Adjust overlay scrollbar appearance.

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 15 matching lines @@
 #include "ui/native_theme/common_theme.h"
 #include "ui/native_theme/native_theme_switches.h"
 #include "ui/native_theme/overlay_scrollbar_constants_aura.h"
 
 namespace ui {
 
 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 = 32;
 
 // 2 pixel border with 1 pixel center patch. The border is 2 pixels despite the
 // stroke width being 1 so that the inner pixel can match the center tile
 // color. This prevents color interpolation between the patches.
 constexpr int kOverlayScrollbarBorderPatchWidth = 2;
 constexpr int kOverlayScrollbarCenterPatchSize = 1;
 
 const SkColor kTrackColor = SkColorSetRGB(0xF1, 0xF1, 0xF1);
 
@@ skipping 19 matching lines @@
 
 NativeThemeAura::NativeThemeAura(bool use_overlay_scrollbars)
     : use_overlay_scrollbars_(use_overlay_scrollbars) {
 // We don't draw scrollbar buttons.
 #if defined(OS_CHROMEOS)
   set_scrollbar_button_length(0);
 #endif
 
   if (use_overlay_scrollbars_) {
     scrollbar_width_ =
-        kOverlayScrollbarThumbWidthPressed + kOverlayScrollbarStrokeWidth * 2;
+        kOverlayScrollbarThumbWidthPressed + kOverlayScrollbarStrokeWidth;
   }
 
   // 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() {}
@@ skipping 105 matching lines @@
   if (state == kDisabled)
     return;
 
   TRACE_EVENT0("blink", "NativeThemeAura::PaintScrollbarThumb");
 
   SkAlpha thumb_alpha = SK_AlphaTRANSPARENT;
   gfx::Rect thumb_rect(rect);
   SkColor thumb_color;
 
   if (use_overlay_scrollbars_) {
-    // Constants used for painting overlay scrollbar thumb.
-    constexpr SkAlpha kOverlayScrollbarFillAlphaNormal = 0x80;
-    constexpr SkAlpha kOverlayScrollbarFillAlphaHovered = 0xB3;
-    constexpr SkAlpha kOverlayScrollbarFillAlphaPressed = 0xB3;
-    constexpr SkAlpha kOverlayScrollbarStrokeAlphaNormal = 0x4D;
-    constexpr SkAlpha kOverlayScrollbarStrokeAlphaHovered = 0x80;
-    constexpr SkAlpha kOverlayScrollbarStrokeAlphaPressed = 0x80;
-
     // Indexed by ScrollbarOverlayColorTheme.
     constexpr SkColor kOverlayScrollbarThumbColor[] = {SK_ColorBLACK,
                                                        SK_ColorWHITE};
     constexpr SkColor kOverlayScrollbarStrokeColor[] = {SK_ColorWHITE,
                                                         SK_ColorBLACK};
 
     thumb_color = kOverlayScrollbarThumbColor[theme];
 
     SkAlpha stroke_alpha = SK_AlphaTRANSPARENT;
     switch (state) {
       case NativeTheme::kDisabled:
         thumb_alpha = SK_AlphaTRANSPARENT;
         stroke_alpha = SK_AlphaTRANSPARENT;
         break;
       case NativeTheme::kHovered:
-        thumb_alpha = kOverlayScrollbarFillAlphaHovered;
-        stroke_alpha = kOverlayScrollbarStrokeAlphaHovered;
+        thumb_alpha = SK_AlphaOPAQUE * kOverlayScrollbarThumbHoverAlpha;
+        stroke_alpha = SK_AlphaOPAQUE * kOverlayScrollbarStrokeHoverAlpha;
         break;
       case NativeTheme::kNormal:
-        thumb_alpha = kOverlayScrollbarFillAlphaNormal;
-        stroke_alpha = kOverlayScrollbarStrokeAlphaNormal;
+        thumb_alpha = SK_AlphaOPAQUE * kOverlayScrollbarThumbNormalAlpha;
+        stroke_alpha = SK_AlphaOPAQUE * kOverlayScrollbarStrokeNormalAlpha;
         break;
       case NativeTheme::kPressed:
-        thumb_alpha = kOverlayScrollbarFillAlphaPressed;
-        stroke_alpha = kOverlayScrollbarStrokeAlphaPressed;
+        thumb_alpha = SK_AlphaOPAQUE * kOverlayScrollbarThumbHoverAlpha;
+        stroke_alpha = SK_AlphaOPAQUE * kOverlayScrollbarStrokeHoverAlpha;
         break;
       case NativeTheme::kNumStates:
         NOTREACHED();
         break;
     }
 
     // In overlay mode, draw a stroke (border).
     constexpr int kStrokeWidth = kOverlayScrollbarStrokeWidth;
     cc::PaintFlags flags;
     flags.setColor(
         SkColorSetA(kOverlayScrollbarStrokeColor[theme], stroke_alpha));
     flags.setStyle(cc::PaintFlags::kStroke_Style);
     flags.setStrokeWidth(kStrokeWidth);
 
     gfx::RectF stroke_rect(thumb_rect);
-    constexpr float kHalfStrokeWidth = kStrokeWidth / 2.f;
-    stroke_rect.Inset(kHalfStrokeWidth, kHalfStrokeWidth);
+    gfx::InsetsF stroke_insets(kStrokeWidth / 2.f);
+    // The edge to which the scrollbar is attached shouldn't have a border.
+    gfx::Insets edge_adjust_insets;
+    if (part == NativeTheme::kScrollbarHorizontalThumb)
+      edge_adjust_insets = gfx::Insets(0, 0, -kStrokeWidth, 0);
+    else
+      edge_adjust_insets = gfx::Insets(0, 0, 0, -kStrokeWidth);
+    stroke_rect.Inset(stroke_insets + edge_adjust_insets);
     canvas->drawRect(gfx::RectFToSkRect(stroke_rect), flags);
 
     // Inset the all the edges edges so we fill-in the stroke below.
-    // The edge to which the scrollbar is attached shouldn't have a border.
     // For left vertical scrollbar, we will horizontally flip the canvas in
     // ScrollbarThemeOverlay::paintThumb.
-    gfx::Insets insets(kStrokeWidth);
-    if (part == NativeTheme::kScrollbarHorizontalThumb)
-      insets -= gfx::Insets(0, 0, kStrokeWidth, 0);
-    else
-      insets -= gfx::Insets(0, 0, 0, kStrokeWidth);
-
-    thumb_rect.Inset(insets);
+    gfx::Insets fill_insets(kStrokeWidth);
+    thumb_rect.Inset(fill_insets + edge_adjust_insets);
   } else {
     switch (state) {
       case NativeTheme::kDisabled:
         thumb_alpha = SK_AlphaTRANSPARENT;
         break;
       case NativeTheme::kHovered:
         thumb_alpha = 0x4D;
         break;
       case NativeTheme::kNormal:
         thumb_alpha = 0x33;
@@ skipping 75 matching lines @@
 
 gfx::Rect NativeThemeAura::GetNinePatchAperture(Part part) const {
   DCHECK(SupportsNinePatch(part));
 
   return gfx::Rect(
       kOverlayScrollbarBorderPatchWidth, kOverlayScrollbarBorderPatchWidth,
       kOverlayScrollbarCenterPatchSize, kOverlayScrollbarCenterPatchSize);
 }
 
 }  // namespace ui