Removes grab input window and extra grab and ungrab in X11WholeScreenMoveLoop

ui/views/widget/desktop_aura/desktop_drag_drop_client_aurax11.cc

 // Copyright (c) 2012 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/views/widget/desktop_aura/desktop_drag_drop_client_aurax11.h"
 
 #include <X11/Xatom.h>
 
 #include "base/event_types.h"
 #include "base/lazy_instance.h"
 #include "base/message_loop/message_loop.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/base/clipboard/clipboard.h"
 #include "ui/base/dragdrop/drop_target_event.h"
 #include "ui/base/dragdrop/os_exchange_data.h"
 #include "ui/base/dragdrop/os_exchange_data_provider_aurax11.h"
 #include "ui/base/x/selection_utils.h"
 #include "ui/base/x/x11_util.h"
 #include "ui/events/event.h"
 #include "ui/events/platform/platform_event_source.h"
+#include "ui/gfx/screen.h"
+#include "ui/views/controls/image_view.h"
 #include "ui/views/widget/desktop_aura/desktop_native_cursor_manager.h"
 #include "ui/views/widget/desktop_aura/x11_topmost_window_finder.h"
+#include "ui/views/widget/widget.h"
 #include "ui/wm/public/drag_drop_client.h"
 #include "ui/wm/public/drag_drop_delegate.h"
 
 using aura::client::DragDropDelegate;
 using ui::OSExchangeData;
 
 namespace {
 
+// The minimum alpha before we declare a pixel transparent when searching in
+// our source image.
+const uint32 kMinAlpha = 32;
+const unsigned char kDragWidgetOpacity = 0xc0;
+
+bool CheckIfIconValid(const gfx::ImageSkia& drag_image) {
+  // Because we need a GL context per window, we do a quick check so that we
+  // don't make another context if the window would just be displaying a mostly
+  // transparent image.
+  const SkBitmap* in_bitmap = drag_image.bitmap();
+  SkAutoLockPixels in_lock(*in_bitmap);
+  for (int y = 0; y < in_bitmap->height(); ++y) {
+    uint32* in_row = in_bitmap->getAddr32(0, y);
+
+    for (int x = 0; x < in_bitmap->width(); ++x) {
+      if (SkColorGetA(in_row[x]) > kMinAlpha)
+        return true;
+    }
+  }
+
+  return false;
+}
+
 const int kMinXdndVersion = 5;
 
 const int kWillAcceptDrop = 1;
 const int kWantFurtherPosEvents = 2;
 
 const char kXdndActionCopy[] = "XdndActionCopy";
 const char kXdndActionMove[] = "XdndActionMove";
 const char kXdndActionLink[] = "XdndActionLink";
 const char kXdndActionDirectSave[] = "XdndActionDirectSave";
 
@@ skipping 448 matching lines @@
     // We were waiting on the status message so we could send the XdndDrop.
     if (negotiated_operation_ == ui::DragDropTypes::DRAG_NONE) {
       move_loop_.EndMoveLoop();
       return;
     }
     source_state_ = SOURCE_STATE_DROPPED;
     SendXdndDrop(source_window);
     return;
   }
 
-  switch (negotiated_operation_) {
-    case ui::DragDropTypes::DRAG_COPY:
-      move_loop_.UpdateCursor(copy_grab_cursor_);
-      break;
-    case ui::DragDropTypes::DRAG_MOVE:
-      move_loop_.UpdateCursor(move_grab_cursor_);
-      break;
-    default:
-      move_loop_.UpdateCursor(grab_cursor_);
-      break;
-  }
+  UpdateCursor();
 
   // Note: event.data.[2,3] specify a rectangle. It is a request by the other
   // window to not send further XdndPosition messages while the cursor is
   // within it. However, it is considered advisory and (at least according to
   // the spec) the other side must handle further position messages within
   // it. GTK+ doesn't bother with this, so neither should we.
 
   if (next_position_message_.get()) {
     // We were waiting on the status message so we could send off the next
     // position message we queued up.
@@ skipping 96 matching lines @@
   ui::SetAtomArrayProperty(xwindow_, "XdndActionList", "ATOM", actions);
 
   // It is possible for the DesktopWindowTreeHostX11 to be destroyed during the
   // move loop, which would also destroy this drag-client. So keep track of
   // whether it is alive after the drag ends.
   base::WeakPtr<DesktopDragDropClientAuraX11> alive(
       weak_ptr_factory_.GetWeakPtr());
 
   // Windows has a specific method, DoDragDrop(), which performs the entire
   // drag. We have to emulate this, so we spin off a nested runloop which will
   // track all cursor movement and reroute events to a specific handler.

