Remove top and bottom margins from TrayBubbleView

ui/views/bubble/tray_bubble_view.cc

Index: ui/views/bubble/tray_bubble_view.cc
diff --git a/ui/views/bubble/tray_bubble_view.cc b/ui/views/bubble/tray_bubble_view.cc
index d83055bef30b98d451d61c0b314741ad9c1c7575..9a7e6b465e3d7421afe138a66ea9e744833fd9f7 100644
--- a/ui/views/bubble/tray_bubble_view.cc
+++ b/ui/views/bubble/tray_bubble_view.cc
@@ -15,6 +15,7 @@
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/insets.h"
 #include "ui/gfx/path.h"
+#include "ui/gfx/rect.h"
 #include "ui/gfx/skia_util.h"
 #include "ui/views/bubble/bubble_frame_view.h"
 #include "ui/views/layout/box_layout.h"
@@ -117,59 +118,41 @@ class TrayBubbleBorder : public views::BubbleBorder {
   DISALLOW_COPY_AND_ASSIGN(TrayBubbleBorder);
 };
 
-// Custom background for TrayBubbleView. Fills in the top and bottom margins
-// with appropriate background colors without overwriting the rounded corners.
-class TrayBubbleBackground : public views::Background {
+// This mask layer clips the bubble's content so that it does not overwrite the
+// rounded bubble corners.
+// TODO(miket): This does not work on Windows. Implement layer masking or
+// alternate solutions if the TrayBubbleView is needed there in the future.
+class TrayBubbleContentMask : public ui::Layer, public ui::LayerDelegate {

[msw, 2012/11/12 19:15:02]

Include layer.h and layer_delegate.h 

[bartfab (slow), 2012/11/13 09:58:54]

Done.

  public:
-  explicit TrayBubbleBackground(views::BubbleBorder* border,
-                                SkColor top_color,
-                                SkColor bottom_color)
-      : border_(border),
-        top_color_(top_color),
-        bottom_color_(bottom_color),
-        radius_(SkIntToScalar(border->GetBorderCornerRadius() - 1)) {
+  TrayBubbleContentMask(views::BubbleBorder* border)

[msw, 2012/11/12 19:15:02]

nit: |border| is only used for its corner radius, perhaps pass that instead? 

[bartfab (slow), 2012/11/13 09:58:54]

Done.

+     : Layer(ui::LAYER_TEXTURED),
+       radius_(SkIntToScalar(border->GetBorderCornerRadius() - 1)) {
+    set_delegate(this);
   }
 
-  SkScalar radius() const { return radius_; }
-
-  // Overridden from Background:
-  virtual void Paint(gfx::Canvas* canvas, views::View* view) const OVERRIDE {
-    canvas->Save();
-
-    // Set a clip mask for the bubble's rounded corners.
-    gfx::Rect bounds(view->GetContentsBounds());
-    const int border_thickness(border_->GetBorderThickness());
-    bounds.Inset(-border_thickness, -border_thickness);
+  // Overridden from LayerDelegate:
+  virtual void OnPaintLayer(gfx::Canvas* canvas) OVERRIDE {
     SkPath path;
-    path.addRoundRect(gfx::RectToSkRect(bounds), radius_, radius_);
-    canvas->ClipPath(path);
-
-    // Paint the header and footer (assumes the bubble contents fill in their
-    // own backgrounds).
+    path.addRoundRect(gfx::RectToSkRect(gfx::Rect(bounds().size())),
+                      radius_, radius_);
     SkPaint paint;
+    paint.setAlpha(255);
     paint.setStyle(SkPaint::kFill_Style);
+    canvas->DrawPath(path, paint);
+  }
 
-    gfx::Rect top_rect(bounds);
-    top_rect.set_height(radius_);
-    paint.setColor(top_color_);
-    canvas->DrawRect(top_rect, paint);
-
-    gfx::Rect bottom_rect(bounds);
-    bottom_rect.set_y(bounds.y() + (bounds.height() - radius_));
-    bottom_rect.set_height(radius_);
-    paint.setColor(bottom_color_);
-    canvas->DrawRect(bottom_rect, paint);
+  virtual void OnDeviceScaleFactorChanged(float device_scale_factor) OVERRIDE {

[msw, 2012/11/12 19:15:02]

Both super classes have a function with this signature, but
Layer::OnDeviceScaleFactorChanged isn't virtual, so perhaps this is okay for
now. Still, should we be concerned? Can you point to a similar class that is
both a Layer and a LayerDelegate?

