Followup b8bc181, don't create unnecessary temporary image

Author: nyalldawson

python/core/effects/qgsimageoperation.sip

@@ -131,12 +131,23 @@ class QgsImageOperation
      */
     static void flipImage( QImage &image, FlipType type );
 
+    /** Calculates the non-transparent region of an image.
+     * @param image source image
+     * @param minSize minimum size for returned region, if desired. If the
+     * non-transparent region of the image is smaller than this minimum size,
+     * it will be centered in the returned rectangle.
+     * @param center return rectangle will be centered on the center of the original image if set to true
+     * @note added in QGIS 2.9
+     * @see cropTransparent
+     */
+    static QRect nonTransparentImageRect( const QImage & image, const QSize& minSize = QSize(), bool center = false );
+
     /** Crop any transparent border from around an image.
      * @param image source image
      * @param minSize minimum size for cropped image, if desired. If the
      * cropped image is smaller than the minimum size, it will be centered
      * in the returned image.
-     * @param center croped image will be centered on the center of the original image
+     * @param center cropped image will be centered on the center of the original image if set to true
      * @note added in QGIS 2.9
      */
     static QImage cropTransparent( const QImage & image, const QSize& minSize = QSize(), bool center = false );

src/core/effects/qgsimageoperation.cpp

@@ -793,7 +793,7 @@ void QgsImageOperation::flipImage( QImage &image, QgsImageOperation::FlipType ty
   runLineOperation( image, flipOperation );
 }
 
-QImage QgsImageOperation::cropTransparent( const QImage &image, const QSize &minSize, bool center )
+QRect QgsImageOperation::nonTransparentImageRect( const QImage &image, const QSize &minSize, bool center )
 {
   int width = image.width();
   int height = image.height();
@@ -838,7 +838,13 @@ QImage QgsImageOperation::cropTransparent( const QImage &image, const QSize &min
     ymin = qMax( 0, height / 2 - dy );
     ymax = qMin( height, height / 2 + dy );
   }
-  return image.copy( xmin, ymin, xmax - xmin, ymax - ymin );
+
+  return QRect( xmin, ymin, xmax - xmin, ymax - ymin );
+}
+
+QImage QgsImageOperation::cropTransparent( const QImage &image, const QSize &minSize, bool center )
+{
+  return image.copy( QgsImageOperation::nonTransparentImageRect( image, minSize, center ) );
 }
 
 void QgsImageOperation::FlipLineOperation::operator()( QRgb *startRef, const int lineLength, const int bytesPerLine )

src/core/effects/qgsimageoperation.h

@@ -162,12 +162,23 @@ class CORE_EXPORT QgsImageOperation
      */
     static void flipImage( QImage &image, FlipType type );
 
+    /** Calculates the non-transparent region of an image.
+     * @param image source image
+     * @param minSize minimum size for returned region, if desired. If the
+     * non-transparent region of the image is smaller than this minimum size,
+     * it will be centered in the returned rectangle.
+     * @param center return rectangle will be centered on the center of the original image if set to true
+     * @note added in QGIS 2.9
+     * @see cropTransparent
+     */
+    static QRect nonTransparentImageRect( const QImage & image, const QSize& minSize = QSize(), bool center = false );
+
     /** Crop any transparent border from around an image.
      * @param image source image
      * @param minSize minimum size for cropped image, if desired. If the
      * cropped image is smaller than the minimum size, it will be centered
      * in the returned image.
-     * @param center croped image will be centered on the center of the original image
+     * @param center cropped image will be centered on the center of the original image if set to true
      * @note added in QGIS 2.9
      */
     static QImage cropTransparent( const QImage & image, const QSize& minSize = QSize(), bool center = false );

src/core/layertree/qgslayertreemodellegendnode.cpp

@@ -163,28 +163,19 @@ QSize QgsSymbolV2LegendNode::minimumIconSize() const
   if ( mItem.symbol() && mItem.symbol()->type() == QgsSymbolV2::Marker )
   {
     QScopedPointer<QgsRenderContext> context( createTemporaryRenderContext() );
-    QPixmap pix = QPixmap::fromImage(
-                    QgsImageOperation::cropTransparent(
-                      QgsSymbolLayerV2Utils::symbolPreviewPixmap(
-                        mItem.symbol(),
-                        QSize( 512, 512 ),
-                        context.data() ).toImage(),
-                      mIconSize,
-                      true ) );
-    minSz = pix.size();
+    minSz = QgsImageOperation::nonTransparentImageRect(
+              QgsSymbolLayerV2Utils::symbolPreviewPixmap( mItem.symbol(), QSize( 512, 512 ), context.data() ).toImage(),
+              mIconSize,
+              true ).size();
   }
   else if ( mItem.symbol() && mItem.symbol()->type() == QgsSymbolV2::Line )
   {
     QScopedPointer<QgsRenderContext> context( createTemporaryRenderContext() );
-    QPixmap pix = QPixmap::fromImage(
-                    QgsImageOperation::cropTransparent(
-                      QgsSymbolLayerV2Utils::symbolPreviewPixmap(
-                        mItem.symbol(),
-                        QSize( mIconSize.width(), 512 ),
-                        context.data() ).toImage(),
-                      mIconSize,
-                      true ) );
-    minSz = pix.size();
+    minSz = QgsImageOperation::nonTransparentImageRect(
+              QgsSymbolLayerV2Utils::symbolPreviewPixmap( mItem.symbol(), QSize( mIconSize.width(), 512 ),
+                  context.data() ).toImage(),
+              mIconSize,
+              true ).size();
   }
   else
   {