Use metal as backend in skia

[Jarlen John]

I want to try the metal with skia, but the surface always return null, and can't find any sample code around..

Here is the code:

      if (_skContext == nullptr) {

        GrContextOptions grContextOptions;

        _skContext = GrDirectContext::MakeMetal((__bridge void*)_device,

                                                (__bridge void*)_commandQueue,

                                                grContextOptions);

        if (_skContext == nullptr) {

            NSAssert(NO, @"Error.");

        }

    }

    

    // Lock Mutex to block the runLoop from overwriting the _texture

    //    std::lock_guard lockGuard(_textureMutex);

    

    id<MTLTexture> texture = _renderTargetTexture;

    

    GrMtlTextureInfo fbInfo;

    fbInfo.fTexture.retain((__bridge void*)texture);

    GrBackendRenderTarget backendRT((int)texture.width,

                                    (int)texture.height,

                                    fbInfo);

    

    const GrSurfaceOrigin origin = kTopLeft_GrSurfaceOrigin;

    const SkColorType colorType = kBGRA_8888_SkColorType;

    sk_sp<SkColorSpace> colorSpace = SkColorSpace::MakeSRGB();

    SkSurfaceProps surfaceProps(0, kRGB_H_SkPixelGeometry);

    sk_sp<SkSurface> skSurface(SkSurface::MakeFromBackendRenderTarget(_skContext.get(), backendRT, origin, colorType, nullptr, &surfaceProps));

    if (skSurface == nullptr) {

        NSLog(@"skSurface is null.");

        return;

    }

    SkCanvas* canvas = skSurface->getCanvas();

    SkSurface* surface = canvas->getSurface();

skSurface is alway null, any help is appreciate!

[Jim Van Verth]

Looks like in principle it should work. Is the MTLPixelFormat in your rendertarget BGRA8Unorm_sRGB? Does the texture have MTLTextureUsageRenderTarget in its usage flags?

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Jim Van Verth | Software Engineer | Google.com

[Jim Van Verth]

Ah, I see you already resolved it.

[Jarlen John]

Thank you, Yes, I have resolved it. 

I find pixelFormat not equal in method of "SkSurface::MakeFromBackendRenderTarget" by run code in debug mode,  so we should check the offscreen texture pixelform must same as colorType parameter. Thanks again!