Fix scroll wheel behavior for Wayland clients

There are inconsistencies between how we represent mouse wheel deltas
and how the Weston compositor does.  For better compatibility with
Weston we need to change our mouse axis events too look like

Up:    positive Y (+10)
Down:  negative Y (-10)
Left:  positive X (+10)
Right: negative X (-10)

Our synthesised mouse wheel deltas are (+ or -)120 with both axes
inversed.

With this change Qt Clients should behave the same way on both Weston
and QtCompositors.

Change-Id: I37b4fd8cbb93e5a1a135a60ae8c3547c823aeba2
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>

2 files changed, 17 insertions, 5 deletions

diff --git a/src/compositor/wayland_wrapper/wlinputdevice.cpp b/src/compositor/wayland_wrapper/wlinputdevice.cpp
index c951ecf05..6b8f36409 100644
--- a/src/compositor/wayland_wrapper/wlinputdevice.cpp
+++ b/src/compositor/wayland_wrapper/wlinputdevice.cpp
@@ -361,7 +361,7 @@ void InputDevice::sendMouseWheelEvent(Qt::Orientation orientation, int delta)
     uint32_t time = m_compositor->currentTimeMsecs();
     uint32_t axis = orientation == Qt::Horizontal ? WL_POINTER_AXIS_HORIZONTAL_SCROLL
                                                   : WL_POINTER_AXIS_VERTICAL_SCROLL;
-    wl_pointer_send_axis(resource, time, axis, wl_fixed_from_double(delta / 120.0));
+    wl_pointer_send_axis(resource, time, axis, wl_fixed_from_int(-delta / 12));
 }
 
 void InputDevice::updateModifierState(uint code, int state)
diff --git a/src/plugins/platforms/wayland/qwaylandinputdevice.cpp b/src/plugins/platforms/wayland/qwaylandinputdevice.cpp
index a3a31e3d7..aaef268e5 100644
--- a/src/plugins/platforms/wayland/qwaylandinputdevice.cpp
+++ b/src/plugins/platforms/wayland/qwaylandinputdevice.cpp
@@ -358,14 +358,26 @@ void QWaylandInputDevice::pointer_axis(void *data,
     Q_UNUSED(pointer);
     QWaylandInputDevice *inputDevice = (QWaylandInputDevice *) data;
     QWaylandWindow *window = inputDevice->mPointerFocus;
-    Qt::Orientation orientation = axis == WL_POINTER_AXIS_HORIZONTAL_SCROLL ? Qt::Horizontal
-                                                                            : Qt::Vertical;
+    QPoint pixelDelta;
+    QPoint angleDelta;
+
+    //normalize value and inverse axis
+    int valueDelta = wl_fixed_to_int(value) * -12;
+
+    if (axis == WL_POINTER_AXIS_HORIZONTAL_SCROLL) {
+        pixelDelta = QPoint();
+        angleDelta.setX(valueDelta);
+    } else {
+        pixelDelta = QPoint();
+        angleDelta.setY(valueDelta);
+    }
+
     QWindowSystemInterface::handleWheelEvent(window->window(),
                                              time,
                                              inputDevice->mSurfacePos,
                                              inputDevice->mGlobalPos,
-                                             int(wl_fixed_to_double(value) * 120.0),
-                                             orientation);
+                                             pixelDelta,
+                                             angleDelta);
 }
 
 #ifndef QT_NO_WAYLAND_XKB