Audio indicator: Mac UI

chrome/browser/ui/cocoa/tabs/tab_audio_indicator_view_mac.mm

+// Copyright (c) 2013 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.
+
+#import "chrome/browser/ui/cocoa/tabs/tab_audio_indicator_view_mac.h"
+
+#include "chrome/browser/ui/tabs/tab_audio_indicator.h"
+#include "ui/gfx/canvas_skia_paint.h"
+#include "ui/gfx/rect.h"
+
+class TabAudioIndicatorDelegateMac : public TabAudioIndicator::Delegate {
+ public:
+  TabAudioIndicatorDelegateMac(TabAudioIndicatorViewMac* view) : view_(view) {}

[Nico, 2013/03/11 02:52:56]

1-element constructors should be marked explicit

[sail, 2013/03/11 23:42:01]

Done.

+
+  virtual ~TabAudioIndicatorDelegateMac() {}
+
+  virtual void ScheduleAudioIndicatorPaint() OVERRIDE {
+    [view_ setNeedsDisplay:YES];
+  }
+
+ private:
+  TabAudioIndicatorViewMac* view_;
+
+  DISALLOW_COPY_AND_ASSIGN(TabAudioIndicatorDelegateMac);
+};
+
+@interface TabAudioIndicatorViewMac ()
+@end
+
+@implementation TabAudioIndicatorViewMac
+
+- (id)initWithFrame:(NSRect)frame {
+  if ((self = [super initWithFrame:frame])) {
+    delegate_.reset(new TabAudioIndicatorDelegateMac(self));
+    tabAudioIndicator_.reset(new TabAudioIndicator(delegate_.get()));
+  }
+  return self;
+}
+
+- (void)setIsPlayingAudio:(BOOL)isPlayingAudio {
+  tabAudioIndicator_->SetIsPlayingAudio(isPlayingAudio);
+}
+
+- (void)setBackgroundImage:(NSImage*)backgroundImage {
+  backgroundImage_.reset([backgroundImage retain]);
+}
+
+- (BOOL)isAnimating {
+  return tabAudioIndicator_->IsAnimating();
+}
+
+- (void)drawRect:(NSRect)rect {
+  [backgroundImage_ drawInRect:[self bounds]
+                      fromRect:NSZeroRect
+                     operation:NSCompositeSourceOver
+                      fraction:1];
+
+  gfx::CanvasSkiaPaint canvas(rect, false);

[Nico, 2013/03/11 02:52:56]

Hm, CanvasSkiaPaint requires allocating a skia backbuffer that's then copied to
the cocoa context in its destructor if I remember correctly. Since this is a
somewhat common operation: How %cpu does that take? Could the xplat api just
hand out a SkBitmap (which can be drawn without a duplicate copy)?

[sail, 2013/03/11 23:42:01]

Hm.. doesn't drawing a SkBitmap require copying to a NSImage or CGImage? It not
I don't mind doing this.

Note, I'll have to manually setup the bitmap and canvas with the correct scale
factor. I'll keep the cross platform code the same and do the work in this
method.

[Nico, 2013/03/11 23:47:56]

My reading of SkCreateCGImageRefWithColorspace() is that it just creates a
different view on the same data, without copying pixels around. But probably
best to try locally if it makes a measurable perf difference.

[sail, 2013/03/12 00:25:12]

Hm... I think I'm doing something wrong.
The current drawing code takes ~57 micro seconds.
If I change it to draw into a SkBitmap it takes ~63 micro seconds.

Here's the code I'm using:
https://docs.google.com/file/d/0B0Odde3V7EhWc1NETFZyOGVmcEE/edit?usp=sharing

This is on a MacBook Pro Retina running on an external display.

+  canvas.set_composite_alpha(true);
+  tabAudioIndicator_->Paint(&canvas, gfx::Rect(NSRectToCGRect([self bounds])));
+}
+
+@end