[pkotwicz, 2014/05/08 00:03:49]

Nits:
- The comment above should be right above the call to RunMoveLoop()
- Does SetDragImage() need to be its own function? It just does assignment of
the two parameters which are passed to it.

[varkha, 2014/05/09 19:01:01]

Done.
I think it is clearer to isolate it in a method, primarily because it has a
piece of logic about keeping Y offset zero.

-  move_loop_.SetDragImage(source_provider_->GetDragImage(),
-                          source_provider_->GetDragImageOffset());
-  move_loop_.RunMoveLoop(source_window, grab_cursor_);
+  SetDragImage(source_provider_->GetDragImage(),
+               source_provider_->GetDragImageOffset());
+  if (!drag_image_.isNull() && CheckIfIconValid(drag_image_))
+    CreateDragImageWindow();

[pkotwicz, 2014/05/08 00:03:49]

We may need to move |grab_input_window_| to this class too. We rely on
|drag_widget_| having capture for the duration of the drag. However,
|drag_widget_| may not be created.
e.g. |drag_widget_| is currently not created if a fully transparent image from a
website is dragged. I am unsure when |drag_image_| can have 0 size.

I am sorry for giving bad advice :(

[varkha, 2014/05/09 19:01:01]

We talked about this offline. I've set up the drag widget to be off screen in
this case. This seems simpler and prevents cases of reentrant move loops.

+  move_loop_.RunMoveLoop(grab_cursor_);
 
   if (alive) {
-    move_loop_.SetDragImage(gfx::ImageSkia(), gfx::Vector2dF());
+    SetDragImage(gfx::ImageSkia(), gfx::Vector2dF());
 
     source_provider_ = NULL;
     g_current_drag_drop_client = NULL;
     drag_operation_ = 0;
     XDeleteProperty(xdisplay_, xwindow_, atom_cache_.GetAtom("XdndActionList"));
     XDeleteProperty(xdisplay_, xwindow_, atom_cache_.GetAtom(kXdndDirectSave0));
 
     return negotiated_operation_;
   }
   return ui::DragDropTypes::DRAG_NONE;
@@ skipping 21 matching lines @@
   DCHECK_EQ(target_window_, window);
   target_window_ = NULL;
 }
 
 void DesktopDragDropClientAuraX11::OnMouseMovement(XMotionEvent* event) {
   gfx::Point screen_point(event->x_root, event->y_root);
 
   if (source_state_ != SOURCE_STATE_OTHER)
     return;
 
+  if (drag_widget_.get()) {
+    gfx::Point location = gfx::ToFlooredPoint(screen_point - drag_offset_);
+    drag_widget_->SetBounds(gfx::Rect(location, drag_image_.size()));
+    drag_widget_->StackAtTop();
+  }
+
   // Find the current window the cursor is over.
   ::Window mouse_window = None;
   ::Window dest_window = None;
   FindWindowFor(screen_point, &mouse_window, &dest_window);
 
   if (source_current_window_ != dest_window) {
     if (source_current_window_ != None)
       SendXdndLeave(source_current_window_);
 
     source_current_window_ = dest_window;
@@ skipping 44 matching lines @@
       // an XdndFinished message.
       StartEndMoveLoopTimer();
       return;
     }
   }
 
   move_loop_.EndMoveLoop();
 }
 
 void DesktopDragDropClientAuraX11::OnMoveLoopEnded() {
+  drag_widget_.reset();
   if (source_current_window_ != None) {
     SendXdndLeave(source_current_window_);
     source_current_window_ = None;
   }
   target_current_context_.reset();
   end_move_loop_timer_.Stop();
 }
 
 void DesktopDragDropClientAuraX11::StartEndMoveLoopTimer() {
   end_move_loop_timer_.Start(FROM_HERE,
@@ skipping 93 matching lines @@
   if (drag_operation_ & ui::DragDropTypes::DRAG_LINK)
     operations.push_back(atom_cache_.GetAtom(kXdndActionLink));
   return operations;
 }
 
 ui::SelectionFormatMap DesktopDragDropClientAuraX11::GetFormatMap() const {
   return source_provider_ ? source_provider_->GetFormatMap() :
       ui::SelectionFormatMap();
 }
 
