…olling

src/lib/platform/OSXScreen.h

@@ -147,7 +147,7 @@ class OSXScreen : public PlatformScreen {
 	SInt32				mapScrollWheelToSynergy(SInt32) const;
 
 	// map synergy scroll wheel value to a mac scroll wheel value
-	SInt32				mapScrollWheelFromSynergy(SInt32) const;
+	SInt32				mapScrollWheelFromSynergy(float) const;
 
 	// get the current scroll wheel speed
 	double				getScrollSpeed() const;

src/lib/platform/OSXScreen.mm

@@ -1426,7 +1426,7 @@
 }
 
 SInt32
-OSXScreen::mapScrollWheelFromSynergy(SInt32 x) const
+OSXScreen::mapScrollWheelFromSynergy(float x) const
 {
 	// use server's acceleration with a little boost since other platforms
 	// take one wheel step as a larger step than the mac does.
@@ -1943,10 +1943,15 @@
 			return event;
 			break;
 		case kCGEventScrollWheel:
+			// http://tinyurl.com/gt98gz7
 			screen->onMouseWheel(screen->mapScrollWheelToSynergy(
-								 CGEventGetIntegerValueField(event, kCGScrollWheelEventDeltaAxis2)),
-								 screen->mapScrollWheelToSynergy(
-								 CGEventGetIntegerValueField(event, kCGScrollWheelEventDeltaAxis1)));
+											CGEventGetIntegerValueField(
+												event,
+												kCGScrollWheelEventFixedPtDeltaAxis2) >> 16),
+											screen->mapScrollWheelToSynergy(
+												CGEventGetIntegerValueField(
+													event,
+													kCGScrollWheelEventFixedPtDeltaAxis1) >> 16));
 			break;
 		case kCGEventKeyDown:
 		case kCGEventKeyUp:

src/lib/platform/XWindowsScreen.cpp

@@ -99,6 +99,7 @@ XWindowsScreen::XWindowsScreen(
 		IEventQueue* events) :
 	m_isPrimary(isPrimary),
 	m_mouseScrollDelta(mouseScrollDelta),
+	m_accumulatedScroll(0),
 	m_display(NULL),
 	m_root(None),
 	m_window(None),
@@ -868,9 +869,11 @@ XWindowsScreen::fakeMouseWheel(SInt32, SInt32 yDelta) const
 		return;
 	}
 
+	int numEvents = accumulateMouseScroll(yDelta);
+
 	// choose button depending on rotation direction
 	const unsigned int xButton = mapButtonToX(static_cast<ButtonID>(
-												(yDelta >= 0) ? -1 : -2));
+												(numEvents >= 0) ? -1 : -2));
 	if (xButton == 0) {
 		// If we get here, then the XServer does not support the scroll
 		// wheel buttons, so send PageUp/PageDown keystrokes instead.
@@ -889,20 +892,14 @@ XWindowsScreen::fakeMouseWheel(SInt32, SInt32 yDelta) const
 		return;
 	}
 
-	// now use absolute value of delta
-	if (yDelta < 0) {
-		yDelta = -yDelta;
-	}
-
-	if (yDelta < m_mouseScrollDelta) {
-		LOG((CLOG_WARN "Wheel scroll delta (%d) smaller than threshold (%d)", yDelta, m_mouseScrollDelta));
-	}
+	numEvents = std::abs(numEvents);
 
 	// send as many clicks as necessary
-	for (; yDelta >= m_mouseScrollDelta; yDelta -= m_mouseScrollDelta) {
+	for (; numEvents > 0; numEvents--) {
 		XTestFakeButtonEvent(m_display, xButton, True, CurrentTime);
 		XTestFakeButtonEvent(m_display, xButton, False, CurrentTime);
 	}
+
 	XFlush(m_display);
 }
 
@@ -1662,6 +1659,15 @@ XWindowsScreen::onMouseMove(const XMotionEvent& xmotion)
 	}
 }
 
+int
+XWindowsScreen::accumulateMouseScroll(SInt32 yDelta) const
+{
+	m_accumulatedScroll += yDelta;
+	int numEvents = m_accumulatedScroll / m_mouseScrollDelta;
+	m_accumulatedScroll -= numEvents * m_mouseScrollDelta;
+	return numEvents;
+}
+
 Cursor
 XWindowsScreen::createBlankCursor() const
 {

src/lib/platform/XWindowsScreen.h

@@ -136,6 +136,10 @@ class XWindowsScreen : public PlatformScreen {
 	void				onMouseRelease(const XButtonEvent&);
 	void				onMouseMove(const XMotionEvent&);
 
+	// Returns the number of scroll events needed after the current delta has
+	// been taken into account
+	int					accumulateMouseScroll(SInt32 yDelta) const;
+
 	bool				detectXI2();
 #ifdef HAVE_XI2
 	void				selectXIRawMotion();
@@ -172,8 +176,15 @@ class XWindowsScreen : public PlatformScreen {
 
 	// true if screen is being used as a primary screen, false otherwise
 	bool				m_isPrimary;
+
+	// The size of a smallest supported scroll event, in points
 	int 				m_mouseScrollDelta;
 
+	// Accumulates scrolls of less than m_mouseScrollDelta across multiple
+	// scroll events. We dispatch a scroll event whenever the accumulated scroll
+	// becomes larger than m_mouseScrollDelta
+	mutable int			m_accumulatedScroll;
+
 	Display*			m_display;
 	Window				m_root;
 	Window				m_window;