Loading/Creating images for mutiple scale factors on the fly

ui/views/controls/menu/menu_image_util.cc

 // 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.
 
 #include "ui/views/controls/menu/menu_image_util.h"
 
 #include "base/i18n/rtl.h"
+#include "base/logging.h"
 #include "grit/ui_resources.h"
 #include "third_party/skia/include/effects/SkGradientShader.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/image/image.h"
 #include "ui/gfx/image/image_skia.h"
+#include "ui/gfx/image/image_skia_source.h"
 #include "ui/gfx/point.h"
 #include "ui/gfx/size.h"
 
 namespace {
 
 // Size of the radio button inciator.
 const int kSelectedIndicatorSize = 5;
 const int kIndicatorSize = 10;
 
 // Used for the radio indicator. See theme_draw for details.
 const double kGradientStop = .5;
 const SkColor kGradient0 = SkColorSetRGB(255, 255, 255);
 const SkColor kGradient1 = SkColorSetRGB(255, 255, 255);
 const SkColor kGradient2 = SkColorSetRGB(0xD8, 0xD8, 0xD8);
 const SkColor kBaseStroke = SkColorSetRGB(0x8F, 0x8F, 0x8F);
 const SkColor kRadioButtonIndicatorGradient0 = SkColorSetRGB(0, 0, 0);
 const SkColor kRadioButtonIndicatorGradient1 = SkColorSetRGB(0x83, 0x83, 0x83);
 const SkColor kIndicatorStroke = SkColorSetRGB(0, 0, 0);
 
-gfx::ImageSkia* CreateRadioButtonImage(bool selected) {
-  // + 2 (1px on each side) to cover rounding error.
-  gfx::Canvas canvas(gfx::Size(kIndicatorSize + 2, kIndicatorSize + 2), false);
-  canvas.Translate(gfx::Point(1, 1));
+class RadioButtonImageSource : public gfx::ImageSkiaSource {
+ public:
+  explicit RadioButtonImageSource(bool selected) : selected_(selected) {
+  }
+  virtual ~RadioButtonImageSource() {}
 
-  SkPoint gradient_points[3];
-  gradient_points[0].iset(0, 0);
-  gradient_points[1].iset(0, static_cast<int>(kIndicatorSize * kGradientStop));
-  gradient_points[2].iset(0, kIndicatorSize);
-  SkColor gradient_colors[3] = { kGradient0, kGradient1, kGradient2 };
-  SkShader* shader = SkGradientShader::CreateLinear(
-      gradient_points, gradient_colors, NULL, arraysize(gradient_points),
-      SkShader::kClamp_TileMode, NULL);
-  SkPaint paint;
-  paint.setStyle(SkPaint::kFill_Style);
-  paint.setAntiAlias(true);
-  paint.setShader(shader);
-  shader->unref();
-  int radius = kIndicatorSize / 2;
-  canvas.sk_canvas()->drawCircle(radius, radius, radius, paint);
+  virtual gfx::ImageSkiaRep GetImageForScale(
+      ui::ScaleFactor scale_factor) OVERRIDE {
+    float scale = GetScaleFactorScale(scale_factor);
+    // + 2 (1px on each side) to cover rounding error.
+    gfx::Size size(kIndicatorSize + 2, kIndicatorSize + 2);
+    gfx::Canvas canvas(size.Scale(scale), false);
+    canvas.Scale(scale, scale);
+    canvas.Translate(gfx::Point(1, 1));
 
