Bug 672175 part.2 MouseScrollHandler should manage system settings r=jimm

widget/windows/WinMouseScrollHandler.cpp

@@ -11,6 +11,7 @@
 
 #include "WinMouseScrollHandler.h"
 #include "nsWindow.h"
+#include "WinUtils.h"
 
 namespace mozilla {
 namespace widget {
@@ -77,9 +78,86 @@ MouseScrollHandler::ProcessMessage(nsWindow* aWindow, UINT msg,
                                    WPARAM wParam, LPARAM lParam,
                                    LRESULT *aRetValue, bool &aEatMessage)
 {
+  switch (msg) {
+    case WM_SETTINGCHANGE:
+      if (!sInstance) {
         return false;
+      }
+      if (wParam == SPI_SETWHEELSCROLLLINES ||
+          wParam == SPI_SETWHEELSCROLLCHARS) {
+        sInstance->mSystemSettings.MarkDirty();
+      }
+      return false;
+    default:
+      return false;
+  }
 }
 
+/******************************************************************************
+ *
+ * SystemSettings
+ *
+ ******************************************************************************/
+
+void
+MouseScrollHandler::SystemSettings::Init()
+{
+  if (mInitialized) {
+    return;
+  }
+
+  mInitialized = true;
+
+  if (!::SystemParametersInfo(SPI_GETWHEELSCROLLLINES, 0, &mScrollLines, 0)) {
+    PR_LOG(gMouseScrollLog, PR_LOG_ALWAYS,
+      ("MouseScroll::SystemSettings::Init(): ::SystemParametersInfo("
+         "SPI_GETWHEELSCROLLLINES) failed"));
+    mScrollLines = 3;
+  } else if (mScrollLines > WHEEL_DELTA) {
+    PR_LOG(gMouseScrollLog, PR_LOG_ALWAYS,
+      ("MouseScroll::SystemSettings::Init(): the result of "
+         "::SystemParametersInfo(SPI_GETWHEELSCROLLLINES) is too large: %d",
+       mScrollLines));
+    // sScrollLines usually equals 3 or 0 (for no scrolling)
+    // However, if sScrollLines > WHEEL_DELTA, we assume that
+    // the mouse driver wants a page scroll.  The docs state that
+    // sScrollLines should explicitly equal WHEEL_PAGESCROLL, but
+    // since some mouse drivers use an arbitrary large number instead,
+    // we have to handle that as well.
+    mScrollLines = WHEEL_PAGESCROLL;
+  }
+
+  if (!::SystemParametersInfo(SPI_GETWHEELSCROLLCHARS, 0, &mScrollChars, 0)) {
+    PR_LOG(gMouseScrollLog, PR_LOG_ALWAYS,
+      ("MouseScroll::SystemSettings::Init(): ::SystemParametersInfo("
+         "SPI_GETWHEELSCROLLCHARS) failed, %s",
+       WinUtils::GetWindowsVersion() >= WinUtils::VISTA_VERSION ?
+         "this is unexpected on Vista or later" :
+         "but on XP or earlier, this is not a problem"));
+    mScrollChars = 1;
+  } else if (mScrollChars > WHEEL_DELTA) {
+    PR_LOG(gMouseScrollLog, PR_LOG_ALWAYS,
+      ("MouseScroll::SystemSettings::Init(): the result of "
+         "::SystemParametersInfo(SPI_GETWHEELSCROLLCHARS) is too large: %d",
+       mScrollChars));
+    // See the comments for the case mScrollLines > WHEEL_DELTA.
+    mScrollChars = WHEEL_PAGESCROLL;
+  }
+
+  PR_LOG(gMouseScrollLog, PR_LOG_ALWAYS,
+    ("MouseScroll::SystemSettings::Init(): initialized, "
+       "mScrollLines=%d, mScrollChars=%d",
+     mScrollLines, mScrollChars));
+}
+
+void
+MouseScrollHandler::SystemSettings::MarkDirty()
+{
+  PR_LOG(gMouseScrollLog, PR_LOG_ALWAYS,
+    ("MouseScrollHandler::SystemSettings::MarkDirty(): "
+       "Marking SystemSettings dirty"));
+  mInitialized = false;
+}
 
 } // namespace widget
 } // namespace mozilla

widget/windows/WinMouseScrollHandler.h

@@ -36,6 +36,41 @@ private:
   ~MouseScrollHandler();
 
   static MouseScrollHandler* sInstance;
+
+public:
+  class SystemSettings {
+  public:
+    SystemSettings() : mInitialized(false) {}
+
+    void Init();
+    void MarkDirty();
+
+    PRInt32 GetScrollAmount(bool aForVertical) const
+    {
+      MOZ_ASSERT(mInitialized, "SystemSettings must be initialized");
+      return aForVertical ? mScrollLines : mScrollChars;
+    }
+
+    bool IsPageScroll(bool aForVertical) const
+    {
+      MOZ_ASSERT(mInitialized, "SystemSettings must be initialized");
+      return aForVertical ? (mScrollLines == WHEEL_PAGESCROLL) :
+                            (mScrollChars == WHEEL_PAGESCROLL);
+    }
+
+  private:
+    bool mInitialized;
+    PRInt32 mScrollLines;
+    PRInt32 mScrollChars;
+  };
+
+  SystemSettings& GetSystemSettings()
+  {
+    return mSystemSettings;
+  }
+
+private:
+  SystemSettings mSystemSettings;
 };
 
 } // namespace widget

widget/windows/nsWindow.cpp

@@ -294,8 +294,6 @@ MSG             nsWindow::sRedirectedKeyDown;
 
 bool            nsWindow::sEnablePixelScrolling = true;
 bool            nsWindow::sNeedsToInitMouseWheelSettings = true;
-ULONG           nsWindow::sMouseWheelScrollLines  = 0;
-ULONG           nsWindow::sMouseWheelScrollChars  = 0;
 
