Enable wheel events on Slider {}

Summary:
So far PC3 version of the slider doesn't react to events, this change
enables it.

Test Plan: Used it with a test.

Reviewers: #plasma, broulik, davidedmundson

Reviewed By: #plasma, davidedmundson

Subscribers: davidedmundson, kde-frameworks-devel

Tags: #frameworks

Differential Revision: https://phabricator.kde.org/D26055

src/declarativeimports/plasmacomponents3/Slider.qml

@@ -28,7 +28,7 @@ T.Slider {
     implicitWidth: control.orientation === Qt.Horizontal ? units.gridUnit * 12 : units.gridUnit * 1.6
     implicitHeight: control.orientation === Qt.Horizontal ? units.gridUnit * 1.6 : units.gridUnit * 12
 
-
+    wheelEnabled: true
     snapMode: T.Slider.SnapOnRelease
 
     PlasmaCore.Svg {
@@ -94,14 +94,16 @@ T.Slider {
 
         Repeater {
             id: repeater
-            model: control.stepSize > 0 ? 1 + (control.to - control.from) / control.stepSize : 0
+            readonly property int stepCount: (control.to - control.from) / control.stepSize
+            model: control.stepSize && stepCount < 20 ? 1 + stepCount : 0
             anchors.fill: parent
 
             Rectangle {
                 color: PlasmaCore.ColorScope.textColor
+                opacity: 0.3
                 width: background.horizontal ? units.devicePixelRatio : units.gridUnit/2
                 height: background.horizontal ? units.gridUnit/2 : units.devicePixelRatio
-                y: background.horizontal ? background.height : handle.height / 2 + index * ((repeater.height - handle.height) / (repeater.count > 1 ? repeater.count - 1 : 1))
+                y: background.horizontal ? background.height + units.devicePixelRatio : handle.height / 2 + index * ((repeater.height - handle.height) / (repeater.count > 1 ? repeater.count - 1 : 1))
                 x: background.horizontal ? handle.width / 2 + index * ((repeater.width - handle.width) / (repeater.count > 1 ? repeater.count - 1 : 1)) : background.width
             }
         }

tests/components/slider3.qml

@@ -0,0 +1,54 @@
+import QtQuick 2.0
+import QtQuick.Layouts 1.3
+
+import org.kde.kirigami 2.5 as Kirigami
+import org.kde.plasma.components 3.0
+import QtQuick.Controls 2.5 as QQC2
+import org.kde.plasma.components 2.0 as PC2
+
+// Run with qmlscene to use qqc2-desktop-style
+
+Kirigami.ApplicationWindow {
+    pageStack.initialPage: Kirigami.Page {
+        Kirigami.FormLayout {
+            anchors.fill: parent
+            PC2.Slider {
+                Layout.fillWidth: true
+                Kirigami.FormData.label: "PC2 slider"
+                maximumValue: slider.to
+                stepSize: slider.stepSize
+            }
+            QQC2.Slider {
+                Layout.fillWidth: true
+                Kirigami.FormData.label: "QQC2 slider"
+                to: slider.to
+                stepSize: slider.stepSize
+            }
+            Slider {
+                id: slider
+                Kirigami.FormData.label: "PC3 slider"
+                to: max.text
+                stepSize: 1
+                clip: true
+            }
+            TextField {
+                id: max
+                Kirigami.FormData.label: "maximumValue: "
+                text: "100"
+            }
+            Label {
+                Kirigami.FormData.label: "value: "
+                text: slider.value
+            }
+            Slider {
+                Kirigami.FormData.label: "Choose step size: "
+                to: slider.to * 2
+                onMoved: slider.stepSize = value
+            }
+            Label {
+                Kirigami.FormData.label: "Step size: "
+                text: slider.stepSize
+            }
+        }
+    }
+}