Add qDrawBorderPixmap() function, Qt::TileRules enum, QMargins struct and QTileRules struct.

Implements a function to allow drawing CSS3-like border-images (also known as nine-grid images). Next step will be to convert the CSS-style code to use this function for drawing border-images.

Task-number: none
Reviewed-by: jbache

4 files changed, 346 insertions, 0 deletions

diff --git a/doc/src/qnamespace.qdoc b/doc/src/qnamespace.qdoc
index 097333b..9ea6b52 100644
--- a/doc/src/qnamespace.qdoc
+++ b/doc/src/qnamespace.qdoc
@@ -2651,3 +2651,16 @@
     \sa QGraphicsWidget::windowFrameSectionAt()
 
 */
+
+/*!
+  \enum Qt::TileRule
+  \since 4.6
+
+  This enum describes how to repeat or stretch the parts of an image when drawing.
+
+  \value Stretch   Scale the image to fit to the available area.
+  \value Repeat    Tile the image until there is no more space. May crop the last image.
+  \value Round     Like Repeat, but scales the images down to ensure that the last image is not cropped.
+
+  \sa QPixmapBorders, qDrawBorderPixmap()
+*/
diff --git a/src/corelib/global/qnamespace.h b/src/corelib/global/qnamespace.h
index a519f4a..9b26ef3 100644
--- a/src/corelib/global/qnamespace.h
+++ b/src/corelib/global/qnamespace.h
@@ -188,6 +188,12 @@ public:
 #endif
     };
 
+    enum TileRule {
+        Stretch,
+        Repeat,
+        Round
+    };
+
     // Text formatting flags for QPainter::drawText and QLabel.
     // The following two enums can be combined to one integer which
     // is passed as 'flags' to drawText and qt_format_text.
diff --git a/src/gui/painting/qdrawutil.cpp b/src/gui/painting/qdrawutil.cpp
index 2beeb0e..4898b7e 100644
--- a/src/gui/painting/qdrawutil.cpp
+++ b/src/gui/painting/qdrawutil.cpp
@@ -1038,4 +1038,295 @@ void qDrawItem(QPainter *p, Qt::GUIStyle gs,
 
