client-side wheel mouse support

remoting/host/event_executor_linux.cc

 // Copyright (c) 2011 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 "remoting/host/event_executor.h"
 
 #include <X11/Xlib.h>
 #include <X11/XF86keysym.h>
 #include <X11/keysym.h>
 #include <X11/extensions/XTest.h>
@@ skipping 50 matching lines @@
 
     case MouseEvent::BUTTON_MIDDLE:
       return 2;
 
     case MouseEvent::BUTTON_UNDEFINED:
     default:
       return -1;
   }
 }
 
+int VerticalScrollWheelToX11ButtonNumber(int dy) {

[Lambros, 2011/10/13 00:56:06]

Personally, I like "dy", but it might fall foul of the Chrome Style Police!  You
should use something long and convoluted, like "vertical_offset_y" instead :)

[garykac, 2011/10/13 21:18:53]

^_^

+  // Positive y-values are wheel down events (button 4), negative y-values are
+  // wheel up (button 5).

[Lambros, 2011/10/13 00:41:13]

Is this comment the wrong way round?  If I touch my wheel and slide my finger
towards me, I think of that as "wheel down".  That generates a button 5 event,
not button 4.

[garykac, 2011/10/13 21:18:53]

Fixed.

+  return (dy > 0 ? 4 : 5);
+}
+
 // Hard-coded mapping from Virtual Key codes to X11 KeySyms.
 // This mapping is only valid if both client and host are using a
 // US English keyboard layout.
 // Because we're passing VK codes on the wire, with no Scancode,
 // "extended" flag, etc, things like distinguishing left & right
 // Shift keys doesn't work.
 //
 // TODO(wez): Replace this with something more closely tied to what
 // WebInputEventFactory does on Linux/GTK, and which respects the
 // host's keyboard layout (see http://crbug.com/74550 ).
@@ skipping 251 matching lines @@
     XTestFakeMotionEvent(display_, DefaultScreen(display_),
                          event.x(), event.y(),
                          CurrentTime);
     XFlush(display_);
   }
 
   if (event.has_button() && event.has_button_down()) {
     int button_number = MouseButtonToX11ButtonNumber(event.button());
 
     if (button_number < 0) {
-      LOG(WARNING) << "Ignoring unknown button type: "
-                   << event.button();
+      LOG(WARNING) << "Ignoring unknown button type: " << event.button();
       return;
     }
 
     VLOG(3) << "Button " << event.button()
             << " received, sending "
             << (event.button_down() ? "down " : "up ")
             << button_number;
     XTestFakeButtonEvent(display_, button_number, event.button_down(),
                          CurrentTime);
     XFlush(display_);
   }
 
-  if (event.has_wheel_offset_x() && event.has_wheel_offset_y()) {
-    NOTIMPLEMENTED() << "No scroll wheel support yet.";
+  if (event.has_wheel_offset_x() && event.wheel_offset_x() != 0) {
+    NOTIMPLEMENTED() << "No horizontal scroll wheel support yet.";
+  }
+  if (event.has_wheel_offset_y()) {
+    int dy = event.wheel_offset_y();
+    int button_number = VerticalScrollWheelToX11ButtonNumber(dy);
+    if (dy < 0)
+      dy = -dy;
+
+    for (int i = 0; i < dy; i++) {
+      // Generate a button-down and a button-up to simulate a wheel click.
+      XTestFakeButtonEvent(display_, button_number, true, CurrentTime);
+      XTestFakeButtonEvent(display_, button_number, false, CurrentTime);
+    }
+    XFlush(display_);
   }
 }
 
 }  // namespace
 
 EventExecutor* EventExecutor::Create(MessageLoop* message_loop,
                                      Capturer* capturer) {
   EventExecutorLinux* executor = new EventExecutorLinux(message_loop, capturer);
   if (!executor->Init()) {
     delete executor;
     executor = NULL;
   }
   return executor;
 }
 
 }  // namespace remoting