Enable Skia GPU backend without creation Skia own EGLContext

[Igor Kuzmenko]

Hi All,

I've tried to create android application where used Skia gpu backend. In my app I already have created EGLContext. 

And I'd like to use my own OpenGL Texture as render target for SkCanvas. Investigating source code I found that Skia 

creates it's own EGLContext. But in my case I want that Skia has used my EGLContext.

Does the current version of Skia support this case? Investegate source code I found out 6 different GLContextType.

enum GLContextType {

      kNative_GLContextType,

      kANGLE_GLContextType,

      kMESA_GLContextType,

      /** Similar to kNative but does not filter NVPR. It will fail if the GL driver does not

          support NVPR */

      kNVPR_GLContextType,

      kNull_GLContextType,

      kDebug_GLContextType,

      kLastGLContextType = kDebug_GLContextType

    };

But no one is suitable for my case.

When I've used kNative_GLContextType Skia creates its own EGLContext but that's not what I want. 

And kNull_GLContextType doesn't work too.

I've used old skia version (may be release of 3 years ago)  where SkNativeGLContext doesn't create own EGLContext, EGLDisplay, EGLSurface, etc. And my code worked fine.

Could someone explain is it possible created GrContext on my own EGLContext?

Thanks a lot!

[Brian Salomon]

Hi,

You shouldn't be using GrContextFactory. That class is really meant for our own test tools.

Since you built for Android you should have compiled GrGLCreateNativeInterface_egl.cpp (as opposed to the other variants based on agl, wgl, glx, ...).  Here are the steps:

1. Call GrContext::Create(kOpenGL_GrBackend, NULL) while your GL context is current on the thread you'll get a GrContext that uses your context.
2. You then use GrContext::wrapBackendTexture() with the kRenderTarget_GrSurfaceFlag set to wrap the texture you want to use.
3. You can use the wrapped texture to create a SkSurface via SkSuface::NewRenderTargetDirect.
   

I put up a CL that would combine steps two and three:

https://codereview.chromium.org/1071603002

 Hope that helps.

Brian

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[Igor Kuzmenko]

Brian, thanks a lot. It really helped!