Wasm: Icons are not displayed correctly in gallery about qskinny

[peter-ha]

Regarding the 2nd issue from above:

The reason why the IOT dashboard is displaying the icons correctly and the gallery doesn't is because in the IOT dashboard we draw our textures with the raster mode (QskSetup::setUpdateFlag( QskItem::PreferRasterForTextures, true );.

I am not sure if we want to detect the Wasm platform and default to raster or so, or if there is a better solution...

[uwerat]

Using the raster mode as default makes sense - at least for small icons. The quality of the antialiasing is better and filling the pixels isn't much more expensive than the tesselation. IIRC my performance tests ( should be in the history of the git repository ) with loading tons of small icons showed the raster path being slightly faster ( Qt 5.4 at that time ).

However using the raster paint engine seems to be a workaround for a general problem that might have to do with the availability of FBOs. Maybe we have to do some additional checks: https://doc.qt.io/qt-6/qopenglfunctions.html#openGLFeatures ?

[peter-ha]

These are the OpenGL functions that are available on desktop and not on Wasm; to me it doesn't look like we are using those, but maybe I just don't know the code well enough:

QOpenGLFunctions::NPOTTextures
QOpenGLFunctions::NPOTTextureRepeat
QOpenGLFunctions::FixedFunctionPipeline
QOpenGLFunctions::TextureRGFormats
QOpenGLFunctions::MultipleRenderTargets
QOpenGLFunctions::BlendEquationAdvanced