Let pinchhandler operate on QQuickItem properties

This requires coordinate system mapping that varies with the
transformOrigin.

The properties exposed from PinchHandler (rotation, scale and translation)
are currently relative to the point when the pinch became active.
(Therefore, rotation, will reset back to 0 when a new pinch is activated).

Its still unclear how the properties that limits the transform should
influence. With this patch, they are like this:

* {min,max}imumRotation applies to the actual rotation of the item.
* {min,max}imumScale applies to the actual scale of the item.
* {min,max}imum{X,Y} applies to the actual position of the item. (This has
  some unfortunate side-effects when the item is scaled or rotated, since
  the items actual position will change as it rotates)

In addition, the behavior described above means that the limits won't
have any effect if there is no target item.

Change-Id: I279fb03667cd75324e8337039ae2594658265d13
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

1 files changed, 26 insertions, 15 deletions

diff --git a/tests/manual/pointer/pinchHandler.qml b/tests/manual/pointer/pinchHandler.qml
index 3ab196a10a..f317f361e2 100644
--- a/tests/manual/pointer/pinchHandler.qml
+++ b/tests/manual/pointer/pinchHandler.qml
@@ -44,25 +44,38 @@ import Qt.labs.handlers 1.0
 Rectangle {
     width: 1024; height: 600
     color: "#eee"
+
+    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) + ")"
+        + "\nrect.scale: " + item.scale.toFixed(2)
+        + "\nrect.rotation: " + item.rotation.toFixed(2)
+        + "\nrect.position: " + "(" + item.x.toFixed(2) + "," + item.y.toFixed(2) + ")"
+    }
+
     Rectangle {
-        id: root
-        color: "black"
-        width: 900
-        height: 600
-        x: 100
+        // Purpose of this item is just to make sure the rectangles are transformed into
+        // a coordinate system that is different from the scene coordinate system.
+        anchors.fill: parent
+        anchors.margins: 50
+        color: "#ffe0e0e0"
 
         Rectangle {
+            id: rect2
             width: 400
             height: 300
             color: "lightsteelblue"
             antialiasing: true
+            x: 100
+            y: 200
+            rotation: 30
+            transformOrigin: Item.TopRight
 
             Text {
                 anchors.centerIn: parent
                 text: "Pinch with 2 fingers to scale, rotate and translate"
-                    + "\ncurrent rotation: " + pinch2.rotation.toFixed(1)
-                    + "\nscale: " + pinch2.scale.toFixed(1)
-                    + "\ntranslation: " + pinch2.translation
+                    + getTransformationDetails(rect2, pinch2)
             }
 
             PinchHandler {
@@ -74,11 +87,12 @@ Rectangle {
                 maximumScale: 3
                 minimumX: 0
                 maximumX: 600
-                pointDistanceThreshold: 150
+                pointDistanceThreshold: 0
             }
         }
 
         Rectangle {
+            id: rect3
             x: 500
             width: 400
             height: 300
@@ -88,9 +102,7 @@ Rectangle {
             Text {
                 anchors.centerIn: parent
                 text: "Pinch with 3 fingers to scale, rotate and translate\nDrag with 1 finger"
-                    + "\ncurrent rotation " + pinch3.rotation.toFixed(1)
-                    + "\nscale: " + pinch3.scale.toFixed(1)
-                    + "\ntranslation: " + pinch3.translation
+                    + getTransformationDetails(rect3, pinch3)
             }
             DragHandler { objectName: "DragHandler" }
 
@@ -102,13 +114,12 @@ Rectangle {
                 maximumScale: 10
             }
         }
-
     }
     Rectangle {
         id: centroidIndicator
         property QtObject pincher: pinch2.active ? pinch2 : pinch3
-        x: pincher.centroid.x
-        y: pincher.centroid.y
+        x: pincher.centroid.x - radius
+        y: pincher.centroid.y - radius
         z: 1
         visible: pincher.active
         radius: width / 2