Implement an SkImage backed by a Android hardware buffer

Create a new SkImage public API to make an image from an Android
hardware buffer. Implementation is using a SkImageGenerator
derived class GrAndroidBufferImageGenerator.
A new EGLImage texture is created, which is then wrapped with
GrTextureProxy.

Bug: skia:
Change-Id: I610a4c5a58198686ce7c03e9a0adad3f9d2342e0
Reviewed-on: https://skia-review.googlesource.com/17789
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Stan Iliev <stani@google.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/src/gpu/GrAHardwareBufferImageGenerator.h b/src/gpu/GrAHardwareBufferImageGenerator.h
new file mode 100644
index 0000000000..4a5004b02e
--- /dev/null
+++ b/src/gpu/GrAHardwareBufferImageGenerator.h
@@ -0,0 +1,52 @@
+/*
+ * 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 GrAHardwareBufferImageGenerator_DEFINED
+#define GrAHardwareBufferImageGenerator_DEFINED
+
+#include "SkImageGenerator.h"
+
+#include <android/hardware_buffer.h>
+
+/**
+ *  GrAHardwareBufferImageGenerator allows to create an SkImage attached to
+ *  an existing android native hardware buffer. A hardware buffer has to be
+ *  created with AHARDWAREBUFFER_USAGE_GPU_SAMPLED_IMAGE usage, because it is
+ *  bound to an external texture using an EGLImage. The image generator will
+ *  keep a reference to the hardware buffer for its lifetime. A hardware buffer
+ *  can be shared between processes and same buffer can be used in multiple GPU
+ *  contexts.
+ *  To implement certain features like tiling, Skia may copy the texture to
+ *  avoid OpenGL API limitations.
+ */
+class GrAHardwareBufferImageGenerator : public SkImageGenerator {
+public:
+    static std::unique_ptr<SkImageGenerator> Make(AHardwareBuffer*, SkAlphaType,
+                                                  sk_sp<SkColorSpace>);
+
+    ~GrAHardwareBufferImageGenerator() override;
+
+protected:
+
+    bool onIsValid(GrContext*) const override;
+
+#if SK_SUPPORT_GPU
+    bool onCanGenerateTexture() const override { return true; }
+    sk_sp<GrTextureProxy> onGenerateTexture(GrContext*, const SkImageInfo&,
+                                            const SkIPoint&) override;
+#endif
+
+private:
+    GrAHardwareBufferImageGenerator(const SkImageInfo&, AHardwareBuffer*, SkAlphaType);
+
+    static void deleteImageTexture(void* ctx);
+
+    AHardwareBuffer* fGraphicBuffer;
+    SkAlphaType fAlphaType;
+
+    typedef SkImageGenerator INHERITED;
+};
+#endif  // GrAHardwareBufferImageGenerator_DEFINED