Client: Add support for animated cursors

[ChangeLog][QPA plugin] Added support for animated cursors.

Previously we would just show the first frame of the animation.

Fixes: QTBUG-48181
Change-Id: Ie06bff8950678b5ff7b7e2e50915c85905a1200b
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

src/plugins/platforms/wayland/qwaylandcursor.cpp

@@ -209,7 +209,7 @@ wl_cursor *QWaylandCursorTheme::requestCursor(WaylandCursor shape)
     return nullptr;
 }
 
-struct wl_cursor_image *QWaylandCursorTheme::cursorImage(Qt::CursorShape shape)
+::wl_cursor_image *QWaylandCursorTheme::cursorImage(Qt::CursorShape shape, uint millisecondsIntoAnimation)
 {
     struct wl_cursor *waylandCursor = nullptr;
 
@@ -227,8 +227,9 @@ struct wl_cursor_image *QWaylandCursorTheme::cursorImage(Qt::CursorShape shape)
         return nullptr;
     }
 
-    struct wl_cursor_image *image = waylandCursor->images[0];
-    struct wl_buffer *buffer = wl_cursor_image_get_buffer(image);
+    int frame = wl_cursor_frame(waylandCursor, millisecondsIntoAnimation);
+    ::wl_cursor_image *image = waylandCursor->images[frame];
+    ::wl_buffer *buffer = wl_cursor_image_get_buffer(image);
     if (!buffer) {
         qCWarning(lcQpaWayland) << "Could not find buffer for cursor";
         return nullptr;

src/plugins/platforms/wayland/qwaylandcursor_p.h

@@ -75,7 +75,7 @@ class Q_WAYLAND_CLIENT_EXPORT QWaylandCursorTheme
 public:
     static QWaylandCursorTheme *create(QWaylandShm *shm, int size, const QString &themeName);
     ~QWaylandCursorTheme();
-    struct wl_cursor_image *cursorImage(Qt::CursorShape shape);
+    ::wl_cursor_image *cursorImage(Qt::CursorShape shape, uint millisecondsIntoAnimation = 0);
 
 private:
     enum WaylandCursor {

src/plugins/platforms/wayland/qwaylandinputdevice.cpp

@@ -191,6 +191,27 @@ QWaylandInputDevice::Pointer::~Pointer()
 
 #if QT_CONFIG(cursor)
 
+class WlCallback : public QtWayland::wl_callback {
+public:
+    explicit WlCallback(::wl_callback *callback, std::function<void(uint32_t)> fn, bool autoDelete = false)
+        : QtWayland::wl_callback(callback)
+        , m_fn(fn)
+        , m_autoDelete(autoDelete)
+    {}
+    ~WlCallback() override { wl_callback_destroy(object()); }
+    bool done() const { return m_done; }
+    void callback_done(uint32_t callback_data) override {
+        m_done = true;
+        m_fn(callback_data);
+        if (m_autoDelete)
+            delete this;
+    }
+private:
+    bool m_done = false;
+    std::function<void(uint32_t)> m_fn;
+    bool m_autoDelete = false;
+};
+
 class CursorSurface : public QWaylandSurface
 {
 public:
@@ -213,7 +234,7 @@ public:
     }
 
     // Size and hotspot are in surface coordinates
-    void update(wl_buffer *buffer, const QPoint &hotspot, const QSize &size, int bufferScale)
+    void update(wl_buffer *buffer, const QPoint &hotspot, const QSize &size, int bufferScale, bool animated = false)
     {
         // Calling code needs to ensure buffer scale is supported if != 1
         Q_ASSERT(bufferScale == 1 || m_version >= 3);
@@ -230,6 +251,13 @@ public:
 
         attach(buffer, 0, 0);
         damage(0, 0, size.width(), size.height());
+        m_frameCallback.reset();
+        if (animated) {
+            m_frameCallback.reset(new WlCallback(frame(), [this](uint32_t time){
+               Q_UNUSED(time);
+               m_pointer->updateCursor();
+            }));
+        }
         commit();
     }
 
@@ -242,6 +270,7 @@ public:
     }
 
 private:
+    QScopedPointer<WlCallback> m_frameCallback;
     QWaylandInputDevice::Pointer *m_pointer = nullptr;
     uint m_version = 0;
     uint m_setSerial = 0;
@@ -320,12 +349,14 @@ void QWaylandInputDevice::Pointer::updateCursor()
         updateCursorTheme();
 
