Bug report #7461
'difference' blending mode not correctly rendered on a qgis composer map item (but exports properly)
|Affected QGIS version:||master||Regression?:||No|
|Operating System:||all||Easy fix?:||No|
|Pull Request or Patch supplied:||No||Resolution:|
|Crashes QGIS or corrupts data:||No||Copied to github as #:||16416|
1. Open the attached QGIS project (test-blend.zip)
2. Have a look at beautiful rendering of raster heatmap (with 'difference' blend mode) over streets vector
3. Open print composer 'Composer 1'
4. Notice how the composer's map item has it all wrong, as if the raster black to white was reversed, or the layer order switched
If the user exports the composer to a PNG, the exported map is rendering properly. There's only an issue with the composer's map item preview. Also, other blend modes, like multiply, are not triggering this bug.
Draw background on painter before rendering map for composer map items (fix #7461)