qgridlayoutengine_p.h

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#ifndef QGRIDLAYOUTENGINE_P_H
#define QGRIDLAYOUTENGINE_P_H

//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists for the convenience
// of the graphics view layout classes.  This header
// file may change from version to version without notice, or even be removed.
//
// We mean it.
//

#include "qalgorithms.h"
#include "qbitarray.h"
#include "qlist.h"
#include "qmap.h"
#include "qpair.h"
#include "qvector.h"
#include "qgraphicslayout_p.h"
#include <float.h>

QT_BEGIN_NAMESPACE

class QGraphicsLayoutItem;
class QStyle;
class QWidget;

// ### deal with Descent in a similar way
enum {
    MinimumSize = Qt::MinimumSize,
    PreferredSize = Qt::PreferredSize,
    MaximumSize = Qt::MaximumSize,
    NSizes
};

// do not reorder
enum {
    Hor,
    Ver,
    NOrientations
};

// do not reorder
enum LayoutSide {
    Left,
    Top,
    Right,
    Bottom
};

enum {
    NoConstraint,
    HorizontalConstraint,   // Width depends on the height
    VerticalConstraint,     // Height depends on the width
    UnknownConstraint,      // need to update cache
    UnfeasibleConstraint    // not feasible, it be has some items with Vertical and others with Horizontal constraints
};

template <typename T>
class QLayoutParameter
{
public:
    enum State { Default, User, Cached };

    inline QLayoutParameter() : q_value(T()), q_state(Default) {}
    inline QLayoutParameter(T value, State state = Default) : q_value(value), q_state(state) {}

    inline void setUserValue(T value) {
        q_value = value;
        q_state = User;
    }
    inline void setCachedValue(T value) const {
        if (q_state != User) {
            q_value = value;
            q_state = Cached;
        }
    }
    inline T value() const { return q_value; }
    inline T value(T defaultValue) const { return isUser() ? q_value : defaultValue; }
    inline bool isDefault() const { return q_state == Default; }
    inline bool isUser() const { return q_state == User; }
    inline bool isCached() const { return q_state == Cached; }

private:
    mutable T q_value;
    mutable State q_state;
};

class QStretchParameter : public QLayoutParameter<int>
{
public:
    QStretchParameter() : QLayoutParameter<int>(-1) {}

};

class QGridLayoutBox
{
public:
    inline QGridLayoutBox()
        : q_minimumSize(0), q_preferredSize(0), q_maximumSize(FLT_MAX),
          q_minimumDescent(-1), q_minimumAscent(-1) {}

    void add(const QGridLayoutBox &other, int stretch, qreal spacing);
    void combine(const QGridLayoutBox &other);
    void normalize();

#ifdef QT_DEBUG
    void dump(int indent = 0) const;
#endif
    // This code could use the union-struct-array trick, but a compiler
    // bug prevents this from working.
    qreal q_minimumSize;
    qreal q_preferredSize;
    qreal q_maximumSize;
    qreal q_minimumDescent;
    qreal q_minimumAscent;
    inline qreal &q_sizes(int which)
    {
        qreal *t;
        switch (which) {
        case Qt::MinimumSize:
            t = &q_minimumSize;
            break;
        case Qt::PreferredSize:
            t = &q_preferredSize;
            break;
        case Qt::MaximumSize:
            t = &q_maximumSize;
            break;
        case Qt::MinimumDescent:
            t = &q_minimumDescent;
            break;
        case (Qt::MinimumDescent + 1):
            t = &q_minimumAscent;
            break;
        default:
            t = 0;
            break;
        }
        return *t;
    }
    inline const qreal &q_sizes(int which) const
    {
        const qreal *t;
        switch (which) {
        case Qt::MinimumSize:
            t = &q_minimumSize;
            break;
        case Qt::PreferredSize:
            t = &q_preferredSize;
            break;
        case Qt::MaximumSize:
            t = &q_maximumSize;
            break;
        case Qt::MinimumDescent:
            t = &q_minimumDescent;
            break;
        case (Qt::MinimumDescent + 1):
            t = &q_minimumAscent;
            break;
        default:
            t = 0;
            break;
        }
        return *t;
    }
};

bool operator==(const QGridLayoutBox &box1, const QGridLayoutBox &box2);
inline bool operator!=(const QGridLayoutBox &box1, const QGridLayoutBox &box2)
    { return !operator==(box1, box2); }

class QGridLayoutMultiCellData
{
public:
    inline QGridLayoutMultiCellData() : q_stretch(-1) {}

    QGridLayoutBox q_box;
    int q_stretch;
};

typedef QMap<QPair<int, int>, QGridLayoutMultiCellData> MultiCellMap;

class QGridLayoutRowInfo;

class QGridLayoutRowData
{
public:
    void reset(int count);
    void distributeMultiCells(const QGridLayoutRowInfo &rowInfo);
    void calculateGeometries(int start, int end, qreal targetSize, qreal *positions, qreal *sizes,
                             qreal *descents, const QGridLayoutBox &totalBox,
                             const QGridLayoutRowInfo &rowInfo);
    QGridLayoutBox totalBox(int start, int end) const;
    void stealBox(int start, int end, int which, qreal *positions, qreal *sizes);

