Aura overlay scrollbars adjust color for dark backgrounds

ui/native_theme/native_theme_aura.cc

 // Copyright (c) 2012 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_aura.h"
 
 #include <limits>
 #include <utility>
 
 #include "base/logging.h"
@@ skipping 17 matching lines @@
 
 namespace {
 
 // Constants for painting overlay scrollbars. Other properties needed outside
 // this painting code are defined in overlay_scrollbar_constants_aura.h.
 constexpr int kOverlayScrollbarStrokeWidth = 1;
 constexpr int kOverlayScrollbarMinimumLength = 12;
 constexpr SkAlpha kOverlayScrollbarAlphaNormal = 0x4D;
 constexpr SkAlpha kOverlayScrollbarAlphaHovered = 0x80;
 constexpr SkAlpha kOverlayScrollbarAlphaPressed = 0x80;
-constexpr SkColor kOverlayScrollbarThumbColor = SK_ColorBLACK;
-constexpr SkColor kOverlayScrollbarStrokeColor = SK_ColorWHITE;
+
+// Indexed by ScrollbarOverlayColorTheme.
+constexpr SkColor kOverlayScrollbarThumbColor[] = {SK_ColorBLACK,
+                                                   SK_ColorWHITE};
+constexpr SkColor kOverlayScrollbarStrokeColor[] = {SK_ColorWHITE,
+                                                    SK_ColorBLACK};
 
 SkAlpha ThumbAlphaForState(NativeTheme::State state) {
   bool overlay = IsOverlayScrollbarEnabled();
   switch (state) {
     case NativeTheme::kDisabled:
       return 0x00;
     case NativeTheme::kHovered:
       return overlay ? kOverlayScrollbarAlphaHovered : 0x4D;
     case NativeTheme::kNormal:
       return overlay ? kOverlayScrollbarAlphaNormal : 0x33;
@@ skipping 16 matching lines @@
   return NativeThemeAura::instance();
 }
 
 // static
 NativeThemeAura* NativeThemeAura::instance() {
   CR_DEFINE_STATIC_LOCAL(NativeThemeAura, s_native_theme, ());
   return &s_native_theme;
 }
 
 NativeThemeAura::NativeThemeAura() {
-  // We don't draw scrollbar buttons.
+// We don't draw scrollbar buttons.
 #if defined(OS_CHROMEOS)
   set_scrollbar_button_length(0);
 #endif
 
   if (IsOverlayScrollbarEnabled()) {
     scrollbar_width_ =
         kOverlayScrollbarThumbWidthPressed + kOverlayScrollbarStrokeWidth * 2;
   }
 
   // Images and alphas declarations assume the following order.
   static_assert(kDisabled == 0, "states unexpectedly changed");
   static_assert(kHovered == 1, "states unexpectedly changed");
   static_assert(kNormal == 2, "states unexpectedly changed");
   static_assert(kPressed == 3, "states unexpectedly changed");
 }
 
-NativeThemeAura::~NativeThemeAura() {
-}
+NativeThemeAura::~NativeThemeAura() {}
 
 // This implementation returns hardcoded colors.
 SkColor NativeThemeAura::GetSystemColor(ColorId color_id) const {
   return GetAuraColor(color_id, this);
 }
 
 void NativeThemeAura::PaintMenuPopupBackground(
     SkCanvas* canvas,
     const gfx::Size& size,
     const MenuBackgroundExtraParams& menu_background) const {
@@ skipping 65 matching lines @@
     State state,
     const ScrollbarTrackExtraParams& extra_params,
     const gfx::Rect& rect) const {
   // Overlay Scrollbar should never paint a scrollbar track.
   DCHECK(!IsOverlayScrollbarEnabled());
   SkPaint paint;
   paint.setColor(kTrackColor);
   canvas->drawIRect(gfx::RectToSkIRect(rect), paint);
 }
 
