MacViews: Overlay Scrollbars with Show/Hide Animations

ui/native_theme/native_theme_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.
 
 #include "ui/native_theme/native_theme_mac.h"
 
 #import <Cocoa/Cocoa.h>
 #include <stddef.h>
 
 #include "base/mac/mac_util.h"
@@ skipping 104 matching lines @@
   // CGColorRefToSkColor will not like. But RGB is additive, so the conversion
   // is easy (RGB to grayscale is less easy).
   const CGFloat* components = CGColorGetComponents(cg_color);
   CGFloat alpha = component_count == 2 ? components[1] : 1.0;
   return SkColorSetARGB(SkScalarRoundToInt(255.0 * alpha),
                         SkScalarRoundToInt(255.0 * components[0]),
                         SkScalarRoundToInt(255.0 * components[0]),
                         SkScalarRoundToInt(255.0 * components[0]));
 }
 
+SkColor GetColorFromOverlayParams(
+    SkColor color,
+    ui::NativeTheme::OverlayParams overlay_params) {
+  return overlay_params.is_overlay
+             ? SkColorSetA(color, SkColorGetA(color) * overlay_params.alpha)
+             : color;
+}
+
 }  // namespace
 
 namespace ui {
 
 // static
 NativeTheme* NativeTheme::GetInstanceForWeb() {
   return NativeThemeMac::instance();
 }
 
 // static
@@ skipping 114 matching lines @@
   // Emulate the non-overlay scroller style from OSX 10.7 and later.
   SkPoint gradient_bounds[2];
   if (part == kScrollbarVerticalTrack) {
     gradient_bounds[0].set(rect.x(), rect.y());
     gradient_bounds[1].set(rect.right(), rect.y());
   } else {
     DCHECK_EQ(part, kScrollbarHorizontalTrack);
     gradient_bounds[0].set(rect.x(), rect.y());
     gradient_bounds[1].set(rect.x(), rect.bottom());
   }
+
+  // TODO(spqchan): Change the opacity of the track when it's overlayed.
   skia::RefPtr<SkShader> shader = skia::AdoptRef(
       SkGradientShader::CreateLinear(gradient_bounds,
                                      kScrollerTrackGradientColors,
                                      NULL,
                                      arraysize(kScrollerTrackGradientColors),
                                      SkShader::kClamp_TileMode));
   SkPaint gradient;
   gradient.setShader(shader.get());
 
   SkIRect track_rect = gfx::RectToSkIRect(rect);
   canvas->drawIRect(track_rect, gradient);
 
   // Draw inner and outer line borders.
   if (part == kScrollbarVerticalTrack) {
     SkPaint paint;
-    paint.setColor(kScrollerTrackInnerBorderColor);
+    paint.setColor(GetColorFromOverlayParams(kScrollerTrackInnerBorderColor,
+                                             extra_params.overlay));
     canvas->drawRectCoords(track_rect.left(),
                            track_rect.top(),
                            track_rect.left() + kScrollerTrackBorderWidth,
                            track_rect.bottom(),
                            paint);
-    paint.setColor(kScrollerTrackOuterBorderColor);
+    paint.setColor(GetColorFromOverlayParams(kScrollerTrackOuterBorderColor,
+                                             extra_params.overlay));
     canvas->drawRectCoords(track_rect.right() - kScrollerTrackBorderWidth,
                            track_rect.top(),
                            track_rect.right(),
                            track_rect.bottom(),
                            paint);
   } else {
     SkPaint paint;
-    paint.setColor(kScrollerTrackInnerBorderColor);
+    paint.setColor(GetColorFromOverlayParams(kScrollerTrackInnerBorderColor,
+                                             extra_params.overlay));
     canvas->drawRectCoords(track_rect.left(),
                            track_rect.top(),
                            track_rect.right(),
                            track_rect.top() + kScrollerTrackBorderWidth,
                            paint);
-    paint.setColor(kScrollerTrackOuterBorderColor);
+    paint.setColor(GetColorFromOverlayParams(kScrollerTrackOuterBorderColor,
+                                             extra_params.overlay));
     canvas->drawRectCoords(track_rect.left(),
                            track_rect.bottom() - kScrollerTrackBorderWidth,
                            track_rect.right(),
                            track_rect.bottom(),
                            paint);
   }
 }
 
-void NativeThemeMac::PaintScrollbarThumb(SkCanvas* canvas,
-                                         Part part,
-                                         State state,
-                                         const gfx::Rect& rect) const {
+void NativeThemeMac::PaintScrollbarThumb(
+    SkCanvas* canvas,
+    Part part,
+    State state,
+    const ScrollbarThumbExtraParams& extra_params,
+    const gfx::Rect& rect) const {
   gfx::Rect thumb_rect(rect);
   switch (part) {
     case kScrollbarHorizontalThumb:
       thumb_rect.Inset(0, kScrollerTrackBorderWidth, 0, 0);
       break;
     case kScrollbarVerticalThumb:
       thumb_rect.Inset(kScrollerTrackBorderWidth, 0, 0, 0);
       break;
     default:
       NOTREACHED();
       break;
   }
 
   thumb_rect.Inset(kScrollerThumbInset, kScrollerThumbInset);
 
   SkPaint paint;
   paint.setAntiAlias(true);
-  paint.setColor(state == kHovered ? thumb_active_color_
-                                   : thumb_inactive_color_);
+
+  SkColor thumb_color =
+      state == kHovered ? thumb_active_color_ : thumb_inactive_color_;
+  paint.setColor(GetColorFromOverlayParams(thumb_color, extra_params.overlay));
+
   const SkScalar radius = std::min(rect.width(), rect.height());
   canvas->drawRoundRect(gfx::RectToSkRect(thumb_rect), radius, radius, paint);
 }
 
 void NativeThemeMac::PaintScrollbarCorner(SkCanvas* canvas,
                                           State state,
                                           const gfx::Rect& rect) const {
   DCHECK_GT(rect.width(), 0);
   DCHECK_GT(rect.height(), 0);
 
@@ skipping 73 matching lines @@
   set_scrollbar_button_length(0);
   SetScrollbarColors(kScrollerThumbColor,
                      kScrollerThumbHoverColor,
                      kScrollerTrackGradientColors[0]);
 }
 
 NativeThemeMac::~NativeThemeMac() {
 }
 
 }  // namespace ui