provide stable struts thickness

--when a floating view is hiding its screen gap
there is no reason for struts to be added
during that phase. Published struts could be
the final expected window position in that case.

BUG:431255

app/view/visibilitymanager.cpp

@@ -178,6 +178,22 @@ VisibilityManager::~VisibilityManager()
     }
 }
 
+//! Struts
+int VisibilityManager::strutsThickness() const
+{
+    return m_strutsThickness;
+}
+
+void VisibilityManager::setStrutsThickness(int thickness)
+{
+    if (m_strutsThickness == thickness) {
+        return;
+    }
+
+    m_strutsThickness = thickness;
+    emit strutsThicknessChanged();
+}
+
 Types::Visibility VisibilityManager::mode() const
 {
     return m_mode;
@@ -254,7 +270,7 @@ void VisibilityManager::setMode(Latte::Types::Visibility mode)
             updateStrutsBasedOnLayoutsAndActivities();
         }
 
-        m_connections[base] = connect(m_latteView, &Latte::View::normalThicknessChanged, this, [&]() {
+        m_connections[base] = connect(this, &VisibilityManager::strutsThicknessChanged, this, [&]() {
             updateStrutsBasedOnLayoutsAndActivities();
         });
 
@@ -392,29 +408,26 @@ QRect VisibilityManager::acceptableStruts()
 {
     QRect calcs;
 
-    int screenEdgeMargin = (m_latteView->behaveAsPlasmaPanel() && m_latteView->screenEdgeMarginEnabled()) ? m_latteView->screenEdgeMargin() : 0;
-    int shownThickness = m_latteView->normalThickness() + screenEdgeMargin;
-
     switch (m_latteView->location()) {
     case Plasma::Types::TopEdge: {
-        calcs = QRect(m_latteView->x(), m_latteView->screenGeometry().top(), m_latteView->width(), shownThickness);
+        calcs = QRect(m_latteView->x(), m_latteView->screenGeometry().top(), m_latteView->width(), m_strutsThickness);
         break;
     }
 
     case Plasma::Types::BottomEdge: {
-        int y = m_latteView->screenGeometry().bottom() - shownThickness + 1 /* +1, is needed in order to not leave a gap at screen_edge*/;
-        calcs = QRect(m_latteView->x(), y, m_latteView->width(), shownThickness);
+        int y = m_latteView->screenGeometry().bottom() - m_strutsThickness + 1 /* +1, is needed in order to not leave a gap at screen_edge*/;
+        calcs = QRect(m_latteView->x(), y, m_latteView->width(), m_strutsThickness);
         break;
     }
 
     case Plasma::Types::LeftEdge: {
-        calcs = QRect(m_latteView->screenGeometry().left(), m_latteView->y(), shownThickness, m_latteView->height());
+        calcs = QRect(m_latteView->screenGeometry().left(), m_latteView->y(), m_strutsThickness, m_latteView->height());
         break;
     }
 
     case Plasma::Types::RightEdge: {
-        int x = m_latteView->screenGeometry().right() - shownThickness + 1 /* +1, is needed in order to not leave a gap at screen_edge*/;
-        calcs = QRect(x, m_latteView->y(), shownThickness, m_latteView->height());
+        int x = m_latteView->screenGeometry().right() - m_strutsThickness + 1 /* +1, is needed in order to not leave a gap at screen_edge*/;
+        calcs = QRect(x, m_latteView->y(), m_strutsThickness, m_latteView->height());
         break;
     }
     }

app/view/visibilitymanager.h

@@ -69,6 +69,9 @@ class VisibilityManager : public QObject
     Q_PROPERTY(int timerShow READ timerShow WRITE setTimerShow NOTIFY timerShowChanged)
     Q_PROPERTY(int timerHide READ timerHide WRITE setTimerHide NOTIFY timerHideChanged)
 
+    //! Struts
+    Q_PROPERTY(int strutsThickness READ strutsThickness WRITE setStrutsThickness NOTIFY strutsThicknessChanged)
+
 public:
     static const QRect ISHIDDENMASK;
 
@@ -109,6 +112,10 @@ public:
 
     bool supportsKWinEdges() const;
 
+    //! Struts
+    int strutsThickness() const;
+    void setStrutsThickness(int thickness);
+
     //! Used mostly to show / hide Sidebars
     void toggleHiddenState();
 
@@ -139,6 +146,7 @@ signals:
     void isHiddenChanged();
     void hidingIsBlockedChanged();
     void containsMouseChanged();
+    void strutsThicknessChanged();
     void timerShowChanged();
     void timerHideChanged();
 
@@ -221,6 +229,8 @@ private:
     int m_timerHideInterval{700};
     Plasma::Types::Location m_frameExtentsLocation{Plasma::Types::BottomEdge};
 
+    int m_strutsThickness{0};
+
     QStringList m_blockHidingEvents;
 
     QRect m_publishedStruts;

containment/package/contents/ui/VisibilityManager.qml

@@ -304,6 +304,23 @@ Item{
         value: plasmoid.configuration.isStickedOnBottomEdge
     }
 
+    //! View::VisibilityManager
+    Binding{
+        target: latteView && latteView.visibility ? latteView.visibility : null
+        property: "strutsThickness"
+        when: latteView && latteView.visibility
+        value: {
+            var isCapableToHideScreenGap = root.screenEdgeMarginEnabled && plasmoid.configuration.hideFloatingGapForMaximized
+
+            if (root.behaveAsPlasmaPanel) {
+                return isCapableToHideScreenGap ? thicknessAsPanel : metrics.mask.screenEdge + thicknessAsPanel;
+            }
+
+            var edgeThickness = isCapableToHideScreenGap ? 0 : metrics.mask.screenEdge;
+            return edgeThickness + metrics.mask.thickness.maxNormalForItemsWithoutScreenEdge;
+        }
+    }
+
     //! View::WindowsTracker bindings
     Binding{
         target: latteView && latteView.windowsTracker ? latteView.windowsTracker : null