     // Set from shape using theme
-    if (struct ::wl_cursor_image *image = mCursor.theme->cursorImage(shape)) {
+    uint time = seat()->mCursor.animationTimer.elapsed();
+    if (struct ::wl_cursor_image *image = mCursor.theme->cursorImage(shape, time)) {
         struct wl_buffer *buffer = wl_cursor_image_get_buffer(image);
         int bufferScale = mCursor.themeBufferScale;
         QPoint hotspot = QPoint(image->hotspot_x, image->hotspot_y) / bufferScale;
         QSize size = QSize(image->width, image->height) / bufferScale;
-        getOrCreateCursorSurface()->update(buffer, hotspot, size, bufferScale);
+        bool animated = image->delay > 0;
+        getOrCreateCursorSurface()->update(buffer, hotspot, size, bufferScale, animated);
         return;
     }
 
@@ -515,6 +546,7 @@ void QWaylandInputDevice::setCursor(const QCursor *cursor, const QSharedPointer<
     mCursor.shape = cursor ? cursor->shape() : Qt::ArrowCursor;
     mCursor.hotspot = cursor ? cursor->hotSpot() : QPoint();
     mCursor.fallbackOutputScale = fallbackOutputScale;
+    mCursor.animationTimer.start();
 
     if (mCursor.shape == Qt::BitmapCursor) {
         mCursor.bitmapBuffer = cachedBuffer ? cachedBuffer : QWaylandCursor::cursorBitmapBuffer(mQDisplay, cursor);

src/plugins/platforms/wayland/qwaylandinputdevice_p.h

@@ -69,7 +69,8 @@
 #endif
 
 #include <QtCore/QDebug>
-#include <QPointer>
+#include <QtCore/QElapsedTimer>
+#include <QtCore/QPointer>
 
 #if QT_CONFIG(cursor)
 struct wl_cursor_image;
@@ -153,6 +154,7 @@ private:
         Qt::CursorShape shape = Qt::ArrowCursor;
         int fallbackOutputScale = 1;
         QPoint hotspot;
+        QElapsedTimer animationTimer;
     } mCursor;
 #endif
 

tests/auto/wayland/seatv4/tst_seatv4.cpp

@@ -80,6 +80,7 @@ private slots:
     void bitmapCursor();
     void hidpiBitmapCursor();
     void hidpiBitmapCursorNonInt();
+    void animatedCursor();
 #endif
 };
 
@@ -554,6 +555,36 @@ void tst_seatv4::hidpiBitmapCursorNonInt()
     QCOMPOSITOR_COMPARE(pointer()->m_hotspot, QPoint(25, 25));
 }
 
+void tst_seatv4::animatedCursor()
+{
+    QRasterWindow window;
+    window.resize(64, 64);
+    window.setCursor(Qt::WaitCursor); // TODO: verify that the theme has an animated wait cursor or skip test
+    window.show();
+    QCOMPOSITOR_TRY_VERIFY(xdgSurface() && xdgSurface()->m_committedConfigureSerial);
+
+    exec([=] { pointer()->sendEnter(xdgSurface()->m_surface, {32, 32}); });
+    QCOMPOSITOR_TRY_VERIFY(cursorSurface());
+
+    // We should get the first buffer without waiting for a frame callback
+    QCOMPOSITOR_TRY_VERIFY(cursorSurface()->m_committed.buffer);
+    QSignalSpy bufferSpy(exec([=] { return cursorSurface(); }), &Surface::bufferCommitted);
+
+    exec([&] {
+        // Make sure no extra buffers have arrived
+        QVERIFY(bufferSpy.empty());
+
+        // The client should send a frame request in order to time animations correctly
+        QVERIFY(!cursorSurface()->m_waitingFrameCallbacks.empty());
+
+        // Tell the client it's time to animate
+        cursorSurface()->sendFrameCallbacks();
+    });
+
+    // Verify that we get a new cursor buffer
+    QTRY_COMPARE(bufferSpy.count(), 1);
+}
+
 #endif // QT_CONFIG(cursor)
 
 QCOMPOSITOR_TEST_MAIN(tst_seatv4)