core: Drop Toplevel::bufferMargins()

It can be expressed via other means.

src/deleted.cpp

@@ -84,7 +84,6 @@ void Deleted::copyToDeleted(Toplevel* c)
     Q_ASSERT(dynamic_cast< Deleted* >(c) == nullptr);
     Toplevel::copyToDeleted(c);
     m_bufferGeometry = c->bufferGeometry();
-    m_bufferMargins = c->bufferMargins();
     m_frameMargins = c->frameMargins();
     m_bufferScale = c->bufferScale();
     desk = c->desktop();
@@ -159,11 +158,6 @@ QRect Deleted::bufferGeometry() const
     return m_bufferGeometry;
 }
 
-QMargins Deleted::bufferMargins() const
-{
-    return m_bufferMargins;
-}
-
 QMargins Deleted::frameMargins() const
 {
     return m_frameMargins;

src/deleted.h

@@ -33,7 +33,6 @@ public:
     void unrefWindow();
     void discard();
     QRect bufferGeometry() const override;
-    QMargins bufferMargins() const override;
     QMargins frameMargins() const override;
     qreal bufferScale() const override;
     int desktop() const override;
@@ -183,7 +182,6 @@ private:
     void removeTransientFor(Deleted *parent);
 
     QRect m_bufferGeometry;
-    QMargins m_bufferMargins;
     QMargins m_frameMargins;
 
     int delete_refcount;

src/scene.cpp

@@ -904,14 +904,10 @@ QRegion Scene::Window::clientShape() const
     if (isShaded())
         return QRegion();
 
+    const QRect clipRect = toplevel->clientGeometry().translated(-toplevel->bufferGeometry().topLeft());
     const QRegion shape = bufferShape();
-    const QMargins bufferMargins = toplevel->bufferMargins();
-    if (bufferMargins.isNull()) {
-        return shape;
-    }
 
-    const QRect clippingRect = QRect(QPoint(0, 0), toplevel->bufferGeometry().size()) - toplevel->bufferMargins();
-    return shape & clippingRect;
+    return shape & clipRect;
 }
 
 QRegion Scene::Window::decorationShape() const

src/toplevel.cpp

@@ -810,11 +810,6 @@ bool Toplevel::isLocalhost() const
     return m_clientMachine->isLocal();
 }
 
-QMargins Toplevel::bufferMargins() const
-{
-    return QMargins();
-}
-
 QMargins Toplevel::frameMargins() const
 {
     return QMargins();

src/toplevel.h

@@ -305,16 +305,6 @@ public:
      * occupies on the screen, in global screen coordinates.
      */
     virtual QRect bufferGeometry() const = 0;
-    /**
-     * Returns the extents of invisible portions in the pixmap.
-     *
-     * An X11 pixmap may contain invisible space around the actual contents of the
-     * client. That space is reserved for server-side decoration, which we usually
-     * want to skip when building contents window quads.
-     *
-     * Default implementation returns a margins object with all margins set to 0.
-     */
-    virtual QMargins bufferMargins() const;
     /**
      * Returns the geometry of the Toplevel, excluding invisible portions, e.g.
      * server-side and client-side drop shadows, etc.

src/x11client.cpp

@@ -2619,11 +2619,6 @@ QRect X11Client::bufferGeometry() const
     return m_bufferGeometry;
 }
 
-QMargins X11Client::bufferMargins() const
-{
-    return QMargins(borderLeft(), borderTop(), borderRight(), borderBottom());
-}
-
 QPoint X11Client::framePosToClientPos(const QPoint &point) const
 {
     int x = point.x();

src/x11client.h

@@ -82,7 +82,6 @@ public:
 
     QRect inputGeometry() const override;
     QRect bufferGeometry() const override;
-    QMargins bufferMargins() const override;
 
     QPoint framePosToClientPos(const QPoint &point) const override;
     QPoint clientPosToFramePos(const QPoint &point) const override;