Enable touch-initiated drag-drop work on Windows

content/browser/web_contents/web_contents_drag_win.cc

Index: content/browser/web_contents/web_contents_drag_win.cc
diff --git a/content/browser/web_contents/web_contents_drag_win.cc b/content/browser/web_contents/web_contents_drag_win.cc
index 9153808d985b3d45cf5d630bc5d0f7d18e38d87d..7513c4e8d5f6b9cc648e839b580bda8954eb199c 100644
--- a/content/browser/web_contents/web_contents_drag_win.cc
+++ b/content/browser/web_contents/web_contents_drag_win.cc
@@ -18,6 +18,7 @@
 #include "base/utf_string_conversions.h"
 #include "content/browser/download/drag_download_file.h"
 #include "content/browser/download/drag_download_util.h"
+#include "content/browser/renderer_host/render_widget_host_view_win.h"
 #include "content/browser/web_contents/web_drag_dest_win.h"
 #include "content/browser/web_contents/web_drag_source_win.h"
 #include "content/browser/web_contents/web_drag_utils_win.h"
@@ -51,6 +52,8 @@ bool run_do_drag_drop = true;
 HHOOK msg_hook = NULL;
 DWORD drag_out_thread_id = 0;
 bool mouse_up_received = false;
+// True if the drag-drop is initiated by touch event.
+bool touch_initiated_drag_drop = false;
 
 LRESULT CALLBACK MsgFilterProc(int code, WPARAM wparam, LPARAM lparam) {
   if (code == base::MessagePumpForUI::kMessageFilterCode &&
@@ -66,11 +69,25 @@ LRESULT CALLBACK MsgFilterProc(int code, WPARAM wparam, LPARAM lparam) {
                         msg->wParam,
                         msg->lParam);
 
-      // If the left button is up, we do not need to forward the message any
-      // more.
+      // If the left button is up, we do not need to forward the message
+      // any more.
       if (msg->message == WM_LBUTTONUP || !(GetKeyState(VK_LBUTTON) & 0x8000))
         mouse_up_received = true;
 
+      if (touch_initiated_drag_drop) {
+        // In case of touch-initiated drag, we need to take care of right
+        // mouse up event since a mouse right button down event is triggered
+        // programmatically for DoDragDrop running.
+        if (msg->message == WM_RBUTTONUP)

[dcheng, 2013/05/28 20:34:02]

Nit: I think you can just fold this into line 64-65 (so you don't need the extra
PostThreadMessage here)

[Hongbo Min, 2013/05/29 06:08:04]

Done.

[girard, 2013/05/29 18:57:52]

Is this code even reachable given the test in line 64-65?

[Hongbo Min, 2013/05/30 01:36:03]

Fixed.

+          PostThreadMessage(drag_out_thread_id,
+                            msg->message,
+                            msg->wParam,
+                            msg->lParam);
+
+        if (msg->message == WM_RBUTTONUP || !(GetKeyState(VK_RBUTTON) & 0x8000))
+          mouse_up_received = true;
+      }
+
       return TRUE;
     }
   }
@@ -161,7 +178,21 @@ void WebContentsDragWin::StartDragging(const WebDropData& drop_data,
                                        const gfx::Vector2d& image_offset) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
-  drag_source_ = new WebDragSource(source_window_, web_contents_);
+  RenderWidgetHostViewWin* rwhv =
+      static_cast<RenderWidgetHostViewWin*>
+          (web_contents_->GetRenderWidgetHostView());

[dcheng, 2013/05/28 20:34:02]

Nit: ( on previous line.

[Hongbo Min, 2013/05/29 06:08:04]

Done.

+
+  ui::DragDropTypes::DragEventSource event_source;
+  if (rwhv->in_long_press_gesture()) {
+    event_source = ui::DragDropTypes::DRAG_EVENT_SOURCE_TOUCH;
+    touch_initiated_drag_drop = true;
+  }
+  else {
+    event_source = ui::DragDropTypes::DRAG_EVENT_SOURCE_MOUSE;
+    touch_initiated_drag_drop = false;
+  }
+
+  drag_source_ = new WebDragSource(source_window_, web_contents_, event_source);
 
   const GURL& page_url = web_contents_->GetURL();
   const std::string& page_encoding = web_contents_->GetEncoding();
@@ -315,6 +346,16 @@ bool WebContentsDragWin::DoDragging(const WebDropData& drop_data,
                                     const gfx::Vector2d& image_offset) {
   ui::OSExchangeData data;
 
+  RenderWidgetHostViewWin* rwhv =
+      static_cast<RenderWidgetHostViewWin*>(
+          web_contents_->GetRenderWidgetHostView());
+  // If RWHV has a valid long press gesture, since DoDragDrop will run into
+  // itself loop and start a dragging session if and only if a mouse button
+  // is down and then moves, so we need to programmatically send out
+  // mouse down event and adjust the cursor position for DoDragDrop.
+  if (rwhv->in_long_press_gesture())
+    SendMouseEventForTouchDnD();
+
   if (!drop_data.download_metadata.empty()) {
     PrepareDragForDownload(drop_data, &data, page_url, page_encoding);
 
@@ -412,6 +453,44 @@ void WebContentsDragWin::CloseThread() {
   drag_drop_thread_.reset();
 }
 
+void WebContentsDragWin::SendMouseEventForTouchDnD() {
+  static const int kMaxAbsoluteCoordinate = 65535;
+
+  RenderWidgetHostViewWin* rwhv =
+      static_cast<RenderWidgetHostViewWin*>(
+          web_contents_->GetRenderWidgetHostView());
+
+  if (!rwhv)
+    return;
+
+  int screen_width = ::GetSystemMetrics(SM_CXSCREEN);
+  int screen_height  = ::GetSystemMetrics(SM_CYSCREEN);

[dcheng, 2013/05/28 20:34:02]

Nit: extra space.

[Hongbo Min, 2013/05/29 06:08:04]

Use gfx::Screen and gfx::Display API instead now.

+  gfx::Point last_touch_position = rwhv->GetLastTouchEventLocation();
+
+  // Map the screen coordinate to the normalized absolute coordinate.
+  int absolute_x =
+      last_touch_position.x() * kMaxAbsoluteCoordinate / screen_width;
+  int absolute_y =
+      last_touch_position.y() * kMaxAbsoluteCoordinate / screen_height;
+
+  // Send MOUSEEVENTF_RIGHTDOWN event followed by MOUSEEVENTF_MOVE event.
+  // The reason why not to merge these 2 mouse events into one is, we don't
+  // want DoDragDrop to get mouse event firstly which lead to drop the drag
+  // source. Once a touch point is removed from screen after long press,
+  // a MOUSEEVENTF_RIGHTUP event will be sent out, so we send the down event
+  // paired with it to complete DoDragDrop session.
+  INPUT input = { 0 };
+  input.type = INPUT_MOUSE;
+  input.mi.dwFlags = MOUSEEVENTF_RIGHTDOWN | MOUSEEVENTF_ABSOLUTE;
+  input.mi.dx = absolute_x;
+  input.mi.dy = absolute_y;
+  ::SendInput(1, &input, sizeof(input));
+
+  // Send MOUSEEVENTF_MOVE input event to set cursor to the right position.
+  input.mi.dwFlags = MOUSEEVENTF_MOVE | MOUSEEVENTF_ABSOLUTE;
+  ::SendInput(1, &input, sizeof(input));
+}
+
 void WebContentsDragWin::OnWaitForData() {
   DCHECK(drag_drop_thread_id_ == base::PlatformThread::CurrentId());