[EXPERIMENT] MacViews: Implement Tab Dragging

ui/views/cocoa/bridged_native_widget.mm

Index: ui/views/cocoa/bridged_native_widget.mm
diff --git a/ui/views/cocoa/bridged_native_widget.mm b/ui/views/cocoa/bridged_native_widget.mm
index 0ccff9d15a0fd3402ed9c1e613f6552cd7de2f62..ca55b5dbc5d91f511efcf9292ab999b5c47c0a2e 100644
--- a/ui/views/cocoa/bridged_native_widget.mm
+++ b/ui/views/cocoa/bridged_native_widget.mm
@@ -35,16 +35,6 @@
 #include "ui/views/widget/widget_aura_utils.h"
 #include "ui/views/widget/widget_delegate.h"
 
-extern "C" {
-
-typedef int32_t CGSConnection;
-CGSConnection _CGSDefaultConnection();
-CGError CGSSetWindowBackgroundBlurRadius(CGSConnection connection,
-                                         NSInteger windowNumber,
-                                         int radius);
-
-}
-
 // The NSView that hosts the composited CALayer drawing the UI. It fills the
 // window but is not hittable so that accessibility hit tests always go to the
 // BridgedContentView.
@@ -106,6 +96,8 @@ const int kResizeAreaCornerSize = 12;
 
 int kWindowPropertiesKey;
 
+bool g_ignore_next_mouse_down_for_draggable_regions = false;
+
 float GetDeviceScaleFactorFromView(NSView* view) {
   gfx::Display display =
       gfx::Screen::GetScreen()->GetDisplayNearestWindow(view);
@@ -203,6 +195,11 @@ NSEvent* RepostEventIfHandledByWindow(NSEvent* ns_event) {
   // - any repost loop.
 
   if (repost_state == NONE) {
+    if (g_ignore_next_mouse_down_for_draggable_regions) {
+      g_ignore_next_mouse_down_for_draggable_regions = false;
+      return ns_event;
+    }
+
     if (WindowWantsMouseDownReposted(ns_event)) {
       repost_state = EXPECTING_REPOST;
       reposted_event_number = event_number;
@@ -311,6 +308,15 @@ NSComparisonResult SubviewSorter(NSViewComparatorValue lhs,
 
 }  // namespace
 
+extern "C" {
+
+typedef int32_t CGSConnection;
+CGSConnection _CGSDefaultConnection();
+CGError CGSSetWindowBackgroundBlurRadius(CGSConnection connection,
+                                         NSInteger windowNumber,
+                                         int radius);
+}
+
 namespace views {
 
 // static
@@ -615,6 +621,79 @@ bool BridgedNativeWidget::HasCapture() {
   return mouse_capture_ && mouse_capture_->IsActive();
 }
 
