provide visual limits for margins/padding

--based on the current indicator there minimum
thickness and indicator padding can be altered.
Providing some visual feedback for the user to
understand these limits is a good practice.

app/view/indicator.cpp

@@ -230,6 +230,21 @@ QStringList Indicator::customLocalPluginIds() const
     return m_corona->indicatorFactory()->customLocalPluginIds();
 }
 
+QQuickItem *Indicator::info() const
+{
+    return m_info;
+}
+
+void Indicator::setIndicatorInfo(QQuickItem *info)
+{
+    if (m_info == info) {
+        return;
+    }
+
+    m_info = info;
+    emit infoChanged();
+}
+
 QQmlComponent *Indicator::component() const
 {
     return m_component;

app/view/indicator.h

@@ -66,6 +66,8 @@ class Indicator: public QObject
     Q_PROPERTY(QStringList customPluginNames READ customPluginNames NOTIFY customPluginsChanged)
     Q_PROPERTY(QStringList customLocalPluginIds READ customLocalPluginIds NOTIFY customPluginsChanged)
 
+    Q_PROPERTY(QQuickItem *info READ info NOTIFY infoChanged)
+
     /**
      * Configuration object: each config key will be a writable property of this object. property bindings work.
      */
@@ -105,6 +107,8 @@ public:
     QStringList customPluginNames() const;
     QStringList customLocalPluginIds() const;
 
+    QQuickItem *info() const;
+
     QObject *configuration() const;
     QQmlComponent *component() const;
     QQmlComponent *plasmaComponent() const;
@@ -116,12 +120,14 @@ public slots:
     Q_INVOKABLE void addIndicator();
     Q_INVOKABLE void downloadIndicator();
     Q_INVOKABLE void removeIndicator(QString pluginId);
+    Q_INVOKABLE void setIndicatorInfo(QQuickItem *info);
 
 signals:
     void customPluginsChanged();
     void enabledChanged();
     void enabledForAppletsChanged();
     void customPluginChanged();
+    void infoChanged();
     void latteTasksArePresentChanged();
     void paddingChanged();
     void plasmaComponentChanged();
@@ -165,6 +171,8 @@ private:
 
     KPluginMetaData m_metadata;
 
+    QPointer<QQuickItem> m_info;
+
     QPointer<KDeclarative::ConfigPropertyMap> m_configuration;
     QPointer<KDeclarative::QmlObjectSharedEngine> m_lastCreatedConfigUi;
 };

containment/package/contents/ui/indicators/Manager.qml

@@ -71,6 +71,15 @@ Item{
         }
     }
 
+    Connections {
+        target: root
+        onLatteViewChanged: {
+            if (latteView) {
+                latteView.indicator.setIndicatorInfo(indicators.info)
+            }
+        }
+    }
+
     //! Metrics and values provided from an invisible indicator
     Loader{
         id: metricsLoader

declarativeimports/components/Slider.qml

@@ -40,12 +40,42 @@ T.Slider {
 
     snapMode: T.Slider.SnapOnRelease
 
+    readonly property bool minimumInternalValueIsSet: (minimumInternalValue!==from && minimumInternalValue !== -10000)
+    property int minimumInternalValue: -10000
+
     PlasmaCore.Svg {
         id: grooveSvg
         imagePath: "widgets/slider"
         colorGroup: PlasmaCore.ColorScope.colorGroup
     }
 
+    PlasmaCore.FrameSvgItem {
+        id: minimumValueGroove
+        imagePath: "widgets/slider"
+        prefix: "groove-highlight"
+        x: limitedX - width/2
+        y: parent.height/2 - height/2
+        width: parent.height * 0.6
+        height: 2
+        rotation: 90
+        visible: minimumInternalValueIsSet
+
+        readonly property int limitedX: limitedPer * parent.width
+        readonly property real limitedPer: ((minimumInternalValue-from)/(to-from))
+
+        opacity: {
+            if (control.enabled && minimumInternalValueIsSet && value < minimumInternalValue) {
+                return 0.3
+            }
+
+            if (control.enabled) {
+                return 1;
+            }
+
+            return 0.4;
+        }
+    }
+
     handle: Item {
         property bool horizontal: control.orientation === Qt.Horizontal
         x: leftFixedPadding + (horizontal ? control.visualPosition * (control.availableWidth - width / 2) : (control.availableWidth - width) / 2)
@@ -85,13 +115,24 @@ T.Slider {
         scale: horizontal && control.mirrored ? -1 : 1
 
         PlasmaCore.FrameSvgItem {
+            id: grooveHighlight
             imagePath: "widgets/slider"
             prefix: "groove-highlight"
             x: parent.horizontal ? 0 : (parent.width - width) / 2
             y: parent.horizontal ? (parent.height - height) / 2 : control.visualPosition * parent.height
             width: parent.horizontal ? control.position * parent.width + invisibleSpacer : parent.width
             height: parent.horizontal ? parent.height : control.position * parent.height + invisibleSpacer
-            opacity: control.enabled ? 1 : 0.4
+            opacity: {
+                if (control.enabled && minimumInternalValueIsSet && value < minimumInternalValue) {
+                    return 0.3
+                }
+
+                if (control.enabled) {
+                    return 1;
+                }
+
+                return 0.4;
+            }
 
             property int invisibleSpacer: control.position === 0 ? 4 : 0
         }

shell/package/contents/configuration/pages/AppearanceConfig.qml

@@ -560,6 +560,7 @@ PlasmaComponents.Page {
                         to: 40
                         stepSize: 1
                         wheelEnabled: false
+                        minimumInternalValue: latteView.indicator.info.minThicknessPadding * 100
 
                         onPressedChanged: {
                             if (!pressed) {
@@ -569,10 +570,12 @@ PlasmaComponents.Page {
                     }
 
                     PlasmaComponents.Label {
-                        text: i18nc("number in percentage, e.g. 85 %","%0 %").arg(thickMarginSlider.value)
+                        text: i18nc("number in percentage, e.g. 85 %","%0 %").arg(currentValue)
                         horizontalAlignment: Text.AlignRight
                         Layout.minimumWidth: theme.mSize(theme.defaultFont).width * 4
                         Layout.maximumWidth: theme.mSize(theme.defaultFont).width * 4
+
+                        readonly property int currentValue: Math.max(thickMarginSlider.minimumInternalValue, thickMarginSlider.value)
                     }
                 }
             }

shell/package/contents/configuration/pages/EffectsConfig.qml

@@ -550,6 +550,7 @@ PlasmaComponents.Page {
                         to: maxMargin
                         stepSize: 1
                         wheelEnabled: false
+                        minimumInternalValue: latteView.indicator.info.minLengthPadding * 100
 
                         readonly property int maxMargin: 25
 
@@ -561,10 +562,12 @@ PlasmaComponents.Page {
                     }
 
                     PlasmaComponents.Label {
-                        text: i18nc("number in percentage, e.g. 85 %","%0 %").arg(lengthIntMarginSlider.value)
+                        text: i18nc("number in percentage, e.g. 85 %","%0 %").arg(currentValue)
                         horizontalAlignment: Text.AlignRight
                         Layout.minimumWidth: theme.mSize(theme.defaultFont).width * 4
                         Layout.maximumWidth: theme.mSize(theme.defaultFont).width * 4
+
+                        readonly property int currentValue: Math.max(lengthIntMarginSlider.minimumInternalValue, lengthIntMarginSlider.value)
                     }
                 }