Make geometry struct_trait shared by Blink and Chromium

ui/gfx/geometry/mojo/geometry_struct_traits.h

 // Copyright 2016 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_GEOMETRY_MOJO_GEOMETRY_STRUCT_TRAITS_H_
 #define UI_GFX_GEOMETRY_MOJO_GEOMETRY_STRUCT_TRAITS_H_
 
 #include "ui/gfx/geometry/insets.h"
 #include "ui/gfx/geometry/insets_f.h"
-#include "ui/gfx/geometry/mojo/geometry.mojom.h"
 #include "ui/gfx/geometry/point.h"
 #include "ui/gfx/geometry/point_f.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/rect_f.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/gfx/geometry/size_f.h"
 #include "ui/gfx/geometry/vector2d.h"
 #include "ui/gfx/geometry/vector2d_f.h"
 
 namespace mojo {
 
-template <>
-struct StructTraits<gfx::mojom::Insets, gfx::Insets> {
+template <typename T>

[dcheng, 2016/07/20 18:16:10]

Why do we need to templatize this? Some of these methods probably should have
been defined out-of-line as well (which I think templatizing will make harder)

[xlai (Olivia), 2016/07/20 19:07:34]

My ultimate intention is to use compositor_frame.mojom in
offscreen_canvas_surface.mojom in Blink. compositor_frame.mojom depends on
render_pass.mojom, which in turn depends on geometry.mojom. I want to do it step
by step, so templatizing geometry.mojom first. There will be more CLs coming
along to templatize more mojom files until eventually compositor_frame.mojom
could be used in Blink. (See crbug.com/629566)

The template is fully specialized as gfx.mojom.Insets in Chromium and as
gfx.mojom.blink.Insets in Blink. If I do not use a template here, then I have to
create one more typemap and one more struct_trait in Blink, which look quite
similar to this file except that every gfx::mojom here is replaced to
gfx::mojom::blink. That will be too much code duplication.

Another similar example is surface_id_struct_trait.h.

+struct StructTraits<T, gfx::Insets> {
   static int top(const gfx::Insets& p) { return p.top(); }
   static int left(const gfx::Insets& p) { return p.left(); }
   static int bottom(const gfx::Insets& p) { return p.bottom(); }
   static int right(const gfx::Insets& p) { return p.right(); }
-  static bool Read(gfx::mojom::InsetsDataView data, gfx::Insets* out) {
+  static bool Read(typename T::DataView data, gfx::Insets* out) {
     out->Set(data.top(), data.left(), data.bottom(), data.right());
     return true;
   }
 };
 
-template <>
-struct StructTraits<gfx::mojom::InsetsF, gfx::InsetsF> {
+template <typename T>
+struct StructTraits<T, gfx::InsetsF> {
   static float top(const gfx::InsetsF& p) { return p.top(); }
   static float left(const gfx::InsetsF& p) { return p.left(); }
   static float bottom(const gfx::InsetsF& p) { return p.bottom(); }
   static float right(const gfx::InsetsF& p) { return p.right(); }
-  static bool Read(gfx::mojom::InsetsFDataView data, gfx::InsetsF* out) {
+  static bool Read(typename T::DataView data, gfx::InsetsF* out) {
     out->Set(data.top(), data.left(), data.bottom(), data.right());
     return true;
   }
 };
 
-template <>
-struct StructTraits<gfx::mojom::Point, gfx::Point> {
+template <typename T>
+struct StructTraits<T, gfx::Point> {
   static int x(const gfx::Point& p) { return p.x(); }
   static int y(const gfx::Point& p) { return p.y(); }
-  static bool Read(gfx::mojom::PointDataView data, gfx::Point* out) {
+  static bool Read(typename T::DataView data, gfx::Point* out) {
     out->SetPoint(data.x(), data.y());
     return true;
   }
 };
 
-template <>
-struct StructTraits<gfx::mojom::PointF, gfx::PointF> {
+template <typename T>
+struct StructTraits<T, gfx::PointF> {
   static float x(const gfx::PointF& p) { return p.x(); }
   static float y(const gfx::PointF& p) { return p.y(); }
-  static bool Read(gfx::mojom::PointFDataView data, gfx::PointF* out) {
+  static bool Read(typename T::DataView data, gfx::PointF* out) {
     out->SetPoint(data.x(), data.y());
     return true;
   }
 };
 
