Add GrExternalTextureData and SkCrossContextImageData

GrExternalTextureData is an API for exporting the backend-specific
information about a texture in a type-safe way, and without pointing
into the GrTexture. The new detachBackendTexture API lets us release
ownership of a texture to the client.

SkCrossContextImageData is the public API that lets clients upload
textures on one thread/GrContext, then safely transfer ownership to
another thread and GrContext for rendering.

Only GL is implemented/supported right now. Vulkan support requires
that we add thread-safe memory pools, or otherwise transfer the
actual memory block containing the texture to the new context.

Re-land of https://skia-review.googlesource.com/c/8529/

BUG=skia:

Change-Id: I48ebd57d1ea0cfd3a1db10c475f2903afb821966
Reviewed-on: https://skia-review.googlesource.com/8960
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/include/gpu/gl/GrGLTypes.h b/include/gpu/gl/GrGLTypes.h
index 5b9e31de1a..d03363c75e 100644
--- a/include/gpu/gl/GrGLTypes.h
+++ b/include/gpu/gl/GrGLTypes.h
@@ -9,6 +9,7 @@
 #ifndef GrGLTypes_DEFINED
 #define GrGLTypes_DEFINED
 
+#include "GrExternalTextureData.h"
 #include "GrGLConfig.h"
 
 /**
@@ -112,6 +113,23 @@ struct GrGLTextureInfo {
     GrGLuint fID;
 };
 
+class GrGLExternalTextureData : public GrExternalTextureData {
+public:
+    GrGLExternalTextureData(const GrGLTextureInfo& info, GrFence fence)
+            : INHERITED(fence)
+            , fInfo(info) {}
+    GrBackend getBackend() const override { return kOpenGL_GrBackend; }
+
+protected:
+    GrBackendObject getBackendObject() const override {
+        return reinterpret_cast<GrBackendObject>(&fInfo);
+    }
+
+    GrGLTextureInfo fInfo;
+
+    typedef GrExternalTextureData INHERITED;
+};
+
 GR_STATIC_ASSERT(sizeof(GrBackendObject) >= sizeof(const GrGLTextureInfo*));
 
 #endif