Merge pull request #3559 from nyalldawson/fix_render_flashing

Fix layers with layer wide opacity "flashing" while rendering

scripts/generate_test_mask_image.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
 """
@@ -35,12 +35,12 @@ import sys
 import argparse
 from PyQt5.QtGui import QImage, QColor, qRed, qBlue, qGreen, qAlpha, qRgb
 import struct
-import urllib2
+import urllib.request, urllib.error, urllib.parse
 import glob
 
 
 def error(msg):
-    print msg
+    print(msg)
     sys.exit(1)
 
 
@@ -53,9 +53,9 @@ def colorDiff(c1, c2):
 
 
 def imageFromPath(path):
-    if (path[:7] == 'http://' or path[:7] == 'file://'):
+    if (path[:7] == 'http://' or path[:7] == 'file://' or path[:8] == 'https://'):
         #fetch remote image
-        data = urllib2.urlopen(path).read()
+        data = urllib.request.urlopen(path).read()
         image = QImage()
         image.loadFromData(data)
     else:
@@ -88,7 +88,7 @@ def getControlImagePath(path):
         error('No matching control images found for {}'.format(path))
 
     found_image = filtered_images[0]
-    print 'Found matching control image: {}'.format(found_image)
+    print('Found matching control image: {}'.format(found_image))
     return found_image
 
 
@@ -101,10 +101,10 @@ def updateMask(control_image_path, rendered_image_path, mask_image_path):
     if not rendered_image:
         error('Could not read rendered image {}'.format(rendered_image_path))
     if not rendered_image.width() == control_image.width() or not rendered_image.height() == control_image.height():
-        print ('Size mismatch - control image is {}x{}, rendered image is {}x{}'.format(control_image.width(),
+        print(('Size mismatch - control image is {}x{}, rendered image is {}x{}'.format(control_image.width(),
                                                                                         control_image.height(),
                                                                                         rendered_image.width(),
-                                                                                        rendered_image.height()))
+                                                                                        rendered_image.height())))
 
     max_width = min(rendered_image.width(), control_image.width())
     max_height = min(rendered_image.height(), control_image.height())
@@ -112,19 +112,19 @@ def updateMask(control_image_path, rendered_image_path, mask_image_path):
     #read current mask, if it exist
     mask_image = imageFromPath(mask_image_path)
     if mask_image.isNull():
-        print 'Mask image does not exist, creating {}'.format(mask_image_path)
+        print('Mask image does not exist, creating {}'.format(mask_image_path))
         mask_image = QImage(control_image.width(), control_image.height(), QImage.Format_ARGB32)
         mask_image.fill(QColor(0, 0, 0))
 
     #loop through pixels in rendered image and compare
     mismatch_count = 0
     linebytes = max_width * 4
-    for y in xrange(max_height):
+    for y in range(max_height):
         control_scanline = control_image.constScanLine(y).asstring(linebytes)
         rendered_scanline = rendered_image.constScanLine(y).asstring(linebytes)
         mask_scanline = mask_image.scanLine(y).asstring(linebytes)
 
-        for x in xrange(max_width):
+        for x in range(max_width):
             currentTolerance = qRed(struct.unpack('I', mask_scanline[x * 4:x * 4 + 4])[0])
 
             if currentTolerance == 255:
@@ -143,9 +143,9 @@ def updateMask(control_image_path, rendered_image_path, mask_image_path):
     if mismatch_count:
         #update mask
         mask_image.save(mask_image_path, "png")
-        print 'Updated {} pixels in {}'.format(mismatch_count, mask_image_path)
+        print('Updated {} pixels in {}'.format(mismatch_count, mask_image_path))
     else:
-        print 'No mismatches in {}'.format(mask_image_path)
+        print('No mismatches in {}'.format(mask_image_path))
 
 parser = argparse.ArgumentParser() # OptionParser("usage: %prog control_image rendered_image mask_image")
 parser.add_argument('control_image')

src/core/qgsmaprenderercustompainterjob.cpp

@@ -260,7 +260,9 @@ void QgsMapRendererCustomPainterJob::doRender()
     if ( job.img )
     {
       // If we flattened this layer for alternate blend modes, composite it now
+      mPainter->setOpacity( job.opacity );
       mPainter->drawImage( 0, 0, *job.img );
+      mPainter->setOpacity( 1.0 );
     }
 
