Refactor transform code in pinchhandler to a separate function

This is needed in order for the wheel handler to have the same behavior.

Change-Id: I42851789787b8da96618d82227b34c53ace15e9b
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

1 files changed, 34 insertions, 0 deletions

diff --git a/src/quick/items/qquickitem.cpp b/src/quick/items/qquickitem.cpp
index ec6bf5a1b8..7469fee72b 100644
--- a/src/quick/items/qquickitem.cpp
+++ b/src/quick/items/qquickitem.cpp
@@ -5122,6 +5122,40 @@ void QQuickItemPrivate::transformChanged()
 #endif
 }
 
+QPointF QQuickItemPrivate::adjustedPosForTransform(const QPointF &centroidParentPos,
+                                                   const QPointF &startPos,
+                                                   const QVector2D &activeTranslation,  //[0,0] means no additional translation from startPos
+                                                   qreal startScale,
+                                                   qreal activeScale,                   // 1.0 means no additional scale from startScale
+                                                   qreal startRotation,
+                                                   qreal activeRotation)                // 0.0 means no additional rotation from startRotation
+{
+    Q_Q(QQuickItem);
+    QVector3D xformOrigin(q->transformOriginPoint());
+    QMatrix4x4 startMatrix;
+    startMatrix.translate(float(startPos.x()), float(startPos.y()));
+    startMatrix.translate(xformOrigin);
+    startMatrix.scale(float(startScale));
+    startMatrix.rotate(float(startRotation), 0, 0, -1);
+    startMatrix.translate(-xformOrigin);
+
+    const QVector3D centroidParentVector(centroidParentPos);
+    QMatrix4x4 mat;
+    mat.translate(centroidParentVector);
+    mat.rotate(float(activeRotation), 0, 0, 1);
+    mat.scale(float(activeScale));
+    mat.translate(-centroidParentVector);
+    mat.translate(QVector3D(activeTranslation));
+
+    mat = mat * startMatrix;
+
+    QPointF xformOriginPoint = q->transformOriginPoint();
+    QPointF pos = mat * xformOriginPoint;
+    pos -= xformOriginPoint;
+
+    return pos;
+}
+
 bool QQuickItemPrivate::filterKeyEvent(QKeyEvent *e, bool post)
 {
     if (!extra.isAllocated() || !extra->keyHandler)