center align starts to work

still not perfect

panelview.cpp

@@ -327,7 +327,11 @@ void PanelView::restore()
 
     static const int MINSIZE = 10;
 
-    m_offset = qMax(0, config().readEntry<int>("offset", 0));
+    m_offset = config().readEntry<int>("offset", 0);
+    if (m_alignment != Qt::AlignCenter) {
+        m_offset = qMax(0, m_offset);
+    }
+
     m_maxLength = config().readEntry<int>("maxLength", -1);
     m_minLength = config().readEntry<int>("minLength", -1);
     m_alignment = (Qt::Alignment)config().readEntry<int>("alignment", Qt::AlignLeft);

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

@@ -36,10 +36,15 @@ PlasmaCore.FrameSvgItem {
     implicitWidth: offsetHandle.width + minimumLengthHandle.width
     implicitHeight: offsetHandle.height + minimumLengthHandle.height
 
+    onMinimumLengthChanged: leftMinimumLengthHandle.value = minimumLength
+    onMaximumLengthChanged: leftMaximumLengthHandle.value = maximumLength
+
     Component.onCompleted: {
         offsetHandle.value = panel.offset
         minimumLengthHandle.value = panel.minimumLength
         maximumLengthHandle.value = panel.maximumLength
+        leftMinimumLengthHandle.value = panel.minimumLength
+        leftMaximumLengthHandle.value = panel.maximumLength
     }
 
     PlasmaCore.Svg {
@@ -49,24 +54,41 @@ PlasmaCore.FrameSvgItem {
 
     SliderHandle {
         id: offsetHandle
-        inverted: panel.alignment == Qt.AlignRight
         graphicElementName: "offsetslider"
         onValueChanged: panel.offset = value
     }
     SliderHandle {
         id: minimumLengthHandle
-        inverted: panel.alignment == Qt.AlignRight
+        alignment: panel.alignment | Qt.AlignLeft
+        visible: panel.alignment != Qt.AlignRight
         offset: panel.offset
         graphicElementName: "minslider"
         onValueChanged: panel.minimumLength = value
     }
     SliderHandle {
         id: maximumLengthHandle
-        inverted: panel.alignment == Qt.AlignRight
+        alignment: panel.alignment | Qt.AlignLeft
+        visible: panel.alignment != Qt.AlignRight
         offset: panel.offset
         graphicElementName: "maxslider"
         onValueChanged: panel.maximumLength = value
     }
+    SliderHandle {
+        id: leftMinimumLengthHandle
+        alignment: panel.alignment | Qt.AlignRight
+        visible: panel.alignment != Qt.AlignLeft
+        offset: panel.offset
+        graphicElementName: "maxslider"
+        onValueChanged: panel.minimumLength = value
+    }
+    SliderHandle {
+        id: leftMaximumLengthHandle
+        alignment: panel.alignment | Qt.AlignRight
+        visible: panel.alignment != Qt.AlignLeft
+        offset: panel.offset
+        graphicElementName: "minslider"
+        onValueChanged: panel.maximumLength = value
+    }
 
     states: [
         State {
@@ -112,6 +134,24 @@ PlasmaCore.FrameSvgItem {
                     right: undefined
                 }
             }
+            AnchorChanges {
+                target: leftMinimumLengthHandle
+                anchors {
+                    top: root.top
+                    bottom: undefined
+                    left: undefined
+                    right: undefined
+                }
+            }
+            AnchorChanges {
+                target: leftMaximumLengthHandle
+                anchors {
+                    top: undefined
+                    bottom: root.bottom
+                    left: undefined
+                    right: undefined
+                }
+            }
         },
         State {
             name: "BottomEdge"
@@ -156,6 +196,24 @@ PlasmaCore.FrameSvgItem {
                     right: undefined
                 }
             }
+            AnchorChanges {
+                target: leftMinimumLengthHandle
+                anchors {
+                    top: undefined
+                    bottom: root.bottom
+                    left: undefined
+                    right: undefined
+                }
+            }
+            AnchorChanges {
+                target: leftMaximumLengthHandle
+                anchors {
+                    top: root.top
+                    bottom: undefined
+                    left: undefined
+                    right: undefined
+                }
+            }
         },
         State {
             name: "LeftEdge"
@@ -200,6 +258,24 @@ PlasmaCore.FrameSvgItem {
                     right: root.right
                 }
             }
+            AnchorChanges {
+                target: leftMinimumLengthHandle
+                anchors {
+                    top: undefined
+                    bottom: undefined
+                    left: root.left
+                    right: undefined
+                }
+            }
+            AnchorChanges {
+                target: leftMaximumLengthHandle
+                anchors {
+                    top: undefined
+                    bottom: undefined
+                    left: undefined
+                    right: root.right
+                }
+            }
         },
         State {
             name: "RightEdge"
@@ -244,6 +320,24 @@ PlasmaCore.FrameSvgItem {
                     right: undefined
                 }
             }
+            AnchorChanges {
+                target: leftMinimumLengthHandle
+                anchors {
+                    top: undefined
+                    bottom: undefined
+                    left: undefined
+                    right: parent.right
+                }
+            }
+            AnchorChanges {
+                target: leftMaximumLengthHandle
+                anchors {
+                    top: undefined
+                    bottom: undefined
+                    left: parent.left
+                    right: undefined
+                }
+            }
         }
     ]
 }

