Refactor Toplevel::opacity

The major difference between this version and the previous is that kwin
no longer forwards the opacity to the app window if it runs as a
window window manager and a compositing manager. As Keith Packard said [1]

> The window manager support is only needed to forward the property from the
> application window to the frame; with the Composite extension, a
> compositing manager can then take that value into account when
> constructing the desktop image.  Any X server can implement the Composite
> extension; the one in the X server project at freedesktop.org is just one
> such.  It would be trivial to implement this extension in a direct FB
> based X server, or any other X server which places windows in off-screen
> images.

There are a couple of reasons to do so: (a) simplifies code, (b) we don't
temper with opacities on override-redirect windows.

[1] https://listman.redhat.com/archives/xdg-list/2003-December/msg00153.html

deleted.cpp

@@ -95,7 +95,6 @@ void Deleted::copyToDeleted(Toplevel* c)
     transparent_rect = c->transparentRect();
     m_layer = c->layer();
     m_frame = c->frameId();
-    m_opacity = c->opacity();
     m_type = c->windowType();
     m_windowRole = c->windowRole();
     if (WinInfo* cinfo = dynamic_cast< WinInfo* >(info))
@@ -252,11 +251,6 @@ xcb_window_t Deleted::frameId() const
     return m_frame;
 }
 
-double Deleted::opacity() const
-{
-    return m_opacity;
-}
-
 QByteArray Deleted::windowRole() const
 {
     return m_windowRole;

deleted.h

@@ -64,7 +64,6 @@ public:
     bool wasClient() const {
         return m_wasClient;
     }
-    double opacity() const override;
     QByteArray windowRole() const override;
 
     const Decoration::Renderer *decorationRenderer() const {
@@ -206,7 +205,6 @@ private:
     QList<AbstractClient*> m_mainClients;
     bool m_wasClient;
     Decoration::Renderer *m_decorationRenderer;
-    double m_opacity;
     NET::WindowType m_type = NET::Unknown;
     QByteArray m_windowRole;
     bool m_fullscreen;

events.cpp

@@ -446,7 +446,6 @@ bool X11Client::windowEvent(xcb_generic_event_t *e)
     if (findEventWindow(e) == window()) { // avoid doing stuff on frame or wrapper
         NET::Properties dirtyProperties;
         NET::Properties2 dirtyProperties2;
-        double old_opacity = opacity();
         info->event(e, &dirtyProperties, &dirtyProperties2);   // pass through the NET stuff
 
         if ((dirtyProperties & NET::WMName) != 0)
@@ -470,8 +469,7 @@ bool X11Client::windowEvent(xcb_generic_event_t *e)
             startupIdChanged();
         if (dirtyProperties2 & NET::WM2Opacity) {
             if (compositing()) {
-                addRepaintFull();
-                emit opacityChanged(this, old_opacity);
+                setOpacity(info->opacityF());
             } else {
                 // forward to the frame if there's possibly another compositing manager running
                 NETWinInfo i(connection(), frameId(), rootWindow(), NET::Properties(), NET::Properties2());
@@ -1298,14 +1296,12 @@ void X11Client::keyPressEvent(uint key_code, xcb_timestamp_t time)
 
 bool Unmanaged::windowEvent(xcb_generic_event_t *e)
 {
-    double old_opacity = opacity();
     NET::Properties dirtyProperties;
     NET::Properties2 dirtyProperties2;
     info->event(e, &dirtyProperties, &dirtyProperties2);   // pass through the NET stuff
     if (dirtyProperties2 & NET::WM2Opacity) {
         if (compositing()) {
-            addRepaintFull();
-            emit opacityChanged(this, old_opacity);
+            setOpacity(info->opacityF());
         }
     }
     if (dirtyProperties2 & NET::WM2OpaqueRegion) {

internal_client.cpp

@@ -38,8 +38,6 @@ InternalClient::InternalClient(QWindow *window)
     connect(m_internalWindow, &QWindow::opacityChanged, this, &InternalClient::setOpacity);
     connect(m_internalWindow, &QWindow::destroyed, this, &InternalClient::destroyClient);
 
-    connect(this, &InternalClient::opacityChanged, this, &InternalClient::addRepaintFull);
-
     const QVariant windowType = m_internalWindow->property("kwin_windowType");
     if (!windowType.isNull()) {
         m_windowType = windowType.value<NET::WindowType>();
@@ -149,23 +147,6 @@ NET::WindowType InternalClient::windowType(bool direct, int supported_types) con
     return m_windowType;
 }
 
-qreal InternalClient::opacity() const
-{
-    return m_opacity;
-}
-
-void InternalClient::setOpacity(qreal opacity)
-{
-    if (m_opacity == opacity) {
-        return;
-    }
-
-    const double oldOpacity = m_opacity;
-    m_opacity = opacity;
-
-    emit opacityChanged(this, oldOpacity);
-}
-
 void InternalClient::killWindow()
 {
     // We don't kill our internal windows.

