Add shadow for md toggle button.

ui/views/controls/button/toggle_button.cc

 // Copyright 2016 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/toggle_button.h"
 
+#include "third_party/skia/include/core/SkDrawLooper.h"
+#include "third_party/skia/include/core/SkPaint.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/color_utils.h"
 #include "ui/views/border.h"
 
 namespace views {
 
 namespace {
 
 // Constants are measured in dip.
 const int kTrackHeight = 14;
 const int kTrackWidth = 36;
 // Margins from edge of track to edge of view.
-const int kTrackVerticalMargin = 4;
-const int kTrackHorizontalMargin = 1;
-// Margin from edge of thumb to closest three edges of view.
-const int kThumbMargin = 1;
+const int kTrackVerticalMargin = 6;
+const int kTrackHorizontalMargin = 2;
+// Margin from edge of thumb to closest edge of view. Note that the thumb
+// margins must be sufficiently large to allow space for the shadow.
+const int kThumbHorizontalMargin = 2;
+// Margin from top/bottom edge of thumb to top/bottom edge of view.
+const int kThumbVerticalMargin = 3;
 
 }  // namespace
 
 ToggleButton::ToggleButton(ButtonListener* listener)
     : CustomButton(listener), is_on_(false), slide_animation_(this) {
   slide_animation_.SetSlideDuration(80 /* ms */);
   slide_animation_.SetTweenType(gfx::Tween::LINEAR);
   SetBorder(Border::CreateEmptyBorder(
       gfx::Insets(kTrackVerticalMargin, kTrackHorizontalMargin)));
 }
@@ skipping 17 matching lines @@
   gfx::Rect rect(0, 0, kTrackWidth, kTrackHeight);
   if (border())
     rect.Inset(-border()->GetInsets());
   return rect.size();
 }
 
 void ToggleButton::OnPaint(gfx::Canvas* canvas) {
   SkAlpha blend =
       static_cast<SkAlpha>(SK_AlphaOPAQUE * slide_animation_.GetCurrentValue());
 
+  // Track.
   gfx::RectF track_rect(GetContentsBounds());
-  SkPaint paint;
-  paint.setAntiAlias(true);
-
-  // Track.
+  SkPaint track_paint;
+  track_paint.setAntiAlias(true);
   const SkColor track_on_color =
       SkColorSetA(GetNativeTheme()->GetSystemColor(
                       ui::NativeTheme::kColorId_CallToActionColor),
                   0xFF / 2);
   // TODO(estade): get this color from the theme.
   const SkColor track_off_color = SkColorSetA(SK_ColorBLACK, 0x61);
-  paint.setColor(
+  track_paint.setColor(
       color_utils::AlphaBlend(track_on_color, track_off_color, blend));
-  canvas->DrawRoundRect(track_rect, track_rect.height() / 2, paint);
+  canvas->DrawRoundRect(track_rect, track_rect.height() / 2, track_paint);
 
   // Thumb.
-  const SkColor thumb_on_color = GetNativeTheme()->GetSystemColor(
-      ui::NativeTheme::kColorId_CallToActionColor);
-  // TODO(estade): get this color from the theme.
-  const SkColor thumb_off_color = SkColorSetRGB(0xFA, 0xFA, 0xFA);
-  paint.setColor(
-      color_utils::AlphaBlend(thumb_on_color, thumb_off_color, blend));
   gfx::Rect thumb_bounds = GetLocalBounds();
-  thumb_bounds.Inset(gfx::Insets(kThumbMargin));
+  thumb_bounds.Inset(gfx::Insets(kThumbVerticalMargin, kThumbHorizontalMargin));
   thumb_bounds.set_x(thumb_bounds.x() +
                      slide_animation_.GetCurrentValue() *
                          (thumb_bounds.width() - thumb_bounds.height()));
   thumb_bounds.set_width(thumb_bounds.height());
   thumb_bounds.set_x(GetMirroredXForRect(thumb_bounds));
+  SkPaint thumb_paint;
+  std::vector<gfx::ShadowValue> shadows;
+  shadows.emplace(shadows.end(), gfx::Vector2d(0, 1), 5.f,

[sadrul, 2016/07/22 03:35:05]

emplace_back instead?

[Evan Stade, 2016/07/22 14:03:28]

done, thanks

+                  SkColorSetA(SK_ColorBLACK, 0x99));
+  thumb_paint.setLooper(gfx::CreateShadowDrawLooperCorrectBlur(shadows));
+  thumb_paint.setStyle(SkPaint::kStrokeAndFill_Style);
+  thumb_paint.setAntiAlias(true);
+  const SkColor thumb_on_color = GetNativeTheme()->GetSystemColor(
+      ui::NativeTheme::kColorId_CallToActionColor);
+  // TODO(estade): get this color from the theme.
+  const SkColor thumb_off_color = SkColorSetRGB(0xFA, 0xFA, 0xFA);
+  thumb_paint.setColor(
+      color_utils::AlphaBlend(thumb_on_color, thumb_off_color, blend));
   canvas->DrawCircle(gfx::RectF(thumb_bounds).CenterPoint(),
-                     thumb_bounds.height() / 2.f, paint);
-  // TODO(estade): add a shadow to the thumb.
+                     thumb_bounds.height() / 2.f, thumb_paint);
 }
 
 void ToggleButton::NotifyClick(const ui::Event& event) {
   SetIsOn(!is_on(), true);
   CustomButton::NotifyClick(event);
 }
 
 void ToggleButton::OnNativeThemeChanged(const ui::NativeTheme* theme) {
   SchedulePaint();
 }
 
 void ToggleButton::AnimationProgressed(const gfx::Animation* animation) {
   if (animation == &slide_animation_)
     SchedulePaint();
   else
     CustomButton::AnimationProgressed(animation);
 }
 
 }  // namespace views