Create and destroy the shell surface when showing and hiding

This changes the shell surface handling for windows, and instead of
creating the shell surface at initialization time, and then attaching
a null buffer to hide it, it creates the shell surface on setVisible(true),
and destroys it on setVisible(false).
This fixes hiding when using xdg_shell, as that interface defines that
attaching a null buffer to an xdg_surface is an error.
Also this should help with bugged EGL drivers which attach a buffer
after eglSwapBuffers() returns, which used to cause a newly hidden
window to get a new valid buffer after we attached a null one, showing
it again.

Task-number: QTBUG-47902
Change-Id: I8e0a0442319a98cc1361803ea7be1d079b36fc8c
Reviewed-by: Johan Helsing <johan.helsing@qt.io>
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

src/plugins/platforms/wayland/qwaylandshellsurface_p.h

@@ -94,15 +94,14 @@ public:
 
     inline QWaylandWindow *window() { return m_window; }
 
+    virtual void setType(Qt::WindowType type, QWaylandWindow *transientParent) = 0;
+
 protected:
     virtual void setMaximized() {}
     virtual void setFullscreen() {}
     virtual void setNormal() {}
     virtual void setMinimized() {}
 
-    virtual void setTopLevel() {}
-    virtual void updateTransientParent(QWindow * /*parent*/) {}
-
 private:
     QWaylandWindow *m_window;
     friend class QWaylandWindow;

src/plugins/platforms/wayland/qwaylandshmbackingstore.cpp

@@ -211,13 +211,7 @@ void QWaylandShmBackingStore::flush(QWindow *window, const QRegion &region, cons
 
     QMargins margins = windowDecorationMargins();
 
-    waylandWindow()->attachOffset(mFrontBuffer);
-    mFrontBuffer->setBusy();
-
-    QVector<QRect> rects = region.rects();
-    foreach (const QRect &rect, rects)
-        waylandWindow()->damage(rect.translated(margins.left(), margins.top()));
-    waylandWindow()->commit();
+    waylandWindow()->commit(mFrontBuffer, region.translated(margins.left(), margins.top()));
 }
 
 void QWaylandShmBackingStore::resize(const QSize &size, const QRegion &)

src/plugins/platforms/wayland/qwaylandwindow.cpp

@@ -96,8 +96,6 @@ QWaylandWindow::QWaylandWindow(QWindow *window)
 {
     static WId id = 1;
     mWindowId = id++;
-    if (window->type() != Qt::Desktop)
-        initWindow();
 }
 
 QWaylandWindow::~QWaylandWindow()
@@ -126,18 +124,28 @@ QWaylandWindow::~QWaylandWindow()
 
 void QWaylandWindow::initWindow()
 {
-    init(mDisplay->createSurface(static_cast<QtWayland::wl_surface *>(this)));
+    if (window()->type() == Qt::Desktop)
+        return;
+
+    if (!isInitialized())
+        init(mDisplay->createSurface(static_cast<QtWayland::wl_surface *>(this)));
 
     if (shouldCreateSubSurface()) {
+        Q_ASSERT(!mSubSurfaceWindow);
+
         QWaylandWindow *p = static_cast<QWaylandWindow *>(QPlatformWindow::parent());
         if (::wl_subsurface *ss = mDisplay->createSubSurface(this, p)) {
             mSubSurfaceWindow = new QWaylandSubSurface(this, p, ss);
         }
     } else if (shouldCreateShellSurface()) {
-        mShellSurface = mDisplay->createShellSurface(this);
-    }
+        Q_ASSERT(!mShellSurface);
+
+        mShellSurface = mDisplay->createShellSurface(this);
+        if (!mShellSurface)
+            qFatal("Could not create a shell surface object.");
+
+        mShellSurface->setType(window()->type(), transientParent());
 
-    if (mShellSurface) {
         // Set initial surface title
         setWindowTitle(window()->title());
 
