Client: Only load cursor theme once

Now cursor themes load once per device pixel ratio, and not once per screen.

Task-number: QTBUG-67796
Change-Id: I4c253e65a791d69e7d510c4228989390a4343110
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

src/plugins/platforms/wayland/qwaylandcursor.cpp

@@ -55,31 +55,11 @@ namespace QtWaylandClient {
 
 QWaylandCursor::QWaylandCursor(QWaylandScreen *screen)
     : mDisplay(screen->display())
+    , mCursorTheme(mDisplay->loadCursorTheme(screen->devicePixelRatio()))
 {
-    //TODO: Make wl_cursor_theme_load arguments configurable here
-    QByteArray cursorTheme = qgetenv("XCURSOR_THEME");
-    if (cursorTheme.isEmpty())
-        cursorTheme = QByteArray("default");
-    int cursorSize = qEnvironmentVariableIntValue("XCURSOR_SIZE");
-    if (cursorSize <= 0)
-        cursorSize = 32;
-
-    // wl_surface.set_buffer_scale is not supported on earlier versions
-    if (mDisplay->compositorVersion() >= 3)
-        cursorSize *= screen->devicePixelRatio();
-
-    mCursorTheme = wl_cursor_theme_load(cursorTheme, cursorSize, mDisplay->shm()->object());
-    if (!mCursorTheme)
-        qDebug() << "Could not load theme" << cursorTheme;
     initCursorMap();
 }
 
-QWaylandCursor::~QWaylandCursor()
-{
-    if (mCursorTheme)
-        wl_cursor_theme_destroy(mCursorTheme);
-}
-
 struct wl_cursor_image *QWaylandCursor::cursorImage(Qt::CursorShape newShape)
 {
     struct wl_cursor *waylandCursor = nullptr;

src/plugins/platforms/wayland/qwaylandcursor_p.h

@@ -73,7 +73,6 @@ class Q_WAYLAND_CLIENT_EXPORT QWaylandCursor : public QPlatformCursor
 {
 public:
     QWaylandCursor(QWaylandScreen *screen);
-    ~QWaylandCursor() override;
 
     void changeCursor(QCursor *cursor, QWindow *window) override;
     void pointerEvent(const QMouseEvent &event) override;

src/plugins/platforms/wayland/qwaylanddisplay.cpp

@@ -50,6 +50,9 @@
 #if QT_CONFIG(wayland_datadevice)
 #include "qwaylanddatadevicemanager_p.h"
 #endif
+#if QT_CONFIG(cursor)
+#include <wayland-cursor.h>
+#endif
 #include "qwaylandhardwareintegration_p.h"
 #include "qwaylandinputcontext_p.h"
 
@@ -151,8 +154,14 @@ QWaylandDisplay::~QWaylandDisplay(void)
         mWaylandIntegration->destroyScreen(screen);
     }
     mScreens.clear();
+
 #if QT_CONFIG(wayland_datadevice)
     delete mDndSelectionHandler.take();
+#endif
+#if QT_CONFIG(cursor)
+    for (auto *cursorTheme : mCursorThemesBySize)
+        wl_cursor_theme_destroy(cursorTheme);
+    mCursorThemesBySize.clear();
 #endif
     if (mDisplay)
         wl_display_disconnect(mDisplay);
@@ -472,6 +481,7 @@ QWaylandInputDevice *QWaylandDisplay::defaultInputDevice() const
 }
 
 #if QT_CONFIG(cursor)
+
 void QWaylandDisplay::setCursor(struct wl_buffer *buffer, struct wl_cursor_image *image, qreal dpr)
 {
     /* Qt doesn't tell us which input device we should set the cursor
@@ -491,6 +501,31 @@ void QWaylandDisplay::setCursor(const QSharedPointer<QWaylandBuffer> &buffer, co
         inputDevice->setCursor(buffer, hotSpot, dpr);
     }
 }
+
+struct ::wl_cursor_theme *QWaylandDisplay::loadCursorTheme(qreal devicePixelRatio)
+{
+    QByteArray themeName = qgetenv("XCURSOR_THEME");
+    if (themeName.isEmpty())
+        themeName = QByteArray("default");
+
+    int cursorSize = qEnvironmentVariableIntValue("XCURSOR_SIZE");
+    if (cursorSize <= 0)
+        cursorSize = 32;
+    if (compositorVersion() >= 3) // set_buffer_scale is not supported on earlier versions
+        cursorSize *= devicePixelRatio;
+
+    if (auto *theme = mCursorThemesBySize.value(cursorSize, nullptr))
+        return theme;
+
+    struct ::wl_cursor_theme *theme = wl_cursor_theme_load(themeName, cursorSize, shm()->object());
+
+    if (!theme)
+        qCWarning(lcQpaWayland) << "Could not load cursor theme" << themeName;
+
+    mCursorThemesBySize[cursorSize] = theme;
+    return theme;
+}
+
 #endif // QT_CONFIG(cursor)
 
 }

src/plugins/platforms/wayland/qwaylanddisplay_p.h

@@ -66,6 +66,7 @@
 #include <QtWaylandClient/private/qwaylandshm_p.h>
 
 struct wl_cursor_image;
+struct wl_cursor_theme;
 
 QT_BEGIN_NAMESPACE
 
@@ -123,6 +124,7 @@ public:
 #if QT_CONFIG(cursor)
     void setCursor(struct wl_buffer *buffer, struct wl_cursor_image *image, qreal dpr);
     void setCursor(const QSharedPointer<QWaylandBuffer> &buffer, const QPoint &hotSpot, qreal dpr);
+    struct ::wl_cursor_theme *loadCursorTheme(qreal devicePixelRatio);
 #endif
     struct wl_display *wl_display() const { return mDisplay; }
     struct ::wl_registry *wl_registry() { return object(); }
@@ -199,6 +201,9 @@ private:
     QList<QWaylandInputDevice *> mInputDevices;
     QList<Listener> mRegistryListeners;
     QWaylandIntegration *mWaylandIntegration = nullptr;
+#if QT_CONFIG(cursor)
+    QMap<int, struct wl_cursor_theme*> mCursorThemesBySize;
+#endif
 #if QT_CONFIG(wayland_datadevice)
     QScopedPointer<QWaylandDataDeviceManager> mDndSelectionHandler;
 #endif