linux aura: Show the drag-image when available.

ui/views/widget/desktop_aura/x11_whole_screen_move_loop.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/x11_whole_screen_move_loop.h"
 
 #include <X11/Xlib.h>
 // Get rid of a macro from Xlib.h that conflicts with Aura's RootWindow class.
 #undef RootWindow
 
 #include "base/debug/stack_trace.h"
 #include "base/message_loop/message_loop.h"
 #include "base/message_loop/message_pump_x11.h"
 #include "base/run_loop.h"
 #include "ui/aura/env.h"
 #include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/base/x/x11_util.h"
 #include "ui/events/event.h"
+#include "ui/gfx/point_conversions.h"
 #include "ui/gfx/screen.h"
+#include "ui/views/controls/image_view.h"
+#include "ui/views/widget/widget.h"
 
 namespace views {
 
 namespace {
 
 class ScopedCapturer {
  public:
   explicit ScopedCapturer(aura::RootWindowHost* host)
       : host_(host) {
     host_->SetCapture();
   }
 
   ~ScopedCapturer() {
     host_->ReleaseCapture();
   }
 
  private:
   aura::RootWindowHost* host_;
 
   DISALLOW_COPY_AND_ASSIGN(ScopedCapturer);
 };
 
 }  // namespace
 
 X11WholeScreenMoveLoop::X11WholeScreenMoveLoop(
     X11WholeScreenMoveLoopDelegate* delegate)
     : delegate_(delegate),
       in_move_loop_(false),
-      grab_input_window_(None) /*,
-                                 root_window_(NULL)*/ {
+      grab_input_window_(None) {
 }
 
 X11WholeScreenMoveLoop::~X11WholeScreenMoveLoop() {}
 
 ////////////////////////////////////////////////////////////////////////////////
 // DesktopRootWindowHostLinux, MessageLoop::Dispatcher implementation:
 
 bool X11WholeScreenMoveLoop::Dispatch(const base::NativeEvent& event) {
   XEvent* xev = event;
 
   // Note: the escape key is handled in the tab drag controller, which has
   // keyboard focus even though we took pointer grab.
   switch (xev->type) {
     case MotionNotify: {
+      if (drag_widget_.get()) {
+        gfx::Screen* screen = gfx::Screen::GetNativeScreen();
+        gfx::Point location = gfx::ToFlooredPoint(
+            screen->GetCursorScreenPoint() - drag_offset_);
+        drag_widget_->SetBounds(gfx::Rect(location, drag_image_.size()));
+      }
       delegate_->OnMouseMovement(&xev->xmotion);
       break;
     }
     case ButtonRelease: {
       if (xev->xbutton.button == Button1) {
         // Assume that drags are being done with the left mouse button. Only
         // break the drag if the left mouse button was released.
         delegate_->OnMouseReleased();
       }
       break;
@@ skipping 10 matching lines @@
                                          gfx::NativeCursor cursor) {
   // Start a capture on the host, so that it continues to receive events during
   // the drag.
   ScopedCapturer capturer(source->GetDispatcher()->host());
 
   DCHECK(!in_move_loop_);  // Can only handle one nested loop at a time.
   in_move_loop_ = true;
 
   XDisplay* display = gfx::GetXDisplay();
 
-  // Creates an invisible, InputOnly toplevel window. This window will receive
-  // all mouse movement for drags. It turns out that normal windows doing a
-  // grab doesn't redirect pointer motion events if the pointer isn't over the
-  // grabbing window. But InputOnly windows are able to grab everything. This
-  // is what GTK+ does, and I found a patch to KDE that did something similar.
-  unsigned long attribute_mask = CWEventMask | CWOverrideRedirect;
-  XSetWindowAttributes swa;
-  memset(&swa, 0, sizeof(swa));
-  swa.event_mask = ButtonPressMask | ButtonReleaseMask | PointerMotionMask |
-                   StructureNotifyMask;
-  swa.override_redirect = True;
-  grab_input_window_ = XCreateWindow(
-      display,
-      DefaultRootWindow(display),
-      -100, -100, 10, 10,
-      0, 0, InputOnly, CopyFromParent,
-      attribute_mask, &swa);
+  grab_input_window_ = CreateDragInputWindow(display);
+  if (!drag_image_.isNull())
+    CreateDragImageWindow();
   base::MessagePumpX11::Current()->AddDispatcherForWindow(
       this, grab_input_window_);
 
