gecko/layout/tables/FixedTableLayoutStrategy.cpp

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
// vim:cindent:ts=4:et:sw=4:
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla's table layout code.
*
* The Initial Developer of the Original Code is the Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2006
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* L. David Baron <dbaron@dbaron.org> (original author)
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
* Algorithms that determine column and table widths used for CSS2's
* 'table-layout: fixed'.
*/
#include "FixedTableLayoutStrategy.h"
#include "nsTableFrame.h"
#include "nsTableColFrame.h"
#include "nsTableCellFrame.h"
FixedTableLayoutStrategy::FixedTableLayoutStrategy(nsTableFrame *aTableFrame)
: nsITableLayoutStrategy(nsITableLayoutStrategy::Fixed)
, mTableFrame(aTableFrame)
{
MarkIntrinsicWidthsDirty();
}
/* virtual */
FixedTableLayoutStrategy::~FixedTableLayoutStrategy()
{
}
/* virtual */ nscoord
FixedTableLayoutStrategy::GetMinWidth(nsRenderingContext* aRenderingContext)
{
DISPLAY_MIN_WIDTH(mTableFrame, mMinWidth);
if (mMinWidth != NS_INTRINSIC_WIDTH_UNKNOWN)
return mMinWidth;
// It's theoretically possible to do something much better here that
// depends only on the columns and the first row (where we look at
// intrinsic widths inside the first row and then reverse the
// algorithm to find the narrowest width that would hold all of
// those intrinsic widths), but it wouldn't be compatible with other
// browsers, or with the use of GetMinWidth by
// nsTableFrame::ComputeSize to determine the width of a fixed
// layout table, since CSS2.1 says:
// The width of the table is then the greater of the value of the
// 'width' property for the table element and the sum of the
// column widths (plus cell spacing or borders).
// XXX Should we really ignore 'min-width' and 'max-width'?
// XXX Should we really ignore widths on column groups?
nsTableCellMap *cellMap = mTableFrame->GetCellMap();
PRInt32 colCount = cellMap->GetColCount();
nscoord spacing = mTableFrame->GetCellSpacingX();
nscoord result = 0;
if (colCount > 0) {
result += spacing * (colCount + 1);
}
for (PRInt32 col = 0; col < colCount; ++col) {
nsTableColFrame *colFrame = mTableFrame->GetColFrame(col);
if (!colFrame) {
NS_ERROR("column frames out of sync with cell map");
continue;
}
const nsStyleCoord *styleWidth =
&colFrame->GetStylePosition()->mWidth;
if (styleWidth->GetUnit() == eStyleUnit_Coord) {
result += nsLayoutUtils::ComputeWidthValue(aRenderingContext,
colFrame, 0, 0, 0, *styleWidth);
} else if (styleWidth->GetUnit() == eStyleUnit_Percent) {
// do nothing
} else {
NS_ASSERTION(styleWidth->GetUnit() == eStyleUnit_Auto ||
styleWidth->GetUnit() == eStyleUnit_Enumerated ||
styleWidth->IsCalcUnit(),
"bad width");
// The 'table-layout: fixed' algorithm considers only cells
// in the first row.
bool originates;
PRInt32 colSpan;
nsTableCellFrame *cellFrame =
cellMap->GetCellInfoAt(0, col, &originates, &colSpan);
if (cellFrame) {
styleWidth = &cellFrame->GetStylePosition()->mWidth;
if (styleWidth->GetUnit() == eStyleUnit_Coord ||
(styleWidth->GetUnit() == eStyleUnit_Enumerated &&
(styleWidth->GetIntValue() == NS_STYLE_WIDTH_MAX_CONTENT ||
styleWidth->GetIntValue() == NS_STYLE_WIDTH_MIN_CONTENT))) {
nscoord cellWidth = nsLayoutUtils::IntrinsicForContainer(
aRenderingContext, cellFrame, nsLayoutUtils::MIN_WIDTH);
if (colSpan > 1) {
// If a column-spanning cell is in the first
// row, split up the space evenly. (XXX This
// isn't quite right if some of the columns it's
// in have specified widths. Should we care?)