 #endif
 
+/*!
+  \struct QMargins
+  \since 4.6
+
+  Holds the borders used to split a pixmap on into nine segments in order to draw it,
+  similar to CSS3 border-images \l http://www.w3.org/TR/css3-background/.
+
+  \sa qDrawBorderPixmap, Qt::TileRule, QTileRules
+ */
+
+/*!
+  \struct QTileRules
+  \since 4.6
+
+  Holds the rules used to draw a pixmap or image split into nine segments, similar to CSS3 border-images.
+
+  \sa qDrawBorderPixmap, Qt::TileRule, QMargins
+ */
+
+/*!
+  \fn qDrawBorderPixmap(QPainter *painter, const QRect &target, const QMargins &margins, const QPixmap &pixmap)
+  \since 4.6
+
+  Draws the given \a pixmap into the given \a target rectangle, using the given \a painter.
+  The pixmap will be splitt into nine segments and drawn according to the given \a margins structure.
+ */
+
+static inline void qVerticalRepeat(QPainter *painter, const QRect &target, const QPixmap &pixmap, const QRect &source,
+                                   void (*drawPixmap)(QPainter*, const QRect&, const QPixmap&, const QRect&))
+{
+    const int x = target.x();
+    const int width = target.width();
+    const int height = source.height();
+    const int bottom = target.bottom() - height;
+    int y = target.y();
+    for (; y < bottom; y += height)
+        (*drawPixmap)(painter, QRect(x, y, width, height), pixmap, source);
+    const QRect remaining(source.x(), source.y(), source.width(), target.bottom() - y + 1);
+    (*drawPixmap)(painter, QRect(x, y, width, remaining.height()), pixmap, remaining);
+}
+
+static inline void qHorizontalRepeat(QPainter *painter, const QRect &target, const QPixmap &pixmap, const QRect &source,
+                                     void (*drawPixmap)(QPainter*, const QRect&, const QPixmap&, const QRect&))
+{
+    const int y = target.y();
+    const int width = source.width();
+    const int height = target.height();
+    const int right = target.right() - width;
+    int x = target.x();
+    for (; x < right; x += width)
+        (*drawPixmap)(painter, QRect(x, y, width, height), pixmap, source);
+    const QRect remaining(source.x(), source.y(), target.right() - x + 1, source.height());
+    (*drawPixmap)(painter, QRect(x, y, remaining.width(), height), pixmap, remaining);
+}
+
+static inline void qVerticalRound(QPainter *painter, const QRect &target, const QPixmap &pixmap, const QRect &source,
+                                  void (*drawPixmap)(QPainter*, const QRect&, const QPixmap&, const QRect&))
+{
+    // qreal based - slow on non-fpu devices
+    const qreal x = target.x();
+    const qreal width = target.width();
+    const qreal verticalFactor = static_cast<qreal>(target.height()) / static_cast<qreal>(source.height());
+    const qreal verticalIncrement = static_cast<qreal>(target.height()) / static_cast<int>(verticalFactor + 0.5);
+    const qreal bottom = target.bottom();
+    for (qreal y = static_cast<qreal>(target.y()); y < bottom; y += verticalIncrement)
+         (*drawPixmap)(painter, QRectF(x, y, width, verticalIncrement).toRect(), pixmap, source);
+
+}
+
+static inline void qHorizontalRound(QPainter *painter, const QRect &target, const QPixmap &pixmap, const QRect &source,
+                                    void (*drawPixmap)(QPainter*, const QRect&, const QPixmap&, const QRect&))
+{
+    // qreal based - slow on non-fpu devices
+    const qreal y = target.y();
+    const qreal height = target.height();
+    const qreal horizontalFactor = static_cast<qreal>(target.width()) / static_cast<qreal>(source.width());
+    const qreal horizontalIncrement = static_cast<qreal>(target.width()) / static_cast<int>(horizontalFactor + 0.5);
+    const qreal right = target.right();
+    for (qreal x = target.x(); x < right; x += horizontalIncrement)
+        (*drawPixmap)(painter, QRectF(x, y, horizontalIncrement, height).toRect(), pixmap, source);
+}
+
+static inline void qDrawPixmap(QPainter *painter, const QRect &target, const QPixmap &pixmap, const QRect &source)
+{
+    painter->drawPixmap(target, pixmap, source);
+}
+
+static inline void qDrawVerticallyRepeatedPixmap(QPainter *painter, const QRect &target, const QPixmap &pixmap, const QRect &source)
+{
+    qVerticalRepeat(painter, target, pixmap, source, qDrawPixmap);
+}
+
+static inline void qDrawHorizontallyRepeatedPixmap(QPainter *painter, const QRect &target, const QPixmap &pixmap, const QRect &source)
+{
+    qHorizontalRepeat(painter, target, pixmap, source, qDrawPixmap);
+}
+
+static inline void qDrawVerticallyRoundedPixmap(QPainter *painter, const QRect &target, const QPixmap &pixmap, const QRect &source)
+{
+    qVerticalRound(painter, target, pixmap, source, qDrawPixmap);
+}
+
+static inline void qDrawHorizontallyRoundedPixmap(QPainter *painter, const QRect &target, const QPixmap &pixmap, const QRect &source)
+{
+    qHorizontalRound(painter, target, pixmap, source, qDrawPixmap);
+}
+
+/*!
+  \since 4.6
+
+  Draws the indicated \a sourceRect rectangle from the given \a pixmap into the given \a targetRect rectangle,
+  using the given \a painter.
+  The pixmap will be splitt into nine segments according to the given \a targetMargins and
+  \a sourceMargins structures and drawn according to the given \a rules.
+
+  This function is used to draw a scaled pixmap, similar to CSS3 border-images.
+
+  \sa Qt::TileRule, QTileRules, QMargins
+ */
+void qDrawBorderPixmap(QPainter *painter, const QRect &targetRect, const QMargins &targetMargins, const QPixmap &pixmap,