+void DesktopDragDropClientAuraX11::UpdateCursor() {
+  gfx::NativeCursor cursor = grab_cursor_;
+  switch (negotiated_operation_) {
+    case ui::DragDropTypes::DRAG_COPY:
+      cursor = copy_grab_cursor_;
+      break;
+    case ui::DragDropTypes::DRAG_MOVE:
+      cursor = move_grab_cursor_;
+      break;
+    default:
+      break;
+  }
+
+  // Update the pointer with the updated cursor if a grab is active.

[pkotwicz, 2014/05/08 00:03:49]

Nit: updated -> new

[varkha, 2014/05/09 19:01:01]

Done.

+  XChangeActivePointerGrab(
+      xdisplay_,
+      ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
+      cursor.platform(),
+      CurrentTime);
+}
+
 void DesktopDragDropClientAuraX11::CompleteXdndPosition(
     ::Window source_window,
     const gfx::Point& screen_point) {
   int drag_operation = ui::DragDropTypes::DRAG_NONE;
   scoped_ptr<ui::OSExchangeData> data;
   scoped_ptr<ui::DropTargetEvent> drop_target_event;
   DragDropDelegate* delegate = NULL;
   DragTranslate(screen_point, &data, &drop_target_event, &delegate);
   if (delegate)
     drag_operation = delegate->OnDragUpdated(*drop_target_event);
@@ skipping 127 matching lines @@
   // success or failure, and when it fails, it then sends an internal
   // GdkEvent about the failed drag. (And sending this message doesn't appear
   // to go through normal xlib machinery, but instead passes through the low
   // level xProto (the x11 wire format) that I don't understand.
   //
   // I'm unsure if I have to jump through those hoops, or if XSendEvent is
   // sufficient.
   XSendEvent(xdisplay_, xid, False, 0, xev);
 }
 
+void DesktopDragDropClientAuraX11::SetDragImage(const gfx::ImageSkia& image,
+                                                gfx::Vector2dF offset) {
+  drag_image_ = image;
+  drag_offset_ = offset;
+  // Reset the Y offset, so that the drag-image is always just below the cursor,
+  // so that it is possible to see where the cursor is going.
+  drag_offset_.set_y(0.f);
+}
+
+void DesktopDragDropClientAuraX11::CreateDragImageWindow() {
+  Widget* widget = new Widget;
+  Widget::InitParams params(Widget::InitParams::TYPE_DRAG);
+  params.opacity = Widget::InitParams::OPAQUE_WINDOW;
+  params.ownership = Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
+  params.accept_events = false;
+
+  gfx::Point location = gfx::ToFlooredPoint(
+      gfx::Screen::GetNativeScreen()->GetCursorScreenPoint() - drag_offset_);
+  params.bounds = gfx::Rect(location, drag_image_.size());
+  widget->set_focus_on_creation(false);
+  widget->set_frame_type(Widget::FRAME_TYPE_FORCE_NATIVE);
+  widget->Init(params);
+  widget->SetOpacity(kDragWidgetOpacity);
+  widget->GetNativeWindow()->SetName("DragWindow");
+
+  ImageView* image = new ImageView();
+  image->SetImage(drag_image_);
+  image->SetBounds(0, 0, drag_image_.width(), drag_image_.height());
+  widget->SetContentsView(image);
+  widget->Show();
+  widget->GetNativeWindow()->layer()->SetFillsBoundsOpaquely(false);
+  widget->GetNativeWindow()->SetCapture();
+  drag_widget_.reset(widget);
+}
+
 }  // namespace views