Set center of rotation [Titanium] - image

Question

I have got some code for rotation of an image. But however, the center of rotation is not equal to the center of the image which is to be rotated.
I have set the center of an image but I don't know how to set the center of the rotation.
Following is the code :
// image code
var image = Titanium.UI.createImageView({
backgroundImage:'test.png',
width: 650,
height: 650,
center:{x:CenterX, y:CenterY},
align:'center'
});
//rotation code
image.addEventListener('touchstart', function(e){
var conv = e.source.convertPointToView({x: e.x, y:e.y}, win);
var newAngle = Math.atan2(conv.y - 500, 380 - conv.x)* -(180 / Math.PI);
diff = (newAngle - old);
});
image.addEventListener('touchmove', function(e){
var conv = e.source.convertPointToView({x: e.x, y:e.y}, win);
var newAngle = Math.atan2(conv.y - 500, 380 - conv.x)* -(180 / Math.PI);
current = (newAngle-diff);
var t = Ti.UI.create2DMatrix().rotate(current);
wheel.transform = t;
});

Answer 1

You have to set the animation / view anchorPoint, on iOS you have to set the Ti.UI.View's anchorPoint, on Android you have to set the Ti.UI.Animation's anchorPoint or in your case, since your using a Matrix, just set the anchorPoint of the Matrix on creation (for Android).
Here is what you do for iOS:
/* iOS */
var image = Titanium.UI.createImageView({
backgroundImage:'test.png',
width: 650,
height: 650,
anchorPoint: {0.5, 0.5}, // ANchor point is at the center
});
Or alternatively, on Android:
/* Android */
// Matrix, inside your event listener
image.addEventListener('touchmove', function(e){
var conv = e.source.convertPointToView({x: e.x, y:e.y}, win);
var newAngle = Math.atan2(conv.y - 500, 380 - conv.x)* -(180 / Math.PI);
current = (newAngle-diff);
// Note that I set the anchor point here.
var t = Ti.UI.create2DMatrix({anchorPoint: {0.5, 0.5}}).rotate(current);
wheel.transform = t;
});