Fix the initial size of the KCMs

Both KCMs had a hard coded default which is obviously bad. Instead we
now calculate a useable implicitWidth and implicitHeight and use this
as the minimum size for the KCM. Which means we need also track changes
to these two root object properties and update the QWidget container
accordingly.

BUG: 332518
BUG: 332519
REVIEW: 117079

kcmkwin/kwincompositing/main.cpp

@@ -74,11 +74,11 @@ KWinCompositingKCM::KWinCompositingKCM(QWidget* parent, const QVariantList& args
     QVBoxLayout *vl = new QVBoxLayout(this);
 
     QWidget *w = QWidget::createWindowContainer(m_view.data(), this);
+    connect(m_view.data(), &QWindow::minimumWidthChanged, w, &QWidget::setMinimumWidth);
+    connect(m_view.data(), &QWindow::minimumHeightChanged, w, &QWidget::setMinimumHeight);
     w->setMinimumSize(m_view->initialSize());
     vl->addWidget(w);
     setLayout(vl);
-    m_view->setWidth(width());
-    m_view->setHeight(height());
     connect(m_view.data(), &KWin::Compositing::EffectView::changed, [this]{
         emit changed(true);
     });

kcmkwin/kwincompositing/model.cpp

@@ -467,6 +467,9 @@ void EffectView::init(ViewType type)
     rootContext()->setContextProperty("engine", this);
     setSource(QUrl(mainFile));
     connect(rootObject(), SIGNAL(changed()), this, SIGNAL(changed()));
+    setMinimumSize(initialSize());
+    connect(rootObject(), SIGNAL(implicitWidthChanged()), this, SLOT(slotImplicitSizeChanged()));
+    connect(rootObject(), SIGNAL(implicitHeightChanged()), this, SLOT(slotImplicitSizeChanged()));
 }
 
 void EffectView::save()
@@ -499,5 +502,11 @@ void EffectView::defaults()
     }
 }
 
+void EffectView::slotImplicitSizeChanged()
+{
+    setMinimumSize(QSize(rootObject()->property("implicitWidth").toInt(),
+                         rootObject()->property("implicitHeight").toInt()));
+}
+
 }//end namespace Compositing
 }//end namespace KWin

kcmkwin/kwincompositing/model.h

@@ -124,6 +124,9 @@ public:
 
 Q_SIGNALS:
     void changed();
+
+private Q_SLOTS:
+    void slotImplicitSizeChanged();
 private:
     void init(ViewType type);
 };

kcmkwin/kwincompositing/qml/CompositingView.qml

@@ -37,11 +37,15 @@ Item {
     property alias compositingTypeIndex: backend.type
     property bool compositingEnabledChecked: useCompositing.checked
 
+    implicitWidth: mainLayout.implicitWidth
+    implicitHeight: mainLayout.implicitHeight
+
     CompositingType {
         id: compositingType
     }
 
     GridLayout {
+        id: mainLayout
         columns: 2
         anchors.fill: parent
 

kcmkwin/kwincompositing/qml/EffectView.qml

@@ -26,6 +26,8 @@ import org.kde.plasma.core 2.0
 
 Item {
     signal changed
+    implicitWidth: col.implicitWidth
+    implicitHeight: col.implicitHeight
 
     Component {
         id: sectionHeading

kcmkwin/kwincompositing/qml/OpenGLErrorView.qml

@@ -27,7 +27,11 @@ import org.kde.plasma.core 2.0
 Item {
     id: openGLErrorView
     signal activated
+    implicitWidth: mainLayout.implicitWidth
+    implicitHeight: mainLayout.implicitHeight
+
     ColumnLayout {
+        id: mainLayout
         Text {
             id: openGLErrorText
             text: i18n("OpenGL compositing (the default) has crashed KWin in the past.\n" +

kcmkwin/kwincompositing/qml/main-compositing.qml

@@ -26,13 +26,14 @@ import org.kde.kwin.kwincompositing 1.0
 
 Rectangle {
     id: window
-    width: 780
-    height: 480
+    implicitWidth: openGLBrokeState ? glError.implicitWidth : view.implicitWidth
+    implicitHeight: openGLBrokeState ? glError.implicitHeight : view.implicitHeight
     color: engine.backgroundViewColor()
     property bool openGLBrokeState: true
     signal changed
 
     OpenGLErrorView {
+        id: glError
         visible: window.openGLBrokeState
         anchors.fill: parent
         onActivated: window.openGLBrokeState = compositing.OpenGLIsBroken();

kcmkwin/kwincompositing/qml/main.qml

@@ -26,13 +26,14 @@ import org.kde.kwin.kwincompositing 1.0
 
 Rectangle {
     id: window
-    width: 780
-    height: 480
+    implicitWidth: openGLBrokeState ? glError.implicitWidth : view.implicitWidth
+    implicitHeight: openGLBrokeState ? glError.implicitHeight : view.implicitHeight
     color: engine.backgroundViewColor()
     property bool openGLBrokeState: true
     signal changed
 
     OpenGLErrorView {
+        id: glError
         visible: window.openGLBrokeState
         anchors.fill: parent
         onActivated: window.openGLBrokeState = compositing.OpenGLIsBroken();