   }

src/core/qgsmaprendererjob.cpp

@@ -245,6 +245,11 @@ LayerRenderJobs QgsMapRendererJob::prepareJobs( QPainter* painter, QgsLabelingEn
     job.cached = false;
     job.img = nullptr;
     job.blendMode = ml->blendMode();
+    job.opacity = 1.0;
+    if ( QgsVectorLayer* vl = qobject_cast<QgsVectorLayer *>( ml ) )
+    {
+      job.opacity = 1.0 - vl->layerTransparency() / 100.0;
+    }
     job.layerId = ml->id();
     job.renderingTime = -1;
 
@@ -360,8 +365,10 @@ QImage QgsMapRendererJob::composeImage( const QgsMapSettings& settings, const La
     const LayerRenderJob& job = *it;
 
     painter.setCompositionMode( job.blendMode );
+    painter.setOpacity( job.opacity );
 
     Q_ASSERT( job.img );
+
     painter.drawImage( 0, 0, *job.img );
   }
 

src/core/qgsmaprendererjob.h

@@ -46,6 +46,7 @@ struct LayerRenderJob
   QImage* img; // may be null if it is not necessary to draw to separate image (e.g. sequential rendering)
   QgsMapLayerRenderer* renderer; // must be deleted
   QPainter::CompositionMode blendMode;
+  double opacity;
   bool cached; // if true, img already contains cached image from previous rendering
   QString layerId;
   int renderingTime; //!< time it took to render the layer in ms (it is -1 if not rendered or still rendering)

src/core/qgsvectorlayerrenderer.cpp

@@ -55,7 +55,6 @@ QgsVectorLayerRenderer::QgsVectorLayerRenderer( QgsVectorLayer* layer, QgsRender
     , mDiagrams( false )
     , mLabelProvider( nullptr )
     , mDiagramProvider( nullptr )
-    , mLayerTransparency( 0 )
 {
   mSource = new QgsVectorLayerFeatureSource( layer );
 
@@ -66,7 +65,6 @@ QgsVectorLayerRenderer::QgsVectorLayerRenderer( QgsVectorLayer* layer, QgsRender
 
   mGeometryType = layer->geometryType();
 
-  mLayerTransparency = layer->layerTransparency();
   mFeatureBlendMode = layer->featureBlendMode();
 
   mSimplifyMethod = layer->simplifyMethod();
@@ -264,18 +262,6 @@ bool QgsVectorLayerRenderer::render()
     mRenderer->paintEffect()->end( mContext );
   }
 
-  //apply layer transparency for vector layers
-  if ( mContext.useAdvancedEffects() && mLayerTransparency != 0 )
-  {
-    // a layer transparency has been set, so update the alpha for the flattened layer
-    // by combining it with the layer transparency
-    QColor transparentFillColor = QColor( 0, 0, 0, 255 - ( 255 * mLayerTransparency / 100 ) );
-    // use destination in composition mode to merge source's alpha with destination
-    mContext.painter()->setCompositionMode( QPainter::CompositionMode_DestinationIn );
-    mContext.painter()->fillRect( 0, 0, mContext.painter()->device()->width(),
-                                  mContext.painter()->device()->height(), transparentFillColor );
-  }
-
   return true;
 }
 

src/core/qgsvectorlayerrenderer.h

@@ -136,7 +136,6 @@ class QgsVectorLayerRenderer : public QgsMapLayerRenderer
     //! may be null. no need to delete: if exists it is owned by labeling engine
     QgsVectorLayerDiagramProvider* mDiagramProvider;
 
-    int mLayerTransparency;
     QPainter::CompositionMode mFeatureBlendMode;
 
     QgsVectorSimplifyMethod mSimplifyMethod;