rulers work for left and right alignments

src/shell/panelview.cpp

@@ -117,6 +117,7 @@ void PanelView::setAlignment(Qt::Alignment alignment)
 
     m_alignment = alignment;
     config().writeEntry("alignment", (int)m_alignment);
+    emit alignmentChanged();
     positionPanel();
 }
 
@@ -324,38 +325,39 @@ void PanelView::restore()
         return;
     }
 
-    m_offset = config().readEntry<int>("offset", 0);
+    static const int MINSIZE = 10;
+
+    m_offset = qMax(0, config().readEntry<int>("offset", 0));
     m_maxLength = config().readEntry<int>("maxLength", -1);
     m_minLength = config().readEntry<int>("minLength", -1);
     m_alignment = (Qt::Alignment)config().readEntry<int>("alignment", Qt::AlignLeft);
 
     setMinimumSize(QSize(-1, -1));
     //FIXME: an invalid size doesn't work with QWindows
-    setMaximumSize(QSize(10000, 10000));
+    setMaximumSize(screen()->size());
 
     if (containment()->formFactor() == Plasma::Vertical) {
-        resize(config().readEntry<int>("thickness", 32),
-               config().readEntry<int>("length", screen()->size().height()));
+        const int maxSize = screen()->size().height() - m_offset;
+        m_maxLength = qBound<int>(MINSIZE, m_maxLength, maxSize);
+        m_minLength = qBound<int>(MINSIZE, m_minLength, maxSize);
 
-        if (m_minLength > 0) {
-            setMinimumHeight(m_minLength);
-        }
-        if (m_maxLength > 0) {
-            setMaximumHeight(m_maxLength);
-        }
+        resize(config().readEntry<int>("thickness", 32),
+               qBound<int>(MINSIZE, config().readEntry<int>("length", screen()->size().height()), maxSize));
+
+        setMinimumHeight(m_minLength);
+        setMaximumHeight(m_maxLength);
 
     //Horizontal
     } else {
-        resize(config().readEntry<int>("length", screen()->size().width()),
+        const int maxSize = screen()->size().width() - m_offset;
+        m_maxLength = qBound<int>(MINSIZE, m_maxLength, maxSize);
+        m_minLength = qBound<int>(MINSIZE, m_minLength, maxSize);
+
+        resize(qBound<int>(MINSIZE, config().readEntry<int>("length", screen()->size().height()), maxSize),
                config().readEntry<int>("thickness", 32));
 
-        if (m_minLength > 0) {
-            setMinimumWidth(m_minLength);
-        }
-
-        if (m_maxLength > 0) {
-            setMaximumWidth(m_maxLength);
-        }
+        setMinimumWidth(m_minLength);
+        setMaximumWidth(m_maxLength);
     }
 
     emit maximumLengthChanged();

src/shell/qmlpackages/desktop/contents/configuration/panelconfiguration/Ruler.qml

@@ -49,17 +49,20 @@ PlasmaCore.FrameSvgItem {
 
     SliderHandle {
         id: offsetHandle
+        inverted: panel.alignment == Qt.AlignRight
         graphicElementName: "offsetslider"
         onValueChanged: panel.offset = value
     }
     SliderHandle {
         id: minimumLengthHandle
+        inverted: panel.alignment == Qt.AlignRight
         offset: panel.offset
         graphicElementName: "minslider"
         onValueChanged: panel.minimumLength = value
     }
     SliderHandle {
         id: maximumLengthHandle
+        inverted: panel.alignment == Qt.AlignRight
         offset: panel.offset
         graphicElementName: "maxslider"
         onValueChanged: panel.maximumLength = value

src/shell/qmlpackages/desktop/contents/configuration/panelconfiguration/SliderHandle.qml

@@ -34,21 +34,30 @@ PlasmaCore.SvgItem {
     property int value
     property string graphicElementName
     property int offset: 0
+    property bool inverted: false
 
-    onValueChanged: {
+    function syncPos() {
         if (panel.location == 5 || panel.location == 6) {
-            y = value + offset - root.height/2
+            if (inverted) {
+                y = root.parent.height - (value + offset + root.height/2)
+            } else {
+                y = value + offset - root.height/2
+            }
         } else {
-            x = value + offset - root.width/2
+            if (inverted) {
+                x = root.parent.width - (value + offset + root.width/2)
+            } else {
+                x = value + offset - root.width/2
+            }
         }
     }
-
-    onOffsetChanged: {
-        if (panel.location == 5 || panel.location == 6) {
-            y = value + offset - root.height/2
-        } else {
-            x = value + offset - root.width/2
-        }
+    onValueChanged: syncPos()
+    onOffsetChanged: syncPos()
+    onInvertedChanged: syncPos()
+    Connections {
+        target: root.parent
+        onWidthChanged: syncPos()
+        onHeightChanged: syncPos()
     }
 
     MouseArea {
@@ -59,9 +68,17 @@ PlasmaCore.SvgItem {
         anchors.fill: parent
         onPositionChanged: {
             if (panel.location == 5 || panel.location == 6) {
-                root.value = parent.y - offset + root.height/2
+                if (root.inverted) {
+                    root.value = root.parent.height - (parent.y + offset + root.height/2)
+                } else {
+                    root.value = parent.y - offset + root.height/2
+                }
             } else {
-                root.value = parent.x - offset + root.width/2
+                if (root.inverted) {
+                    root.value = root.parent.width - (parent.x + offset + root.width/2)
+                } else {
+                    root.value = parent.x - offset + root.width/2
+                }
             }
         }
     }