ash: Better and faster text shadows.

- Add a DrawStringWithShadows that draws text with shadows to canvas skia
  and RenderText;
- Use DrawStringWithShadows in DropShadowLabel for better and faster text
  shadows;

BUG=121694
TEST=Verify fix for issue 121694.


Review URL: http://codereview.chromium.org/10008027

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@131696 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 58 insertions, 0 deletions

diff --git a/ui/gfx/shadow_value.h b/ui/gfx/shadow_value.h
new file mode 100644
index 0000000..8ca9196
--- /dev/null
+++ b/ui/gfx/shadow_value.h
@@ -0,0 +1,58 @@
+// Copyright (c) 2012 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_SHADOW_VALUE_
+#define UI_GFX_SHADOW_VALUE_
+#pragma once
+
+#include <string>
+#include <vector>
+
+#include "third_party/skia/include/core/SkColor.h"
+#include "ui/base/ui_export.h"
+#include "ui/gfx/point.h"
+
+namespace gfx {
+
+class Insets;
+
+// ShadowValue encapsulates parameters needed to define a shadow, including the
+// shadow's offset, blur amount and color.
+class UI_EXPORT ShadowValue {
+ public:
+  ShadowValue();
+  ShadowValue(const gfx::Point& offset, double blur, SkColor color);
+  ~ShadowValue();
+
+  int x() const { return offset_.x(); }
+  int y() const { return offset_.y(); }
+  const gfx::Point& offset() const { return offset_; }
+  double blur() const { return blur_; }
+  SkColor color() const { return color_; }
+
+  std::string ToString() const;
+
+  // Gets margin space needed for shadows. Note that values in returned Insets
+  // are negative because shadow margins are outside a boundary.
+  static Insets GetMargin(const std::vector<ShadowValue>& shadows);
+
+ private:
+  gfx::Point offset_;
+
+  // Blur amount of the shadow in pixels. If underlying implementation supports
+  // (e.g. Skia), it can have fraction part such as 0.5 pixel. The value
+  // defines a range from full shadow color at the start point inside the
+  // shadow to fully transparent at the end point outside it. The range is
+  // perpendicular to and centered on the shadow edge. For example, a blur
+  // amount of 4.0 means to have a blurry shadow edge of 4 pixels that
+  // transitions from full shadow color to fully transparent and with 2 pixels
+  // inside the shadow and 2 pixels goes beyond the edge.
+  double blur_;
+
+  SkColor color_;
+};
+
+}  // namespace gfx
+
+#endif  // UI_GFX_SHADOW_VALUE_