-template <>
-struct StructTraits<gfx::mojom::Rect, gfx::Rect> {
+template <typename T>
+struct StructTraits<T, gfx::Rect> {
   static int x(const gfx::Rect& p) { return p.x(); }
   static int y(const gfx::Rect& p) { return p.y(); }
   static int width(const gfx::Rect& p) { return p.width(); }
   static int height(const gfx::Rect& p) { return p.height(); }
-  static bool Read(gfx::mojom::RectDataView data, gfx::Rect* out) {
+  static bool Read(typename T::DataView data, gfx::Rect* out) {
     if (data.width() < 0 || data.height() < 0)
       return false;
 
     out->SetRect(data.x(), data.y(), data.width(), data.height());
     return true;
   }
 };
 
-template <>
-struct StructTraits<gfx::mojom::RectF, gfx::RectF> {
+template <typename T>
+struct StructTraits<T, gfx::RectF> {
   static float x(const gfx::RectF& p) { return p.x(); }
   static float y(const gfx::RectF& p) { return p.y(); }
   static float width(const gfx::RectF& p) { return p.width(); }
   static float height(const gfx::RectF& p) { return p.height(); }
-  static bool Read(gfx::mojom::RectFDataView data, gfx::RectF* out) {
+  static bool Read(typename T::DataView data, gfx::RectF* out) {
     if (data.width() < 0 || data.height() < 0)
       return false;
 
     out->SetRect(data.x(), data.y(), data.width(), data.height());
     return true;
   }
 };
 
-template <>
-struct StructTraits<gfx::mojom::Size, gfx::Size> {
+template <typename T>
+struct StructTraits<T, gfx::Size> {
   static int width(const gfx::Size& p) { return p.width(); }
   static int height(const gfx::Size& p) { return p.height(); }
-  static bool Read(gfx::mojom::SizeDataView data, gfx::Size* out) {
+  static bool Read(typename T::DataView data, gfx::Size* out) {
     if (data.width() < 0 || data.height() < 0)
       return false;
 
     out->SetSize(data.width(), data.height());
     return true;
   }
 };
 
-template <>
-struct StructTraits<gfx::mojom::SizeF, gfx::SizeF> {
+template <typename T>
+struct StructTraits<T, gfx::SizeF> {
   static float width(const gfx::SizeF& p) { return p.width(); }
   static float height(const gfx::SizeF& p) { return p.height(); }
-  static bool Read(gfx::mojom::SizeFDataView data, gfx::SizeF* out) {
+  static bool Read(typename T::DataView data, gfx::SizeF* out) {
     if (data.width() < 0 || data.height() < 0)
       return false;
 
     out->SetSize(data.width(), data.height());
     return true;
   }
 };
 
-template <>
-struct StructTraits<gfx::mojom::Vector2d, gfx::Vector2d> {
+template <typename T>
+struct StructTraits<T, gfx::Vector2d> {
   static int x(const gfx::Vector2d& v) { return v.x(); }
   static int y(const gfx::Vector2d& v) { return v.y(); }
-  static bool Read(gfx::mojom::Vector2dDataView data, gfx::Vector2d* out) {
+  static bool Read(typename T::DataView data, gfx::Vector2d* out) {
     out->set_x(data.x());
     out->set_y(data.y());
     return true;
   }
 };
 
-template <>
-struct StructTraits<gfx::mojom::Vector2dF, gfx::Vector2dF> {
+template <typename T>
+struct StructTraits<T, gfx::Vector2dF> {
   static float x(const gfx::Vector2dF& v) { return v.x(); }
   static float y(const gfx::Vector2dF& v) { return v.y(); }
-  static bool Read(gfx::mojom::Vector2dFDataView data, gfx::Vector2dF* out) {
+  static bool Read(typename T::DataView data, gfx::Vector2dF* out) {
     out->set_x(data.x());
     out->set_y(data.y());
     return true;
   }
 };
 
 }  // namespace mojo
 
 #endif  // UI_GFX_GEOMETRY_MOJO_GEOMETRY_STRUCT_TRAITS_H_