qtextdocumentlayout.cpp

奇趣公司比较新的qt/emd版本

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#include "qtextdocumentlayout_p.h"
#include "qtextdocument_p.h"
#include "qtextimagehandler_p.h"
#include "qtexttable.h"
#include "qtextlist.h"
#include "qtextengine_p.h"
#include "private/qcssutil_p.h"
#include "private/qmath_p.h"

#include "qabstracttextdocumentlayout_p.h"
#include "qcssparser_p.h"

#include <qpainter.h>
#include <qrect.h>
#include <qpalette.h>
#include <qdebug.h>
#include <qvarlengtharray.h>
#include <limits.h>
#include <qstyle.h>
#include <qbasictimer.h>

// #define LAYOUT_DEBUG

#ifdef LAYOUT_DEBUG
#define LDEBUG qDebug()
#define INC_INDENT debug_indent += "  "
#define DEC_INDENT debug_indent = debug_indent.left(debug_indent.length()-2)
#else
#define LDEBUG if(0) qDebug()
#define INC_INDENT do {} while(0)
#define DEC_INDENT do {} while(0)
#endif

// ################ should probably add frameFormatChange notification!

struct QLayoutStruct;

class QTextFrameData : public QTextFrameLayoutData
{
public:
    QTextFrameData();

    // relative to parent frame
    QFixedPoint position;
    QFixedSize size;

    // contents starts at (margin+border/margin+border)
    QFixed topMargin;
    QFixed bottomMargin;
    QFixed leftMargin;
    QFixed rightMargin;
    QFixed border;
    QFixed padding;
    // contents width includes padding (as we need to treat this on a per cell basis for tables)
    QFixed contentsWidth;
    QFixed contentsHeight;
    QFixed oldContentsWidth;

    // accumulated margins
    QFixed effectiveTopMargin;
    QFixed effectiveBottomMargin;

    QFixed minimumWidth;
    QFixed maximumWidth;

    QLayoutStruct *currentLayoutStruct;

    bool sizeDirty;
    bool layoutDirty;

    QList<QPointer<QTextFrame> > floats;
};

QTextFrameData::QTextFrameData()
    : maximumWidth(QFIXED_MAX),
      currentLayoutStruct(0), sizeDirty(true), layoutDirty(true)
{
}

struct QLayoutStruct {
    QLayoutStruct() : maximumWidth(QFIXED_MAX), fullLayout(false)
    {}
    QTextFrame *frame;
    QFixed x_left;
    QFixed x_right;
    QFixed frameY; // absolute y position of the current frame
    QFixed y; // always relative to the current frame
    QFixed contentsWidth;
    QFixed minimumWidth;
    QFixed maximumWidth;
    bool fullLayout;
    QList<QTextFrame *> pendingFloats;
    QFixed pageHeight;
    QFixed pageBottom;
    QFixed pageTopMargin;
    QFixed pageBottomMargin;
    QRectF updateRect;

    inline QFixed absoluteY() const
    { return frameY + y; }

    inline int currentPage() const
    { return pageHeight == 0 ? 0 : (absoluteY() / pageHeight).truncate(); }

    inline void newPage()
    { if (pageHeight == QFIXED_MAX) return; pageBottom += pageHeight; y = pageBottom - pageHeight + pageBottomMargin + pageTopMargin - frameY; }
};

class QTextTableData : public QTextFrameData
{
public:
    QFixed cellSpacing, cellPadding;
    QVector<QFixed> minWidths;
    QVector<QFixed> maxWidths;
    QVector<QFixed> widths;
    QVector<QFixed> heights;
    QVector<QFixed> columnPositions;
    QVector<QFixed> rowPositions;

    QVector<QFixed> cellVerticalOffsets;

    QFixed headerHeight;

    // maps from cell index (row + col * rowCount) to child frames belonging to
    // the specific cell
    QMultiHash<int, QTextFrame *> childFrameMap;

    inline QFixed cellWidth(int column, int colspan) const
    { return columnPositions.at(column + colspan - 1) + widths.at(column + colspan - 1)
             - columnPositions.at(column) - 2 * cellPadding; }

    inline void calcRowPosition(int row)
    {
        if (row > 0)
            rowPositions[row] = rowPositions.at(row - 1) + heights.at(row - 1) + border + cellSpacing + border;
    }

