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.

BUG=skia:

Change-Id: I784a3a74be69807df038c7d192eaed002c7e45ca
Reviewed-on: https://skia-review.googlesource.com/8529
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/gpu/GrGpuResource.h b/include/gpu/GrGpuResource.h
index cc7e7aaa20..e0a7903f1d 100644
--- a/include/gpu/GrGpuResource.h
+++ b/include/gpu/GrGpuResource.h
@@ -260,6 +260,11 @@ protected:
     // final class).
     void registerWithCacheWrapped();
 
+    // This is only called by resources that are being exported from Ganesh to client code. It
+    // ensures that the cache can no longer reach this resource, and that it no longer counts
+    // against the budget.
+    void detachFromCache();
+
     GrGpuResource(GrGpu*);
     virtual ~GrGpuResource();