@@ -171,17 +179,6 @@ void QWaylandWindow::initWindow()
         }
     }
 
-    if (mShellSurface) {
-        if (window()->transientParent()) {
-            if (window()->type() != Qt::Popup) {
-                mShellSurface->updateTransientParent(window()->transientParent());
-            }
-        } else {
-            if (window()->type() != Qt::ToolTip)
-                mShellSurface->setTopLevel();
-        }
-    }
-
     // Enable high-dpi rendering. Scale() returns the screen scale factor and will
     // typically be integer 1 (normal-dpi) or 2 (high-dpi). Call set_buffer_scale()
     // to inform the compositor that high-resolution buffers will be provided.
@@ -244,6 +241,9 @@ WId QWaylandWindow::winId() const
 
 void QWaylandWindow::setParent(const QPlatformWindow *parent)
 {
+    if (!window()->isVisible())
+        return;
+
     QWaylandWindow *oldparent = mSubSurfaceWindow ? mSubSurfaceWindow->parent() : 0;
     if (oldparent == parent)
         return;
@@ -287,8 +287,7 @@ void QWaylandWindow::setGeometry_helper(const QRect &rect)
         QMargins m = QPlatformWindow::parent()->frameMargins();
         mSubSurfaceWindow->set_position(rect.x() + m.left(), rect.y() + m.top());
         mSubSurfaceWindow->parent()->window()->requestUpdate();
-    } else if (shellSurface() && window()->transientParent() && window()->type() != Qt::Popup)
-        shellSurface()->updateTransientParent(window()->transientParent());
+    }
 }
 
 void QWaylandWindow::setGeometry(const QRect &rect)
@@ -313,20 +312,8 @@ void QWaylandWindow::setGeometry(const QRect &rect)
 void QWaylandWindow::setVisible(bool visible)
 {
     if (visible) {
-        if (mShellSurface) {
-            if (window()->type() == Qt::Popup) {
-                QWaylandWindow *parent = transientParent();
-                if (parent) {
-                    QWaylandWlShellSurface *wlshellSurface = qobject_cast<QWaylandWlShellSurface*>(mShellSurface);
-                    if (wlshellSurface)
-                        wlshellSurface->setPopup(parent, mDisplay->lastInputDevice(), mDisplay->lastInputSerial());
-                }
-            } else if (window()->type() == Qt::ToolTip) {
-                if (QWaylandWindow *parent = transientParent()) {
-                    mShellSurface->updateTransientParent(parent->window());
-                }
-            }
-        }
+        initWindow();
+        mDisplay->flushRequests();
 
         setGeometry(window()->geometry());
         // Don't flush the events here, or else the newly visible window may start drawing, but since
@@ -338,10 +325,8 @@ void QWaylandWindow::setVisible(bool visible)
         // case 'this' will be deleted. When that happens, we must abort right away.
         QPointer<QWaylandWindow> deleteGuard(this);
         QWindowSystemInterface::flushWindowSystemEvents();
-        if (!deleteGuard.isNull()) {
-            attach(static_cast<QWaylandBuffer *>(0), 0, 0);
-            commit();
-        }
+        if (!deleteGuard.isNull())
+            reset();
     }
 }
 
@@ -374,7 +359,7 @@ void QWaylandWindow::setMask(const QRegion &mask)
         wl_region_destroy(region);
     }
 
-    commit();
+    wl_surface::commit();
 }
 
 void QWaylandWindow::configure(uint32_t edges, int32_t width, int32_t height)
@@ -461,6 +446,7 @@ void QWaylandWindow::attach(QWaylandBuffer *buffer, int x, int y)
         wl_callback_add_listener(callback, &QWaylandWindow::callbackListener, this);
         mFrameCallback = callback;
         mWaitingForFrameSync = true;
+        buffer->setBusy();
 
         attach(buffer->buffer(), x, y);
     } else {
@@ -479,6 +465,18 @@ void QWaylandWindow::damage(const QRect &rect)
     damage(rect.x(), rect.y(), rect.width(), rect.height());
 }
 
