Add support for bitmap cursors

So far QtWayland did not support custom bitmap/pixmap QCursors.
This change adds support for them by creating a QWaylandShmBuffer and
copying the pixmap data into that buffer. The internal API to set
cursors images is changed to not only rely on wl_cursor_image, but also
allow to just set the buffer with a specific size and a hot spot.

The created WaylandShmBuffer is passed around as a shared pointer, so
that it can be automatically cleaned up once the cursor image is no
longer used on any seat.

Task-number: QTBUG-51604
Change-Id: I1f1ee87f03186c3d564468d3e8ea2a3141d7e2fb
Reviewed-by: Giulio Camuffo <giulio.camuffo@kdab.com>
Reviewed-by: Johan Helsing <johan.helsing@theqtcompany.com>

src/plugins/platforms/wayland/qwaylandcursor.cpp

@@ -85,7 +85,8 @@ struct wl_cursor_image *QWaylandCursor::cursorImage(Qt::CursorShape newShape)
     if (newShape < Qt::BitmapCursor) {
         waylandCursor = requestCursor((WaylandCursor)newShape);
     } else if (newShape == Qt::BitmapCursor) {
-        //TODO: Bitmap cursor logic
+        // cannot create a wl_cursor_image for a CursorShape
+        return Q_NULLPTR;
     } else {
         //TODO: Custom cursor logic (for resize arrows)
     }
@@ -105,12 +106,28 @@ struct wl_cursor_image *QWaylandCursor::cursorImage(Qt::CursorShape newShape)
     return image;
 }
 
+QSharedPointer<QWaylandBuffer> QWaylandCursor::cursorBitmapImage(const QCursor *cursor)
+{
+    if (cursor->shape() != Qt::BitmapCursor)
+        return QSharedPointer<QWaylandShmBuffer>();
+
+    const QImage &img = cursor->pixmap().toImage();
+    QSharedPointer<QWaylandShmBuffer> buffer(new QWaylandShmBuffer(mDisplay, img.size(), img.format()));
+    memcpy(buffer->image()->bits(), img.bits(), img.byteCount());
+    return buffer;
+}
+
 void QWaylandCursor::changeCursor(QCursor *cursor, QWindow *window)
 {
     Q_UNUSED(window)
 
     const Qt::CursorShape newShape = cursor ? cursor->shape() : Qt::ArrowCursor;
 
+    if (newShape == Qt::BitmapCursor) {
+        mDisplay->setCursor(cursorBitmapImage(cursor), cursor->hotSpot());
+        return;
+    }
+
     struct wl_cursor_image *image = cursorImage(newShape);
     if (!image) {
         return;
@@ -130,6 +147,16 @@ void QWaylandDisplay::setCursor(struct wl_buffer *buffer, struct wl_cursor_image
     }
 }
 
+void QWaylandDisplay::setCursor(const QSharedPointer<QWaylandBuffer> &buffer, const QPoint &hotSpot)
+{
+    /* Qt doesn't tell us which input device we should set the cursor
+     * for, so set it for all devices. */
+    for (int i = 0; i < mInputDevices.count(); i++) {
+        QWaylandInputDevice *inputDevice = mInputDevices.at(i);
+        inputDevice->setCursor(buffer, hotSpot);
+    }
+}
+
 QWaylandInputDevice *QWaylandDisplay::defaultInputDevice() const
 {
     return mInputDevices.isEmpty() ? 0 : mInputDevices.first();

src/plugins/platforms/wayland/qwaylandcursor_p.h

@@ -57,6 +57,7 @@ QT_BEGIN_NAMESPACE
 
 namespace QtWaylandClient {
 
+class QWaylandBuffer;
 class QWaylandDisplay;
 class QWaylandScreen;
 
@@ -72,6 +73,7 @@ public:
     void setPos(const QPoint &pos);
 
     struct wl_cursor_image *cursorImage(Qt::CursorShape shape);
+    QSharedPointer<QWaylandBuffer> cursorBitmapImage(const QCursor *cursor);
 
 private:
     enum WaylandCursor {

src/plugins/platforms/wayland/qwaylanddisplay_p.h

@@ -118,6 +118,7 @@ public:
     QWaylandWindowManagerIntegration *windowManagerIntegration() const;
 
     void setCursor(struct wl_buffer *buffer, struct wl_cursor_image *image);
+    void setCursor(const QSharedPointer<QWaylandBuffer> &buffer, const QPoint &hotSpot);
 
     struct wl_display *wl_display() const { return mDisplay; }
     struct ::wl_registry *wl_registry() { return object(); }

src/plugins/platforms/wayland/qwaylandinputdevice.cpp

@@ -42,6 +42,7 @@
 #include "qwaylandscreen_p.h"
 #include "qwaylandcursor_p.h"
 #include "qwaylanddisplay_p.h"
+#include "qwaylandshmbackingstore_p.h"
 #include "../shared/qwaylandxkb.h"
 
 #include <QtGui/private/qpixmap_raster_p.h>
@@ -329,9 +330,26 @@ void QWaylandInputDevice::setCursor(Qt::CursorShape newShape, QWaylandScreen *sc
     setCursor(buffer, image);
 }
 