+                       const QRect &sourceRect, const QMargins &sourceMargins, const QTileRules &rules)
+{
+    // source center
+    const int sourceTop = sourceRect.top();
+    const int sourceLeft = sourceRect.left();
+    const int sourceCenterTop = sourceTop + sourceMargins.top;
+    const int sourceCenterLeft = sourceLeft + sourceMargins.left;
+    const int sourceCenterBottom = sourceRect.bottom() - sourceMargins.bottom + 1;
+    const int sourceCenterRight = sourceRect.right() - sourceMargins.right + 1;
+    const int sourceCenterWidth = sourceCenterRight - sourceMargins.left;
+    const int sourceCenterHeight = sourceCenterBottom - sourceMargins.top;
+    // target center
+    const int targetTop = targetRect.top();
+    const int targetLeft = targetRect.left();
+    const int targetCenterTop = targetTop + targetMargins.top;
+    const int targetCenterLeft = targetLeft + targetMargins.left;
+    const int targetCenterBottom = targetRect.bottom() - targetMargins.bottom + 1;
+    const int targetCenterRight = targetRect.right() - targetMargins.right + 1;
+    const int targetCenterWidth = targetCenterRight - targetCenterLeft;
+    const int targetCenterHeight = targetCenterBottom - targetCenterTop;
+
+    // corners
+    if (targetMargins.top > 0 && targetMargins.left > 0 && sourceMargins.top > 0 && sourceMargins.left > 0) { // top left
+        const QRect targetTopLeftRect(targetLeft, targetTop, targetMargins.left, targetMargins.top);
+        const QRect sourceTopLeftRect(sourceLeft, sourceTop, sourceMargins.left, sourceMargins.top);
+        qDrawPixmap(painter, targetTopLeftRect, pixmap, sourceTopLeftRect);
+    }
+    if (targetMargins.top > 0 && targetMargins.right > 0 && sourceMargins.top > 0 && sourceMargins.right > 0) { // top right
+        const QRect targetTopRightRect(targetCenterRight, targetTop, targetMargins.right, targetMargins.top);
+        const QRect sourceTopRightRect(sourceCenterRight, sourceTop, sourceMargins.right, sourceMargins.top);
+        qDrawPixmap(painter, targetTopRightRect, pixmap, sourceTopRightRect);
+    }
+    if (targetMargins.bottom > 0 && targetMargins.left > 0 && sourceMargins.bottom > 0 && sourceMargins.left > 0) { // bottom left
+        const QRect targetBottomLeftRect(targetLeft, targetCenterBottom, targetMargins.left, targetMargins.bottom);
+        const QRect sourceBottomLeftRect(sourceLeft, sourceCenterBottom, sourceMargins.left, sourceMargins.bottom);
+        qDrawPixmap(painter, targetBottomLeftRect, pixmap, sourceBottomLeftRect);
+    }
+    if (targetMargins.bottom > 0 && targetMargins.right > 0 && sourceMargins.bottom > 0 && sourceMargins.right > 0) { // bottom right
+        const QRect targetBottomRightRect(targetCenterRight, targetCenterBottom, targetMargins.right, targetMargins.bottom);
+        const QRect sourceBottomRightRect(sourceCenterRight, sourceCenterBottom, sourceMargins.right, sourceMargins.bottom);
+        qDrawPixmap(painter, targetBottomRightRect, pixmap, sourceBottomRightRect);
+    }
+
+    // horizontal edges
+    switch (rules.horizontal) {
+        case Qt::Stretch:
+        if (targetMargins.top > 0 && sourceMargins.top > 0) { // top
+            const QRect targetTopRect(targetCenterLeft, targetTop, targetCenterWidth, targetMargins.top);
+            const QRect sourceTopRect(sourceCenterLeft, sourceTop, sourceCenterWidth, sourceMargins.top);
+            qDrawPixmap(painter, targetTopRect, pixmap, sourceTopRect);
+        }
+        if (targetMargins.bottom > 0 && sourceMargins.bottom > 0) { // bottom
+            const QRect targetBottomRect(targetCenterLeft, targetCenterBottom, targetCenterWidth, targetMargins.bottom);
+            const QRect sourceBottomRect(sourceCenterLeft, sourceCenterBottom, sourceCenterWidth, sourceMargins.bottom);
+            qDrawPixmap(painter, targetBottomRect, pixmap, sourceBottomRect);
+        }
+        break;
+        case Qt::Repeat:
+        if (targetMargins.top > 0 && sourceMargins.top > 0) { // top
+            const QRect targetTopRect(targetCenterLeft, targetTop, targetCenterWidth, targetMargins.top);
+            const QRect sourceTopRect(sourceCenterLeft, sourceTop, sourceCenterWidth, sourceMargins.top);
+            qDrawHorizontallyRepeatedPixmap(painter, targetTopRect, pixmap, sourceTopRect);
+        }
+        if (targetMargins.bottom > 0 && sourceMargins.bottom > 0) { // bottom
+            const QRect targetBottomRect(targetCenterLeft, targetCenterBottom, targetCenterWidth, targetMargins.bottom);
+            const QRect sourceBottomRect(sourceCenterLeft, sourceCenterBottom, sourceCenterWidth, sourceMargins.bottom);
+            qDrawHorizontallyRepeatedPixmap(painter, targetBottomRect, pixmap, sourceBottomRect);
+        }
+        break;
+        case Qt::Round:
+        if (targetMargins.top > 0 && sourceMargins.top > 0) { // top
+            const QRect targetTopRect(targetCenterLeft, targetTop, targetCenterWidth, targetMargins.top);
+            const QRect sourceTopRect(sourceCenterLeft, sourceTop, sourceCenterWidth, sourceMargins.top);
+            qDrawHorizontallyRoundedPixmap(painter, targetTopRect, pixmap, sourceTopRect);
+        }
+        if (targetMargins.bottom > 0 && sourceMargins.bottom > 0) { // bottom
+            const QRect targetBottomRect(targetCenterLeft, targetCenterBottom, targetCenterWidth, targetMargins.bottom);
+            const QRect sourceBottomRect(sourceCenterLeft, sourceCenterBottom, sourceCenterWidth, sourceMargins.bottom);
