Add PinchHandler.scaleAxis, rotationAxis; hold values in axes

Pointer Handlers that manipulate target item properties should now
use QQuickDragAxis consistently to:
- enforce minimum and maximum values
- hold the persistent and active values
- make those available via properties
- emit a new activeValueChanged(delta) signal when the value changes,
  so that it's possible to incrementally update a target item
  property in JS (onValueDelta: target.property += delta)

In the pinchHandler.qml example, you can use the PinchHandler to adjust
4 properties of one Rectangle independently (it requires coordination).

m_boundedActiveValue controls whether m_activeValue will be
kept between minimum and maximum. For rotation,
tst_QQuickPinchHandler::scaleNativeGesture() expects it to be,
although that seems questionable now, and may be addressed later.

[ChangeLog][QtQuick][Event Handlers] PinchHandler now has scaleAxis and
rotationAxis grouped properties, alongside the existing xAxis and yAxis;
and all of these now have activeValue and persistentValue properties.
The activeValueChanged signal includes a delta value, giving the
incremental change since the previous activeValue. The persistentValue
is settable, in case some target item property can be adjusted in
multiple ways: the handler's stored value can then be synced up with the
item property value after each external change. These features are
also added to DragHandler's xAxis and yAxis properties.

Task-number: QTBUG-68108
Task-number: QTBUG-76380
Task-number: QTBUG-76379
Task-number: QTBUG-94168
Change-Id: I78a5b43e9ba580448ef05054b6c4bc71b1834dd6
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

1 files changed, 35 insertions, 0 deletions

diff --git a/examples/quick/pointerhandlers/pinchHandler.qml b/examples/quick/pointerhandlers/pinchHandler.qml
index f8febc47ee..016bb0c00c 100644
--- a/examples/quick/pointerhandlers/pinchHandler.qml
+++ b/examples/quick/pointerhandlers/pinchHandler.qml
@@ -142,6 +142,41 @@ Rectangle {
                 TapHandler { gesturePolicy: TapHandler.DragThreshold; onTapped: rect3.z = rect2.z + 1 }
                 MomentumAnimation { id: anim; target: rect3 }
             }
+
+            Rectangle {
+                id: rect4
+                x: 400
+                y: 250
+                width: 300
+                height: 220
+                color: "#609cbc3d"
+                radius: 10
+                antialiasing: true
+                border {
+                    width: 5
+                    color: "maroon"
+                }
+                PinchHandler {
+                    id: pinch4
+                    target: null
+                    xAxis.onActiveValueChanged: (delta) => rect4.width = Math.min(500, Math.max(120, 15 * Math.round((rect4.width + delta) / 15)))
+                    yAxis.onActiveValueChanged: (delta) => rect4.opacity = Math.max(0.1, Math.min(0.9, rect4.opacity - delta / 200))
+                    rotationAxis.onActiveValueChanged: (delta) => rect4.radius = Math.max(0, Math.min(60, rect4.radius + delta))
+                    scaleAxis.onActiveValueChanged: (delta) => rect4.border.width *= delta
+                }
+                Text {
+                    anchors.fill: parent
+                    anchors.margins: rect4.radius / Math.PI + rect4.border.width
+                    text: "Pinch with 2 fingers to tweak various properties"
+                    wrapMode: Text.WordWrap
+                }
+                Text {
+                    anchors.top: rect4.bottom
+                    anchors.left: rect4.left
+                    text: "opacity " + rect4.opacity.toFixed(3) + " width " + rect4.width +
+                          " border " + rect4.border.width.toFixed(1) + " radius " + rect4.radius.toFixed(1)
+                }
+            }
         }
     }
     Rectangle {