Improve painting of cros tray separators.

ash/common/system/tray/tray_background_view.cc

Index: ash/common/system/tray/tray_background_view.cc
diff --git a/ash/common/system/tray/tray_background_view.cc b/ash/common/system/tray/tray_background_view.cc
index fb988555461b5df0a564ecaa62eaf36c381cc646..1546277fa6e8b16a365cf931046a94ceca5cfb2f 100644
--- a/ash/common/system/tray/tray_background_view.cc
+++ b/ash/common/system/tray/tray_background_view.cc
@@ -567,21 +567,15 @@ void TrayBackgroundView::OnPaintFocus(gfx::Canvas* canvas) {
   // sure clicking on the edges brings up the popup. However, the focus border
   // should be only around the container.
   gfx::RectF paint_bounds;
-  if (MaterialDesignController::IsShelfMaterial()) {
-    paint_bounds = gfx::RectF(GetBackgroundBounds());
-    paint_bounds.Inset(gfx::Insets(-kFocusBorderThickness));
-  } else {
-    paint_bounds = gfx::RectF(GetContentsBounds());
-    paint_bounds.Inset(gfx::Insets(1));
-  }
+  paint_bounds = gfx::RectF(GetBackgroundBounds());
+  paint_bounds.Inset(gfx::Insets(-kFocusBorderThickness));
   canvas->DrawSolidFocusRect(paint_bounds, kFocusBorderColor,
                              kFocusBorderThickness);
 }
 
 void TrayBackgroundView::OnPaint(gfx::Canvas* canvas) {
   ActionableView::OnPaint(canvas);
-  if (!MaterialDesignController::IsShelfMaterial() ||
-      shelf()->GetBackgroundType() ==
+  if (shelf()->GetBackgroundType() ==
           ShelfBackgroundType::SHELF_BACKGROUND_DEFAULT ||
       !separator_visible_) {
     return;
@@ -590,33 +584,21 @@ void TrayBackgroundView::OnPaint(gfx::Canvas* canvas) {
   // right or left of the TrayBackgroundView when the system is LTR or RTL
   // aligned, respectively. For a vertical shelf draw the separator line
   // underneath the items instead.
-  const bool horizontal_shelf = IsHorizontalAlignment(shelf_alignment_);
   const gfx::Rect local_bounds = GetLocalBounds();
-  const int height = kTrayItemSize;
-  const int x =
-      horizontal_shelf
-          ? (base::i18n::IsRTL() ? 0 : (local_bounds.width() - kSeparatorWidth))
-          : (local_bounds.height() - kSeparatorWidth);
-  const int y = (GetShelfConstant(SHELF_SIZE) - kTrayItemSize) / 2;
-  gfx::ScopedCanvas scoped_canvas(canvas);
-  const float scale = canvas->UndoDeviceScaleFactor();
-  cc::PaintFlags flags;
-  flags.setColor(kTraySeparatorColor);
-  flags.setAntiAlias(true);

[Evan Stade, 2017/02/28 05:07:49]

this is a little crazy and requires explanation.

You will notice that the old tray separator color was white * 0.6a, whereas the
spec is white * 0.3a. However it still sorta looked right, because the values we
pass to DrawLine are off of pixel centers (whole numbers that lie between two
pixels) and we enabled anti aliasing, so you get two ~half filled pixels. We
only actually saw one of the two pixels because it was drawn right on the canvas
border, so the other pixel was clipped.

-
-  const gfx::Rect bounds = horizontal_shelf
-                               ? gfx::Rect(x, y, kSeparatorWidth, height)
-                               : gfx::Rect(y, x, height, kSeparatorWidth);
-  gfx::RectF rect(gfx::ScaleRect(gfx::RectF(bounds), scale));
-  gfx::PointF line_start =
-      horizontal_shelf
-          ? (base::i18n::IsRTL() ? rect.origin() : rect.top_right())
-          : rect.bottom_left();
-  gfx::PointF line_end =
-      (horizontal_shelf && base::i18n::IsRTL() ? rect.bottom_left()
-                                               : rect.bottom_right());
-
-  canvas->DrawLine(line_start, line_end, flags);
+  const SkColor color = SkColorSetA(SK_ColorWHITE, 0x4D);
+
+  if (IsHorizontalAlignment(shelf_alignment_)) {
+    const gfx::PointF point(
+        base::i18n::IsRTL() ? 0 : (local_bounds.width() - kSeparatorWidth),
+        (GetShelfConstant(SHELF_SIZE) - kTrayItemSize) / 2);
+    const gfx::Vector2dF vector(0, kTrayItemSize);
+    canvas->Draw1pxLine(point, point + vector, color);
+  } else {
+    const gfx::PointF point((GetShelfConstant(SHELF_SIZE) - kTrayItemSize) / 2,
+                            local_bounds.height() - kSeparatorWidth);
+    const gfx::Vector2dF vector(kTrayItemSize, 0);
+    canvas->Draw1pxLine(point, point + vector, color);
+  }
 }
 
 gfx::Insets TrayBackgroundView::GetBackgroundInsets() const {