ui/base/win/mouse_wheel_util.cc

   1 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "ui/base/win/mouse_wheel_util.h"
   6
   7 #include <windowsx.h>
   8
   9 #include "base/auto_reset.h"
  10 #include "ui/base/view_prop.h"
  11 #include "ui/gfx/win/hwnd_util.h"
  12
  13 namespace ui {
  14
  15 // Property used to indicate the HWND supports having mouse wheel messages
  16 // rerouted to it.
  17 static const char* const kHWNDSupportMouseWheelRerouting =
  18     "__HWND_MW_REROUTE_OK";
  19
  20 static bool WindowSupportsRerouteMouseWheel(HWND window) {
  21   while (GetWindowLong(window, GWL_STYLE) & WS_CHILD) {
  22     if (!IsWindow(window))
  23       break;
  24
  25     if (ViewProp::GetValue(window, kHWNDSupportMouseWheelRerouting) != NULL) {
  26       return true;
  27     }
  28     window = GetParent(window);
  29   }
  30   return false;
  31 }
  32
  33 static bool IsCompatibleWithMouseWheelRedirection(HWND window) {
  34   std::wstring class_name = gfx::GetClassName(window);
  35   // Mousewheel redirection to comboboxes is a surprising and
  36   // undesireable user behavior.
  37   return !(class_name == L"ComboBox" ||
  38            class_name == L"ComboBoxEx32");
  39 }
  40
  41 static bool CanRedirectMouseWheelFrom(HWND window) {
  42   std::wstring class_name = gfx::GetClassName(window);
  43
  44   // Older Thinkpad mouse wheel drivers create a window under mouse wheel
  45   // pointer. Detect if we are dealing with this window. In this case we
  46   // don't need to do anything as the Thinkpad mouse driver will send
  47   // mouse wheel messages to the right window.
  48   if ((class_name == L"Syn Visual Class") ||
  49      (class_name == L"SynTrackCursorWindowClass"))
  50     return false;
  51
  52   return true;
  53 }
  54
  55 ViewProp* SetWindowSupportsRerouteMouseWheel(HWND hwnd) {
  56   return new ViewProp(hwnd, kHWNDSupportMouseWheelRerouting,
  57                       reinterpret_cast<HANDLE>(true));
  58 }
  59
  60 bool RerouteMouseWheel(HWND window, WPARAM w_param, LPARAM l_param) {
  61   // Since this is called from a subclass for every window, we can get
  62   // here recursively. This will happen if, for example, a control
  63   // reflects wheel scroll messages to its parent. Bail out if we got
  64   // here recursively.
  65   static bool recursion_break = false;
  66   if (recursion_break)
  67     return false;
  68   // Check if this window's class has a bad interaction with rerouting.
  69   if (!IsCompatibleWithMouseWheelRedirection(window))
  70     return false;
  71
  72   DWORD current_process = GetCurrentProcessId();
  73   POINT wheel_location = { GET_X_LPARAM(l_param), GET_Y_LPARAM(l_param) };
  74   HWND window_under_wheel = WindowFromPoint(wheel_location);
  75
  76   if (!CanRedirectMouseWheelFrom(window_under_wheel))
  77     return false;
  78
  79   // Find the lowest Chrome window in the hierarchy that can be the
  80   // target of mouse wheel redirection.
  81   while (window != window_under_wheel) {
  82     // If window_under_wheel is not a valid Chrome window, then return true to
  83     // suppress further processing of the message.
  84     if (!::IsWindow(window_under_wheel))
  85       return true;
  86     DWORD wheel_window_process = 0;
  87     GetWindowThreadProcessId(window_under_wheel, &wheel_window_process);
  88     if (current_process != wheel_window_process) {
  89       if (IsChild(window, window_under_wheel)) {
  90         // If this message is reflected from a child window in a different
  91         // process (happens with out of process windowed plugins) then
  92         // we don't want to reroute the wheel message.
  93         return false;
  94       } else {
  95         // The wheel is scrolling over an unrelated window. Make sure that we
  96         // have marked that window as supporting mouse wheel rerouting.
  97         // Otherwise, we cannot send random WM_MOUSEWHEEL messages to arbitrary
  98         // windows. So just drop the message.
  99         if (!WindowSupportsRerouteMouseWheel(window_under_wheel))
 100           return true;
 101       }
 102     }
 103
 104     // If the child window is transparent, then it is not interested in
 105     // receiving wheel events.
 106     if (IsChild(window, window_under_wheel) &&
 107         ::GetWindowLong(
 108             window_under_wheel, GWL_EXSTYLE) & WS_EX_TRANSPARENT) {
 109       return false;
 110     }
 111
 112     // window_under_wheel is a Chrome window.  If allowed, redirect.
 113     if (IsCompatibleWithMouseWheelRedirection(window_under_wheel)) {
 114       base::AutoReset<bool> auto_reset_recursion_break(&recursion_break, true);
 115       SendMessage(window_under_wheel, WM_MOUSEWHEEL, w_param, l_param);
 116       return true;
 117     }
 118     // If redirection is disallowed, try the parent.
 119     window_under_wheel = GetAncestor(window_under_wheel, GA_PARENT);
 120   }
 121   // If we traversed back to the starting point, we should process
 122   // this message normally; return false.
 123   return false;
 124 }
 125
 126 }  // namespace ui