Implement a callout widget for the active panel.

ash/wm/panel_layout_manager.cc

Index: ash/wm/panel_layout_manager.cc
diff --git a/ash/wm/panel_layout_manager.cc b/ash/wm/panel_layout_manager.cc
index 997271d5bc686c06c6caf471a47cc493721f82f9..a1d1154126dd2b45adedd9fe08ebd27589614af8 100644
--- a/ash/wm/panel_layout_manager.cc
+++ b/ash/wm/panel_layout_manager.cc
@@ -8,16 +8,26 @@
 
 #include "ash/launcher/launcher.h"
 #include "ash/shell.h"
+#include "ash/wm/frame_painter.h"
 #include "ash/wm/property_util.h"
 #include "base/auto_reset.h"
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "third_party/skia/include/core/SkColor.h"
+#include "third_party/skia/include/core/SkPaint.h"
+#include "third_party/skia/include/core/SkPath.h"
 #include "ui/aura/client/activation_client.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
+#include "ui/gfx/canvas.h"
 #include "ui/gfx/rect.h"
-#include "ui/gfx/size.h"
+#include "ui/views/background.h"
 #include "ui/views/widget/widget.h"
 
+namespace ash {
+namespace internal {
+
 namespace {
 const int kPanelMarginEdge = 4;
 const int kPanelMarginMiddle = 8;
@@ -26,10 +36,34 @@ const int kMinimizedHeight = 24;
 
 const float kMaxHeightFactor = .80f;
 const float kMaxWidthFactor = .50f;
-}
 
-namespace ash {
-namespace internal {
+// Callout arrow dimensions.
+const int kArrowWidth = 20;
+const int kArrowHeight = 10;
+
+class CalloutWidgetBackground : public views::Background {
+ public:
+  CalloutWidgetBackground() {}
+  virtual void Paint(gfx::Canvas* canvas, views::View* view) const OVERRIDE {
+    SkPath path;
+    // TODO(dcheng): Verify if this results in off by one errors.
+    path.moveTo(SkIntToScalar(0), SkIntToScalar(0));
+    path.lineTo(SkIntToScalar(kArrowWidth / 2), SkIntToScalar(kArrowHeight));
+    path.lineTo(SkIntToScalar(kArrowWidth), SkIntToScalar(0));
+
+    // Use the same opacity and colors as the header for now.
+    SkPaint paint;
+    paint.setStyle(SkPaint::kFill_Style);
+    paint.setColor(
+        SkColorSetARGB(FramePainter::kActiveWindowOpacity, 189, 189, 189));
+    canvas->DrawPath(path, paint);
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CalloutWidgetBackground);
+};
+
+}  // namespace
 
 ////////////////////////////////////////////////////////////////////////////////
 // PanelLayoutManager public implementation:
@@ -38,8 +72,25 @@ PanelLayoutManager::PanelLayoutManager(aura::Window* panel_container)
       in_layout_(false),
       dragged_panel_(NULL),
       launcher_(NULL),
-      last_active_panel_(NULL) {
+      last_active_panel_(NULL),
+      callout_widget_(new views::Widget),
+      weak_factory_(this) {
   DCHECK(panel_container);
+  views::Widget::InitParams params;
+  params.type = views::Widget::InitParams::TYPE_POPUP;
+  params.transparent = true;
+  params.can_activate = false;
+  params.keep_on_top = true;
+  params.ownership = views::Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
+  params.parent = panel_container_;
+  params.bounds.set_width(kArrowWidth);
+  params.bounds.set_height(kArrowHeight);
+  // Why do we need this and can_activate = false?
+  callout_widget_->set_focus_on_creation(false);
+  callout_widget_->Init(params);
+  views::View* content_view = new views::View;
+  content_view->set_background(new CalloutWidgetBackground);
+  callout_widget_->SetContentsView(content_view);
   Shell::GetRootWindow()->AddObserver(this);
 }
 
@@ -101,6 +152,8 @@ void PanelLayoutManager::OnWindowResized() {
 }
 
 void PanelLayoutManager::OnWindowAddedToLayout(aura::Window* child) {
+  if (child == callout_widget_->GetNativeWindow())
+    return;
   panel_windows_.push_back(child);
   Relayout();
 }
@@ -175,8 +228,12 @@ void PanelLayoutManager::OnWindowPropertyChanged(aura::Window* window,
   if (key == aura::client::kRootWindowActiveWindowKey) {
     aura::Window* active = window->GetProperty(
         aura::client::kRootWindowActiveWindowKey);
-    if (active && active->type() == aura::client::WINDOW_TYPE_PANEL)
+    if (active && active->type() == aura::client::WINDOW_TYPE_PANEL) {
       UpdateStacking(active);
+      UpdateCallout(active);
+    } else {
+      UpdateCallout(NULL);
+    }
   }
 }
 
@@ -188,6 +245,7 @@ void PanelLayoutManager::Relayout() {
     return;
   AutoReset<bool> auto_reset_in_layout(&in_layout_, true);
 
+  int launcher_top = launcher_->widget()->GetWindowScreenBounds().y();
   aura::Window* active_panel = NULL;
   for (PanelList::iterator iter = panel_windows_.begin();
        iter != panel_windows_.end(); ++iter) {
@@ -218,11 +276,12 @@ void PanelLayoutManager::Relayout() {
     gfx::Rect bounds = panel->bounds();
     bounds.set_x(
         icon_origin.x() + icon_bounds.width() / 2 - bounds.width() / 2);
-    bounds.set_y(icon_origin.y() - bounds.height());
+    bounds.set_y(launcher_top - bounds.height());
     SetChildBoundsDirect(panel, bounds);
   }
 
   UpdateStacking(active_panel);
+  UpdateCallout(active_panel);
 }
 
 void PanelLayoutManager::UpdateStacking(aura::Window* active_panel) {
@@ -271,5 +330,33 @@ void PanelLayoutManager::UpdateStacking(aura::Window* active_panel) {
   last_active_panel_ = active_panel;
 }
 
+void PanelLayoutManager::UpdateCallout(aura::Window* active_panel) {
+  weak_factory_.InvalidateWeakPtrs();
+  // TODO(dcheng): This doesn't account for panels in overflow. They should have
+  // a callout as well.
+  if (!active_panel ||
+      launcher_->GetScreenBoundsOfItemIconForWindow(active_panel).IsEmpty()) {
+    callout_widget_->Hide();
+    return;
+  }
+  MessageLoop::current()->PostTask(
+      FROM_HERE,
+      base::Bind(&PanelLayoutManager::ShowCalloutHelper,
+                 weak_factory_.GetWeakPtr(),
+                 active_panel));
+}
+
+void PanelLayoutManager::ShowCalloutHelper(aura::Window* active_panel) {
+  DCHECK(active_panel);
+  gfx::Rect bounds = active_panel->GetBoundsInRootWindow();
+  gfx::Rect callout_bounds = callout_widget_->GetWindowScreenBounds();
+  callout_bounds.set_x(
+      bounds.x() + (bounds.width() - callout_bounds.width()) / 2);
+  callout_bounds.set_y(bounds.bottom());
+  SetChildBoundsDirect(callout_widget_->GetNativeWindow(), callout_bounds);
+  panel_container_->StackChildAtTop(callout_widget_->GetNativeWindow());
+  callout_widget_->Show();
+}
+
 }  // namespace internal
 }  // namespace ash