Client: Fix cursor hotspot on high-dpi

QWaylandInputDevice::setCursor(wl_buffer, QPoint, QSize, bufferscale) assumes a
hotspot and a size in surface coordinates, while wl_cursor_image uses pixel
coordinates.

Divide by bufferScale to get the correct values.

This breaks hidpi cursors on kwin 5.13.1 and earlier, where buffer scale for
cursor surfaces are ignored.

Change-Id: I7c86bc541ccf5fb878facebbe93d2b1f842dfc5c
Reviewed-by: David Edmundson <davidedmundson@kde.org>
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

1 files changed, 9 insertions, 3 deletions

diff --git a/src/client/qwaylandinputdevice.cpp b/src/client/qwaylandinputdevice.cpp
index 4835bd68e..b4b7c4ef3 100644
--- a/src/client/qwaylandinputdevice.cpp
+++ b/src/client/qwaylandinputdevice.cpp
@@ -389,11 +389,17 @@ void QWaylandInputDevice::setCursor(const QCursor &cursor, QWaylandScreen *scree
 
 void QWaylandInputDevice::setCursor(struct wl_buffer *buffer, struct wl_cursor_image *image, int bufferScale)
 {
-    setCursor(buffer,
-              image ? QPoint(image->hotspot_x, image->hotspot_y) : QPoint(),
-              image ? QSize(image->width, image->height) : QSize(), bufferScale);
+    if (image) {
+        // Convert from pixel coordinates to surface coordinates
+        QPoint hotspot = QPoint(image->hotspot_x, image->hotspot_y) / bufferScale;
+        QSize size = QSize(image->width, image->height) / bufferScale;
+        setCursor(buffer, hotspot, size, bufferScale);
+    } else {
+        setCursor(buffer, QPoint(), QSize(), bufferScale);
+    }
 }
 
+// size and hotspot are in surface coordinates
 void QWaylandInputDevice::setCursor(struct wl_buffer *buffer, const QPoint &hotSpot, const QSize &size, int bufferScale)
 {
     if (mCaps & WL_SEAT_CAPABILITY_POINTER) {