Moving the mouse-wheel message rerouting code out of the focus manager.

This is part of the effort of making the focus manager not window specific.

BUG=None
TEST=Make sure mouse-wheel scrolls the Chrome window under the cursor (try with a Chrome window, the option window, the task manager table) when it is active and when it is inactive. Also try using the mouse-wheel on a plugin with a scroll-view (for example http://java.sun.com/products/plugin/1.4/demos/plugin/jfc/SwingSet2/SwingSet2.html) when the browser window is not active, the plugin should scroll.
Review URL: http://codereview.chromium.org/53037

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@12498 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 142 insertions, 107 deletions

diff --git a/chrome/views/focus/focus_manager.cc b/chrome/views/focus/focus_manager.cc
index e11d43f..d8fb23f 100644
--- a/chrome/views/focus/focus_manager.cc
+++ b/chrome/views/focus/focus_manager.cc
@@ -43,109 +43,6 @@ static const wchar_t* const kFocusSubclassInstalled =
 
 namespace views {
 
-static bool IsCompatibleWithMouseWheelRedirection(HWND window) {
-  std::wstring class_name = win_util::GetClassName(window);
-  // Mousewheel redirection to comboboxes is a surprising and
-  // undesireable user behavior.
-  return !(class_name == L"ComboBox" ||
-           class_name == L"ComboBoxEx32");
-}
-
-static bool CanRedirectMouseWheelFrom(HWND window) {
-  std::wstring class_name = win_util::GetClassName(window);
-
-  // Older Thinkpad mouse wheel drivers create a window under mouse wheel
-  // pointer. Detect if we are dealing with this window. In this case we
-  // don't need to do anything as the Thinkpad mouse driver will send
-  // mouse wheel messages to the right window.
-  if ((class_name == L"Syn Visual Class") ||
-     (class_name == L"SynTrackCursorWindowClass"))
-    return false;
-
-  return true;
-}
-
-bool IsPluginWindow(HWND window) {
-  HWND current_window = window;
-  while (GetWindowLong(current_window, GWL_STYLE) & WS_CHILD) {
-    current_window = GetParent(current_window);
-    if (!IsWindow(current_window))
-      break;
-
-    std::wstring class_name = win_util::GetClassName(current_window);
-    if (class_name == kRenderWidgetHostHWNDClass)
-      return true;
-  }
-
-  return false;
-}
-
-// Forwards mouse wheel messages to the window under it.
-// Windows sends mouse wheel messages to the currently active window.
-// This causes a window to scroll even if it is not currently under the
-// mouse wheel. The following code gives mouse wheel messages to the
-// window under the mouse wheel in order to scroll that window. This
-// is arguably a better user experience.  The returns value says whether
-// the mouse wheel message was successfully redirected.
-static bool RerouteMouseWheel(HWND window, WPARAM wParam, LPARAM lParam) {
-  // Since this is called from a subclass for every window, we can get
-  // here recursively. This will happen if, for example, a control
-  // reflects wheel scroll messages to its parent. Bail out if we got
-  // here recursively.
-  static bool recursion_break = false;
-  if (recursion_break)
-    return false;
-  // Check if this window's class has a bad interaction with rerouting.
-  if (!IsCompatibleWithMouseWheelRedirection(window))
-    return false;
-
-  DWORD current_process = GetCurrentProcessId();
-  POINT wheel_location = { GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam) };
-  HWND window_under_wheel = WindowFromPoint(wheel_location);
-
-  if (!CanRedirectMouseWheelFrom(window_under_wheel))
-    return false;
-
-  // Find the lowest Chrome window in the hierarchy that can be the
-  // target of mouse wheel redirection.
-  while (window != window_under_wheel) {
-    // If window_under_wheel is not a valid Chrome window, then return
-    // true to suppress further processing of the message.
-    if (!::IsWindow(window_under_wheel))
