Add WheelHandler

It can be used to change any qreal property of its target Item in
response to wheel rotation, or it can be used in other ways that involve
bindings but without a target item.

[ChangeLog][QtQuick][Event Handlers] Added WheelHandler, which handles
mouse wheel rotation by modifying arbitrary Item properties.

Fixes: QTBUG-68119
Change-Id: I247e2325ee993cc1b91a47fbd6c4ba0ffde7ad49
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

5 files changed, 273 insertions, 47 deletions

diff --git a/tests/manual/pointer/content/FakeFlickable.qml b/tests/manual/pointer/content/FakeFlickable.qml
index ffb5c4e914..636399ba2c 100644
--- a/tests/manual/pointer/content/FakeFlickable.qml
+++ b/tests/manual/pointer/content/FakeFlickable.qml
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2019 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the manual tests of the Qt Toolkit.
@@ -26,10 +26,12 @@
 **
 ****************************************************************************/
 
-import QtQuick 2.12
+import QtQuick 2.14
+import Qt.labs.animation 1.0
 
 Item {
     id: root
+    objectName: "viewport"
     default property alias data: __contentItem.data
     property alias velocity: anim.velocity
     property alias contentX: __contentItem.x // sign is reversed compared to Flickable.contentX
@@ -45,52 +47,81 @@ Item {
         width: childrenRect.width
         height: childrenRect.height
 
-        property real xlimit: root.width - __contentItem.width
-        property real ylimit: root.height - __contentItem.height
+        BoundaryRule on x {
+            id: xbr
+            minimum: root.width - __contentItem.width
+            maximum: 0
+            minimumOvershoot: 100
+            maximumOvershoot: 100
+            overshootFilter: BoundaryRule.Peak
+        }
 
-        function returnToBounds() {
-            if (x > 0) {
-                returnXAnim.to = 0
-                returnXAnim.start()
-            } else if (x < xlimit) {
-                returnXAnim.to = xlimit
-                returnXAnim.start()
-            }
-            if (y > 0) {
-                returnYAnim.to = 0
-                returnYAnim.start()
-            } else if (y < ylimit) {
-                returnYAnim.to = ylimit
-                returnYAnim.start()
-            }
+        BoundaryRule on y {
+            id: ybr
+            minimum: root.height - __contentItem.height
+            maximum: 0
+            minimumOvershoot: 100
+            maximumOvershoot: 100
+            overshootFilter: BoundaryRule.Peak
         }
 
         DragHandler {
             id: dragHandler
-            onActiveChanged: if (!active) anim.restart(centroid.velocity)
+            onActiveChanged:
+                if (active) {
+                    anim.stop()
+                    root.flickStarted()
+                } else {
+                    var vel = centroid.velocity
+                    if (xbr.returnToBounds())
+                        vel.x = 0
+                    if (ybr.returnToBounds())
+                        vel.y = 0
+                    if (vel.x !== 0 || vel.y !== 0)
+                        anim.restart(vel)
+                    else
+                        root.flickEnded()
+                }
+        }
+        WheelHandler {
+            rotationScale: 15
+            property: "x"
+            orientation: Qt.Horizontal
+            acceptedDevices: PointerDevice.Mouse | PointerDevice.TouchPad
+            onActiveChanged:
+                // emitting signals in both instances is redundant but hard to avoid
+                // when the touchpad is flicking along both axes
+                if (active) {
+                    anim.stop()
+                    root.flickStarted()
+                } else {
+                    xbr.returnToBounds()
+                    root.flickEnded()
+                }
+        }
+        WheelHandler {
+            rotationScale: 15
+            property: "y"
+            orientation: Qt.Vertical
+            acceptedDevices: PointerDevice.Mouse | PointerDevice.TouchPad
+            onActiveChanged:
+                if (active) {
+                    anim.stop()
+                    root.flickStarted()
+                } else {
+                    ybr.returnToBounds()
+                    root.flickEnded()
+                }
         }
         MomentumAnimation {
             id: anim
             target: __contentItem
             onStarted: root.flickStarted()
             onStopped: {
-                __contentItem.returnToBounds()
+                xbr.returnToBounds()
+                ybr.returnToBounds()
                 root.flickEnded()
             }
         }
-        NumberAnimation {
-            id: returnXAnim
-            target: __contentItem
-            property: "x"
-            duration: 200
-            easing.type: Easing.OutQuad
-        }
-        NumberAnimation {
-            id: returnYAnim
-            target: __contentItem
-            property: "y"
-            duration: 200
-            easing.type: Easing.OutQuad
-        }
     }
 }
diff --git a/tests/manual/pointer/content/Slider.qml b/tests/manual/pointer/content/Slider.qml
index e3e02b0a2f..beb84b176b 100644
--- a/tests/manual/pointer/content/Slider.qml
+++ b/tests/manual/pointer/content/Slider.qml
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2017 The Qt Company Ltd.
+** Copyright (C) 2019 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the manual tests of the Qt Toolkit.
@@ -26,7 +26,8 @@
 **
 ****************************************************************************/
 
