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- /*
- * Copyright 2017 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
- #ifndef GrBackendTextureImageGenerator_DEFINED
- #define GrBackendTextureImageGenerator_DEFINED
- #include "include/core/SkImageGenerator.h"
- #include "include/gpu/GrBackendSurface.h"
- #include "include/private/GrResourceKey.h"
- #include "include/private/SkMutex.h"
- class GrSemaphore;
- /*
- * This ImageGenerator is used to wrap a texture in one GrContext and can then be used as a source
- * in another GrContext. It holds onto a semaphore which the producing GrContext will signal and the
- * consuming GrContext will wait on before using the texture. Only one GrContext can ever be used
- * as a consumer (this is mostly because Vulkan can't allow multiple things to wait on the same
- * semaphore).
- *
- * In practice, this capability is used by clients to create backend-specific texture resources in
- * one thread (with, say, GrContext-A) and then ship them over to another GrContext (say,
- * GrContext-B) which will then use the texture as a source for draws. GrContext-A uses the
- * semaphore to notify GrContext-B when the shared texture is ready to use.
- */
- class GrBackendTextureImageGenerator : public SkImageGenerator {
- public:
- static std::unique_ptr<SkImageGenerator> Make(sk_sp<GrTexture>, GrSurfaceOrigin,
- sk_sp<GrSemaphore>, SkColorType,
- SkAlphaType, sk_sp<SkColorSpace>);
- ~GrBackendTextureImageGenerator() override;
- protected:
- // NOTE: We would like to validate that the owning context hasn't been abandoned, but we can't
- // do that safely (we might be on another thread). So assume everything is fine.
- bool onIsValid(GrContext*) const override { return true; }
- TexGenType onCanGenerateTexture() const override { return TexGenType::kCheap; }
- sk_sp<GrTextureProxy> onGenerateTexture(GrRecordingContext*, const SkImageInfo&,
- const SkIPoint&, bool willNeedMipMaps) override;
- private:
- GrBackendTextureImageGenerator(const SkImageInfo& info, GrTexture*, GrSurfaceOrigin,
- uint32_t owningContextID, sk_sp<GrSemaphore>,
- const GrBackendTexture&);
- static void ReleaseRefHelper_TextureReleaseProc(void* ctx);
- class RefHelper : public SkNVRefCnt<RefHelper> {
- public:
- RefHelper(GrTexture*, uint32_t owningContextID);
- ~RefHelper();
- GrTexture* fOriginalTexture;
- uint32_t fOwningContextID;
- // We use this key so that we don't rewrap the GrBackendTexture in a GrTexture for each
- // proxy created from this generator for a particular borrowing context.
- GrUniqueKey fBorrowedTextureKey;
- // There is no ref associated with this pointer. We rely on our atomic bookkeeping with the
- // context ID to know when this pointer is valid and safe to use. This is used to make sure
- // all uses of the wrapped texture are finished on the borrowing context before we open
- // this back up to other contexts. In general a ref to this release proc is owned by all
- // proxies and gpu uses of the backend texture.
- GrRefCntedCallback* fBorrowingContextReleaseProc;
- uint32_t fBorrowingContextID;
- };
- RefHelper* fRefHelper;
- // This Mutex is used to guard the borrowing of the texture to one GrContext at a time as well
- // as the creation of the fBorrowingContextReleaseProc. The latter happening if two threads with
- // the same consuming GrContext try to generate a texture at the same time.
- SkMutex fBorrowingMutex;
- sk_sp<GrSemaphore> fSemaphore;
- GrBackendTexture fBackendTexture;
- GrSurfaceOrigin fSurfaceOrigin;
- typedef SkImageGenerator INHERITED;
- };
- #endif // GrBackendTextureImageGenerator_DEFINED
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