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..ae6d097b511be698937fb93f4dbeb3ada0a3a30e 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 &&
@@ -59,18 +62,26 @@ LRESULT CALLBACK MsgFilterProc(int code, WPARAM wparam, LPARAM lparam) {
     // We do not care about WM_SYSKEYDOWN and WM_SYSKEYUP because when ALT key
     // is pressed down on drag-and-drop, it means to create a link.
     if (msg->message == WM_MOUSEMOVE || msg->message == WM_LBUTTONUP ||
-        msg->message == WM_KEYDOWN || msg->message == WM_KEYUP) {
+        msg->message == WM_KEYDOWN || msg->message == WM_KEYUP ||

[dcheng, 2013/05/29 20:16:43]

WM_LBUTTONUP here and lines 75 should probably be tied to
!touch_initiated_drag_drop.

[Hongbo Min, 2013/05/30 01:31:50]

Done.

+        (touch_initiated_drag_drop && msg->message == WM_RBUTTONUP)) {
       // Forward the message from the UI thread to the drag-and-drop thread.
       PostThreadMessage(drag_out_thread_id,
                         msg->message,
                         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;
 
+      // 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 (touch_initiated_drag_drop && (msg->message == WM_RBUTTONUP ||

[dcheng, 2013/05/29 20:16:43]

I think this should be (touch_initiated_drag_drop && ((msg->message == ... ||
!(GetKeyState(...))))

[Hongbo Min, 2013/05/30 01:31:50]

Why do we need additional '(...)' to wrap "msg->message == .." again?

[dcheng, 2013/05/31 00:57:05]

I mismatched the parens. See my next comment =)

+          !(GetKeyState(VK_RBUTTON) & 0x8000)))
+          mouse_up_received = true;
+
       return TRUE;
     }
   }
@@ -161,7 +172,21 @@ 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());
+
+  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 +340,16 @@ 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 +447,46 @@ 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;
+
+  gfx::Point last_touch_position = rwhv->GetLastTouchEventLocation();
+  gfx::Screen* screen = gfx::Screen::GetScreenFor(rwhv->GetNativeView());
+  gfx::Display display = screen->GetDisplayNearestPoint(last_touch_position);

[oshima, 2013/05/29 14:41:01]

It may be better to use GetDisplayNearestWindow as you have access to
native view. Please ignore if you think it's better to use touch position
instead.

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

Thanks for your information. I still think it should be better to use the touch
position since the native window may cross more than one display, but the point
can be tied to only one display.

+  int screen_width = display.size().width();
+  int screen_height = display.size().height();
+
+  // 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());