#ifdef QT_DEBUG
    void dump(int indent = 0) const;
#endif

    QBitArray ignore;   // ### rename q_
    QVector<QGridLayoutBox> boxes;
    MultiCellMap multiCellMap;
    QVector<int> stretches;
    QVector<qreal> spacings;
    bool hasIgnoreFlag;
};

class QGridLayoutEngine;

class QGridLayoutItem
{
public:
    QGridLayoutItem(QGridLayoutEngine *engine, QGraphicsLayoutItem *layoutItem, int row, int column,
                    int rowSpan = 1, int columnSpan = 1, Qt::Alignment alignment = 0,
                    int itemAtIndex = -1);

    inline int firstRow() const { return q_firstRows[Ver]; }
    inline int firstColumn() const { return q_firstRows[Hor]; }
    inline int rowSpan() const { return q_rowSpans[Ver]; }
    inline int columnSpan() const { return q_rowSpans[Hor]; }
    inline int lastRow() const { return firstRow() + rowSpan() - 1; }
    inline int lastColumn() const { return firstColumn() + columnSpan() - 1; }

    int firstRow(Qt::Orientation orientation) const;
    int firstColumn(Qt::Orientation orientation) const;
    int lastRow(Qt::Orientation orientation) const;
    int lastColumn(Qt::Orientation orientation) const;
    int rowSpan(Qt::Orientation orientation) const;
    int columnSpan(Qt::Orientation orientation) const;
    void setFirstRow(int row, Qt::Orientation orientation = Qt::Vertical);
    void setRowSpan(int rowSpan, Qt::Orientation orientation = Qt::Vertical);

    int stretchFactor(Qt::Orientation orientation) const;
    void setStretchFactor(int stretch, Qt::Orientation orientation);

    inline Qt::Alignment alignment() const { return q_alignment; }
    inline void setAlignment(Qt::Alignment alignment) { q_alignment = alignment; }

    QSizePolicy::Policy sizePolicy(Qt::Orientation orientation) const;

    bool hasDynamicConstraint() const;
    Qt::Orientation dynamicConstraintOrientation() const;

    QSizePolicy::ControlTypes controlTypes(LayoutSide side) const;
    QSizeF sizeHint(Qt::SizeHint which, const QSizeF &constraint = QSizeF()) const;
    QGridLayoutBox box(Qt::Orientation orientation, qreal constraint = -1.0) const;
    QRectF geometryWithin(qreal x, qreal y, qreal width, qreal height, qreal rowDescent) const;

    QGraphicsLayoutItem *layoutItem() const { return q_layoutItem; }

    void setGeometry(const QRectF &rect);
    void transpose();
    void insertOrRemoveRows(int row, int delta, Qt::Orientation orientation = Qt::Vertical);
    QSizeF effectiveMaxSize(const QSizeF &constraint) const;

#ifdef QT_DEBUG
    void dump(int indent = 0) const;
#endif

private:
    QGridLayoutEngine *q_engine;   // ### needed?
    QGraphicsLayoutItem *q_layoutItem;
    int q_firstRows[NOrientations];
    int q_rowSpans[NOrientations];
    int q_stretches[NOrientations];
    Qt::Alignment q_alignment;
};

class QGridLayoutRowInfo
{
public:
    inline QGridLayoutRowInfo() : count(0) {}

    void insertOrRemoveRows(int row, int delta);

#ifdef QT_DEBUG
    void dump(int indent = 0) const;
#endif

    int count;
    QVector<QStretchParameter> stretches;
    QVector<QLayoutParameter<qreal> > spacings;
    QVector<Qt::Alignment> alignments;
    QVector<QGridLayoutBox> boxes;
};

class QGridLayoutEngine
{
public:
    QGridLayoutEngine();
    inline ~QGridLayoutEngine() { qDeleteAll(q_items); }

    int rowCount(Qt::Orientation orientation) const;
    int columnCount(Qt::Orientation orientation) const;
    inline int rowCount() const { return q_infos[Ver].count; }
    inline int columnCount() const { return q_infos[Hor].count; }
    // returns the number of items inserted, which may be less than (rowCount * columnCount)
    int itemCount() const;
    QGridLayoutItem *itemAt(int index) const;
    int indexOf(QGraphicsLayoutItem *item) const;

    int effectiveFirstRow(Qt::Orientation orientation = Qt::Vertical) const;
    int effectiveLastRow(Qt::Orientation orientation = Qt::Vertical) const;

    void setSpacing(qreal spacing, Qt::Orientations orientations);
    qreal spacing(const QLayoutStyleInfo &styleInfo, Qt::Orientation orientation) const;
    // ### setSpacingAfterRow(), spacingAfterRow()
    void setRowSpacing(int row, qreal spacing, Qt::Orientation orientation = Qt::Vertical);
    qreal rowSpacing(int row, Qt::Orientation orientation = Qt::Vertical) const;

    void setRowStretchFactor(int row, int stretch, Qt::Orientation orientation = Qt::Vertical);
    int rowStretchFactor(int row, Qt::Orientation orientation = Qt::Vertical) const;