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

@@ -31,29 +31,49 @@ PlasmaCore.SvgItem {
     width: naturalSize.width
     height: naturalSize.height
 
+    //value expressed by this slider
     property int value
+    //name of the graphics to load
     property string graphicElementName
+    //where the point "0" is
     property int offset: 0
-    property bool inverted: false
+    //handle type: behave in different ways based on the alignment
+    property int alignment: panel.alignment
 
     function syncPos() {
         if (panel.location == 5 || panel.location == 6) {
-            if (inverted) {
+            if (alignment == Qt.AlignRight) {
                 y = root.parent.height - (value + offset + root.height/2)
-            } else {
+            } else if (alignment == Qt.AlignLeft) {
                 y = value + offset - root.height/2
+            } else {
+                if (root.alignment & Qt.AlignRight) {
+                    y = root.parent.height/2 - value/2 - offset + root.height/2
+                } else if (root.alignment & Qt.AlignLeft) {
+                    y = root.parent.height/2 + value/2 + offset - root.height/2
+                } else {
+                    y = root.parent.height/2 + value + offset -root.height/2
+                }
             }
         } else {
-            if (inverted) {
+            if (alignment == Qt.AlignRight) {
                 x = root.parent.width - (value + offset + root.width/2)
-            } else {
+            } else if (alignment == Qt.AlignLeft) {
                 x = value + offset - root.width/2
+            } else {
+                if (root.alignment & Qt.AlignRight) {
+                    x = root.parent.width/2 - value/2 + offset - root.width/2
+                } else if (root.alignment & Qt.AlignLeft) {
+                    x = root.parent.width/2 + value/2 + offset -root.width/2
+                } else {
+                    x = root.parent.width/2 + value + offset -root.width/2
+                }
             }
         }
     }
     onValueChanged: syncPos()
     onOffsetChanged: syncPos()
-    onInvertedChanged: syncPos()
+    onAlignmentChanged: syncPos()
     Connections {
         target: root.parent
         onWidthChanged: syncPos()
@@ -68,16 +88,25 @@ PlasmaCore.SvgItem {
         anchors.fill: parent
         onPositionChanged: {
             if (panel.location == 5 || panel.location == 6) {
-                if (root.inverted) {
+                if (root.alignment == Qt.AlignRight) {
                     root.value = root.parent.height - (parent.y + offset + root.height/2)
-                } else {
+                } else if (alignment == Qt.AlignLeft) {
                     root.value = parent.y - offset + root.height/2
                 }
             } else {
-                if (root.inverted) {
+                if (root.alignment == Qt.AlignRight) {
                     root.value = root.parent.width - (parent.x + offset + root.width/2)
-                } else {
+                } else if (alignment == Qt.AlignLeft) {
                     root.value = parent.x - offset + root.width/2
+                //Center
+                } else {
+                    if (root.alignment & Qt.AlignRight) {
+                        root.value = (root.parent.width/2 - parent.x + offset)*2  + root.width/2
+                    } else if (root.alignment & Qt.AlignLeft) {
+                        root.value = (parent.x - offset - root.parent.width/2)*2  + root.width/2
+                    } else {
+                        root.value = parent.x - root.parent.width/2 - offset + root.width/2
+                    }
                 }
             }
         }