AntiAliasing not working with skia hardware rendering

[Abhishek Gupta]

Hi,
I have been trying to use hardware accelerated (GPU backed) 2D rendering using Skia. I have been able to do so, but I am seeing jagged edges even when I have enabled antialiasing.
The simplified relevant code is as follows:-

    context = GrContext::Create( GrBackend::kOpenGL_GrBackend, NULL /*backendContext*/ );

    GrBackendRenderTargetDesc desc;
    desc.fWidth = width;
    desc.fHeight = height;
    desc.fConfig = kRGBA_8888_GrPixelConfig;
    desc.fOrigin = kBottomLeft_GrSurfaceOrigin;
    desc.fSampleCnt = 2;
    desc.fStencilBits = 0;
    desc.fRenderTargetHandle = 0;
   
    sk_sp<SkSurface> surface = SkSurface::MakeFromBackendRenderTarget( context, desc, nullptr /*surfaceProps*/ )
    SkCanvas* canvas = surface->getCanvas();
   
    SkPaint paint;
    paint.setAntiAlias( true );
    paint.setColor( color );
    paint.setStyle( SkPaint::kFill_Style );
   
    canvas->drawOval( rectangle, paint );
   
I have attached the screenshot. I cannot repro the issue on fiddle. Any help in this matter would be greatly appreciated.

Thanks,
Abhishek

[Brian Salomon]

Hi, the circle is antialiased using multisampling. You'll only get as many color steps in the antialiasing as there are samples per pixel in the destination. If the quality isn't high enough you can either increase the sample count or turn off multisampling which will cause Skia to use alpha blending to perform antialiasing. 

Brian

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