-import QtQuick 2.12
+import QtQuick 2.14
+import Qt.labs.animation 1.0
 
 Item {
     id: root
@@ -42,8 +43,16 @@ Item {
         objectName: label.text + " DragHandler"
         target: knob
         xAxis.enabled: false
-        yAxis.minimum: slot.y
-        yAxis.maximum: slot.height + slot.y - knob.height
+    }
+
+    WheelHandler {
+        id: wheelHandler
+        objectName: label.text + " WheelHandler"
+        acceptedDevices: PointerDevice.Mouse | PointerDevice.TouchPad
+        invertible: false   // Don't let the system "natural scrolling" setting affect this
+        rotationScale: -0.5 // But make it go consistently in the same direction as the fingers or wheel, a bit slow
+        target: knob
+        property: "y"
     }
 
     Rectangle {
@@ -82,10 +91,10 @@ Item {
         height: root.width / 2
         width: implicitWidth / implicitHeight * height
         property bool programmatic: false
-        property real multiplier: root.maximumValue / (dragHandler.yAxis.maximum - dragHandler.yAxis.minimum)
-        onYChanged: if (!programmatic) root.value = root.maximumValue - (knob.y - dragHandler.yAxis.minimum) * multiplier
+        property real multiplier: root.maximumValue / (ybr.maximum - ybr.minimum)
+        onYChanged: if (!programmatic) root.value = root.maximumValue - (knob.y - ybr.minimum) * multiplier
         transformOrigin: Item.Center
-        function setValue(value) { knob.y = dragHandler.yAxis.maximum - value / knob.multiplier }
+        function setValue(value) { knob.y = ybr.maximum - value / knob.multiplier }
         TapHandler {
             id: tap
             objectName: label.text + " TapHandler"
@@ -95,6 +104,11 @@ Item {
                 root.tapped
             }
         }
+        BoundaryRule on y {
+            id: ybr
+            minimum: slot.y
+            maximum: slot.height + slot.y - knob.height
+        }
     }
 
     Text {
diff --git a/tests/manual/pointer/fakeFlickable.qml b/tests/manual/pointer/fakeFlickable.qml
index 3007848c9f..be52e4dbaa 100644
--- a/tests/manual/pointer/fakeFlickable.qml
+++ b/tests/manual/pointer/fakeFlickable.qml
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2019 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the manual tests of the Qt Toolkit.
@@ -30,6 +30,7 @@ import QtQuick 2.12
 import "content"
 
 Rectangle {
+    id: root
     color: "#444"
     width: 480
     height: 640
@@ -49,8 +50,14 @@ Rectangle {
                                        ", parent " + parent + " geom " + parent.width + "x" + parent.height)
         }
 
-        onFlickStarted: console.log("flick started with velocity " + velocity)
-        onFlickEnded: console.log("flick ended with velocity " + velocity)
+        onFlickStarted: {
+            root.border.color = "green"
+            console.log("flick started with velocity " + velocity)
+        }
+        onFlickEnded: {
+            root.border.color = "transparent"
+            console.log("flick ended with velocity " + velocity)
+        }
 
         Component.onCompleted: {
             var request = new XMLHttpRequest()
diff --git a/tests/manual/pointer/map.qml b/tests/manual/pointer/map.qml
index c400874d58..0e815ccd9c 100644
--- a/tests/manual/pointer/map.qml
+++ b/tests/manual/pointer/map.qml
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2018 The Qt Company Ltd.
+** Copyright (C) 2019 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the manual tests of the Qt Toolkit.
@@ -26,7 +26,7 @@
 **
 ****************************************************************************/
 
-import QtQuick 2.12
+import QtQuick 2.14
 
 Item {
     width: 640
@@ -41,6 +41,20 @@ Item {
         height: image.height
         transform: Rotation { id: tilt; origin.x: width / 2; origin.y: height / 2; axis { x: 1; y: 0; z: 0 } }
 