cellWidth = ((cellWidth + spacing) / colSpan) - spacing;
}
result += cellWidth;
} else if (styleWidth->GetUnit() == eStyleUnit_Percent) {
if (colSpan > 1) {
// XXX Can this force columns to negative
// widths?
result -= spacing * (colSpan - 1);
}
}
// else, for 'auto', '-moz-available', '-moz-fit-content',
// and 'calc()', do nothing
}
}
}
return (mMinWidth = result);
}
/* virtual */ nscoord
FixedTableLayoutStrategy::GetPrefWidth(nsRenderingContext* aRenderingContext,
bool aComputingSize)
{
// It's theoretically possible to do something much better here that
// depends only on the columns and the first row (where we look at
// intrinsic widths inside the first row and then reverse the
// algorithm to find the narrowest width that would hold all of
// those intrinsic widths), but it wouldn't be compatible with other
// browsers.
nscoord result = nscoord_MAX;
DISPLAY_PREF_WIDTH(mTableFrame, result);
return result;
}
/* virtual */ void
FixedTableLayoutStrategy::MarkIntrinsicWidthsDirty()
{
mMinWidth = NS_INTRINSIC_WIDTH_UNKNOWN;
mLastCalcWidth = nscoord_MIN;
}
static inline nscoord
AllocateUnassigned(nscoord aUnassignedSpace, float aShare)
{
if (aShare == 1.0f) {
// This happens when the numbers we're dividing to get aShare
// are equal. We want to return unassignedSpace exactly, even
// if it can't be precisely round-tripped through float.
return aUnassignedSpace;
}
return NSToCoordRound(float(aUnassignedSpace) * aShare);
}
/* virtual */ void
FixedTableLayoutStrategy::ComputeColumnWidths(const nsHTMLReflowState& aReflowState)
{
nscoord tableWidth = aReflowState.ComputedWidth();
if (mLastCalcWidth == tableWidth)
return;
mLastCalcWidth = tableWidth;
nsTableCellMap *cellMap = mTableFrame->GetCellMap();
PRInt32 colCount = cellMap->GetColCount();
nscoord spacing = mTableFrame->GetCellSpacingX();
if (colCount == 0) {
// No Columns - nothing to compute
return;
}
// border-spacing isn't part of the basis for percentages.
tableWidth -= spacing * (colCount + 1);
// store the old column widths. We might call multiple times SetFinalWidth
// on the columns, due to this we can't compare at the last call that the
// width has changed with the respect to the last call to
// ComputeColumnWidths. In order to overcome this we store the old values
// in this array. A single call to SetFinalWidth would make it possible to
// call GetFinalWidth before and to compare when setting the final width.
nsTArray<nscoord> oldColWidths;
// XXX This ignores the 'min-width' and 'max-width' properties
// throughout. Then again, that's what the CSS spec says to do.
// XXX Should we really ignore widths on column groups?
PRUint32 unassignedCount = 0;
nscoord unassignedSpace = tableWidth;
const nscoord unassignedMarker = nscoord_MIN;
// We use the PrefPercent on the columns to store the percentages
// used to compute column widths in case we need to shrink or expand
// the columns.
float pctTotal = 0.0f;
// Accumulate the total specified (non-percent) on the columns for
// distributing excess width to the columns.
