Consult used QQuickPaintedItem or QQuickItem everyone:

I painted with functions of mobile drag the vertices in the rotation of the rectangle, call setRotation () to rotate the graphics, found that rotate vertices become can't control, after qDebug () found that have taken place in the larger offset each point coordinates, the coordinates of the points is not display images on

A mouse in the blank space coincidence to the actual control point coordinates, drag control points, the image will change accordingly

Coordinate transfer problems solved I use mapToItem

But this rotation may make every vertex coordinate shift problem is a headache