    void setStretchFactor(QGraphicsLayoutItem *layoutItem, int stretch,
                          Qt::Orientation orientation);
    int stretchFactor(QGraphicsLayoutItem *layoutItem, Qt::Orientation orientation) const;

    void setRowSizeHint(Qt::SizeHint which, int row, qreal size,
                        Qt::Orientation orientation = Qt::Vertical);
    qreal rowSizeHint(Qt::SizeHint which, int row,
                      Qt::Orientation orientation = Qt::Vertical) const;

    void setRowAlignment(int row, Qt::Alignment alignment, Qt::Orientation orientation);
    Qt::Alignment rowAlignment(int row, Qt::Orientation orientation) const;

    void setAlignment(QGraphicsLayoutItem *layoutItem, Qt::Alignment alignment);
    Qt::Alignment alignment(QGraphicsLayoutItem *layoutItem) const;
    Qt::Alignment effectiveAlignment(const QGridLayoutItem *layoutItem) const;


    void insertItem(QGridLayoutItem *item, int index);
    void addItem(QGridLayoutItem *item);
    void removeItem(QGridLayoutItem *item);
    QGridLayoutItem *findLayoutItem(QGraphicsLayoutItem *layoutItem) const;
    QGridLayoutItem *itemAt(int row, int column, Qt::Orientation orientation = Qt::Vertical) const;
    inline void insertRow(int row, Qt::Orientation orientation = Qt::Vertical)
        { insertOrRemoveRows(row, +1, orientation); }
    inline void removeRows(int row, int count, Qt::Orientation orientation)
        { insertOrRemoveRows(row, -count, orientation); }

    void invalidate();
    void setGeometries(const QLayoutStyleInfo &styleInfo, const QRectF &contentsGeometry);
    QRectF cellRect(const QLayoutStyleInfo &styleInfo, const QRectF &contentsGeometry, int row,
                    int column, int rowSpan, int columnSpan) const;
    QSizeF sizeHint(const QLayoutStyleInfo &styleInfo, Qt::SizeHint which,
                    const QSizeF &constraint) const;

    // heightForWidth / widthForHeight support
    QSizeF dynamicallyConstrainedSizeHint(Qt::SizeHint which, const QSizeF &constraint) const;
    bool ensureDynamicConstraint() const;
    bool hasDynamicConstraint() const;
    Qt::Orientation constraintOrientation() const;


    QSizePolicy::ControlTypes controlTypes(LayoutSide side) const;
    void transpose();
    void setVisualDirection(Qt::LayoutDirection direction);
    Qt::LayoutDirection visualDirection() const;
#ifdef QT_DEBUG
    void dump(int indent = 0) const;
#endif

private:
    static int grossRoundUp(int n) { return ((n + 2) | 0x3) - 2; }

    void maybeExpandGrid(int row, int column, Qt::Orientation orientation = Qt::Vertical);
    void regenerateGrid();
    inline int internalGridRowCount() const { return grossRoundUp(rowCount()); }
    inline int internalGridColumnCount() const { return grossRoundUp(columnCount()); }
    void setItemAt(int row, int column, QGridLayoutItem *item);
    void insertOrRemoveRows(int row, int delta, Qt::Orientation orientation = Qt::Vertical);
    void fillRowData(QGridLayoutRowData *rowData, const QLayoutStyleInfo &styleInfo,
                                    qreal *colPositions, qreal *colSizes,
                                    Qt::Orientation orientation = Qt::Vertical) const;
    void ensureEffectiveFirstAndLastRows() const;
    void ensureColumnAndRowData(QGridLayoutRowData *rowData, QGridLayoutBox *totalBox,
                                            const QLayoutStyleInfo &styleInfo,
                                            qreal *colPositions, qreal *colSizes,
                                            Qt::Orientation orientation) const;

    void ensureGeometries(const QLayoutStyleInfo &styleInfo, const QSizeF &size) const;

    // User input
    QVector<QGridLayoutItem *> q_grid;
    QList<QGridLayoutItem *> q_items;
    QLayoutParameter<qreal> q_defaultSpacings[NOrientations];
    QGridLayoutRowInfo q_infos[NOrientations];
    Qt::LayoutDirection m_visualDirection;

    // Lazily computed from the above user input
    mutable int q_cachedEffectiveFirstRows[NOrientations];
    mutable int q_cachedEffectiveLastRows[NOrientations];
    mutable quint8 q_cachedConstraintOrientation : 3;

    // Layout item input
    mutable QLayoutStyleInfo q_cachedDataForStyleInfo;
    mutable QGridLayoutRowData q_columnData;
    mutable QGridLayoutRowData q_rowData;
    mutable QGridLayoutBox q_totalBoxes[NOrientations];

    // Output
    mutable QSizeF q_cachedSize;
    mutable QVector<qreal> q_xx;
    mutable QVector<qreal> q_yy;
    mutable QVector<qreal> q_widths;
    mutable QVector<qreal> q_heights;
    mutable QVector<qreal> q_descents;

    friend class QGridLayoutItem;
};

QT_END_NAMESPACE

#endif