-  paint.setStrokeWidth(SkIntToScalar(0));
-  paint.setShader(NULL);
-  paint.setStyle(SkPaint::kStroke_Style);
-  paint.setColor(kBaseStroke);
-  canvas.sk_canvas()->drawCircle(radius, radius, radius, paint);
-
-  if (selected) {
-    SkPoint selected_gradient_points[2];
-    selected_gradient_points[0].iset(0, 0);
-    selected_gradient_points[1].iset(0, kSelectedIndicatorSize);
-    SkColor selected_gradient_colors[2] = { kRadioButtonIndicatorGradient0,
-                                            kRadioButtonIndicatorGradient1 };
-    shader = SkGradientShader::CreateLinear(
-        selected_gradient_points, selected_gradient_colors, NULL,
-        arraysize(selected_gradient_points), SkShader::kClamp_TileMode, NULL);
+    SkPoint gradient_points[3];
+    gradient_points[0].iset(0, 0);
+    gradient_points[1].iset(0,
+                            static_cast<int>(kIndicatorSize * kGradientStop));
+    gradient_points[2].iset(0, kIndicatorSize);
+    SkColor gradient_colors[3] = { kGradient0, kGradient1, kGradient2 };
+    SkShader* shader = SkGradientShader::CreateLinear(
+        gradient_points, gradient_colors, NULL, arraysize(gradient_points),
+        SkShader::kClamp_TileMode, NULL);
+    SkPaint paint;
+    paint.setStyle(SkPaint::kFill_Style);
+    paint.setAntiAlias(true);
     paint.setShader(shader);
     shader->unref();
-    paint.setStyle(SkPaint::kFill_Style);
-    canvas.sk_canvas()->drawCircle(radius, radius,
-                                   kSelectedIndicatorSize / 2, paint);
-
+    int radius = kIndicatorSize / 2;
+    canvas.sk_canvas()->drawCircle(radius, radius, radius, paint);
     paint.setStrokeWidth(SkIntToScalar(0));
     paint.setShader(NULL);
     paint.setStyle(SkPaint::kStroke_Style);
-    paint.setColor(kIndicatorStroke);
-    canvas.sk_canvas()->drawCircle(radius, radius,
-                                   kSelectedIndicatorSize / 2, paint);
+    paint.setColor(kBaseStroke);
+    canvas.sk_canvas()->drawCircle(radius, radius, radius, paint);
+
+    if (selected_) {
+      SkPoint selected_gradient_points[2];
+      selected_gradient_points[0].iset(0, 0);
+      selected_gradient_points[1].iset(0, kSelectedIndicatorSize);
+      SkColor selected_gradient_colors[2] = { kRadioButtonIndicatorGradient0,
+                                              kRadioButtonIndicatorGradient1 };
+      shader = SkGradientShader::CreateLinear(
+          selected_gradient_points, selected_gradient_colors, NULL,
+          arraysize(selected_gradient_points), SkShader::kClamp_TileMode, NULL);
+      paint.setShader(shader);
+      shader->unref();
+      paint.setStyle(SkPaint::kFill_Style);
+      canvas.sk_canvas()->drawCircle(radius, radius,
+                                     kSelectedIndicatorSize / 2, paint);
+
+      paint.setStrokeWidth(SkIntToScalar(0));
+      paint.setShader(NULL);
+      paint.setStyle(SkPaint::kStroke_Style);
+      paint.setColor(kIndicatorStroke);
+      canvas.sk_canvas()->drawCircle(radius, radius,
+                                     kSelectedIndicatorSize / 2, paint);
+    }
+    LOG(ERROR) << "Generating:" << selected_;
+    return gfx::ImageSkiaRep(canvas.ExtractBitmap(), scale_factor);
   }
-  return new gfx::ImageSkia(canvas.ExtractBitmap());
+
+ private:
+  bool selected_;
+
+  DISALLOW_COPY_AND_ASSIGN(RadioButtonImageSource);
+};
+
+gfx::ImageSkia* CreateRadioButtonImage(bool selected) {
+  return new gfx::ImageSkia(new RadioButtonImageSource(selected),
+                            gfx::Size(kIndicatorSize + 2, kIndicatorSize + 2));
 }
 
 gfx::ImageSkia* GetRtlSubmenuArrowImage() {
   static gfx::ImageSkia* kRtlArrow = NULL;
   if (!kRtlArrow) {
     ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
     const gfx::ImageSkia* r = rb.GetImageNamed(IDR_MENU_ARROW).ToImageSkia();
     gfx::Canvas canvas(gfx::Size(r->width(), r->height()), false);
     canvas.Scale(-1, 1);
     canvas.DrawImageInt(*r, - r->width(), 0);
@@ skipping 13 matching lines @@
   return selected ? kRadioOn : kRadioOff;
 }
 
 const gfx::ImageSkia* GetSubmenuArrowImage() {
   ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
   return base::i18n::IsRTL() ? GetRtlSubmenuArrowImage()
                              : rb.GetImageNamed(IDR_MENU_ARROW).ToImageSkia();
 }
 
 }  // namespace views