autotablelayout.cpp

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/*
 * Copyright (C) 2002 Lars Knoll ([e-mail])
 *           (C) 2002 Dirk Mueller ([e-mail])
 * Copyright (C) 2003, 2006, 2008 Apple Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#include "config.h"
#include "AutoTableLayout.h"

#include "RenderTable.h"
#include "RenderTableCell.h"
#include "RenderTableCol.h"
#include "RenderTableSection.h"

using namespace std;

namespace WebCore {

AutoTableLayout::AutoTableLayout(RenderTable* table)
    : TableLayout(table)
    , m_hasPercent(false)
    , m_percentagesDirty(true)
    , m_effWidthDirty(true)
    , m_totalPercent(0)
{
}

AutoTableLayout::~AutoTableLayout()
{
}

/* recalculates the full structure needed to do layouting and minmax calculations.
   This is usually calculated on the fly, but needs to be done fully when table cells change
   dynamically
*/
void AutoTableLayout::recalcColumn(int effCol)
{
    Layout &l = m_layoutStruct[effCol];

    RenderObject* child = m_table->firstChild();
    // first we iterate over all rows.

    RenderTableCell* fixedContributor = 0;
    RenderTableCell* maxContributor = 0;

    while (child) {
        if (child->isTableSection()) {
            RenderTableSection* section = static_cast<RenderTableSection*>(child);
            int numRows = section->numRows();
            RenderTableCell* last = 0;
            for (int i = 0; i < numRows; i++) {
                RenderTableSection::CellStruct current = section->cellAt(i, effCol);
                RenderTableCell* cell = current.cell;
                
                bool cellHasContent = cell && (cell->firstChild() || cell->style()->hasBorder() || cell->style()->hasPadding());
                if (cellHasContent)
                    l.emptyCellsOnly = false;
                    
                if (current.inColSpan)
                    continue;
                if (cell && cell->colSpan() == 1) {
                    // A cell originates in this column.  Ensure we have
                    // a min/max width of at least 1px for this column now.
                    l.minWidth = max(l.minWidth, cellHasContent ? 1 : 0);
                    l.maxWidth = max(l.maxWidth, 1);
                    if (cell->prefWidthsDirty())
                        cell->calcPrefWidths();
                    l.minWidth = max(cell->minPrefWidth(), l.minWidth);
                    if (cell->maxPrefWidth() > l.maxWidth) {
                        l.maxWidth = cell->maxPrefWidth();
                        maxContributor = cell;
                    }

                    Length w = cell->styleOrColWidth();
                    // FIXME: What is this arbitrary value?
                    if (w.rawValue() > 32760)
                        w.setRawValue(32760);
                    if (w.isNegative())
                        w.setValue(0);
                    switch(w.type()) {
                    case Fixed:
                        // ignore width=0
                        if (w.value() > 0 && (int)l.width.type() != Percent) {
                            int wval = cell->calcBorderBoxWidth(w.value());
                            if (l.width.isFixed()) {
                                // Nav/IE weirdness
                                if ((wval > l.width.value()) ||
                                    ((l.width.value() == wval) && (maxContributor == cell))) {
                                    l.width.setValue(wval);
                                    fixedContributor = cell;
                                }
                            } else {
                                l.width.setValue(Fixed, wval);
                                fixedContributor = cell;
                            }
                        }
                        break;
                    case Percent:
                        m_hasPercent = true;
                        if (w.isPositive() && (!l.width.isPercent() || w.rawValue() > l.width.rawValue()))
                            l.width = w;
                        break;
                    case Relative:
                        // FIXME: Need to understand this case and whether it makes sense to compare values
                        // which are not necessarily of the same type.
                        if (w.isAuto() || (w.isRelative() && w.value() > l.width.rawValue()))
                            l.width = w;
                    default:
                        break;
                    }
                } else {
                    if (cell && (!effCol || section->cellAt(i, effCol-1).cell != cell)) {
                        // This spanning cell originates in this column.  Ensure we have
                        // a min/max width of at least 1px for this column now.
                        l.minWidth = max(l.minWidth, cellHasContent ? 1 : 0);
                        l.maxWidth = max(l.maxWidth, 1);
                        insertSpanCell(cell);
                    }
                    last = cell;
                }
            }
        }
        child = child->nextSibling();
    }