nscoord specTotal = 0;
for (PRInt32 col = 0; col < colCount; ++col) {
nsTableColFrame *colFrame = mTableFrame->GetColFrame(col);
if (!colFrame) {
oldColWidths.AppendElement(0);
NS_ERROR("column frames out of sync with cell map");
continue;
}
oldColWidths.AppendElement(colFrame->GetFinalWidth());
colFrame->ResetPrefPercent();
const nsStyleCoord *styleWidth =
&colFrame->GetStylePosition()->mWidth;
nscoord colWidth;
if (styleWidth->GetUnit() == eStyleUnit_Coord) {
colWidth = nsLayoutUtils::ComputeWidthValue(
aReflowState.rendContext,
colFrame, 0, 0, 0, *styleWidth);
specTotal += colWidth;
} else if (styleWidth->GetUnit() == eStyleUnit_Percent) {
float pct = styleWidth->GetPercentValue();
colWidth = NSToCoordFloor(pct * float(tableWidth));
colFrame->AddPrefPercent(pct);
pctTotal += pct;
} else {
NS_ASSERTION(styleWidth->GetUnit() == eStyleUnit_Auto ||
styleWidth->GetUnit() == eStyleUnit_Enumerated ||
styleWidth->IsCalcUnit(),
"bad width");
// The 'table-layout: fixed' algorithm considers only cells
// in the first row.
bool originates;
PRInt32 colSpan;
nsTableCellFrame *cellFrame =
cellMap->GetCellInfoAt(0, col, &originates, &colSpan);
if (cellFrame) {
styleWidth = &cellFrame->GetStylePosition()->mWidth;
if (styleWidth->GetUnit() == eStyleUnit_Coord ||
(styleWidth->GetUnit() == eStyleUnit_Enumerated &&
(styleWidth->GetIntValue() == NS_STYLE_WIDTH_MAX_CONTENT ||
styleWidth->GetIntValue() == NS_STYLE_WIDTH_MIN_CONTENT))) {
// XXX This should use real percentage padding
// Note that the difference between MIN_WIDTH and
// PREF_WIDTH shouldn't matter for any of these
// values of styleWidth; use MIN_WIDTH for symmetry
// with GetMinWidth above, just in case there is a
// difference.
colWidth = nsLayoutUtils::IntrinsicForContainer(
aReflowState.rendContext,
cellFrame, nsLayoutUtils::MIN_WIDTH);
} else if (styleWidth->GetUnit() == eStyleUnit_Percent) {
// XXX This should use real percentage padding
nsIFrame::IntrinsicWidthOffsetData offsets =
cellFrame->IntrinsicWidthOffsets(aReflowState.rendContext);
float pct = styleWidth->GetPercentValue();
colWidth = NSToCoordFloor(pct * float(tableWidth)) +
offsets.hPadding + offsets.hBorder;
pct /= float(colSpan);
colFrame->AddPrefPercent(pct);
pctTotal += pct;
} else {
// 'auto', '-moz-available', '-moz-fit-content', and
// 'calc()'
colWidth = unassignedMarker;
}
if (colWidth != unassignedMarker) {
if (colSpan > 1) {
// If a column-spanning cell is in the first
// row, split up the space evenly. (XXX This
// isn't quite right if some of the columns it's
// in have specified widths. Should we care?)
colWidth = ((colWidth + spacing) / colSpan) - spacing;
if (colWidth < 0)
colWidth = 0;
}
if (styleWidth->GetUnit() != eStyleUnit_Percent) {
specTotal += colWidth;
}
}
} else {
colWidth = unassignedMarker;
}
}
colFrame->SetFinalWidth(colWidth);
if (colWidth == unassignedMarker) {
++unassignedCount;
} else {
unassignedSpace -= colWidth;
}
}
if (unassignedSpace < 0) {
if (pctTotal > 0) {
// If the columns took up too much space, reduce those that
// had percentage widths. The spec doesn't say to do this,
// but we've always done it in the past, and so does WinIE6.
nscoord pctUsed = NSToCoordFloor(pctTotal * float(tableWidth));
nscoord reduce = NS_MIN(pctUsed, -unassignedSpace);
float reduceRatio = float(reduce) / pctTotal;
for (PRInt32 col = 0; col < colCount; ++col) {
nsTableColFrame *colFrame = mTableFrame->GetColFrame(col);
if (!colFrame) {
NS_ERROR("column frames out of sync with cell map");
continue;
}
nscoord colWidth = colFrame->GetFinalWidth();
colWidth -= NSToCoordFloor(colFrame->GetPrefPercent() *
reduceRatio);
if (colWidth < 0)
colWidth = 0;
colFrame->SetFinalWidth(colWidth);
}
}
unassignedSpace = 0;
}
if (unassignedCount > 0) {
// The spec says to distribute the remaining space evenly among
// the columns.
