xcb: Map touch points to screen coordinates

Add QPointF overloads for QXcbScreen::mapToNative() and
QXcbScreen::mapFromNative(). Use mapFromNative() to map
the coordinates of a touch point to screen coordinates
as we do it for mouse events. It fixes touch events when
QT_DEVICE_PIXEL_RATIO is set.

Change-Id: Id8362cda526e0f837b76899eba21d9bfc895988c
Task-number: QTBUG-44840
Reviewed-by: Shawn Rutledge <shawn.rutledge@theqtcompany.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/src/plugins/platforms/xcb/qxcbscreen.cpp b/src/plugins/platforms/xcb/qxcbscreen.cpp
index c14ec0bb3f..993566b11c 100644
--- a/src/plugins/platforms/xcb/qxcbscreen.cpp
+++ b/src/plugins/platforms/xcb/qxcbscreen.cpp
@@ -282,6 +282,18 @@ QPoint QXcbScreen::mapFromNative(const QPoint &pos) const
     return (pos - m_nativeGeometry.topLeft()) / dpr + m_geometry.topLeft();
 }
 
+QPointF QXcbScreen::mapToNative(const QPointF &pos) const
+{
+    const int dpr = int(devicePixelRatio());
+    return (pos - m_geometry.topLeft()) * dpr + m_nativeGeometry.topLeft();
+}
+
+QPointF QXcbScreen::mapFromNative(const QPointF &pos) const
+{
+    const int dpr = int(devicePixelRatio());
+    return (pos - m_nativeGeometry.topLeft()) / dpr + m_geometry.topLeft();
+}
+
 QRect QXcbScreen::mapToNative(const QRect &rect) const
 {
     const int dpr = int(devicePixelRatio());