+void QWaylandWindow::commit(QWaylandBuffer *buffer, const QRegion &damage)
+{
+    if (!isInitialized())
+        return;
+
+    attachOffset(buffer);
+    const QVector<QRect> rects = damage.rects();
+    for (const QRect &rect: rects)
+        wl_surface::damage(rect.x(), rect.y(), rect.width(), rect.height());
+    wl_surface::commit();
+}
+
 const wl_callback_listener QWaylandWindow::callbackListener = {
     QWaylandWindow::frameCallback
 };
@@ -555,7 +553,7 @@ void QWaylandWindow::handleContentOrientationChange(Qt::ScreenOrientation orient
     }
     set_buffer_transform(transform);
     // set_buffer_transform is double buffered, we need to commit.
-    commit();
+    wl_surface::commit();
 }
 
 void QWaylandWindow::setOrientationMask(Qt::ScreenOrientations mask)
@@ -681,15 +679,13 @@ static QWindow *topLevelWindow(QWindow *window)
 
 QWaylandWindow *QWaylandWindow::transientParent() const
 {
-    if (window()->transientParent()) {
-        // Take the top level window here, since the transient parent may be a QWidgetWindow
-        // or some other window without a shell surface, which is then not able to get mouse
-        // events.
-        return static_cast<QWaylandWindow *>(topLevelWindow(window()->transientParent())->handle());
-    }
-    // Try with the current focus window. It should be the right one and anyway
-    // better than having no parent at all.
-    return mDisplay->lastInputWindow();
+    // Take the top level window here, since the transient parent may be a QWidgetWindow
+    // or some other window without a shell surface, which is then not able to get mouse
+    // events.
+    if (auto transientParent = window()->transientParent())
+        return static_cast<QWaylandWindow *>(topLevelWindow(transientParent)->handle());
+
+    return nullptr;
 }
 
 void QWaylandWindow::handleMouse(QWaylandInputDevice *inputDevice, const QWaylandPointerEvent &e)

src/plugins/platforms/wayland/qwaylandwindow_p.h

@@ -132,6 +132,8 @@ public:
     using QtWayland::wl_surface::damage;
     void damage(const QRect &rect);
 
+    void commit(QWaylandBuffer *buffer, const QRegion &damage);
+
     void waitForFrameSync();
 
     QMargins frameMargins() const Q_DECL_OVERRIDE;

src/plugins/platforms/wayland/qwaylandwlshellsurface.cpp

@@ -215,6 +215,16 @@ void QWaylandWlShellSurface::setPopup(QWaylandWindow *parent, QWaylandInputDevic
               transientPos.x(), transientPos.y(), 0);
 }
 
+void QWaylandWlShellSurface::setType(Qt::WindowType type, QWaylandWindow *transientParent)
+{
+    if (type == Qt::Popup && transientParent)
+        setPopup(transientParent, m_window->display()->lastInputDevice(), m_window->display()->lastInputSerial());
+    else if (transientParent)
+        updateTransientParent(transientParent->window());
+    else
+        setTopLevel();
+}
+
 void QWaylandWlShellSurface::shell_surface_ping(uint32_t serial)
 {
     pong(serial);

src/plugins/platforms/wayland/qwaylandwlshellsurface_p.h

@@ -92,14 +92,16 @@ public:
     void setWindowFlags(Qt::WindowFlags flags) Q_DECL_OVERRIDE;
     void sendProperty(const QString &name, const QVariant &value) Q_DECL_OVERRIDE;
 
+    void setType(Qt::WindowType type, QWaylandWindow *transientParent) override;
+
 private:
     void setMaximized() Q_DECL_OVERRIDE;
     void setFullscreen() Q_DECL_OVERRIDE;
     void setNormal() Q_DECL_OVERRIDE;
     void setMinimized() Q_DECL_OVERRIDE;
 
-    void setTopLevel() Q_DECL_OVERRIDE;
-    void updateTransientParent(QWindow *parent) Q_DECL_OVERRIDE;
+    void setTopLevel();
+    void updateTransientParent(QWindow *parent);
     void setPopup(QWaylandWindow *parent, QWaylandInputDevice *device, int serial);
 