 HWND            nsWindow::sLastMouseWheelWnd = NULL;
 PRInt32         nsWindow::sRemainingDeltaForScroll = 0;
@@ -6315,30 +6313,6 @@ nsWindow::InitMouseWheelScrollData()
   sNeedsToInitMouseWheelSettings = false;
   ResetRemainingWheelDelta();
 
-  if (!::SystemParametersInfo(SPI_GETWHEELSCROLLLINES, 0,
-                              &sMouseWheelScrollLines, 0)) {
-    NS_WARNING("Failed to get SPI_GETWHEELSCROLLLINES");
-    sMouseWheelScrollLines = 3;
-  } else if (sMouseWheelScrollLines > WHEEL_DELTA) {
-    // sMouseWheelScrollLines usually equals 3 or 0 (for no scrolling)
-    // However, if sMouseWheelScrollLines > WHEEL_DELTA, we assume that
-    // the mouse driver wants a page scroll.  The docs state that
-    // sMouseWheelScrollLines should explicitly equal WHEEL_PAGESCROLL, but
-    // since some mouse drivers use an arbitrary large number instead,
-    // we have to handle that as well.
-    sMouseWheelScrollLines = WHEEL_PAGESCROLL;
-  }
-
-  if (!::SystemParametersInfo(SPI_GETWHEELSCROLLCHARS, 0,
-                              &sMouseWheelScrollChars, 0)) {
-    NS_ASSERTION(WinUtils::GetWindowsVersion() < WinUtils::VISTA_VERSION,
-                 "Failed to get SPI_GETWHEELSCROLLCHARS");
-    sMouseWheelScrollChars = 1;
-  } else if (sMouseWheelScrollChars > WHEEL_DELTA) {
-    // See the comments for the case sMouseWheelScrollLines > WHEEL_DELTA.
-    sMouseWheelScrollChars = WHEEL_PAGESCROLL;
-  }
-
   sEnablePixelScrolling =
     Preferences::GetBool("mousewheel.enable_pixel_scrolling", true);
 }
@@ -6367,10 +6341,12 @@ nsWindow::OnMouseWheelInternal(UINT aMessage, WPARAM aWParam, LPARAM aLParam,
                                LRESULT *aRetValue)
 {
   InitMouseWheelScrollData();
+  MouseScrollHandler::SystemSettings& systemSettings =
+    MouseScrollHandler::GetInstance()->GetSystemSettings();
+  systemSettings.Init();
 
   bool isVertical = (aMessage == WM_MOUSEWHEEL);
-  if ((isVertical && sMouseWheelScrollLines == 0) ||
-      (!isVertical && sMouseWheelScrollChars == 0)) {
+  if (systemSettings.GetScrollAmount(isVertical) == 0) {
     // XXX I think that we should dispatch mouse wheel events even if the
     // operation will not scroll because the wheel operation really happened
     // and web application may want to handle the event for non-scroll action.
@@ -6386,9 +6362,7 @@ nsWindow::OnMouseWheelInternal(UINT aMessage, WPARAM aWParam, LPARAM aLParam,
     return; // We cannot process this message
   }
 
-  bool isPageScroll =
-    ((isVertical && sMouseWheelScrollLines == WHEEL_PAGESCROLL) ||
-     (!isVertical && sMouseWheelScrollChars == WHEEL_PAGESCROLL));
+  bool isPageScroll = systemSettings.IsPageScroll(isVertical);
 
   // Discard the remaining delta if current wheel message and last one are
   // received by different window or to scroll different direction or
@@ -6445,8 +6419,8 @@ nsWindow::OnMouseWheelInternal(UINT aMessage, WPARAM aWParam, LPARAM aLParam,
   PRInt32 actualScrollAction = nsQueryContentEvent::SCROLL_ACTION_NONE;
   PRInt32 pixelsPerUnit = 0;
   // the amount is the number of lines (or pages) per WHEEL_DELTA
-  PRInt32 computedScrollAmount = isPageScroll ? 1 :
-    (isVertical ? sMouseWheelScrollLines : sMouseWheelScrollChars);
+  PRInt32 computedScrollAmount =
+    isPageScroll ? 1 : systemSettings.GetScrollAmount(isVertical);
 
   if (sEnablePixelScrolling) {
     nsMouseScrollEvent testEvent(true, NS_MOUSE_SCROLL, this);
@@ -6519,11 +6493,11 @@ nsWindow::OnMouseWheelInternal(UINT aMessage, WPARAM aWParam, LPARAM aLParam,
     double deltaPerUnit;
     if (isVertical) {
       scrollEvent.scrollFlags |= nsMouseScrollEvent::kIsVertical;
-      deltaPerUnit = (double)WHEEL_DELTA / sMouseWheelScrollLines;
     } else {
       scrollEvent.scrollFlags |= nsMouseScrollEvent::kIsHorizontal;
-      deltaPerUnit = (double)WHEEL_DELTA / sMouseWheelScrollChars;
     }
+    deltaPerUnit =
+      (double)WHEEL_DELTA / systemSettings.GetScrollAmount(isVertical);
     scrollEvent.delta =
       RoundDelta((double)nativeDeltaForScroll * orienter / deltaPerUnit);
     PRInt32 recomputedNativeDelta =

widget/windows/nsWindow.h

@@ -610,8 +610,6 @@ protected:
 
   static bool sEnablePixelScrolling;
   static bool sNeedsToInitMouseWheelSettings;
-  static ULONG sMouseWheelScrollLines;
-  static ULONG sMouseWheelScrollChars;
   static void InitMouseWheelScrollData();
 
   static HWND sLastMouseWheelWnd;