    QRectF cellRect(const QTextTableCell &cell) const;

    inline QFixedPoint cellPosition(int row, int col) const
    { return QFixedPoint(columnPositions.at(col) + cellPadding, rowPositions.at(row) + cellPadding + cellVerticalOffsets.at(col + row * widths.size())); }
    inline QFixedPoint cellPosition(const QTextTableCell &cell) const
    { return cellPosition(cell.row(), cell.column()); }

    void updateTableSize();
};

static QTextFrameData *createData(QTextFrame *f)
{
    QTextFrameData *data;
    if (qobject_cast<QTextTable *>(f))
        data = new QTextTableData;
    else
        data = new QTextFrameData;
    f->setLayoutData(data);
    return data;
}

static inline QTextFrameData *data(QTextFrame *f)
{
    QTextFrameData *data = static_cast<QTextFrameData *>(f->layoutData());
    if (!data)
        data = createData(f);
    return data;
}

static bool isFrameFromInlineObject(QTextFrame *f)
{
    return f->firstPosition() > f->lastPosition();
}

void QTextTableData::updateTableSize()
{
    const QFixed effectiveTopMargin = this->topMargin + border + padding;
    const QFixed effectiveBottomMargin = this->bottomMargin + border + padding;
    const QFixed effectiveLeftMargin = this->leftMargin + border + padding;
    const QFixed effectiveRightMargin = this->rightMargin + border + padding;
    size.height = contentsHeight == -1
                   ? rowPositions.last() + heights.last() + padding + border + cellSpacing + effectiveBottomMargin
                   : effectiveTopMargin + contentsHeight + effectiveBottomMargin;
    size.width = effectiveLeftMargin + contentsWidth + effectiveRightMargin;
}

QRectF QTextTableData::cellRect(const QTextTableCell &cell) const
{
    const int row = cell.row();
    const int rowSpan = cell.rowSpan();
    const int column = cell.column();
    const int colSpan = cell.columnSpan();

    return QRectF(columnPositions.at(column).toReal(),
                  rowPositions.at(row).toReal(),
                  (columnPositions.at(column + colSpan - 1) + widths.at(column + colSpan - 1) - columnPositions.at(column)).toReal(),
                  (rowPositions.at(row + rowSpan - 1) + heights.at(row + rowSpan - 1) - rowPositions.at(row)).toReal());
}

static inline bool isEmptyBlockBeforeTable(const QTextBlock &block, const QTextFrame::Iterator &nextIt)
{
    QTextBlockFormat format = block.blockFormat();
    return !nextIt.atEnd()
           && qobject_cast<QTextTable *>(nextIt.currentFrame())
           && block.isValid()
           && block.length() == 1
           && !format.hasProperty(QTextFormat::BlockTrailingHorizontalRulerWidth)
           && !format.hasProperty(QTextFormat::BackgroundBrush)
           && nextIt.currentFrame()->firstPosition() == block.position() + 1
           ;
}

static inline bool isEmptyBlockBeforeTable(QTextFrame::Iterator it)
{
    QTextFrame::Iterator next = it; ++next;
    return it.currentFrame() == 0
           && isEmptyBlockBeforeTable(it.currentBlock(), next);
}

static inline bool isEmptyBlockAfterTable(const QTextBlock &block, const QTextFrame *lastFrame)
{
    return qobject_cast<const QTextTable *>(lastFrame)
           && block.isValid()
           && block.length() == 1
           && lastFrame->lastPosition() == block.position() - 1
           ;
}

static inline bool isLineSeparatorBlockAfterTable(const QTextBlock &block, const QTextFrame *lastFrame)
{
    return qobject_cast<const QTextTable *>(lastFrame)
           && block.isValid()
           && block.length() > 1
           && block.text().at(0) == QChar::LineSeparator
           && lastFrame->lastPosition() == block.position() - 1
           ;
}

/*

Optimisation strategies:

HTML layout:

* Distinguish between normal and special flow. For normal flow the condition:
  y1 > y2 holds for all blocks with b1.key() > b2.key().
* Special flow is: floats, table cells

* Normal flow within table cells. Tables (not cells) are part of the normal flow.


* If blocks grows/shrinks in height and extends over whole page width at the end, move following blocks.
* If height doesn't change, no need to do anything

Table cells:

* If minWidth of cell changes, recalculate table width, relayout if needed.
* What about maxWidth when doing auto layout?

Floats:
* need fixed or proportional width, otherwise don't float!
* On width/height change relayout surrounding paragraphs.

Document width change:
* full relayout needed


Float handling:

* Floats are specified by a special format object.
* currently only floating images are implemented.

*/

/*

   On the table layouting:

   +---[ table border ]-------------------------
   |      [ cell spacing ]
   |  +------[ cell border ]-----+  +--------
   |  |                          |  |
   |  |
   |  |
   |  |
   |

   rowPositions[i] and columnPositions[i] point at the cell content
   position. So for example the left border is drawn at
   x = columnPositions[i] - fd->border and similar for y.

*/

enum {
    TextIndentValue = 40
};

struct QCheckPoint
{
    QFixed y;
    QFixed frameY; // absolute y position of the current frame
    int positionInFrame;
    QFixed minimumWidth;
    QFixed maximumWidth;
    QFixed contentsWidth;
};
Q_DECLARE_TYPEINFO(QCheckPoint, Q_PRIMITIVE_TYPE);