-      return true;
-    DWORD wheel_window_process = 0;
-    GetWindowThreadProcessId(window_under_wheel, &wheel_window_process);
-    if (current_process != wheel_window_process) {
-      if (IsChild(window, window_under_wheel)) {
-        // If this message is reflected from a child window in a different
-        // process (happens with out of process windowed plugins) then
-        // we don't want to reroute the wheel message.
-        return false;
-      } else {
-        // The wheel is scrolling over an unrelated window. If that window
-        // is a plugin window in a different chrome then we can send it a
-        // WM_MOUSEWHEEL. Otherwise, we cannot send random WM_MOUSEWHEEL
-        // messages to arbitrary windows. So just drop the message.
-        if (!IsPluginWindow(window_under_wheel))
-          return true;
-      }
-    }
-
-    // window_under_wheel is a Chrome window.  If allowed, redirect.
-    if (IsCompatibleWithMouseWheelRedirection(window_under_wheel)) {
-      recursion_break = true;
-      SendMessage(window_under_wheel, WM_MOUSEWHEEL, wParam, lParam);
-      recursion_break = false;
-      return true;
-    }
-    // If redirection is disallowed, try the parent.
-    window_under_wheel = GetAncestor(window_under_wheel, GA_PARENT);
-  }
-  // If we traversed back to the starting point, we should process
-  // this message normally; return false.
-  return false;
-}
-
 // Callback installed via InstallFocusSubclass.
 static LRESULT CALLBACK FocusWindowCallback(HWND window, UINT message,
                                             WPARAM wParam, LPARAM lParam) {
@@ -187,10 +84,6 @@ static LRESULT CALLBACK FocusWindowCallback(HWND window, UINT message,
           return 0;
         return result;
       }
-      case WM_MOUSEWHEEL:
-        if (RerouteMouseWheel(window, wParam, lParam))
-          return 0;
-        break;
       case WM_IME_CHAR:
         // Issue 7707: A rich-edit control may crash when it receives a
         // WM_IME_CHAR message while it is processing a WM_IME_COMPOSITION
diff --git a/chrome/views/focus/focus_util_win.cc b/chrome/views/focus/focus_util_win.cc
new file mode 100644
index 0000000..ec77519
--- /dev/null
+++ b/chrome/views/focus/focus_util_win.cc
@@ -0,0 +1,116 @@
+// Copyright (c) 2009 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 "chrome/views/focus/focus_util_win.h"
+
+#include "base/win_util.h"
+
+namespace views {
+
+// Property used to indicate the HWND supports having mouse wheel messages
+// rerouted to it.
+static const wchar_t* const kHWNDSupportMouseWheelRerouting =
+    L"__HWND_MW_REROUTE_OK";
+
+static bool WindowSupportsRerouteMouseWheel(HWND window) {
+  while (GetWindowLong(window, GWL_STYLE) & WS_CHILD) {
+    if (!IsWindow(window))
+      break;
+
+    if (reinterpret_cast<bool>(GetProp(window,
+                                       kHWNDSupportMouseWheelRerouting))) {
+      return true;
+    }
+    window = GetParent(window);
+  }
+  return false;
+}
+
+static bool IsCompatibleWithMouseWheelRedirection(HWND window) {
+  std::wstring class_name = win_util::GetClassName(window);
+  // Mousewheel redirection to comboboxes is a surprising and
+  // undesireable user behavior.
+  return !(class_name == L"ComboBox" ||
+           class_name == L"ComboBoxEx32");
+}
+
+static bool CanRedirectMouseWheelFrom(HWND window) {
+  std::wstring class_name = win_util::GetClassName(window);
+
+  // Older Thinkpad mouse wheel drivers create a window under mouse wheel
+  // pointer. Detect if we are dealing with this window. In this case we
+  // don't need to do anything as the Thinkpad mouse driver will send
+  // mouse wheel messages to the right window.
+  if ((class_name == L"Syn Visual Class") ||
+     (class_name == L"SynTrackCursorWindowClass"))
+    return false;
+
+  return true;
+}
+
+void SetWindowSupportsRerouteMouseWheel(HWND hwnd) {
+  SetProp(hwnd, kHWNDSupportMouseWheelRerouting,
