Resolves: fdo#65634 improve wheel-scrolling sidebar panels

Change-Id: I213d85a1e2bbd2377f6f0326433ddd57dc346721

sfx2/source/sidebar/Deck.cxx

@@ -190,9 +190,6 @@ void Deck::DataChanged (const DataChangedEvent& rEvent)
     RequestLayout();
 }
 
-
-
-
 bool Deck::Notify (NotifyEvent& rEvent)
 {
     if (rEvent.GetType() == EVENT_COMMAND)
@@ -202,7 +199,7 @@ bool Deck::Notify (NotifyEvent& rEvent)
             switch (pCommandEvent->GetCommand())
             {
                 case COMMAND_WHEEL:
-                    return ProcessWheelEvent(pCommandEvent, rEvent);
+                    return ProcessWheelEvent(pCommandEvent);
 
                 default:
                     break;
@@ -212,24 +209,13 @@ bool Deck::Notify (NotifyEvent& rEvent)
     return Window::Notify(rEvent);
 }
 
-
-
-
-bool Deck::ProcessWheelEvent (
-    CommandEvent* pCommandEvent,
-    NotifyEvent& rEvent)
+bool Deck::ProcessWheelEvent(CommandEvent* pCommandEvent)
 {
     if ( ! mpVerticalScrollBar)
         return false;
     if ( ! mpVerticalScrollBar->IsVisible())
         return false;
 
-    // Ignore all wheel commands from outside the vertical scroll bar.
-    // Otherwise after a scroll we might land on a spin field and
-    // subsequent wheel events would change the value of that control.
-    if (rEvent.GetWindow() != mpVerticalScrollBar.get())
-        return true;
-
     // Get the wheel data and check that it describes a valid vertical
     // scroll.
     const CommandWheelData* pData = pCommandEvent->GetWheelData();
@@ -246,9 +232,6 @@ bool Deck::ProcessWheelEvent (
     return true;
 }
 
-
-
-
 void Deck::SetPanels (const SharedPanelContainer& rPanels)
 {
     maPanels = rPanels;
@@ -256,13 +239,6 @@ void Deck::SetPanels (const SharedPanelContainer& rPanels)
     RequestLayout();
 }
 
-
-
-
-
-
-
-
 void Deck::RequestLayout (void)
 {
     mnMinimalWidth = 0;
@@ -278,17 +254,11 @@ void Deck::RequestLayout (void)
         *mpVerticalScrollBar);
 }
 
-
-
-
 ::Window* Deck::GetPanelParentWindow (void)
 {
     return mpScrollContainer.get();
 }
 
-
-
-
 void Deck::ShowPanel (const Panel& rPanel)
 {
     if (mpVerticalScrollBar && mpVerticalScrollBar->IsVisible())

sfx2/source/sidebar/Deck.hxx

@@ -100,12 +100,9 @@ private:
     ::boost::scoped_ptr<ScrollBar> mpVerticalScrollBar;
 
     DECL_LINK(HandleVerticalScrollBarChange,void*);
-    bool ProcessWheelEvent (
-        CommandEvent* pCommandEvent,
-        NotifyEvent& rEvent);
+    bool ProcessWheelEvent(CommandEvent* pCommandEvent);
 };
 
-
 } } // end of namespace sfx2::sidebar
 
 #endif

vcl/source/window/winproc.cxx

@@ -1366,8 +1366,22 @@ static bool acceptableWheelScrollTarget(const Window *pMouseWindow)
     return (pMouseWindow && pMouseWindow->IsInputEnabled() && !pMouseWindow->IsInModalMode());
 }
 
+//If the last event at the same absolute screen position was handled by a
+//different window then reuse that window if the event occurs within 1/2 a
+//second, i.e. so scrolling down something like the calc sidebar that contains
+//widgets that respond to wheel events will continue to send the event to the
+//scrolling widget in favour of the widget that happens to end up under the
+//mouse.
+static bool shouldReusePreviousMouseWindow(const SalWheelMouseEvent& rPrevEvt, const SalWheelMouseEvent& rEvt)
+{
+    return (rEvt.mnX == rPrevEvt.mnX && rEvt.mnY == rPrevEvt.mnY && rEvt.mnTime-rPrevEvt.mnTime < 500/*ms*/);
+}
+
 static bool ImplHandleWheelEvent( Window* pWindow, const SalWheelMouseEvent& rEvt, bool scaleDirectly = false )
 {
+    static SalWheelMouseEvent aPreviousEvent;
+    static Window *pPreviousWindow;
+
     ImplDelData aDogTag( pWindow );
 
     ImplSVData* pSVData = ImplGetSVData();
@@ -1431,6 +1445,16 @@ static bool ImplHandleWheelEvent( Window* pWindow, const SalWheelMouseEvent& rEv
         pMouseWindow = pMouseWindow->GetParent();
     }
 
+    // avoid the problem that scrolling via wheel to this point brings a widget
+    // under the mouse that also accepts wheel commands, so stick with the old
+    // widget if the time gap is very small
+    if (shouldReusePreviousMouseWindow(aPreviousEvent, rEvt) && acceptableWheelScrollTarget(pPreviousWindow))
+    {
+        pMouseWindow = pPreviousWindow;
+    }
+
+    aPreviousEvent = rEvt;
+
     if (acceptableWheelScrollTarget(pMouseWindow) && pMouseWindow->IsEnabled())
     {
         // transform coordinates to float window frame coordinates
@@ -1441,6 +1465,8 @@ static bool ImplHandleWheelEvent( Window* pWindow, const SalWheelMouseEvent& rEv
         bRet = ImplCallWheelCommand( pMouseWindow, aRelMousePos, &aWheelData );
     }
 
+    pPreviousWindow = !bRet ? pMouseWindow : NULL;
+
     // if the command was not handled try the focus window
     if ( bRet )
     {