First shot at implementing drag&drop for Aura

ui/aura_shell/drag_drop_controller.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ui/aura_shell/drag_drop_controller.h"
+
+#include "base/message_loop.h"
+#include "ui/aura/desktop.h"
+#include "ui/aura/window.h"
+#include "ui/aura/window_drag_drop_delegate.h"
+#include "ui/base/dragdrop/drag_drop_types.h"
+#include "ui/base/dragdrop/os_exchange_data_provider_aura.h"
+#include "ui/gfx/point.h"
+#include "ui/gfx/rect.h"
+#include "views/controls/image_view.h"
+#include "views/widget/widget.h"
+
+namespace aura_shell {
+namespace internal {
+
+using aura::Desktop;
+
+namespace {
+using views::Widget;
+
+Widget* CreateDragWidget() {

[Ben Goodger (Google), 2011/11/11 17:26:53]

I'd like it if the whole "view" part of the drag&drop code was a separate class,
let's call it DragImage. When created, it creates a widget, and offers an API
SetDragImage(). This way you don't need to futz around with views classes
(ImageView) in the controller (StartDragAndDrop) and can just let the DragImage
class deal with that in its implementation.

[varunjain, 2011/11/15 19:39:33]

Done.

+  Widget* drag_widget = new Widget;
+  Widget::InitParams params;
+  params.type = Widget::InitParams::TYPE_TOOLTIP;
+  params.keep_on_top = true;
+  params.accept_events = false;
+  params.ownership = Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
+  params.transparent = true;
+  drag_widget->Init(params);
+  drag_widget->SetOpacity(0xFF);
+  return drag_widget;
+}
+
+}  // namespace
+
+DragDropController::DragDropController()
+    : drag_widget_(NULL),
+      drag_data_(NULL),
+      drag_operation_(0),
+      dragged_window_(NULL),
+      drag_drop_in_progress_(false),
+      should_block_during_drag_drop_(true) {
+}
+
+DragDropController::~DragDropController() {
+  Cleanup();
+}
+
+void DragDropController::StartDragAndDrop(const ui::OSExchangeData& data,
+                                          int operation) {
+  DCHECK(!drag_drop_in_progress_);
+  aura::Window* capture_window = Desktop::GetInstance()->capture_window();
+  if (capture_window)
+    Desktop::GetInstance()->ReleaseCapture(capture_window);
+  drag_drop_in_progress_ = true;
+
+  DCHECK(drag_data_ == NULL && drag_operation_ == 0);
+  DCHECK(drag_widget_.get() == NULL);
+  drag_data_ = &data;
+  drag_widget_.reset(CreateDragWidget());

[Ben Goodger (Google), 2011/11/11 17:26:53]

This would become something like 

drag_image_.reset(new DragImage(provider.drag_image(), location));

[varunjain, 2011/11/15 19:39:33]

Done.

+  drag_operation_ = operation;
+  gfx::Point location = Desktop::GetInstance()->last_mouse_location();
+  const ui::OSExchangeDataProviderAura& provider =
+      static_cast<const ui::OSExchangeDataProviderAura&>(data.provider());
+
+  views::ImageView* image_view = new views::ImageView();
+  image_view->SetImage(provider.drag_image());
+  drag_widget_->SetContentsView(image_view);
+  drag_widget_->SetBounds(gfx::Rect(location,
+      image_view->GetPreferredSize()));
+  drag_widget_->Show();
+
+  dragged_window_ = Desktop::GetInstance()->GetEventHandlerForPoint(location);
+
+  if (should_block_during_drag_drop_) {
+    MessageLoopForUI::current()->RunWithDispatcher(
+        Desktop::GetInstance()->GetDispatcher());
+  }
+}
+
+void DragDropController::DragUpdate(aura::Window* target,
+                                    const aura::MouseEvent& event) {
+  if (target != dragged_window_) {
+    if (dragged_window_ && dragged_window_->drag_drop_delegate())
+      dragged_window_->drag_drop_delegate()->OnDragExited();
+
+    dragged_window_ = target;
+    if (dragged_window_ && dragged_window_->drag_drop_delegate()) {
+      aura::DropTargetEvent e(*drag_data_, event.location(), drag_operation_);
+      if (dragged_window_->drag_drop_delegate()->CanDrop(e))
+        dragged_window_->drag_drop_delegate()->OnDragEntered(e);
+    }
+  } else {
+    if (dragged_window_ && dragged_window_->drag_drop_delegate()) {
+      aura::DropTargetEvent e(*drag_data_, event.location(), drag_operation_);
+      dragged_window_->drag_drop_delegate()->OnDragUpdated(e);
+      // TODO(varunjain): uncomment the following lines when cursor issue with
+      // X for tests is fixed.
+      // gfx::NativeCursor cursor = (op == ui::DragDropTypes::DRAG_NONE)?
+      //     aura::kCursorMove : aura::kCursorHand;
+      // Desktop::GetInstance()->SetCursor(cursor);
+    }
+  }
+
+  DCHECK(drag_widget_.get());
+  if (drag_widget_->IsVisible()) {
+    gfx::Rect bounds = drag_widget_->GetClientAreaScreenBounds();
+    bounds.set_origin(Desktop::GetInstance()->last_mouse_location());
+    drag_widget_->SetBounds(bounds);

[Ben Goodger (Google), 2011/11/11 17:26:53]

And this would become drag_image_->SetPosition(Desktop...);

[varunjain, 2011/11/15 19:39:33]

Done.

+  }
+}
+
+void DragDropController::Drop(aura::Window* target,
+                              const aura::MouseEvent& event) {
+  DCHECK(target == dragged_window_);
+  if (dragged_window_ && dragged_window_->drag_drop_delegate() ) {
+    aura::DropTargetEvent e(*drag_data_, event.location(), drag_operation_);
+    if (dragged_window_->drag_drop_delegate()->CanDrop(e))
+      dragged_window_->drag_drop_delegate()->OnPerformDrop(e);
+    // TODO(varunjain): else Do drag widget flying back animation
+  }
+
+  Cleanup();
+  if (should_block_during_drag_drop_)
+    MessageLoop::current()->Quit();
+}
+
+void DragDropController::DragCancel() {
+  // TODO(varunjain): Do drag widget flying back animation
+  Cleanup();
+  if (should_block_during_drag_drop_)
+    MessageLoop::current()->Quit();
+}
+
+bool DragDropController::IsDragAndDropInProgress() {
+  return drag_drop_in_progress_;
+}
+
+void DragDropController::Cleanup() {
+  if (drag_widget_.get())
+    drag_widget_->Hide();

[Ben Goodger (Google), 2011/11/11 17:26:53]

This should all be done by drag_image_'s dtor.

[varunjain, 2011/11/15 19:39:33]

Done.

+  drag_widget_.reset();
+  drag_data_ = NULL;
+  drag_operation_ = 0;
+  drag_drop_in_progress_ = false;
+}
+
+}  // namespace internal
+}  // namespace aura_shell