eglfs: kms: Fix hw cursor with multiple screens

We used to have the assumption that moving the cursor to an out of
range position is valid and will result in a hidden cursor.

This is apparently not the case. For example, on an RPi4 with Mesa
V3D we get lots of funny artifacts after doing drmModeMoveCursor()
to invalid positions.

To remedy this, start hiding the cursor correctly when the position
is clearly out of the screen's bounds.

Task-number: QTBUG-79924
Change-Id: I3ef7ad0ce928546399443f21452f0b6deadf8036
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

1 files changed, 32 insertions, 12 deletions

diff --git a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmcursor.cpp b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmcursor.cpp
index 4d0cf0c47e..1125bcb390 100644
--- a/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmcursor.cpp
+++ b/src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmcursor.cpp
@@ -214,7 +214,8 @@ void QEglFSKmsGbmCursor::changeCursor(QCursor *windowCursor, QWindow *window)
 
     Q_FOREACH (QPlatformScreen *screen, m_screen->virtualSiblings()) {
         QEglFSKmsScreen *kmsScreen = static_cast<QEglFSKmsScreen *>(screen);
-
+        if (kmsScreen->isCursorOutOfRange())
+            continue;
         int status = drmModeSetCursor(kmsScreen->device()->fd(), kmsScreen->output().crtc_id, handle,
                                       m_cursorSize.width(), m_cursorSize.height());
         if (status != 0)
@@ -232,17 +233,36 @@ void QEglFSKmsGbmCursor::setPos(const QPoint &pos)
 {
     Q_FOREACH (QPlatformScreen *screen, m_screen->virtualSiblings()) {
         QEglFSKmsScreen *kmsScreen = static_cast<QEglFSKmsScreen *>(screen);
-        QPoint origin = kmsScreen->geometry().topLeft();
-        QPoint localPos = pos - origin;
-        QPoint adjustedPos = localPos - m_cursorImage.hotspot();
-
-        int ret = drmModeMoveCursor(kmsScreen->device()->fd(), kmsScreen->output().crtc_id, adjustedPos.x(), adjustedPos.y());
-        if (ret == 0)
-            m_pos = pos;
-        else
-            qWarning("Failed to move cursor on screen %s: %d", kmsScreen->name().toLatin1().constData(), ret);
-
-        kmsScreen->handleCursorMove(pos);
+        const QRect screenGeom = kmsScreen->geometry();
+        const QPoint origin = screenGeom.topLeft();
+        const QPoint localPos = pos - origin;
+        const QPoint adjustedLocalPos = localPos - m_cursorImage.hotspot();
+
+        if (localPos.x() < 0 || localPos.y() < 0
+            || localPos.x() >= screenGeom.width() || localPos.y() >= screenGeom.height())
+        {
+            if (!kmsScreen->isCursorOutOfRange()) {
+                kmsScreen->setCursorOutOfRange(true);
+                drmModeSetCursor(kmsScreen->device()->fd(), kmsScreen->output().crtc_id, 0, 0, 0);
+            }
+        } else {
+            int ret;
+            if (kmsScreen->isCursorOutOfRange()) {
+                kmsScreen->setCursorOutOfRange(false);
+                uint32_t handle = gbm_bo_get_handle(m_bo).u32;
+                ret = drmModeSetCursor(kmsScreen->device()->fd(), kmsScreen->output().crtc_id,
+                                       handle, m_cursorSize.width(), m_cursorSize.height());
+            } else {
+                ret = drmModeMoveCursor(kmsScreen->device()->fd(), kmsScreen->output().crtc_id,
+                                        adjustedLocalPos.x(), adjustedLocalPos.y());
+            }
+            if (ret == 0)
+                m_pos = pos;
+            else
+                qWarning("Failed to move cursor on screen %s: %d", kmsScreen->name().toLatin1().constData(), ret);
+
+            kmsScreen->handleCursorMove(pos);
+        }
     }
 }