+            qDrawHorizontallyRoundedPixmap(painter, targetBottomRect, pixmap, sourceBottomRect);
+        }
+        break;
+    }
+
+    // vertical edges
+    switch (rules.vertical) {
+        case Qt::Stretch:
+        if (targetMargins.left > 0 && sourceMargins.left > 0) { // left
+            const QRect targetLeftRect(targetLeft, targetCenterTop, targetMargins.left, targetCenterHeight);
+            const QRect sourceLeftRect(sourceLeft, sourceCenterTop, sourceMargins.left, sourceCenterHeight);
+            qDrawPixmap(painter, targetLeftRect, pixmap, sourceLeftRect);
+        }
+        if (targetMargins.right > 0 && sourceMargins.right > 0) { // right
+            const QRect targetRightRect(targetCenterRight, targetCenterTop, targetMargins.right, targetCenterHeight);
+            const QRect sourceRightRect(sourceCenterRight, sourceCenterTop, sourceMargins.right, sourceCenterHeight);
+            qDrawPixmap(painter, targetRightRect, pixmap, sourceRightRect);
+        }
+        break;
+        case Qt::Repeat:
+        if (targetMargins.left > 0 && sourceMargins.left > 0) { // left
+            const QRect targetLeftRect(targetLeft, targetCenterTop, targetMargins.left, targetCenterHeight);
+            const QRect sourceLeftRect(sourceLeft, sourceCenterTop, sourceMargins.left, sourceCenterHeight);
+            qDrawVerticallyRepeatedPixmap(painter, targetLeftRect, pixmap, sourceLeftRect);
+        }
+        if (targetMargins.right > 0 && sourceMargins.right > 0) { // right
+            const QRect targetRightRect(targetCenterRight, targetCenterTop, targetMargins.right, targetCenterHeight);
+            const QRect sourceRightRect(sourceCenterRight, sourceCenterTop, sourceMargins.right, sourceCenterHeight);
+            qDrawVerticallyRepeatedPixmap(painter, targetRightRect, pixmap, sourceRightRect);
+        }
+        break;
+        case Qt::Round:
+        if (targetMargins.left > 0 && sourceMargins.left > 0) { // left
+            const QRect targetLeftRect(targetLeft, targetCenterTop, targetMargins.left, targetCenterHeight);
+            const QRect sourceLeftRect(sourceLeft, sourceCenterTop, sourceMargins.left, sourceCenterHeight);
+            qDrawVerticallyRoundedPixmap(painter, targetLeftRect, pixmap, sourceLeftRect);
+        }
+        if (targetMargins.right > 0 && sourceMargins.right > 0) { // right
+            const QRect targetRightRect(targetCenterRight, targetCenterTop, targetMargins.right, targetCenterHeight);
+            const QRect sourceRightRect(sourceCenterRight, sourceCenterTop, sourceMargins.right, sourceCenterHeight);
+            qDrawVerticallyRoundedPixmap(painter, targetRightRect, pixmap, sourceRightRect);
+        }
+        break;
+    }
+
+    // center
+    if (targetCenterWidth > 0 && targetCenterHeight > 0 && sourceCenterWidth > 0 && sourceCenterHeight > 0) {
+        const QRect targetCenterRect(targetCenterLeft, targetCenterTop, targetCenterWidth, targetCenterHeight);
+        const QRect sourceCenterRect(sourceCenterLeft, sourceCenterTop, sourceCenterWidth, sourceCenterHeight);
+        switch (rules.horizontal) {
+        case Qt::Stretch:
+            switch (rules.vertical) {
+                case Qt::Stretch: // stretch stretch
+                    qDrawPixmap(painter, targetCenterRect, pixmap, sourceCenterRect);
+                break;
+                case Qt::Repeat: // stretch repeat
+                    qVerticalRepeat(painter, targetCenterRect, pixmap, sourceCenterRect, qDrawPixmap);
+                break;
+                case Qt::Round: // stretch round
+                    qVerticalRound(painter, targetCenterRect, pixmap, sourceCenterRect, qDrawPixmap);
+                break;
+            }
+            break;
+        case Qt::Repeat:
+            switch (rules.vertical) {
+                case Qt::Stretch: // repeat stretch
+                    qHorizontalRepeat(painter, targetCenterRect, pixmap, sourceCenterRect, qDrawPixmap);
+                break;
+                case Qt::Repeat: // repeat repeat
+                    qVerticalRepeat(painter, targetCenterRect, pixmap, sourceCenterRect, qDrawHorizontallyRepeatedPixmap);
+                break;
+                case Qt::Round: // repeat round
+                    qVerticalRound(painter, targetCenterRect, pixmap, sourceCenterRect, qDrawHorizontallyRepeatedPixmap);
+                break;
+            }
+            break;
+        case Qt::Round:
+            switch (rules.vertical) {
+                case Qt::Stretch: // round stretch
+                    qHorizontalRound(painter, targetCenterRect, pixmap, sourceCenterRect, qDrawPixmap);
+                break;
+                case Qt::Repeat: // round repeat
+                    qHorizontalRound(painter, targetCenterRect, pixmap, sourceCenterRect, qDrawVerticallyRepeatedPixmap);
+                break;
+                case Qt::Round: // round round
+                    qHorizontalRound(painter, targetCenterRect, pixmap, sourceCenterRect, qDrawVerticallyRoundedPixmap);
+                break;
+            }
+            break;
+        }
+    }
+}
+
 QT_END_NAMESPACE
diff --git a/src/gui/painting/qdrawutil.h b/src/gui/painting/qdrawutil.h
index 14901f3..08fa1ab 100644
--- a/src/gui/painting/qdrawutil.h
+++ b/src/gui/painting/qdrawutil.h
@@ -133,6 +133,42 @@ Q_GUI_EXPORT QT3_SUPPORT void qDrawArrow(QPainter *p, Qt::ArrowType type, Qt::GU
                           const QPalette &pal, bool enabled);
 #endif
 
