MacViews: Implement scrollbar theming.

ui/native_theme/native_theme_mac.mm

Index: ui/native_theme/native_theme_mac.mm
diff --git a/ui/native_theme/native_theme_mac.mm b/ui/native_theme/native_theme_mac.mm
index 2477af8ea0b3b20754a2e138685c892134c67f06..90a1d56cde9247b2d514518968e11ec2f9121dee 100644
--- a/ui/native_theme/native_theme_mac.mm
+++ b/ui/native_theme/native_theme_mac.mm
@@ -12,10 +12,23 @@
 #include "base/mac/sdk_forward_declarations.h"
 #include "ui/native_theme/common_theme.h"
 #import "skia/ext/skia_utils_mac.h"
+#include "third_party/skia/include/effects/SkGradientShader.h"
+#include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/skia_util.h"
 
 namespace {
 
+const SkColor kScrollerTrackGradientColors[] = {
+    SkColorSetRGB(0xF0, 0xF0, 0xF0),
+    SkColorSetRGB(0xFA, 0xFA, 0xFA),
+    SkColorSetRGB(0xFD, 0xFD, 0xFD),
+    SkColorSetRGB(0xF5, 0xF5, 0xF5) };
+const SkColor kScrollerTrackBorderColor = SkColorSetRGB(0xE4, 0xE4, 0xE4);
+const SkColor kScrollerThumbColor = SkColorSetARGB(0x38, 0, 0, 0);
+const SkColor kScrollerThumbHoverColor = SkColorSetARGB(0x80, 0, 0, 0);
+const int kScrollerTrackBorderWidth = 1;
+const int kScrollerThumbInset = 3;

[tapted, 2014/08/13 01:13:29]

nit: this one probably needs a comment - it's a bit subtle that it's inset from
both the ends and the sides.

[Andre, 2014/08/13 20:04:21]

Done.

+
 // Values calculated by reading pixels and solving simultaneous equations
 // derived from "A over B" alpha compositing. Steps: Sample the semi-transparent
 // pixel over two backgrounds; P1, P2 over backgrounds B1, B2. Use the color
@@ -184,6 +197,80 @@ SkColor NativeThemeMac::GetSystemColor(ColorId color_id) const {
   return FallbackTheme::GetSystemColor(color_id);
 }
 
+void NativeThemeMac::PaintScrollbarTrack(
+    SkCanvas* canvas,
+    Part part,
+    State state,
+    const ScrollbarTrackExtraParams& extra_params,
+    const gfx::Rect& rect) const {
+  SkPoint gradient_bounds[2];

[tapted, 2014/08/13 01:13:29]

nit: perhaps a comment in here saying which style is being targeted (e.g. OSX
10.7 - 10.10 ?), and that the non-overlay style is always used.

[Andre, 2014/08/13 20:04:22]

Done.

+  if (part == kScrollbarVerticalTrack) {
+    gradient_bounds[0].set(rect.x() + kScrollerTrackBorderWidth, rect.y());
+    gradient_bounds[1].set(rect.right(), rect.y());
+  } else {
+    gradient_bounds[0].set(rect.x(), rect.y() + kScrollerTrackBorderWidth);

[tapted, 2014/08/13 01:13:29]

nit: DCHECK_EQ(part, kScrollbarHorizontalTrack);

[Andre, 2014/08/13 20:04:22]

Done.

+    gradient_bounds[1].set(rect.x(), rect.bottom());
+  }
+  skia::RefPtr<SkShader> shader = skia::AdoptRef(
+      SkGradientShader::CreateLinear(gradient_bounds,
+                                     kScrollerTrackGradientColors,
+                                     NULL,
+                                     4,

[tapted, 2014/08/13 01:13:29]

nit: 4 -> arraysize(kScrollerTrackGradientColors)  (from macros.h)

[Andre, 2014/08/13 20:04:22]

Done.

+                                     SkShader::kClamp_TileMode));
+  SkPaint gradient;
+  gradient.setShader(shader.get());
+
+  SkIRect track_rect;
+  track_rect.set(rect.x(), rect.y(), rect.right(), rect.bottom());
+  canvas->drawIRect(track_rect, gradient);
+
+  // Draw line border next to content area.
+  SkPaint paint;
+  paint.setColor(kScrollerTrackBorderColor);
+  if (part == kScrollbarVerticalTrack) {
+    canvas->drawRectCoords(track_rect.left(),
+                           track_rect.top(),
+                           track_rect.left() + kScrollerTrackBorderWidth,
+                           track_rect.bottom(),
+                           paint);
+  } else {
+    canvas->drawRectCoords(track_rect.left(),
+                           track_rect.top(),
+                           track_rect.right(),
+                           track_rect.top() + kScrollerTrackBorderWidth,
+                           paint);
+  }
+}
+
+void NativeThemeMac::PaintScrollbarThumb(SkCanvas* canvas,
+                                         Part part,
+                                         State state,
+                                         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;

[tapted, 2014/08/13 01:13:29]

Looking at the screenshots.. I think we want paint.setAntiAlias(true); after
this

[Andre, 2014/08/13 20:04:22]

Done.

+  paint.setColor(state == kHovered ? thumb_active_color_

[tapted, 2014/08/13 01:13:29]

hm - it's odd there are protected data members in the base class - style guide
doesn't allow those. See what owners say maybe

[Andre, 2014/08/13 20:04:22]

Acknowledged.

+                                   : thumb_inactive_color_);
+  SkRect skrect;
+  skrect.set(
+      thumb_rect.x(), thumb_rect.y(), thumb_rect.right(), thumb_rect.bottom());
+  const SkScalar radius = std::min(skrect.width(), skrect.height());
+  canvas->drawRoundRect(skrect, radius, radius, paint);
+}
+
 void NativeThemeMac::PaintMenuPopupBackground(
     SkCanvas* canvas,
     const gfx::Size& size,
@@ -217,6 +304,10 @@ void NativeThemeMac::PaintMenuItemBackground(
 }
 
 NativeThemeMac::NativeThemeMac() {
+  set_scrollbar_button_length(0);
+  SetScrollbarColors(kScrollerThumbColor,
+                     kScrollerThumbHoverColor,
+                     kScrollerTrackGradientColors[0]);
 }
 
 NativeThemeMac::~NativeThemeMac() {