Support dragging panels to stack and snap.

chrome/browser/ui/panels/stacked_panel_collection.cc

Index: chrome/browser/ui/panels/stacked_panel_collection.cc
diff --git a/chrome/browser/ui/panels/stacked_panel_collection.cc b/chrome/browser/ui/panels/stacked_panel_collection.cc
index 86eff23e1d1d2ef4f57ce3acb4ce26a6ee7defe1..fe76ddde9cc173179ce838b3792c015345bb9bb3 100644
--- a/chrome/browser/ui/panels/stacked_panel_collection.cc
+++ b/chrome/browser/ui/panels/stacked_panel_collection.cc
@@ -6,12 +6,16 @@
 
 #include <algorithm>
 #include "base/logging.h"
+#include "chrome/browser/ui/panels/detached_panel_collection.h"
+#include "chrome/browser/ui/panels/native_panel_stack.h"
 #include "chrome/browser/ui/panels/panel.h"
 #include "chrome/browser/ui/panels/panel_manager.h"
 
 StackedPanelCollection::StackedPanelCollection(PanelManager* panel_manager)
     : PanelCollection(PanelCollection::STACKED),
-      panel_manager_(panel_manager) {
+      panel_manager_(panel_manager),
+      native_stack_(NULL) {
+  native_stack_ = NativePanelStack::Create(make_scoped_ptr(this).Pass());
 }
 
 StackedPanelCollection::~StackedPanelCollection() {
@@ -23,15 +27,55 @@ void StackedPanelCollection::OnDisplayAreaChanged(
 }
 
 void StackedPanelCollection::RefreshLayout() {
+  if (panels_.empty())
+    return;
+
+  Panels::const_iterator iter = panels_.begin();
+  Panel* top_panel = *iter;
+  gfx::Rect top_panel_bounds = top_panel->GetBounds();
+  int common_width = top_panel_bounds.width();
+  int common_x = top_panel_bounds.x();
+  int y = top_panel_bounds.bottom();
+
+  ++iter;
+  for (; iter != panels_.end(); ++iter) {
+    Panel* panel = *iter;
+
+    // Don't update the stacked panel that is in preview mode.
+    gfx::Rect bounds = panel->GetBounds();
+    if (!panel->in_preview_mode()) {
+      bounds.set_x(common_x);
+      bounds.set_y(y);
+      bounds.set_width(common_width);
+      panel->SetPanelBounds(bounds);
+      gfx::Size full_size = bounds.size();
+      full_size.set_width(common_width);
+      panel->set_full_size(full_size);
+    }
+
+    y += bounds.height();
+  }
+
+  // Compute and apply the enclosing bounds.
+  gfx::Rect enclosing_bounds = top_panel->GetBounds();
+  enclosing_bounds.set_height(
+      bottom_panel()->GetBounds().bottom() - enclosing_bounds.y());
+  native_stack_->SetBounds(enclosing_bounds);
 }
 
 void StackedPanelCollection::AddPanel(Panel* panel,
                                       PositioningMask positioning_mask) {
   DCHECK_NE(this, panel->collection());
   panel->set_collection(this);
-  panels_.push_back(panel);
+  if (positioning_mask & PanelCollection::TOP_POSITION)
+    panels_.push_front(panel);
+  else
+    panels_.push_back(panel);
 
-  RefreshLayout();
+  if ((positioning_mask & NO_LAYOUT_REFRESH) == 0)
+    RefreshLayout();
+
+  native_stack_->OnPanelAddedOrRemoved(panel);
 }
 
 void StackedPanelCollection::RemovePanel(Panel* panel) {
@@ -39,6 +83,8 @@ void StackedPanelCollection::RemovePanel(Panel* panel) {
   panels_.remove(panel);
 
   RefreshLayout();
+
+  native_stack_->OnPanelAddedOrRemoved(panel);
 }
 
 void StackedPanelCollection::CloseAll() {
@@ -48,6 +94,8 @@ void StackedPanelCollection::CloseAll() {
   for (Panels::const_iterator iter = panels_copy.begin();
        iter != panels_copy.end(); ++iter)
     (*iter)->Close();
+
+  native_stack_->Close();
 }
 
 void StackedPanelCollection::OnPanelAttentionStateChanged(Panel* panel) {
@@ -86,12 +134,48 @@ bool StackedPanelCollection::IsPanelMinimized(const Panel* panel) const {
 }
 
 void StackedPanelCollection::SavePanelPlacement(Panel* panel) {
+  DCHECK(!saved_panel_placement_.panel);
+  saved_panel_placement_.panel = panel;
+
+  if (top_panel() != panel)
+    saved_panel_placement_.top_panel = top_panel();
+  else
+    saved_panel_placement_.position = panel->GetBounds().origin();
+
+  saved_panel_placement_.top_panel = top_panel() != panel ? top_panel() : NULL;
 }
 
 void StackedPanelCollection::RestorePanelToSavedPlacement() {
+  DCHECK(saved_panel_placement_.panel);
+
+  if (saved_panel_placement_.top_panel) {
+    // Restore the top panel if it has been moved out of the stack. This could
+    // happen when there're 2 panels in the stack and the bottom panel is being
+    // dragged out of the stack and thus cause both panels become detached.
+    if (saved_panel_placement_.top_panel->stack() != this) {
+      DCHECK_EQ(PanelCollection::DETACHED,
+                saved_panel_placement_.top_panel->collection()->type());
+      panel_manager_->MovePanelToCollection(saved_panel_placement_.top_panel,
+                                            this,
+                                            PanelCollection::TOP_POSITION);
+    }
+  } else {
+    // Restore the position when the top panel is being dragged.
+    DCHECK_EQ(top_panel(), saved_panel_placement_.panel);
+    gfx::Rect new_bounds(saved_panel_placement_.panel->GetBounds());
+    new_bounds.set_origin(saved_panel_placement_.position);
+    saved_panel_placement_.panel->SetPanelBounds(new_bounds);
+  }
+
+  RefreshLayout();
+
+  DiscardSavedPanelPlacement();
 }
 
 void StackedPanelCollection::DiscardSavedPanelPlacement() {
+  DCHECK(saved_panel_placement_.panel);
+  saved_panel_placement_.panel = NULL;
+  saved_panel_placement_.top_panel = NULL;
 }
 
 panel::Resizability StackedPanelCollection::GetPanelResizability(
@@ -108,6 +192,12 @@ bool StackedPanelCollection::HasPanel(Panel* panel) const {
 }
 
 void StackedPanelCollection::UpdatePanelOnCollectionChange(Panel* panel) {
+  panel->set_attention_mode(
+      static_cast<Panel::AttentionMode>(Panel::USE_PANEL_ATTENTION |
+                                        Panel::USE_SYSTEM_ATTENTION));
+  panel->SetAlwaysOnTop(false);
+  panel->EnableResizeByMouse(true);
+  panel->UpdateMinimizeRestoreButtonVisibility();
 }
 
 void StackedPanelCollection::OnPanelActiveStateChanged(Panel* panel) {
@@ -127,3 +217,13 @@ Panel* StackedPanelCollection::GetPanelAbove(Panel* panel) const {
   }
   return NULL;
 }
+
+void StackedPanelCollection::MoveAllDraggingPanelsInstantly(
+    const gfx::Vector2d& delta_origin) {
+  for (Panels::const_iterator iter = panels_.begin();
+       iter != panels_.end(); iter++) {
+    Panel* panel = *iter;
+    if (panel->in_preview_mode())
+      panel->MoveByInstantly(delta_origin);
+  }
+}