-  // Wait for the window to be mapped. If we don't, XGrabPointer fails.
-  XMapRaised(display, grab_input_window_);
-  base::MessagePumpX11::Current()->BlockUntilWindowMapped(
-      grab_input_window_);
-
   if (!GrabPointerWithCursor(cursor))
     return false;
 
   // We are handling a mouse drag outside of the aura::RootWindow system. We
   // must manually make aura think that the mouse button is pressed so that we
   // don't draw extraneous tooltips.
   aura::Env::GetInstance()->set_mouse_button_flags(ui::EF_LEFT_MOUSE_BUTTON);
 
   base::MessageLoopForUI* loop = base::MessageLoopForUI::current();
   base::MessageLoop::ScopedNestableTaskAllower allow_nested(loop);
@@ skipping 18 matching lines @@
   // TODO(erg): Is this ungrab the cause of having to click to give input focus
   // on drawn out windows? Not ungrabbing here screws the X server until I kill
   // the chrome process.
 
   // Ungrab before we let go of the window.
   XDisplay* display = gfx::GetXDisplay();
   XUngrabPointer(display, CurrentTime);
 
   base::MessagePumpX11::Current()->RemoveDispatcherForWindow(
       grab_input_window_);
+  drag_widget_.reset();
   delegate_->OnMoveLoopEnded();
   XDestroyWindow(display, grab_input_window_);
 
   in_move_loop_ = false;
   quit_closure_.Run();
 }
 
+void X11WholeScreenMoveLoop::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);
+}
+
 bool X11WholeScreenMoveLoop::GrabPointerWithCursor(gfx::NativeCursor cursor) {
   XDisplay* display = gfx::GetXDisplay();
   XGrabServer(display);
   XUngrabPointer(display, CurrentTime);
   int ret = XGrabPointer(
       display,
       grab_input_window_,
       False,
       ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
       GrabModeAsync,
       GrabModeAsync,
       None,
       cursor.platform(),
       CurrentTime);
   XUngrabServer(display);
   if (ret != GrabSuccess) {
     DLOG(ERROR) << "Grabbing new tab for dragging failed: "
                 << ui::GetX11ErrorString(display, ret);
     return false;
   }
 
   return true;
 }
 
+Window X11WholeScreenMoveLoop::CreateDragInputWindow(XDisplay* display) {
+  // Creates an invisible, InputOnly toplevel window. This window will receive
+  // all mouse movement for drags. It turns out that normal windows doing a
+  // grab doesn't redirect pointer motion events if the pointer isn't over the
+  // grabbing window. But InputOnly windows are able to grab everything. This
+  // is what GTK+ does, and I found a patch to KDE that did something similar.
+  unsigned long attribute_mask = CWEventMask | CWOverrideRedirect;
+  XSetWindowAttributes swa;
+  memset(&swa, 0, sizeof(swa));
+  swa.event_mask = ButtonPressMask | ButtonReleaseMask | PointerMotionMask |
+                   StructureNotifyMask;
+  swa.override_redirect = True;
+  Window window = XCreateWindow(display,
+                                DefaultRootWindow(display),
+                                -100, -100, 10, 10,
+                                0, CopyFromParent, InputOnly, CopyFromParent,
+                                attribute_mask, &swa);
+  XMapRaised(display, window);
+  base::MessagePumpX11::Current()->BlockUntilWindowMapped(window);
+  return window;
+}
+
+void X11WholeScreenMoveLoop::CreateDragImageWindow() {
+  Widget* widget = new Widget;
+  Widget::InitParams params(Widget::InitParams::TYPE_POPUP);

[Elliot Glaysher, 2013/11/22 20:19:19]

I'm pretty sure you want to do something here that will set
_NET_WM_WINDOW_TYPE_DND. Add a type to Widget::InitParams::Type and check handle
it in DesktopRootWindowHostX11::InitX11Window()?

(A month or so ago, I wouldn't have blocked on this, but I've sort of learned
that window managers really care about the value of _NET_WM_WINDOW_TYPE.)

[sadrul, 2013/11/22 21:16:30]

Good point. Done.

+  params.opacity = Widget::InitParams::OPAQUE_WINDOW;
+  params.ownership = Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
+  params.can_activate = false;
+  params.keep_on_top = true;
+  params.accept_events = true;
+
+  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->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);
+
+  drag_widget_.reset(widget);
+}
+
 }  // namespace views