Make audio volume icon HDC

ash/system/audio/tray_volume.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 "ash/system/audio/tray_volume.h"
 
+#include <cmath>
+
 #include "ash/shell.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "ash/system/tray/tray_constants.h"
 #include "ash/system/tray/tray_views.h"
 #include "base/utf_string_conversions.h"
 #include "grit/ash_strings.h"
 #include "grit/ui_resources.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkPaint.h"
 #include "third_party/skia/include/core/SkRect.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_operations.h"
 #include "ui/views/controls/button/image_button.h"
 #include "ui/views/controls/image_view.h"
 #include "ui/views/controls/label.h"
 #include "ui/views/controls/slider.h"
 #include "ui/views/layout/box_layout.h"
 #include "ui/views/view.h"
 
 namespace ash {
 namespace internal {
 
 namespace {
 const int kVolumeImageWidth = 25;
 const int kVolumeImageHeight = 25;
 const int kVolumeLevel = 4;

[Daniel Erat, 2012/07/24 00:24:33]

nit: Add a comment describing what this represents.  Number of non-zero image
indices?

[oshima, 2012/07/24 00:44:21]

Done.

 }
 
 namespace tray {
 
 class VolumeButton : public views::ToggleImageButton {
  public:
   explicit VolumeButton(views::ButtonListener* listener)
       : views::ToggleImageButton(listener),
         image_index_(-1) {
     SetImageAlignment(ALIGN_CENTER, ALIGN_MIDDLE);
     image_ = ui::ResourceBundle::GetSharedInstance().GetImageNamed(
         IDR_AURA_UBER_TRAY_VOLUME_LEVELS);
     SetPreferredSize(gfx::Size(kTrayPopupItemHeight, kTrayPopupItemHeight));
     Update();
   }
 
   virtual ~VolumeButton() {}
 
   void Update() {
     ash::SystemTrayDelegate* delegate =
         ash::Shell::GetInstance()->tray_delegate();
-    int level = static_cast<int>(delegate->GetVolumeLevel() * 100);
-    int image_index = level / (100 / kVolumeLevel);
-    if (level > 0 && image_index == 0)
-      ++image_index;
-    if (level == 100)
-      image_index = kVolumeLevel - 1;
-    else if (image_index == kVolumeLevel - 1)
-      --image_index;
-    // Index 0 is reserved for mute.
-    if (delegate->IsAudioMuted())
-      image_index = 0;
-    else
-      ++image_index;
+    int image_index = delegate->IsAudioMuted() ?
+        0 : std::ceil(delegate->GetVolumeLevel() * kVolumeLevel);

[Daniel Erat, 2012/07/24 00:24:33]

Not your fault, but do you mind updating ash/system/tray/system_tray_delegate.h
to document whether the level is in the range [0, 100] or [0, 1]?  I'm guessing
from this code that it's the latter, but I hate seeing this stuff be
undocumented.

[Daniel Erat, 2012/07/24 00:24:33]

The old code looks like it used kVolumeLevel - 1 for the maximum level, but this
appears to be using kVolumeLevel instead.  Intentional?

[oshima, 2012/07/24 00:44:21]

Done.

[oshima, 2012/07/24 00:44:21]

overlooked original behavior. Fixed.

+
     if (image_index != image_index_) {
-      SkIRect region = SkIRect::MakeXYWH(0, image_index * kVolumeImageHeight,
-          kVolumeImageWidth, kVolumeImageHeight);
-      gfx::ImageSkia image_skia;
-      image_.ToImageSkia()->extractSubset(&image_skia, region);
+      gfx::Rect region(0, image_index * kVolumeImageHeight,
+                       kVolumeImageWidth, kVolumeImageHeight);
+      gfx::ImageSkia image_skia = gfx::ImageSkiaOperations::ExtractSubset(
+          *(image_.ToImageSkia()), region);
       SetImage(views::CustomButton::BS_NORMAL, &image_skia);
       image_index_ = image_index;
     }
     SchedulePaint();
   }
 
  private:
   // Overridden from views::View.
   virtual gfx::Size GetPreferredSize() OVERRIDE {
     gfx::Size size = views::ToggleImageButton::GetPreferredSize();
@@ skipping 127 matching lines @@
       percent = 0.0;
     volume_view_->SetVolumeLevel(percent);
     SetDetailedViewCloseDelay(kTrayPopupAutoCloseDelayInSeconds);
     return;
   }
   PopupDetailedView(kTrayPopupAutoCloseDelayInSeconds, false);
 }
 
 }  // namespace internal
 }  // namespace ash