nscoord toAssign = unassignedSpace / unassignedCount;
for (PRInt32 col = 0; col < colCount; ++col) {
nsTableColFrame *colFrame = mTableFrame->GetColFrame(col);
if (!colFrame) {
NS_ERROR("column frames out of sync with cell map");
continue;
}
if (colFrame->GetFinalWidth() == unassignedMarker)
colFrame->SetFinalWidth(toAssign);
}
} else if (unassignedSpace > 0) {
// The spec doesn't say how to distribute the unassigned space.
if (specTotal > 0) {
// Distribute proportionally to non-percentage columns.
nscoord specUndist = specTotal;
for (PRInt32 col = 0; col < colCount; ++col) {
nsTableColFrame *colFrame = mTableFrame->GetColFrame(col);
if (!colFrame) {
NS_ERROR("column frames out of sync with cell map");
continue;
}
if (colFrame->GetPrefPercent() == 0.0f) {
NS_ASSERTION(colFrame->GetFinalWidth() <= specUndist,
"widths don't add up");
nscoord toAdd = AllocateUnassigned(unassignedSpace,
float(colFrame->GetFinalWidth()) / float(specUndist));
specUndist -= colFrame->GetFinalWidth();
colFrame->SetFinalWidth(colFrame->GetFinalWidth() + toAdd);
unassignedSpace -= toAdd;
if (specUndist <= 0) {
NS_ASSERTION(specUndist == 0,
"math should be exact");
break;
}
}
}
NS_ASSERTION(unassignedSpace == 0, "failed to redistribute");
} else if (pctTotal > 0) {
// Distribute proportionally to percentage columns.
float pctUndist = pctTotal;
for (PRInt32 col = 0; col < colCount; ++col) {
nsTableColFrame *colFrame = mTableFrame->GetColFrame(col);
if (!colFrame) {
NS_ERROR("column frames out of sync with cell map");
continue;
}
if (pctUndist < colFrame->GetPrefPercent()) {
// This can happen with floating-point math.
NS_ASSERTION(colFrame->GetPrefPercent() - pctUndist
< 0.0001,
"widths don't add up");
pctUndist = colFrame->GetPrefPercent();
}
nscoord toAdd = AllocateUnassigned(unassignedSpace,
colFrame->GetPrefPercent() / pctUndist);
colFrame->SetFinalWidth(colFrame->GetFinalWidth() + toAdd);
unassignedSpace -= toAdd;
pctUndist -= colFrame->GetPrefPercent();
if (pctUndist <= 0.0f) {
break;
}
}
NS_ASSERTION(unassignedSpace == 0, "failed to redistribute");
} else {
// Distribute equally to the zero-width columns.
PRInt32 colsLeft = colCount;
for (PRInt32 col = 0; col < colCount; ++col) {
nsTableColFrame *colFrame = mTableFrame->GetColFrame(col);
if (!colFrame) {
NS_ERROR("column frames out of sync with cell map");
continue;
}
NS_ASSERTION(colFrame->GetFinalWidth() == 0, "yikes");
nscoord toAdd = AllocateUnassigned(unassignedSpace,
1.0f / float(colsLeft));
colFrame->SetFinalWidth(toAdd);
unassignedSpace -= toAdd;
--colsLeft;
}
NS_ASSERTION(unassignedSpace == 0, "failed to redistribute");
}
}
for (PRInt32 col = 0; col < colCount; ++col) {
nsTableColFrame *colFrame = mTableFrame->GetColFrame(col);
if (!colFrame) {
NS_ERROR("column frames out of sync with cell map");
continue;
}
if (oldColWidths.ElementAt(col) != colFrame->GetFinalWidth()) {
mTableFrame->DidResizeColumns();
break;
}
}
}