLOAT_RIGHT, "unexpected float");
nscoord& sideYMost = (floatStyle == NS_STYLE_FLOAT_LEFT) ? info.mLeftYMost
: info.mRightYMost;
nscoord thisYMost = info.mRect.YMost();
if (thisYMost > sideYMost)
sideYMost = thisYMost;
if (!mFloats.AppendElement(info))
return NS_ERROR_OUT_OF_MEMORY;
return NS_OK;
}
nsRect
nsFloatManager::CalculateRegionFor(nsIFrame* aFloat,
const nsMargin& aMargin)
{
nsRect region = aFloat->GetRect();
// Float region includes its margin
region.Inflate(aMargin);
// If the element is relatively positioned, then adjust x and y
// accordingly so that we consider relatively positioned frames
// at their original position.
const nsStyleDisplay* display = aFloat->GetStyleDisplay();
region -= aFloat->GetRelativeOffset(display);
// Don't store rectangles with negative margin-box width or height in
// the float manager; it can't deal with them.
if (region.width < 0) {
// Preserve the right margin-edge for left floats and the left
// margin-edge for right floats
if (NS_STYLE_FLOAT_LEFT == display->mFloats) {
region.x = region.XMost();
}
region.width = 0;
}
if (region.height < 0) {
region.height = 0;
}
return region;
}
NS_DECLARE_FRAME_PROPERTY(FloatRegionProperty, nsIFrame::DestroyMargin)
nsRect
nsFloatManager::GetRegionFor(nsIFrame* aFloat)
{
nsRect region = aFloat->GetRect();
void* storedRegion = aFloat->Properties().Get(FloatRegionProperty());
if (storedRegion) {
nsMargin margin = *static_cast<nsMargin*>(storedRegion);
region.Inflate(margin);
}
return region;
}
void
nsFloatManager::StoreRegionFor(nsIFrame* aFloat,
nsRect& aRegion)
{
nsRect rect = aFloat->GetRect();
FrameProperties props = aFloat->Properties();
if (aRegion.IsEqualEdges(rect)) {
props.Delete(FloatRegionProperty());
}
else {
nsMargin* storedMargin = static_cast<nsMargin*>
(props.Get(FloatRegionProperty()));
if (!storedMargin) {
storedMargin = new nsMargin();
props.Set(FloatRegionProperty(), storedMargin);
}
*storedMargin = aRegion - rect;
}
}
nsresult
nsFloatManager::RemoveTrailingRegions(nsIFrame* aFrameList)
{
if (!aFrameList) {
return NS_OK;
}
// This could be a good bit simpler if we could guarantee that the
// floats given were at the end of our list, so we could just search
// for the head of aFrameList. (But we can't;
// layout/reftests/bugs/421710-1.html crashes.)
nsTHashtable<nsPtrHashKey<nsIFrame> > frameSet;
frameSet.Init(1);
for (nsIFrame* f = aFrameList; f; f = f->GetNextSibling()) {
frameSet.PutEntry(f);
}
PRUint32 newLength = mFloats.Length();
while (newLength > 0) {
if (!frameSet.Contains(mFloats[newLength - 1].mFrame)) {
break;
}
--newLength;
}
mFloats.TruncateLength(newLength);
#ifdef DEBUG
for (PRUint32 i = 0; i < mFloats.Length(); ++i) {
NS_ASSERTION(!frameSet.Contains(mFloats[i].mFrame),
"Frame region deletion was requested but we couldn't delete it");
}
#endif
return NS_OK;
}
void
nsFloatManager::PushState(SavedState* aState)
{
NS_PRECONDITION(aState, "Need a place to save state");
// This is a cheap push implementation, which
// only saves the (x,y) and last frame in the mFrameInfoMap
// which is enough info to get us back to where we should be
// when pop is called.
//
// This push/pop mechanism is used to undo any
// floats that were added during the unconstrained reflow
// in nsBlockReflowContext::DoReflowBlock(). (See bug 96736)
//
// It should also be noted that the state for mFloatDamage is
// intentionally not saved or restored in PushState() and PopState(),
// since that could lead to bugs where damage is missed/dropped when
// we move from position A to B (during the intermediate incremental
// reflow mentioned above) and then from B to C during the subsequent
// reflow. In the typical case A and C will be the same, but not always.
// Allowing mFloatDamage to accumulate the damage incurred during both
// reflows ensures that nothing gets missed.
