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ui/gfx/image/mojo/image_skia_struct_traits.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_GFX_IMAGE_MOJO_IMAGE_SKIA_STRUCT_TRAITS_H_
+#define UI_GFX_IMAGE_MOJO_IMAGE_SKIA_STRUCT_TRAITS_H_
+
+#include <stdint.h>
+
+#include <vector>
+
+#include "third_party/skia/include/core/SkBitmap.h"
+#include "ui/gfx/image/image_skia.h"
+#include "ui/gfx/image/image_skia_rep.h"
+#include "ui/gfx/image/mojo/image_skia.mojom-shared.h"
+
+namespace mojo {
+
+template <>
+struct StructTraits<gfx::mojom::ImageSkiaRepDataView, gfx::ImageSkiaRep> {
+  struct Context {
+    Context();
+    ~Context();
+
+    mojo::ScopedSharedBufferHandle shared_buffer_handle;
+    uint32_t buffer_byte_size = 0;
+  };
+
+  static void* SetUpContext(const gfx::ImageSkiaRep& input);
+  static void TearDownContext(const gfx::ImageSkiaRep& input, void* context);
+  static mojo::ScopedSharedBufferHandle shared_buffer_handle(
+      const gfx::ImageSkiaRep& input,
+      void* context);
+  static uint32_t buffer_byte_size(const gfx::ImageSkiaRep& input,
+                                   void* context);
+  static float scale(const gfx::ImageSkiaRep& input) { return input.scale(); }
+
+  static bool IsNull(const gfx::ImageSkiaRep& input) {
+    return input.sk_bitmap().drawsNothing();

[msw, 2017/03/23 20:47:52]

nit: use ImageSkiaRep::is_null() or input.sk_bitmap().isNull()?
(I'm not exactly sure what the tradeoff is here...)

[xiyuan, 2017/03/24 05:45:21]

is_null does not check empty bitmap (0x0 image). drawsNothing covers both cases
and it is cheap to call.
 
https://cs.chromium.org/chromium/src/third_party/skia/include/core/SkBitmap.h...

+  }
+  static void SetToNull(gfx::ImageSkiaRep* out) { *out = gfx::ImageSkiaRep(); }
+
+  static bool Read(gfx::mojom::ImageSkiaRepDataView data,
+                   gfx::ImageSkiaRep* out);
+};
+
+template <>
+struct StructTraits<gfx::mojom::ImageSkiaDataView, gfx::ImageSkia> {
+  static void* SetUpContext(const gfx::ImageSkia& input);
+  static void TearDownContext(const gfx::ImageSkia& input, void* context);
+  static const std::vector<gfx::ImageSkiaRep>& image_reps(
+      const gfx::ImageSkia& input,
+      void* context);
+
+  static bool IsNull(const gfx::ImageSkia& input) {
+    return input.image_reps().empty();

[msw, 2017/03/23 20:47:52]

q: I wonder if it's always safe to call this; image_reps() has CHECK(CanRead());

[xiyuan, 2017/03/24 05:45:22]

CanRead() only fails if ImageSkia is not marked as thread safe and is accessed
from a thread different from where it is created.

We should be good now since we call MakeThreadSafe().

+  }
+  static void SetToNull(gfx::ImageSkia* out) { *out = gfx::ImageSkia(); }
+
+  static bool Read(gfx::mojom::ImageSkiaDataView data, gfx::ImageSkia* out);
+};
+
+}  // namespace mojo
+
+#endif  // UI_GFX_IMAGE_MOJO_IMAGE_SKIA_STRUCT_TRAITS_H_