new Effects API for mask United/Subtracted regions

--View::Effects now provides in API in order for
elements to publish regions that need to be added
or removed from View::mask(). A good example for this
is View Config windows that must remove a rectangle
for their bottom edge in order for users to have
fully access to their action buttons at the bottom.

app/view/effects.cpp

@@ -54,6 +54,9 @@ void Effects::init()
     connect(this, &Effects::enabledBordersChanged, this, &Effects::updateEffects);
     connect(this, &Effects::rectChanged, this, &Effects::updateEffects);
 
+    connect(this, &Effects::subtractedMaskRegionsChanged, this, &Effects::updateMask);
+    connect(this, &Effects::unitedMaskRegionsChanged, this, &Effects::updateMask);
+
     connect(this, &Effects::drawShadowsChanged, this, [&]() {
         if (m_view->behaveAsPlasmaPanel()) {
             updateEnabledBorders();
@@ -67,7 +70,6 @@ void Effects::init()
     connect(m_view, &Latte::View::behaveAsPlasmaPanelChanged, this, &Effects::updateShadows);
     connect(m_view, &Latte::View::configWindowGeometryChanged, this, &Effects::updateMask);
 
-
     connect(&m_theme, &Plasma::Theme::themeChanged, this, [&]() {
         auto background = m_background;
         m_background = new Plasma::FrameSvg(this);
@@ -245,13 +247,68 @@ void Effects::forceMaskRedraw()
     updateMask();
 }
 
+void Effects::setSubtractedMaskRegion(const QString &regionid, const QRegion &region)
+{
+    if (!m_subtractedMaskRegions.contains(regionid) || m_subtractedMaskRegions[regionid] != region) {
+        return;
+    }
+
+    m_subtractedMaskRegions[regionid] = region;
+    emit subtractedMaskRegionsChanged();
+}
+
+void Effects::removeSubtractedMaskRegion(const QString &regionid)
+{
+    if (!m_subtractedMaskRegions.contains(regionid)) {
+        return;
+    }
+
+    m_subtractedMaskRegions.remove(regionid);
+    emit subtractedMaskRegionsChanged();
+}
+
+void Effects::setUnitedMaskRegion(const QString &regionid, const QRegion &region)
+{
+    if (!m_unitedMaskRegions.contains(regionid) || m_unitedMaskRegions[regionid] != region) {
+        return;
+    }
+
+    m_unitedMaskRegions[regionid] = region;
+    emit unitedMaskRegionsChanged();
+}
+
+void Effects::removeUnitedMaskRegion(const QString &regionid)
+{
+    if (!m_unitedMaskRegions.contains(regionid)) {
+        return;
+    }
+
+    m_unitedMaskRegions.remove(regionid);
+    emit unitedMaskRegionsChanged();
+}
+
+QRegion Effects::maskCombinedRegion()
+{
+    QRegion region = m_mask;
+
+    for(auto subregion : m_subtractedMaskRegions) {
+        region = region.subtracted(subregion);
+    }
+
+    for(auto subregion : m_unitedMaskRegions) {
+        region = region.united(subregion);
+    }
+
+    return region;
+}
+
 void Effects::updateMask()
 {
     if (KWindowSystem::compositingActive()) {
         if (m_view->behaveAsPlasmaPanel()) {
             m_view->setMask(QRect());
         } else {
-            m_view->setMask(m_mask);
+            m_view->setMask(maskCombinedRegion());
         }
     } else {
         //! this is used when compositing is disabled and provides

app/view/effects.h

@@ -90,6 +90,10 @@ public:
 
 public slots:
     Q_INVOKABLE void forceMaskRedraw();
+    Q_INVOKABLE void setSubtractedMaskRegion(const QString &regionid, const QRegion &region);
+    Q_INVOKABLE void removeSubtractedMaskRegion(const QString &regionid);
+    Q_INVOKABLE void setUnitedMaskRegion(const QString &regionid, const QRegion &region);
+    Q_INVOKABLE void removeUnitedMaskRegion(const QString &regionid);
 
     void clearShadows();
     void updateShadows();
@@ -108,6 +112,9 @@ signals:
     void innerShadowChanged();
     void rectChanged();
 
+    void subtractedMaskRegionsChanged();
+    void unitedMaskRegionsChanged();
+
 private slots:
     void init();
 
@@ -115,6 +122,7 @@ private slots:
 
 private:
     qreal currentMidValue(const qreal &max, const qreal &factor, const qreal &min) const;
+    QRegion maskCombinedRegion();
 
 private:
     bool m_animationsBlocked{false};
@@ -143,6 +151,10 @@ private:
 
     //only for the mask, not to actually paint
     Plasma::FrameSvg::EnabledBorders m_enabledBorders{Plasma::FrameSvg::AllBorders};
+
+    //! Subtracted and United Mask regions
+    QHash<QString, QRegion> m_subtractedMaskRegions;
+    QHash<QString, QRegion> m_unitedMaskRegions;
 };
 
 }