aState->mX = mX;
aState->mY = mY;
aState->mPushedLeftFloatPastBreak = mPushedLeftFloatPastBreak;
aState->mPushedRightFloatPastBreak = mPushedRightFloatPastBreak;
aState->mSplitLeftFloatAcrossBreak = mSplitLeftFloatAcrossBreak;
aState->mSplitRightFloatAcrossBreak = mSplitRightFloatAcrossBreak;
aState->mFloatInfoCount = mFloats.Length();
}
void
nsFloatManager::PopState(SavedState* aState)
{
NS_PRECONDITION(aState, "No state to restore?");
mX = aState->mX;
mY = aState->mY;
mPushedLeftFloatPastBreak = aState->mPushedLeftFloatPastBreak;
mPushedRightFloatPastBreak = aState->mPushedRightFloatPastBreak;
mSplitLeftFloatAcrossBreak = aState->mSplitLeftFloatAcrossBreak;
mSplitRightFloatAcrossBreak = aState->mSplitRightFloatAcrossBreak;
NS_ASSERTION(aState->mFloatInfoCount <= mFloats.Length(),
"somebody misused PushState/PopState");
mFloats.TruncateLength(aState->mFloatInfoCount);
}
nscoord
nsFloatManager::GetLowestFloatTop() const
{
if (mPushedLeftFloatPastBreak || mPushedRightFloatPastBreak) {
return nscoord_MAX;
}
if (!HasAnyFloats()) {
return nscoord_MIN;
}
return mFloats[mFloats.Length() - 1].mRect.y - mY;
}
#ifdef DEBUG
void
DebugListFloatManager(const nsFloatManager *aFloatManager)
{
aFloatManager->List(stdout);
}
nsresult
nsFloatManager::List(FILE* out) const
{
if (!HasAnyFloats())
return NS_OK;
for (PRUint32 i = 0; i < mFloats.Length(); ++i) {
const FloatInfo &fi = mFloats[i];
printf("Float %u: frame=%p rect={%d,%d,%d,%d} ymost={l:%d, r:%d}\n",
i, static_cast<void*>(fi.mFrame),
fi.mRect.x, fi.mRect.y, fi.mRect.width, fi.mRect.height,
fi.mLeftYMost, fi.mRightYMost);
}
return NS_OK;
}
#endif
nscoord
nsFloatManager::ClearFloats(nscoord aY, PRUint8 aBreakType,
PRUint32 aFlags) const
{
if (!(aFlags & DONT_CLEAR_PUSHED_FLOATS) && ClearContinues(aBreakType)) {
return nscoord_MAX;
}
if (!HasAnyFloats()) {
return aY;
}
nscoord bottom = aY + mY;
const FloatInfo &tail = mFloats[mFloats.Length() - 1];
switch (aBreakType) {
case NS_STYLE_CLEAR_LEFT_AND_RIGHT:
bottom = NS_MAX(bottom, tail.mLeftYMost);
bottom = NS_MAX(bottom, tail.mRightYMost);
break;
case NS_STYLE_CLEAR_LEFT:
bottom = NS_MAX(bottom, tail.mLeftYMost);
break;
case NS_STYLE_CLEAR_RIGHT:
bottom = NS_MAX(bottom, tail.mRightYMost);
break;
default:
// Do nothing
break;
}
bottom -= mY;
return bottom;
}
bool
nsFloatManager::ClearContinues(PRUint8 aBreakType) const
{
return ((mPushedLeftFloatPastBreak || mSplitLeftFloatAcrossBreak) &&
(aBreakType == NS_STYLE_CLEAR_LEFT_AND_RIGHT ||
aBreakType == NS_STYLE_CLEAR_LEFT)) ||
((mPushedRightFloatPastBreak || mSplitRightFloatAcrossBreak) &&
(aBreakType == NS_STYLE_CLEAR_LEFT_AND_RIGHT ||
aBreakType == NS_STYLE_CLEAR_RIGHT));
}
/////////////////////////////////////////////////////////////////////////////
// FloatInfo
nsFloatManager::FloatInfo::FloatInfo(nsIFrame* aFrame, const nsRect& aRect)
: mFrame(aFrame), mRect(aRect)
{
MOZ_COUNT_CTOR(nsFloatManager::FloatInfo);
}
#ifdef NS_BUILD_REFCNT_LOGGING
nsFloatManager::FloatInfo::FloatInfo(const FloatInfo& aOther)
: mFrame(aOther.mFrame),
mRect(aOther.mRect),
mLeftYMost(aOther.mLeftYMost),
mRightYMost(aOther.mRightYMost)
{
MOZ_COUNT_CTOR(nsFloatManager::FloatInfo);
}
nsFloatManager::FloatInfo::~FloatInfo()
{
MOZ_COUNT_DTOR(nsFloatManager::FloatInfo);
}
#endif
//----------------------------------------------------------------------
nsAutoFloatManager::~nsAutoFloatManager()
{
// Restore the old float manager in the reflow state if necessary.
if (mNew) {
#ifdef NOISY_FLOATMANAGER
printf("restoring old float manager %p\n", mOld);
#endif
mReflowState.mFloatManager = mOld;
#ifdef NOISY_FLOATMANAGER
if (mOld) {
static_cast<nsFrame *>(mReflowState.frame)->ListTag(stdout);
printf(": space-manager %p after reflow\n", mOld);
mOld->List(stdout);
}
#endif
delete mNew;
}
}
nsresult
nsAutoFloatManager::CreateFloatManager(nsPresContext *aPresContext)
{
// Create a new float manager and install it in the reflow
// state. `Remember' the old float manager so we can restore it
// later.
mNew = new nsFloatManager(aPresContext->PresShell());
if (! mNew)
return NS_ERROR_OUT_OF_MEMORY;
#ifdef NOISY_FLOATMANAGER
printf("constructed new float manager %p (replacing %p)\n",
mNew, mReflowState.mFloatManager);
#endif
// Set the float manager in the existing reflow state
mOld = mReflowState.mFloatManager;
mReflowState.mFloatManager = mNew;
return NS_OK;
}