Add a 1px border stroke to the shelf button active app indicator.

ash/common/shelf/shelf_button.cc

 // Copyright 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.
 
 #include "ash/common/shelf/shelf_button.h"
 
 #include <algorithm>
 
 #include "ash/common/ash_constants.h"
 #include "ash/common/shelf/ink_drop_button_listener.h"
@@ skipping 128 matching lines @@
     gfx::ScopedCanvas scoped(canvas);
     if (show_attention_) {
       SkAlpha alpha = ShelfButtonAnimation::GetInstance()->HasObserver(this)
                           ? ShelfButtonAnimation::GetInstance()->GetAlpha()
                           : SK_AlphaOPAQUE;
       canvas->SaveLayerAlpha(alpha);
     }
 
     DCHECK_EQ(width(), height());
     DCHECK_EQ(kIndicatorRadiusDip, width() / 2);
+    const float dsf = canvas->UndoDeviceScaleFactor();

[Daniel Erat, 2017/03/03 23:15:52]

i don't know much about device scale factors, but should you be wrapping all of
this in Save/Restore calls to ensure that the original scale is restored? is it
just safe to do here because this is at the end of the method?

[Evan Stade, 2017/03/04 01:02:22]

the scopedcanvas above takes care of that. Technically I think it isn't even
necessary because a new canvas is created for every View::OnPaint, but it's hard
to keep track of when you need it and when not, so I just always add it.

[Daniel Erat, 2017/03/04 01:17:05]

ah, sorry. i missed both the fact that a ScopedCanvas class exists and that you
were already using it here. carry on.

+    const int kStrokeWidthPx = 1;
+    gfx::PointF center = gfx::RectF(GetLocalBounds()).CenterPoint();
+    center.Scale(dsf);
+
+    // Fill the center.
     cc::PaintFlags flags;
     flags.setColor(kIndicatorColor);
     flags.setFlags(cc::PaintFlags::kAntiAlias_Flag);
-    canvas->DrawCircle(gfx::Point(width() / 2, height() / 2),
-                       kIndicatorRadiusDip, flags);
+    canvas->DrawCircle(center, dsf * kIndicatorRadiusDip - kStrokeWidthPx,
+                       flags);
+
+    // Stroke the border.
+    flags.setColor(SkColorSetA(SK_ColorBLACK, 0x29));
+    flags.setStyle(SkPaint::kStroke_Style);
+    canvas->DrawCircle(
+        center, dsf * kIndicatorRadiusDip - kStrokeWidthPx / 2.0f, flags);
   }
 
   // ShelfButtonAnimation::Observer
   void AnimationProgressed() override {
     UpdateAnimating();
     SchedulePaint();
   }
 
   void ShowAttention(bool show) {
     if (show_attention_ == show)
@@ skipping 329 matching lines @@
   icon_view_->SetHorizontalAlignment(is_horizontal_shelf
                                          ? views::ImageView::CENTER
                                          : views::ImageView::LEADING);
   icon_view_->SetVerticalAlignment(is_horizontal_shelf
                                        ? views::ImageView::LEADING
                                        : views::ImageView::CENTER);
   SchedulePaint();
 }
 
 }  // namespace ash