Refactor intra-strip panel drags by introducing PanelDragController.

chrome/browser/ui/panels/detached_panel_strip.cc

Index: chrome/browser/ui/panels/detached_panel_strip.cc
diff --git a/chrome/browser/ui/panels/detached_panel_strip.cc b/chrome/browser/ui/panels/detached_panel_strip.cc
index 44cc362dce49c81c1d207228d03b4b412e146830..fc34b6d5db7f68cd2879bb88d95cd024160b925b 100644
--- a/chrome/browser/ui/panels/detached_panel_strip.cc
+++ b/chrome/browser/ui/panels/detached_panel_strip.cc
@@ -10,7 +10,8 @@
 
 DetachedPanelStrip::DetachedPanelStrip(PanelManager* panel_manager)
     : PanelStrip(PanelStrip::DETACHED),
-      panel_manager_(panel_manager) {
+      panel_manager_(panel_manager),
+      dragging_panel_(NULL) {
 }
 
 DetachedPanelStrip::~DetachedPanelStrip() {
@@ -79,3 +80,34 @@ void DetachedPanelStrip::RestorePanel(Panel* panel) {
   NOTIMPLEMENTED();
 }
 
+bool DetachedPanelStrip::CanDragPanel(Panel* panel) const {
+  // All detached panels are draggable.
+  return true;
+}
+
+void DetachedPanelStrip::StartDraggingPanel(Panel* panel) {
+  DCHECK(!dragging_panel_);
+
+  dragging_panel_ = panel;
+  dragging_panel_original_position_ = panel->GetBounds().origin();
+}
+
+void DetachedPanelStrip::DragPanel(int delta_x, int delta_y) {
+  DCHECK(dragging_panel_);
+
+  gfx::Rect new_bounds(dragging_panel_->GetBounds());
+  new_bounds.Offset(delta_x, delta_y);
+  dragging_panel_->SetPanelBounds(new_bounds);
+}
+
+void DetachedPanelStrip::EndDraggingPanel(bool cancelled) {
+  DCHECK(dragging_panel_);
+
+  if (cancelled) {
+    gfx::Rect new_bounds(dragging_panel_->GetBounds());
+    new_bounds.set_origin(dragging_panel_original_position_);
+    dragging_panel_->SetPanelBounds(new_bounds);
+  }

[Andrei, 2012/02/17 00:08:18]

It looks like cancelling the drag will happen very differently depending on
whether this panel changed strips during drag or not. If the drag was within one
strip, you simply call EndDraggingPanel() with cancelled=true. If strips were
changed, the controller has to remove/add it to where it started from, and to
use its own copy of dragging panel's original position. Is that so? Maybe we can
have the controller do the job in both cases?

[jianli, 2012/02/17 00:15:13]

Yes. Inter-strip drags are not included in this patch and I only assume the
drags are within this trip. When we add handling for inter-strip drags,
PanelDragController might do the job for both cases.

+
+  dragging_panel_ = NULL;
+}