Fallback to vgWritePixels in drawPixmap.

Use vgWritePixels, if possible, in case where VGImage
for QPixmap can't be allocated due to low GPU memory
situation. This patch also renames some VG paint engine
internal functions to clarify their purpose.

Task-number: QT-3589
Reviewed-by: Jason Barron

1 files changed, 77 insertions, 9 deletions

diff --git a/src/openvg/qpaintengine_vg.cpp b/src/openvg/qpaintengine_vg.cpp
index ce9d11a..9df32d9 100644
--- a/src/openvg/qpaintengine_vg.cpp
+++ b/src/openvg/qpaintengine_vg.cpp
@@ -55,6 +55,8 @@
 #include <QtGui/private/qfontengine_p.h>
 #include <QtGui/private/qpainterpath_p.h>
 #include <QtGui/private/qstatictext_p.h>
+#include <QtGui/QApplication>
+#include <QtGui/QDesktopWidget>
 #include <QtCore/qmath.h>
 #include <QDebug>
 #include <QSet>
@@ -3060,6 +3062,21 @@ void qt_vg_drawVGImageStencil
     vgDrawImage(vgImg);
 }
 
+bool QVGPaintEngine::canVgWritePixels(const QImage &image) const
+{
+    Q_D(const QVGPaintEngine);
+    // vgWritePixels ignores masking, blending and xforms so we can only use it if
+    // ALL of the following conditions are true:
+    // - It is a simple translate, or a scale of -1 on the y-axis (inverted)
+    // - The opacity is totally opaque
+    // - The composition mode is "source" OR "source over" provided the image is opaque
+    return ( d->imageTransform.type() <= QTransform::TxScale
+            && d->imageTransform.m11() == 1.0 && qAbs(d->imageTransform.m22()) == 1.0)
+            && d->opacity == 1.0f
+            && (d->blendMode == VG_BLEND_SRC || (d->blendMode == VG_BLEND_SRC_OVER &&
+                                                !image.hasAlphaChannel()));
+}
+
 void QVGPaintEngine::drawPixmap(const QRectF &r, const QPixmap &pm, const QRectF &sr)
 {
     QPixmapData *pd = pm.pixmapData();
@@ -3074,9 +3091,18 @@ void QVGPaintEngine::drawPixmap(const QRectF &r, const QPixmap &pm, const QRectF
             drawVGImage(d, r, vgpd->toVGImage(), vgpd->size(), sr);
         else
             drawVGImage(d, r, vgpd->toVGImage(d->opacity), vgpd->size(), sr);
-    } else {
-        drawImage(r, *(pd->buffer()), sr, Qt::AutoColor);
+
+        if(!vgpd->failedToAlloc)
+            return;
+
+        // try to reallocate next time if reasonable small pixmap
+        QSize screenSize = QApplication::desktop()->screenGeometry().size();
+        if (pm.size().width() <= screenSize.width()
+            && pm.size().height() <= screenSize.height())
+            vgpd->failedToAlloc = false;
     }
+
+    drawImage(r, *(pd->buffer()), sr, Qt::AutoColor);
 }
 
 void QVGPaintEngine::drawPixmap(const QPointF &pos, const QPixmap &pm)
@@ -3093,9 +3119,18 @@ void QVGPaintEngine::drawPixmap(const QPointF &pos, const QPixmap &pm)
             drawVGImage(d, pos, vgpd->toVGImage());
         else
             drawVGImage(d, pos, vgpd->toVGImage(d->opacity));
-    } else {
-        drawImage(pos, *(pd->buffer()));
+
+        if (!vgpd->failedToAlloc)
+            return;
+
+        // try to reallocate next time if reasonable small pixmap
+        QSize screenSize = QApplication::desktop()->screenGeometry().size();
+        if (pm.size().width() <= screenSize.width()
+            && pm.size().height() <= screenSize.height())
+            vgpd->failedToAlloc = false;
     }
+
+    drawImage(pos, *(pd->buffer()));
 }
 
 void QVGPaintEngine::drawImage
@@ -3116,9 +3151,31 @@ void QVGPaintEngine::drawImage
                         QRectF(QPointF(0, 0), sr.size()));
         }
     } else {
-        // Monochrome images need to use the vgChildImage() path.
-        vgImg = toVGImage(image, flags);
-        drawVGImage(d, r, vgImg, image.size(), sr);
+        if (canVgWritePixels(image) && (r.size() == sr.size()) && !flags) {
+            // Optimization for straight blits, no blending
+            int x = sr.x();
+            int y = sr.y();
+            int bpp = image.depth() >> 3; // bytes
+            int offset = 0;
+            int bpl = image.bytesPerLine();
+            if (d->imageTransform.m22() < 0) {
+                // inverted
+                offset = ((y + sr.height()) * bpl) - ((image.width() - x) * bpp);
+                bpl = -bpl;
+            } else {
+                offset = (y * bpl) + (x * bpp);
+            }
+            const uchar *bits = image.constBits() + offset;
+
+            QPointF mapped = d->imageTransform.map(r.topLeft());
+            vgWritePixels(bits, bpl, qt_vg_image_to_vg_format(image.format()),
+                        mapped.x(), mapped.y() - sr.height(), r.width(), r.height());
+            return;
+        } else {
+            // Monochrome images need to use the vgChildImage() path.
+            vgImg = toVGImage(image, flags);
+            drawVGImage(d, r, vgImg, image.size(), sr);
+        }
     }
     vgDestroyImage(vgImg);
 }
@@ -3127,10 +3184,21 @@ void QVGPaintEngine::drawImage(const QPointF &pos, const QImage &image)
 {
     Q_D(QVGPaintEngine);
     VGImage vgImg;
-    if (d->simpleTransform || d->opacity == 1.0f)
+    if (canVgWritePixels(image)) {
+        // Optimization for straight blits, no blending
+        bool inverted = (d->imageTransform.m22() < 0);
+        const uchar *bits = inverted ? image.constBits() + image.byteCount() : image.constBits();
+        int bpl = inverted ? -image.bytesPerLine() : image.bytesPerLine();
+
+        QPointF mapped = d->imageTransform.map(pos);
+        vgWritePixels(bits, bpl, qt_vg_image_to_vg_format(image.format()),
+                             mapped.x(), mapped.y() - image.height(), image.width(), image.height());
+        return;
+    } else if (d->simpleTransform || d->opacity == 1.0f) {
         vgImg = toVGImage(image);
-    else
+    } else {
         vgImg = toVGImageWithOpacity(image, d->opacity);
+    }
     drawVGImage(d, pos, vgImg);
     vgDestroyImage(vgImg);
 }