Sharpen MdTextButton border for fractional scale factors.

ui/views/controls/button/md_text_button.cc

 // Copyright 2015 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/button/md_text_button.h"
 
 #include "base/i18n/case_conversion.h"
 #include "ui/base/material_design/material_design_controller.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/color_utils.h"
@@ skipping 220 matching lines @@
   set_has_ink_drop_action_on_click(true);
   SetHorizontalAlignment(gfx::ALIGN_CENTER);
   SetFocusForPlatform();
   SetMinSize(gfx::Size(kMinWidth, 0));
   SetFocusPainter(nullptr);
   label()->SetAutoColorReadabilityEnabled(false);
   AddChildView(focus_ring_);
   focus_ring_->SetVisible(false);
   set_request_focus_on_press(false);
   LabelButton::SetFontList(GetMdFontList());
+
+  // Paint to a layer so that the canvas is snapped to pixel boundaries (useful
+  // for fractional DSF).
+  SetPaintToLayer(true);

[sky, 2016/09/07 21:22:37]

It makes me sad that you have to do this.

[Evan Stade, 2016/09/07 22:31:25]

yea, me too, an angel is losing its wings. Is there a better way to get
pixel-snappery?

[Evan Stade, 2016/09/07 22:43:40]

I mean, I assume there isn't currently, but perhaps there's a way we can make it
possible?

+  layer()->SetFillsBoundsOpaquely(false);
 }
 
 MdTextButton::~MdTextButton() {}
 
 void MdTextButton::UpdatePadding() {
   // Don't use font-based padding when there's no text visible.
   if (GetText().empty()) {
     SetBorder(Border::NullBorder());
     return;
   }
@@ skipping 38 matching lines @@
 
   SkColor text_color = label()->enabled_color();
   SkColor bg_color =
       bg_color_override_
           ? *bg_color_override_
           : is_cta_
                 ? theme->GetSystemColor(
                       ui::NativeTheme::kColorId_CallToActionColor)
                 : is_default()
                       ? color_utils::BlendTowardOppositeLuma(text_color, 0xD8)
-                      : SK_ColorTRANSPARENT;
+                      : theme->GetSystemColor(
+                            ui::NativeTheme::kColorId_DialogBackground);
 
   bg_color = PlatformStyle::BackgroundColorForMdButton(bg_color, state());
 
   const SkAlpha kStrokeOpacity = 0x1A;
   SkColor stroke_color = (is_cta_ || color_utils::IsDark(text_color))
                              ? SkColorSetA(SK_ColorBLACK, kStrokeOpacity)
                              : SkColorSetA(SK_ColorWHITE, 2 * kStrokeOpacity);
 
+  DCHECK_EQ(SK_AlphaOPAQUE, static_cast<int>(SkColorGetA(bg_color)));
   set_background(Background::CreateBackgroundPainter(
       true, Painter::CreateRoundRectWith1PxBorderPainter(
                 bg_color, stroke_color, kInkDropSmallCornerRadius)));
 }
 
 }  // namespace views