internal_client.h

@@ -35,8 +35,6 @@ public:
     QSize maxSize() const override;
     QRect transparentRect() const override;
     NET::WindowType windowType(bool direct = false, int supported_types = 0) const override;
-    qreal opacity() const override;
-    void setOpacity(qreal opacity) override;
     void killWindow() override;
     bool isPopupWindow() const override;
     QByteArray windowRole() const override;
@@ -88,7 +86,6 @@ private:
     QWindow *m_internalWindow = nullptr;
     QString m_captionNormal;
     QString m_captionSuffix;
-    qreal m_opacity = 1.0;
     NET::WindowType m_windowType = NET::Normal;
     Qt::WindowFlags m_internalWindowFlags = Qt::WindowFlags();
     bool m_userNoBorder = false;

toplevel.cpp

@@ -129,6 +129,7 @@ void Toplevel::copyToDeleted(Toplevel* c)
     m_skipCloseAnimation = c->m_skipCloseAnimation;
     m_internalFBO = c->m_internalFBO;
     m_internalImage = c->m_internalImage;
+    m_opacity = c->m_opacity;
 }
 
 // before being deleted, remove references to everything that's now
@@ -249,28 +250,20 @@ bool Toplevel::resourceMatch(const Toplevel *c1, const Toplevel *c2)
 
 qreal Toplevel::opacity() const
 {
-    if (!info) {
-        return 1.0;
-    }
-    if (info->opacity() == 0xffffffff)
-        return 1.0;
-    return info->opacity() * 1.0 / 0xffffffff;
+    return m_opacity;
 }
 
-void Toplevel::setOpacity(qreal new_opacity)
+void Toplevel::setOpacity(qreal opacity)
 {
-    if (!info) {
+    opacity = qBound(0.0, opacity, 1.0);
+    if (m_opacity == opacity) {
         return;
     }
-
-    qreal old_opacity = opacity();
-    new_opacity = qBound(0.0, new_opacity, 1.0);
-    if (old_opacity == new_opacity)
-        return;
-    info->setOpacity(static_cast< unsigned long >(new_opacity * 0xffffffff));
+    const qreal oldOpacity = m_opacity;
+    m_opacity = opacity;
     if (compositing()) {
         addRepaintFull();
-        emit opacityChanged(this, old_opacity);
+        emit opacityChanged(this, oldOpacity);
     }
 }
 

toplevel.h

@@ -448,8 +448,8 @@ public:
     xcb_visualid_t visual() const;
     bool shape() const;
     QRegion inputShape() const;
-    virtual void setOpacity(qreal opacity);
-    virtual qreal opacity() const;
+    void setOpacity(qreal opacity);
+    qreal opacity() const;
     int depth() const;
     bool hasAlpha() const;
     virtual bool setupCompositing();
@@ -756,6 +756,7 @@ private:
     KWaylandServer::SurfaceInterface *m_surface = nullptr;
     // when adding new data members, check also copyToDeleted()
     qreal m_screenScale = 1.0;
+    qreal m_opacity = 1.0;
 };
 
 inline xcb_window_t Toplevel::window() const

waylandclient.cpp

@@ -107,23 +107,6 @@ bool WaylandClient::isLocalhost() const
     return true;
 }
 
-qreal WaylandClient::opacity() const
-{
-    return m_opacity;
-}
-
-void WaylandClient::setOpacity(qreal opacity)
-{
-    const qreal newOpacity = qBound(0.0, opacity, 1.0);
-    if (newOpacity == m_opacity) {
-        return;
-    }
-    const qreal oldOpacity = m_opacity;
-    m_opacity = newOpacity;
-    addRepaintFull();
-    emit opacityChanged(this, oldOpacity);
-}
-
 AbstractClient *WaylandClient::findModal(bool allow_itself)
 {
     Q_UNUSED(allow_itself)

waylandclient.h

@@ -34,8 +34,6 @@ public:
     pid_t pid() const override;
     bool isLockScreen() const override;
     bool isLocalhost() const override;
-    qreal opacity() const override;
-    void setOpacity(qreal opacity) override;
     AbstractClient *findModal(bool allow_itself = false) override;
     void resizeWithChecks(const QSize &size, ForceGeometry_t force = NormalGeometrySet) override;
     void setFrameGeometry(const QRect &rect, ForceGeometry_t force = NormalGeometrySet) override;
@@ -81,7 +79,6 @@ private:
 
     QString m_captionNormal;
     QString m_captionSuffix;
-    qreal m_opacity = 1.0;
     QRect m_requestedFrameGeometry;
     QRect m_bufferGeometry;
     QRect m_requestedClientGeometry;

x11client.cpp

@@ -777,6 +777,7 @@ bool X11Client::manage(xcb_window_t w, bool isMapped)
             demandAttention();
         if (info->state() & NET::Modal)
             setModal(true);
+        setOpacity(info->opacityF());
 
         setFullScreen(rules()->checkFullScreen(info->state() & NET::FullScreen, !isMapped), false);
     }
@@ -876,7 +877,7 @@ bool X11Client::manage(xcb_window_t w, bool isMapped)
                 return;
             }
             NETWinInfo info(connection(), frameId(), rootWindow(), NET::Properties(), NET::Properties2());
-            info.setOpacity(static_cast<unsigned long>(opacity() * 0xffffffff));
+            info.setOpacityF(opacity());
         }
     );