[3/5] Add translated rasterization support for RasterBuffer & below

cc/base/scale_translate2d.h

+// Copyright (c) 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 CC_BASE_SCALE_TRANSLATE2D_H_
+#define CC_BASE_SCALE_TRANSLATE2D_H_
+
+#include "ui/gfx/geometry/rect_f.h"
+#include "ui/gfx/geometry/vector2d_f.h"
+
+class SkCanvas;
+
+namespace cc {
+
+class ScaleTranslate2d {
+ public:
+  constexpr ScaleTranslate2d() : scale_(1.f) { }
+  constexpr ScaleTranslate2d(float scale, const gfx::Vector2dF& translation)
+      : scale_(scale), translation_(translation) {}
+
+  bool operator==(const ScaleTranslate2d& other) const {
+    return scale_ == other.scale_ && translation_ == other.translation_;
+  }
+  bool operator!=(const ScaleTranslate2d& other) const {
+    return !(*this == other);
+  }
+
+  static ScaleTranslate2d PreScale(const ScaleTranslate2d& t, float scale) {
+    return ScaleTranslate2d(t.scale_ * scale, t.translation_);
+  }
+  void PreScale(float scale) { *this = PreScale(*this, scale); }
+
+  static ScaleTranslate2d PostScale(const ScaleTranslate2d& t, float scale) {
+    return ScaleTranslate2d(t.scale_ * scale,
+                            gfx::ScaleVector2d(t.translation_, scale));
+  }
+  void PostScale(float scale) { *this = PostScale(*this, scale); }
+
+  static ScaleTranslate2d PreTranslate(const ScaleTranslate2d& t,
+                                       const gfx::Vector2dF& translation) {
+    return ScaleTranslate2d(
+        t.scale_,
+        gfx::ScaleVector2d(translation, t.scale_) + t.translation_);
+  }
+  void PreTranslate(const gfx::Vector2dF& translation) {
+    *this = PreTranslate(*this, translation);
+  }
+
+  static ScaleTranslate2d PostTranslate(const ScaleTranslate2d& t,
+                                        const gfx::Vector2dF& translation) {
+    return ScaleTranslate2d(t.scale_, t.translation_ + translation);
+  }
+  void PostTranslate(const gfx::Vector2dF& translation) {
+    *this = PostTranslate(*this, translation);
+  }
+
+  static ScaleTranslate2d Concat(const ScaleTranslate2d& post,
+                                 const ScaleTranslate2d& pre) {
+    return ScaleTranslate2d(
+        pre.scale_ * post.scale_,
+        gfx::ScaleVector2d(pre.translation_, post.scale_) +
+            post.translation_);
+  }
+  void PreConcat(const ScaleTranslate2d& other) {
+    *this = Concat(*this, other);
+  }
+  void PostConcat(const ScaleTranslate2d& other) {
+    *this = Concat(other, *this);
+  }
+
+  static ScaleTranslate2d Inverse(const ScaleTranslate2d& t) {
+    return ScaleTranslate2d(
+        1 / t.scale_,
+        gfx::ScaleVector2d(-t.translation_, 1 / t.scale_));
+  }
+  void Invert() { *this = Inverse(*this); }
+
+  gfx::PointF TransformPoint(const gfx::PointF& p) const {
+    return gfx::ScalePoint(p, scale_) + translation_;
+  }
+  gfx::PointF TransformPointReverse(const gfx::PointF& p) const {
+    return gfx::ScalePoint(p - translation_, 1.f / scale_);
+  }
+
+  gfx::RectF TransformRect(const gfx::RectF& r) const {
+    return gfx::ScaleRect(r, scale_) + translation_;
+  }
+  gfx::RectF TransformRectReverse(const gfx::RectF& r) const {
+    return gfx::ScaleRect(r - translation_, 1.f / scale_);
+  }
+
+  void ApplyToCanvas(SkCanvas* canvas) const;
+
+  float scale() const { return scale_; }
+  gfx::Vector2dF translation() const { return translation_; }
+
+  std::string ToString() const { return "todo"; }
+
+ private:
+  // Scale is applied before translation, i.e.
+  // this->Transform(p) == scale_ * p + translation_
+  float scale_;
+  gfx::Vector2dF translation_;
+};
+
+}  // namespace cc
+
+#endif  // CC_BASE_SCALE_TRANSLATE2D_H_