+        WheelHandler {
+            id: wheelHandler
+            objectName: "vertical mouse wheel for scaling"
+            property: "scale"
+            onWheel: console.log("rotation " + event.angleDelta + " scaled " + rotation + " @ " + point.position + " => " + map.scale)
+        }
+
+        WheelHandler {
+            id: horizontalWheelHandler
+            objectName: "horizontal mouse wheel for side-scrolling"
+            property: "x"
+            orientation: Qt.Horizontal
+        }
+
         Image {
             id: image
             anchors.centerIn: parent
diff --git a/tests/manual/pointer/pinchAndWheel.qml b/tests/manual/pointer/pinchAndWheel.qml
new file mode 100644
index 0000000000..0944717bb7
--- /dev/null
+++ b/tests/manual/pointer/pinchAndWheel.qml
@@ -0,0 +1,160 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the manual tests of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+import QtQuick 2.14
+import Qt.labs.animation 1.0
+import "content"
+
+Rectangle {
+    id: root
+    width: 1024; height: 600
+    color: "#eee"
+
+    CheckBox {
+        id: cbTouchpadEnabled
+        x: 10; y: 6
+        label: "Touchpad wheel emulation enabled"
+    }
+
+    CheckBox {
+        id: cbHorzWheelEnabled
+        x: cbTouchpadEnabled.width + 20; y: 6
+        label: "Horizontal wheel rotation"
+    }
+
+    function getTransformationDetails(item, pinchhandler) {
+        return "\n\npinch.scale:" + pinchhandler.scale.toFixed(2)
+                + "\npinch.rotation:" + pinchhandler.rotation.toFixed(2)
+                + "°\npinch.translation:" + "(" + pinchhandler.translation.x.toFixed(2) + "," + pinchhandler.translation.y.toFixed(2) + ")"
+                + "\nscale wheel.rotation:" + scaleWheelHandler.rotation.toFixed(2)
+                + "°\nhorizontal wheel.rotation:" + horizontalRotationWheelHandler.rotation.toFixed(2)
+                + "°\ncontrol-rotation wheel.rotation:" + controlRotationWheelHandler.rotation.toFixed(2)
+                + "°\nrect.scale: " + item.scale.toFixed(2)
+                + "\nrect.rotation: " + item.rotation.toFixed(2)
+                + "°\nrect.position: " + "(" + item.x.toFixed(2) + "," + item.y.toFixed(2) + ")"
+    }
+
+    Rectangle {
+        id: transformable
+        width: parent.width - 100; height: parent.height - 100; x: 50; y: 50
+        color: "#ffe0e0e0"
+        antialiasing: true
+
+        PinchHandler {
+            id: parentPinch
+            objectName: "parent pinch"
+            minimumScale: 0.5
+            maximumScale: 3
+        }
+
+        WheelHandler {
+            id: scaleWheelHandler
+            objectName: "mouse wheel for scaling"
+            acceptedDevices: cbTouchpadEnabled.checked ? PointerDevice.Mouse | PointerDevice.TouchPad : PointerDevice.Mouse
+            acceptedModifiers: Qt.NoModifier
+            property: "scale"
+            onActiveChanged: if (!active) sbr.returnToBounds();
+            onWheel: console.log(objectName + ": rotation " + event.angleDelta.y + " scaled " + rotation + " @ " + point.position + " => " + parent.scale)
+        }
+
+        BoundaryRule on scale {
+            id: sbr
+            minimum: 0.1
+            maximum: 2
+            minimumOvershoot: 0.05
+            maximumOvershoot: 0.05
+        }
+
+        BoundaryRule on rotation {
+            id: rbr
+            minimum: -90
+            maximum: 360
+            minimumOvershoot: 10
+            maximumOvershoot: 10
+        }
+
+        WheelHandler {
+            id: horizontalRotationWheelHandler
+            enabled: cbHorzWheelEnabled.checked
+            objectName: "horizontal mouse wheel for rotation"
+            acceptedDevices: cbTouchpadEnabled.checked ? PointerDevice.Mouse | PointerDevice.TouchPad : PointerDevice.Mouse
+            acceptedModifiers: Qt.NoModifier
+            property: "rotation"
+            orientation: Qt.Horizontal
+            onActiveChanged: if (!active) rbr.returnToBounds()
+            onWheel: console.log(objectName + ": rotation " + event.angleDelta.y + " scaled " + rotation + " @ " + point.position + " => " + parent.rotation)
+        }
+
+        WheelHandler {
+            id: controlRotationWheelHandler
+            objectName: "control-mouse wheel for rotation"
+            acceptedDevices: cbTouchpadEnabled.checked ? PointerDevice.Mouse | PointerDevice.TouchPad : PointerDevice.Mouse
+            acceptedModifiers: Qt.ControlModifier
+            property: "rotation"
+            orientation: Qt.Vertical // already the default
+            // TODO returnToBounds() causes trouble because position isn't being adjusted when this happens
+            onActiveChanged: if (!active) rbr.returnToBounds()
+            onWheel: console.log(objectName + ": rotation " + event.angleDelta.y + " scaled " + rotation + " @ " + point.position + " => " + parent.rotation)
+        }
+
+        HoverHandler {
+            id: hover
+            acceptedDevices: PointerDevice.AllDevices
+            property var scenePoint: transformable.mapToItem(root, point.position.x, point.position.y)
+        }
+
+        Text {
+            text: "Pinch with 2 fingers to scale, rotate and translate\nMouse wheel to scale, Ctrl+mouse wheel or horizontal wheel to rotate"
+                  + getTransformationDetails(parent, parentPinch)
+        }
+    }
+
+    Rectangle {
+        width: 1; height: parent.height
+        color: "blue"
+        x: hover.scenePoint.x
+        Text {
+            x: implicitWidth / -2; style: Text.Outline; styleColor: "white"
+            y: 30
+            color: "blue"
+            text: "outer " + parent.x.toFixed(2) + " inner " + hover.point.position.x.toFixed(2)
+        }
+    }
+
+    Rectangle {
+        width: parent.width; height: 1
+        color: "blue"
+        y: hover.scenePoint.y
+        Text {
+            x: 45
+            y: implicitHeight / -2; style: Text.Outline; styleColor: "white"
+            color: "blue"
+            text: "outer " + parent.y.toFixed(2) + " inner " + hover.point.position.y.toFixed(2)
+        }
+    }
+}