+void QWaylandInputDevice::setCursor(const QCursor &cursor, QWaylandScreen *screen)
+{
+    if (cursor.shape() == Qt::BitmapCursor) {
+        setCursor(screen->waylandCursor()->cursorBitmapImage(&cursor), cursor.hotSpot());
+        return;
+    }
+    setCursor(cursor.shape(), screen);
+}
+
 void QWaylandInputDevice::setCursor(struct wl_buffer *buffer, struct wl_cursor_image *image)
+{
+    setCursor(buffer,
+              image ? QPoint(image->hotspot_x, image->hotspot_y) : QPoint(),
+              image ? QSize(image->width, image->height) : QSize());
+}
+
+void QWaylandInputDevice::setCursor(struct wl_buffer *buffer, const QPoint &hotSpot, const QSize &size)
 {
     if (mCaps & WL_SEAT_CAPABILITY_POINTER) {
+        mPixmapCursor.clear();
         mPointer->mCursorSerial = mPointer->mEnterSerial;
         /* Hide cursor */
         if (!buffer)
@@ -341,13 +359,19 @@ void QWaylandInputDevice::setCursor(struct wl_buffer *buffer, struct wl_cursor_i
         }
 
         mPointer->set_cursor(mPointer->mEnterSerial, pointerSurface,
-                             image->hotspot_x, image->hotspot_y);
+                             hotSpot.x(), hotSpot.y());
         wl_surface_attach(pointerSurface, buffer, 0, 0);
-        wl_surface_damage(pointerSurface, 0, 0, image->width, image->height);
+        wl_surface_damage(pointerSurface, 0, 0, size.width(), size.height());
         wl_surface_commit(pointerSurface);
     }
 }
 
+void QWaylandInputDevice::setCursor(const QSharedPointer<QWaylandBuffer> &buffer, const QPoint &hotSpot)
+{
+    setCursor(buffer->buffer(), hotSpot, buffer->size());
+    mPixmapCursor = buffer;
+}
+
 class EnterEvent : public QWaylandPointerEvent
 {
 public:

src/plugins/platforms/wayland/qwaylandinputdevice_p.h

@@ -93,7 +93,10 @@ public:
     struct ::wl_seat *wl_seat() { return QtWayland::wl_seat::object(); }
 
     void setCursor(Qt::CursorShape cursor, QWaylandScreen *screen);
+    void setCursor(const QCursor &cursor, QWaylandScreen *screen);
     void setCursor(struct wl_buffer *buffer, struct ::wl_cursor_image *image);
+    void setCursor(struct wl_buffer *buffer, const QPoint &hotSpot, const QSize &size);
+    void setCursor(const QSharedPointer<QWaylandBuffer> &buffer, const QPoint &hotSpot);
     void handleWindowDestroyed(QWaylandWindow *window);
 
     void setDataDevice(QWaylandDataDevice *device);
@@ -137,6 +140,8 @@ private:
 
     QTouchDevice *mTouchDevice;
 
+    QSharedPointer<QWaylandBuffer> mPixmapCursor;
+
     friend class QWaylandTouchExtension;
     friend class QWaylandQtKeyExtension;
 };

src/plugins/platforms/wayland/qwaylandwindow.cpp

@@ -73,7 +73,7 @@ QWaylandWindow::QWaylandWindow(QWindow *window)
     , mWindowDecoration(0)
     , mMouseEventsInContentArea(false)
     , mMousePressedInContentArea(Qt::NoButton)
-    , m_cursorShape(Qt::ArrowCursor)
+    , m_cursor(Qt::ArrowCursor)
     , mWaitingForFrameSync(false)
     , mFrameCallback(0)
     , mRequestResizeSent(false)
@@ -732,17 +732,17 @@ void QWaylandWindow::handleMouseEventWithDecoration(QWaylandInputDevice *inputDe
     }
 }
 
-void QWaylandWindow::setMouseCursor(QWaylandInputDevice *device, Qt::CursorShape shape)
+void QWaylandWindow::setMouseCursor(QWaylandInputDevice *device, const QCursor &cursor)
 {
-    if (m_cursorShape != shape || device->serial() > device->cursorSerial()) {
+    if (device->serial() >= device->cursorSerial()) {
-        device->setCursor(shape, mScreen);
+        device->setCursor(cursor, mScreen);
-        m_cursorShape = shape;
+        m_cursor = cursor;
     }
 }
 
 void QWaylandWindow::restoreMouseCursor(QWaylandInputDevice *device)
 {
-    setMouseCursor(device, window()->cursor().shape());
+    setMouseCursor(device, window()->cursor());
 }
 
 void QWaylandWindow::requestActivateWindow()

src/plugins/platforms/wayland/qwaylandwindow_p.h

@@ -168,7 +168,7 @@ public:
     inline bool isMaximized() const { return mState == Qt::WindowMaximized; }
     inline bool isFullscreen() const { return mState == Qt::WindowFullScreen; }
 
-    void setMouseCursor(QWaylandInputDevice *device, Qt::CursorShape shape);
+    void setMouseCursor(QWaylandInputDevice *device, const QCursor &cursor);
     void restoreMouseCursor(QWaylandInputDevice *device);
 
     QWaylandWindow *transientParent() const;
@@ -206,7 +206,7 @@ protected:
     QWaylandAbstractDecoration *mWindowDecoration;
     bool mMouseEventsInContentArea;
     Qt::MouseButtons mMousePressedInContentArea;
-    Qt::CursorShape m_cursorShape;
+    QCursor m_cursor;
 
     WId mWindowId;
     bool mWaitingForFrameSync;