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