-void NativeThemeAura::PaintScrollbarThumb(SkCanvas* canvas,
-                                          Part part,
-                                          State state,
-                                          const gfx::Rect& rect) const {
+void NativeThemeAura::PaintScrollbarThumb(
+    SkCanvas* canvas,
+    Part part,
+    State state,
+    const gfx::Rect& rect,
+    ScrollbarOverlayColorTheme theme) const {
   // Do not paint if state is disabled.
   if (state == kDisabled)
     return;
 
-  PaintScrollbarThumbStateTransition(canvas, part, state, state, 1.0, rect);
-}
+  TRACE_EVENT0("blink", "NativeThemeAura::PaintScrollbarThumb");
 
-void NativeThemeAura::PaintScrollbarThumbStateTransition(
-    SkCanvas* canvas,
-    Part part,
-    State start_state,
-    State end_state,
-    double progress,
-    const gfx::Rect& rect) const {
-  TRACE_EVENT0("blink", "NativeThemeAura::PaintScrollbarThumbStateTransition");
   gfx::Rect thumb_rect(rect);
   SkColor thumb_color;
+  SkAlpha thumb_alpha = ThumbAlphaForState(state);
+
   if (IsOverlayScrollbarEnabled()) {
+    thumb_color = kOverlayScrollbarThumbColor[theme];
+
     // In overlay mode, draw a stroke (border).
     constexpr int kStrokeWidth = kOverlayScrollbarStrokeWidth;
-    SkAlpha stroke_alpha = gfx::Tween::IntValueBetween(
-        progress, ThumbAlphaForState(start_state),
-        ThumbAlphaForState(end_state));
     SkPaint paint;
-    paint.setColor(SkColorSetA(kOverlayScrollbarStrokeColor, stroke_alpha));
+    paint.setColor(
+        SkColorSetA(kOverlayScrollbarStrokeColor[theme], thumb_alpha));
     paint.setStyle(SkPaint::kStroke_Style);
     paint.setStrokeWidth(kStrokeWidth);
 
     gfx::RectF stroke_rect(thumb_rect);
     constexpr float kHalfStrokeWidth = kStrokeWidth / 2.f;
     stroke_rect.Inset(kHalfStrokeWidth, kHalfStrokeWidth);
     canvas->drawRect(gfx::RectFToSkRect(stroke_rect), paint);
 
     // Inset the all the edges edges so we fill-in the stroke below.
     thumb_rect.Inset(kStrokeWidth, kStrokeWidth);
-    thumb_color = kOverlayScrollbarThumbColor;
   } else {
     // If there are no scrollbuttons then provide some padding so that the thumb
     // doesn't touch the top of the track.
     const int kThumbPadding = 2;
     const int extra_padding =
         (scrollbar_button_length() == 0) ? kThumbPadding : 0;
     if (part == NativeTheme::kScrollbarVerticalThumb)
       thumb_rect.Inset(kThumbPadding, extra_padding);
     else
       thumb_rect.Inset(extra_padding, kThumbPadding);
 
     thumb_color = SK_ColorBLACK;
   }
 
   SkPaint paint;
-  SkAlpha alpha = gfx::Tween::IntValueBetween(
-      progress, ThumbAlphaForState(start_state), ThumbAlphaForState(end_state));
-  paint.setColor(SkColorSetA(thumb_color, alpha));
+  paint.setColor(SkColorSetA(thumb_color, thumb_alpha));
   canvas->drawIRect(gfx::RectToSkIRect(thumb_rect), paint);
 }
 
 void NativeThemeAura::PaintScrollbarCorner(SkCanvas* canvas,
                                            State state,
                                            const gfx::Rect& rect) const {
   // Overlay Scrollbar should never paint a scrollbar corner.
   DCHECK(!IsOverlayScrollbarEnabled());
   SkPaint paint;
   paint.setColor(SkColorSetRGB(0xDC, 0xDC, 0xDC));
@@ skipping 21 matching lines @@
         // branch return 0 for parts that don't exist or assert NOTREACHED.
         // crbug.com/657159.
         break;
     }
   }
 
   return NativeThemeBase::GetPartSize(part, state, extra);
 }
 
 }  // namespace ui