+Widget::MoveLoopResult BridgedNativeWidget::RunMoveLoop(
+    const gfx::Vector2d& drag_offset) {
+  DCHECK(!HasCapture());
+  DCHECK(!window_move_loop_);
+
+  // First, position the window in the right place. The point |drag_offset|
+  // away from the top-left corner needs to be positioned under the mouse.
+  // TODO(tapted): Figure out why the toolkit-views drag controller doesn't get
+  // this right when it first initializes the Widget.
+  gfx::Point mouse_in_screen = gfx::Screen::GetScreen()->GetCursorScreenPoint();
+
+  // A window can't be moved vertically up out of the work area. Treat this case
+  // as if the mouse location is at the point it would be when the window first
+  // stopped moving. That is, vertically down such that the top edge of the
+  // window touches the menubar (or top of the screen in a dual-screen setup).
+  // Note on Mac we can assume that the y-coordinate of the work area origin is
+  // the bottom of the menu bar and not the Dock which doesn't affect window
+  // movement, but can reduce the work area on the bottom, left and right.
+  const gfx::Display display =
+      gfx::Screen::GetScreen()->GetDisplayNearestPoint(mouse_in_screen);
+  int min_y = display.work_area().y() + drag_offset.y();
+  if (mouse_in_screen.y() < min_y)
+    mouse_in_screen.set_y(min_y);
+
+  gfx::Rect frame = gfx::ScreenRectFromNSRect([window_ frame]);
+  frame.set_x(mouse_in_screen.x() - drag_offset.x());
+  frame.set_y(mouse_in_screen.y() - drag_offset.y());
+  DCHECK_GE(frame.y(), display.work_area().y());
+
+  // After setting the frame to correct the initial offset, the drag controller
+  // may immediately want to quit when it's notified of the new bounds. So the
+  // MoveLoop must be set up before the call to setFrame.
+  window_move_loop_.reset(new CocoaWindowMoveLoop(this, mouse_in_screen));
+
+  // Animating may provide a less janky UX, but something custom would be
+  // required so that it follows updates to the mouse position.
+  const NSRect ns_frame = gfx::ScreenRectToNSRect(frame);
+  [window_ setFrame:ns_frame display:YES animate:NO];
+
+  // Setting the frame will call OnWidgetBoundsChanged(), which could result in
+  // a call to EndMoveLoop().
+  if (!window_move_loop_)
+    return Widget::MOVE_LOOP_SUCCESSFUL;
+
+  // Make sure WindowServer has caught up with moving the window, this is
+  // required in order to send the MouseDown click to the intended position.
+  // I was able to always replicate old window coordinates from
+  // CGSGetWindowBounds() on El Capitan.
+  // DetachToBrowserTabDragControllerTest.MacDetachesAndReattachesSecondTab will
+  // fail without the following NSRunLoop pass.
+  [[NSRunLoop currentRunLoop]
+      runUntilDate:[NSDate dateWithTimeIntervalSinceNow:0]];
+  DCHECK(NSEqualRects(ns_frame, gfx::ScreenRectToNSRect(
+                                    native_widget_mac()->WindowServerFrame())));
+
+  return window_move_loop_->Run();
+
+  // |this| may be destroyed during the RunLoop, causing it to exit early.
+  // Even if that doesn't happen, CocoaWindowMoveLoop will clean itself up by
+  // calling EndMoveLoop(). So window_move_loop_ will always be null before the
+  // function returns. But don't DCHECK since |this| might not be valid.
+}
+
+void BridgedNativeWidget::EndMoveLoop() {
+  DCHECK(window_move_loop_);
+  window_move_loop_->End();
+  window_move_loop_.reset();
+}
+
+bool BridgedNativeWidget::IsRunMoveLoopActive() const {
+  return window_move_loop_.get();
+}
+
 void BridgedNativeWidget::SetNativeWindowProperty(const char* name,
                                                   void* value) {
   NSString* key = [NSString stringWithUTF8String:name];
@@ -636,6 +715,7 @@ void BridgedNativeWidget::SetCursor(NSCursor* cursor) {
 }
 
 void BridgedNativeWidget::OnWindowWillClose() {
+  DCHECK(!drag_run_loop_);
   if (parent_) {
     parent_->RemoveChildWindow(this);
     parent_ = nullptr;
@@ -733,6 +813,10 @@ void BridgedNativeWidget::OnSizeChanged() {
     [bridged_view_ updateWindowMask];
 }
 
+void BridgedNativeWidget::OnPositionChanged() {
+  native_widget_mac_->GetWidget()->OnNativeWidgetMove();
+}
+
 void BridgedNativeWidget::OnVisibilityChanged() {
   OnVisibilityChangedTo([window_ isVisible]);
 }
@@ -1306,4 +1390,9 @@ void BridgedNativeWidget::SetDraggable(bool draggable) {
   [window_ setMovableByWindowBackground:YES];
 }
 
+// static
+void BridgedNativeWidget::IgnoreNextMouseDownForDraggableRegions() {
+  g_ignore_next_mouse_down_for_draggable_regions = true;
+}
+
 }  // namespace views