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>

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)
@@ -232,11 +233,29 @@ void QEglFSKmsGbmCursor::setPos(const QPoint &pos)
 {
     Q_FOREACH (QPlatformScreen *screen, m_screen->virtualSiblings()) {
         QEglFSKmsScreen *kmsScreen = static_cast<QEglFSKmsScreen *>(screen);
-        QPoint origin = kmsScreen->geometry().topLeft();
+        const QRect screenGeom = kmsScreen->geometry();
-        QPoint localPos = pos - origin;
+        const QPoint origin = screenGeom.topLeft();
-        QPoint adjustedPos = localPos - m_cursorImage.hotspot();
+        const QPoint localPos = pos - origin;
+        const QPoint adjustedLocalPos = localPos - m_cursorImage.hotspot();
 
-        int ret = drmModeMoveCursor(kmsScreen->device()->fd(), kmsScreen->output().crtc_id, adjustedPos.x(), adjustedPos.y());
+        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
@@ -245,6 +264,7 @@ void QEglFSKmsGbmCursor::setPos(const QPoint &pos)
             kmsScreen->handleCursorMove(pos);
         }
     }
+}
 
 void QEglFSKmsGbmCursor::initCursorAtlas()
 {

src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmcursor.h

@@ -85,6 +85,8 @@ public:
 
     void updateMouseStatus();
 
+    void reevaluateVisibilityForScreens() { setPos(pos()); }
+
 private:
     void initCursorAtlas();
 

src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmdevice.cpp

@@ -155,4 +155,14 @@ void QEglFSKmsGbmDevice::registerScreenCloning(QPlatformScreen *screen,
     gbmScreen->initCloning(screenThisScreenClones, screensCloningThisScreen);
 }
 
+void QEglFSKmsGbmDevice::registerScreen(QPlatformScreen *screen,
+                                        bool isPrimary,
+                                        const QPoint &virtualPos,
+                                        const QList<QPlatformScreen *> &virtualSiblings)
+{
+    QEglFSKmsDevice::registerScreen(screen, isPrimary, virtualPos, virtualSiblings);
+    if (screenConfig()->hwCursor() && m_globalCursor)
+        m_globalCursor->reevaluateVisibilityForScreens();
+}
+
 QT_END_NAMESPACE

src/plugins/platforms/eglfs/deviceintegration/eglfs_kms/qeglfskmsgbmdevice.h

@@ -70,6 +70,10 @@ public:
     void registerScreenCloning(QPlatformScreen *screen,
                                QPlatformScreen *screenThisScreenClones,
                                const QVector<QPlatformScreen *> &screensCloningThisScreen) override;
+    void registerScreen(QPlatformScreen *screen,
+                        bool isPrimary,
+                        const QPoint &virtualPos,
+                        const QList<QPlatformScreen *> &virtualSiblings) override;
 
 private:
     Q_DISABLE_COPY(QEglFSKmsGbmDevice)

src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_support/qeglfskmsscreen.cpp

@@ -72,6 +72,7 @@ QEglFSKmsScreen::QEglFSKmsScreen(QKmsDevice *device, const QKmsOutput &output, b
     : QEglFSScreen(static_cast<QEglFSIntegration *>(QGuiApplicationPrivate::platformIntegration())->display())
     , m_device(device)
     , m_output(output)
+    , m_cursorOutOfRange(false)
     , m_powerState(PowerStateOn)
     , m_interruptHandler(new QEglFSKmsInterruptHandler(this))
     , m_headless(headless)

src/plugins/platforms/eglfs/deviceintegration/eglfs_kms_support/qeglfskmsscreen.h

@@ -99,12 +99,16 @@ public:
     QPlatformScreen::PowerState powerState() const override;
     void setPowerState(QPlatformScreen::PowerState state) override;
 
+    bool isCursorOutOfRange() const { return m_cursorOutOfRange; }
+    void setCursorOutOfRange(bool b) { m_cursorOutOfRange = b; }
+
 protected:
     QKmsDevice *m_device;
 
     QKmsOutput m_output;
     QEdidParser m_edid;
     QPoint m_pos;
+    bool m_cursorOutOfRange;
 
     QList<QPlatformScreen *> m_siblings;