+          reinterpret_cast<HANDLE>(true));
+}
+
+bool RerouteMouseWheel(HWND window, WPARAM w_param, LPARAM l_param) {
+  // Since this is called from a subclass for every window, we can get
+  // here recursively. This will happen if, for example, a control
+  // reflects wheel scroll messages to its parent. Bail out if we got
+  // here recursively.
+  static bool recursion_break = false;
+  if (recursion_break)
+    return false;
+  // Check if this window's class has a bad interaction with rerouting.
+  if (!IsCompatibleWithMouseWheelRedirection(window))
+    return false;
+
+  DWORD current_process = GetCurrentProcessId();
+  POINT wheel_location = { GET_X_LPARAM(l_param), GET_Y_LPARAM(l_param) };
+  HWND window_under_wheel = WindowFromPoint(wheel_location);
+
+  if (!CanRedirectMouseWheelFrom(window_under_wheel))
+    return false;
+
+  // Find the lowest Chrome window in the hierarchy that can be the
+  // target of mouse wheel redirection.
+  while (window != window_under_wheel) {
+    // If window_under_wheel is not a valid Chrome window, then return true to
+    // suppress further processing of the message.
+    if (!::IsWindow(window_under_wheel))
+      return true;
+    DWORD wheel_window_process = 0;
+    GetWindowThreadProcessId(window_under_wheel, &wheel_window_process);
+    if (current_process != wheel_window_process) {
+      if (IsChild(window, window_under_wheel)) {
+        // If this message is reflected from a child window in a different
+        // process (happens with out of process windowed plugins) then
+        // we don't want to reroute the wheel message.
+        return false;
+      } else {
+        // The wheel is scrolling over an unrelated window. Make sure that we
+        // have marked that window as supporting mouse wheel rerouting.
+        // Otherwise, we cannot send random WM_MOUSEWHEEL messages to arbitrary
+        // windows. So just drop the message.
+        if (!WindowSupportsRerouteMouseWheel(window_under_wheel))
+          return true;
+      }
+    }
+
+    // window_under_wheel is a Chrome window.  If allowed, redirect.
+    if (IsCompatibleWithMouseWheelRedirection(window_under_wheel)) {
+      recursion_break = true;
+      SendMessage(window_under_wheel, WM_MOUSEWHEEL, w_param, l_param);
+      recursion_break = false;
+      return true;
+    }
+    // If redirection is disallowed, try the parent.
+    window_under_wheel = GetAncestor(window_under_wheel, GA_PARENT);
+  }
+  // If we traversed back to the starting point, we should process
+  // this message normally; return false.
+  return false;
+}
+
+}  // namespace views
diff --git a/chrome/views/focus/focus_util_win.h b/chrome/views/focus/focus_util_win.h
new file mode 100644
index 0000000..b7a8625
--- /dev/null
+++ b/chrome/views/focus/focus_util_win.h
@@ -0,0 +1,26 @@
+// Copyright (c) 2009 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.
+
+#ifndef CHROME_VIEWS_FOCUS_FOCUS_UTIL_WIN_H_
+#define CHROME_VIEWS_FOCUS_FOCUS_UTIL_WIN_H_
+
+namespace views {
+
+// Marks the passed |hwnd| as supporting mouse-wheel message rerouting.
+// We reroute the mouse wheel messages to such HWND when they are under the
+// mouse pointer (but are not the active window)
+void SetWindowSupportsRerouteMouseWheel(HWND hwnd);
+
+// Forwards mouse wheel messages to the window under it.
+// Windows sends mouse wheel messages to the currently active window.
+// This causes a window to scroll even if it is not currently under the mouse
+// wheel. The following code gives mouse wheel messages to the window under the
+// mouse wheel in order to scroll that window. This is arguably a better user
+// experience.  The returns value says whether the mouse wheel message was
+// successfully redirected.
+bool RerouteMouseWheel(HWND window, WPARAM w_param, LPARAM l_param);
+
+}   // namespace views
+
+#endif  // CHROME_VIEWS_FOCUS_FOCUS_UTIL_WIN_H_