+struct Q_GUI_EXPORT QMargins
+{
+    inline QMargins(int margin = 0)
+        : top(margin),
+          left(margin),
+          bottom(margin),
+          right(margin) {}
+    inline QMargins(int topMargin, int leftMargin, int bottomMargin, int rightMargin)
+         : top(topMargin),
+           left(leftMargin),
+           bottom(bottomMargin),
+           right(rightMargin) {}
+    int top;
+    int left;
+    int bottom;
+    int right;
+};
+
+struct Q_GUI_EXPORT QTileRules
+{
+    inline QTileRules(Qt::TileRule horizontalRule = Qt::Stretch,
+                      Qt::TileRule verticalRule = Qt::Stretch)
+            : horizontal(horizontalRule),
+              vertical(verticalRule) {}
+    Qt::TileRule horizontal;
+    Qt::TileRule vertical;
+};
+
+Q_GUI_EXPORT void qDrawBorderPixmap(QPainter *painter, const QRect &targetRect, const QMargins &targetMargins, const QPixmap &pixmap,
+                                    const QRect &sourceRect, const QMargins &sourceMargins, const QTileRules &rules = QTileRules());
+
+Q_GUI_EXPORT inline void qDrawBorderPixmap(QPainter *painter, const QRect &target, const QMargins &margins, const QPixmap &pixmap)
+{
+    qDrawBorderPixmap(painter, target, margins, pixmap, pixmap.rect(), margins);
+}
+
 QT_END_NAMESPACE
 
 QT_END_HEADER