[bartfab (slow), 2012/11/13 09:58:54]

The implementation of OnDeviceScaleFactorChanged actually was nonsense. I should
have left it empty as it was - Layer does the right thing, LayerDelegate does
not need to do anything.

Regarding your question: Yes, there is precedent for this double inheritance in
ui/aura/bench/bench_main.cc:
  class ColoredLayer : public Layer, public LayerDelegate

But if it concerns you, the double inheritance can trivially be avoided.
TrayBubbleContentMask really only needs to be a LayerDelegate. I made it a Layer
as well purely for convenience so that the Layer always gets torn down together
with its delegate. I changed it now so that TrayBubbleContentMask has a Layer
member, managing lifetime as effectively and avoiding any double inheritance
issues.

+    Layer::OnDeviceScaleFactorChanged(device_scale_factor);
+  }
 
-    canvas->Restore();
+  virtual base::Closure PrepareForLayerBoundsChange() OVERRIDE {
+    return base::Closure();
   }
 
  private:
-  views::BubbleBorder* border_;
-  SkColor top_color_;
-  SkColor bottom_color_;
   SkScalar radius_;
 
-  DISALLOW_COPY_AND_ASSIGN(TrayBubbleBackground);
+  DISALLOW_COPY_AND_ASSIGN(TrayBubbleContentMask);
 };
 
 // Custom layout for the bubble-view. Does the default box-layout if there is
@@ -212,7 +195,7 @@ class BottomAlignedBoxLayout : public views::BoxLayout {
 }  // namespace internal
 
 using internal::TrayBubbleBorder;
-using internal::TrayBubbleBackground;
+using internal::TrayBubbleContentMask;
 using internal::BottomAlignedBoxLayout;
 
 // static
@@ -227,7 +210,6 @@ TrayBubbleView::InitParams::InitParams(AnchorType anchor_type,
       max_height(0),
       can_activate(false),
       close_on_deactivate(true),
-      top_color(SK_ColorBLACK),
       arrow_color(SK_ColorBLACK),
       arrow_location(views::BubbleBorder::NONE),
       arrow_offset(kArrowDefaultOffset),
@@ -265,23 +247,17 @@ TrayBubbleView::TrayBubbleView(gfx::NativeView parent_window,
       params_(init_params),
       delegate_(delegate),
       bubble_border_(NULL),
-      bubble_background_(NULL),
       is_gesture_dragging_(false) {
   set_parent_window(parent_window);
   set_notify_enter_exit_on_child(true);
   set_close_on_deactivate(init_params.close_on_deactivate);
+  set_margins(gfx::Insets());
   SetPaintToLayer(true);
   SetFillsBoundsOpaquely(true);
 
   bubble_border_ = new TrayBubbleBorder(this, anchor_view(), params_);
 
-  bubble_background_ = new TrayBubbleBackground(
-      bubble_border_, init_params.top_color, init_params.arrow_color);
-
-  // Inset the view on the top and bottom by the corner radius to avoid drawing
-  // over the the bubble corners.
-  const int radius = bubble_background_->radius();
-  set_margins(gfx::Insets(radius, 0, radius, 0));
+  bubble_content_mask_.reset(new TrayBubbleContentMask(bubble_border_));
 }
 
 TrayBubbleView::~TrayBubbleView() {
@@ -295,12 +271,15 @@ void TrayBubbleView::InitializeAndShowBubble() {
   SetAlignment(views::BubbleBorder::ALIGN_EDGE_TO_ANCHOR_EDGE);
   bubble_border_->UpdateArrowOffset();
 
+  layer()->parent()->SetMaskLayer(bubble_content_mask_.get());
+
   Show();
   UpdateBubble();
 }
 
 void TrayBubbleView::UpdateBubble() {
   SizeToContents();
+  bubble_content_mask_->SetBounds(layer()->bounds());
   GetWidget()->GetRootView()->SchedulePaint();
 }
 
@@ -336,12 +315,11 @@ bool TrayBubbleView::CanActivate() const {
   return params_.can_activate;
 }
 
-// Overridden to create BubbleFrameView and set a custom border and background.
+// Overridden to create BubbleFrameView and set a custom border.
 views::NonClientFrameView* TrayBubbleView::CreateNonClientFrameView(
     views::Widget* widget) {
   views::BubbleFrameView* bubble_frame_view =
       new views::BubbleFrameView(margins(), bubble_border_);
-  bubble_frame_view->set_background(bubble_background_);
   return bubble_frame_view;
 }