    // Nav/IE weirdness
    if (l.width.isFixed()) {
        if (m_table->style()->htmlHacks() && l.maxWidth > l.width.value() && fixedContributor != maxContributor) {
            l.width = Length();
            fixedContributor = 0;
        }
    }

    l.maxWidth = max(l.maxWidth, l.minWidth);

    // ### we need to add col elements as well
}

void AutoTableLayout::fullRecalc()
{
    m_percentagesDirty = true;
    m_hasPercent = false;
    m_effWidthDirty = true;

    int nEffCols = m_table->numEffCols();
    m_layoutStruct.resize(nEffCols);
    m_layoutStruct.fill(Layout());
    m_spanCells.fill(0);

    RenderObject *child = m_table->firstChild();
    Length grpWidth;
    int cCol = 0;
    while (child) {
        if (child->isTableCol()) {
            RenderTableCol *col = static_cast<RenderTableCol*>(child);
            int span = col->span();
            if (col->firstChild()) {
                grpWidth = col->style()->width();
            } else {
                Length w = col->style()->width();
                if (w.isAuto())
                    w = grpWidth;
                if ((w.isFixed() || w.isPercent()) && w.isZero())
                    w = Length();
                int cEffCol = m_table->colToEffCol(cCol);
                if (!w.isAuto() && span == 1 && cEffCol < nEffCols) {
                    if (m_table->spanOfEffCol(cEffCol) == 1) {
                        m_layoutStruct[cEffCol].width = w;
                        if (w.isFixed() && m_layoutStruct[cEffCol].maxWidth < w.value())
                            m_layoutStruct[cEffCol].maxWidth = w.value();
                    }
                }
                cCol += span;
            }
        } else {
            break;
        }

        RenderObject *next = child->firstChild();
        if (!next)
            next = child->nextSibling();
        if (!next && child->parent()->isTableCol()) {
            next = child->parent()->nextSibling();
            grpWidth = Length();
        }
        child = next;
    }


    for (int i = 0; i < nEffCols; i++)
        recalcColumn(i);
}

static bool shouldScaleColumns(RenderTable* table)
{
    // A special case.  If this table is not fixed width and contained inside
    // a cell, then don't bloat the maxwidth by examining percentage growth.
    bool scale = true;
    while (table) {
        Length tw = table->style()->width();
        if ((tw.isAuto() || tw.isPercent()) && !table->isPositioned()) {
            RenderBlock* cb = table->containingBlock();
            while (cb && !cb->isRenderView() && !cb->isTableCell() &&
                cb->style()->width().isAuto() && !cb->isPositioned())
                cb = cb->containingBlock();

            table = 0;
            if (cb && cb->isTableCell() &&
                (cb->style()->width().isAuto() || cb->style()->width().isPercent())) {
                if (tw.isPercent())
                    scale = false;
                else {
                    RenderTableCell* cell = static_cast<RenderTableCell*>(cb);
                    if (cell->colSpan() > 1 || cell->table()->style()->width().isAuto())
                        scale = false;
                    else
                        table = cell->table();
                }
            }
        }
        else
            table = 0;
    }
    return scale;
}

void AutoTableLayout::calcPrefWidths(int& minWidth, int& maxWidth)
{
    fullRecalc();

    int spanMaxWidth = calcEffectiveWidth();
    minWidth = 0;
    maxWidth = 0;
    float maxPercent = 0;
    float maxNonPercent = 0;
    bool scaleColumns = shouldScaleColumns(m_table);

    // We substitute 0 percent by (epsilon / percentScaleFactor) percent in two places below to avoid division by zero.
    // FIXME: Handle the 0% cases properly.
    const int epsilon = 1;

    int remainingPercent = 100 * percentScaleFactor;
    for (unsigned int i = 0; i < m_layoutStruct.size(); i++) {
        minWidth += m_layoutStruct[i].effMinWidth;
        maxWidth += m_layoutStruct[i].effMaxWidth;
        if (scaleColumns) {
            if (m_layoutStruct[i].effWidth.isPercent()) {