     QWaylandWindow *m_window;

src/plugins/platforms/wayland/qwaylandxdgpopup.cpp

@@ -56,6 +56,12 @@ QWaylandXdgPopup::~QWaylandXdgPopup()
     delete m_extendedWindow;
 }
 
+void QWaylandXdgPopup::setType(Qt::WindowType type, QWaylandWindow *transientParent)
+{
+    Q_UNUSED(type);
+    Q_UNUSED(transientParent);
+}
+
 }
 
 QT_END_NAMESPACE

src/plugins/platforms/wayland/qwaylandxdgpopup_p.h

@@ -68,6 +68,8 @@ public:
     QWaylandXdgPopup(struct ::xdg_popup *popup, QWaylandWindow *window);
     virtual ~QWaylandXdgPopup();
 
+    void setType(Qt::WindowType type, QWaylandWindow *transientParent) override;
+
 private:
     QWaylandExtendedSurface *m_extendedWindow;
 };

src/plugins/platforms/wayland/qwaylandxdgsurface.cpp

@@ -128,17 +128,11 @@ void QWaylandXdgSurface::setMinimized()
     set_minimized();
 }
 
-void QWaylandXdgSurface::setTopLevel()
+void QWaylandXdgSurface::updateTransientParent(QWaylandWindow *parent)
 {
-    // There's no xdg_shell_surface API for this, ignoring
-}
-
-void QWaylandXdgSurface::updateTransientParent(QWindow *parent)
-{
-    QWaylandWindow *parent_wayland_window = static_cast<QWaylandWindow *>(parent->handle());
-    if (!parent_wayland_window)
+    if (!parent)
         return;
-    auto parentXdgSurface = qobject_cast<QWaylandXdgSurface *>(parent_wayland_window->shellSurface());
+    auto parentXdgSurface = qobject_cast<QWaylandXdgSurface *>(parent->shellSurface());
     Q_ASSERT(parentXdgSurface);
     set_parent(parentXdgSurface->object());
 }
@@ -183,6 +177,13 @@ void QWaylandXdgSurface::sendProperty(const QString &name, const QVariant &value
         m_extendedWindow->updateGenericProperty(name, value);
 }
 
+void QWaylandXdgSurface::setType(Qt::WindowType type, QWaylandWindow *transientParent)
+{
+    Q_UNUSED(type)
+    if (transientParent)
+        updateTransientParent(transientParent);
+}
+
 void QWaylandXdgSurface::xdg_surface_configure(int32_t width, int32_t height, struct wl_array *states,uint32_t serial)
 {
     uint32_t *state = reinterpret_cast<uint32_t*>(states->data);

src/plugins/platforms/wayland/qwaylandxdgsurface_p.h

@@ -99,14 +99,15 @@ public:
     bool isFullscreen() const { return m_fullscreen; }
     bool isMaximized() const { return m_maximized; }
 
+    void setType(Qt::WindowType type, QWaylandWindow *transientParent) override;
+
 private:
     void setMaximized() Q_DECL_OVERRIDE;
     void setFullscreen() Q_DECL_OVERRIDE;
     void setNormal() Q_DECL_OVERRIDE;
     void setMinimized() Q_DECL_OVERRIDE;
 
-    void setTopLevel() Q_DECL_OVERRIDE;
-    void updateTransientParent(QWindow *parent) Q_DECL_OVERRIDE;
+    void updateTransientParent(QWaylandWindow *parent);
 
 private:
     QWaylandWindow *m_window;

tests/auto/wayland/client/tst_client.cpp

@@ -248,8 +248,8 @@ void tst_WaylandClient::backingStore()
 
     window.hide();
 
-    // hiding the window should detach the buffer
-    QTRY_VERIFY(surface->image.isNull());
+    // hiding the window should destroy the surface
+    QTRY_VERIFY(!compositor->surface());
 }
 
 class DndWindow : public QWindow