Hi Everyone,
I'm creating a subclass of UIImageView that detects touches, and will move, rotate and scale the image based on the touches. However, I really feel like I'm reinventing the wheel here, and it's driving me nuts. Shouldn't this already exist somewhere?
Does anyone have any examples, or links to a class that is already doing this? Or if you have a class you've written, that'd be helpful too.
Thanks a lot in advance.
I figured it out... I answered my own question.
Hopefully this is useful to someone.
For anyone who is interested, here is the implementation for a UIImageView subclass, that you can use to move, scale, and rotate an image. It works pretty well for me.
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
if( [touches count] == 1 ) {
float difx = [[touches anyObject] locationInView:self].x - [[touches anyObject] previousLocationInView:self].x;
float dify = [[touches anyObject] locationInView:self].y - [[touches anyObject] previousLocationInView:self].y;
CGAffineTransform newTransform1 = CGAffineTransformTranslate(self.transform, difx, dify);
self.transform = newTransform1;
} else if( [touches count] == 2 ) {
int prevmidx = ([[[touches allObjects] objectAtIndex:0] previousLocationInView:self].x + [[[touches allObjects] objectAtIndex:1] previousLocationInView:self].x) / 2;
int prevmidy = ([[[touches allObjects] objectAtIndex:0] previousLocationInView:self].y + [[[touches allObjects] objectAtIndex:1] previousLocationInView:self].y) / 2;
int curmidx = ([[[touches allObjects] objectAtIndex:0] locationInView:self].x + [[[touches allObjects] objectAtIndex:1] locationInView:self].x) / 2;
int curmidy = ([[[touches allObjects] objectAtIndex:0] locationInView:self].y + [[[touches allObjects] objectAtIndex:1] locationInView:self].y) / 2;
int difx = curmidx - prevmidx;
int dify = curmidy - prevmidy;
CGPoint prevPoint1 = [[[touches allObjects] objectAtIndex:0] previousLocationInView:self];
CGPoint prevPoint2 = [[[touches allObjects] objectAtIndex:1] previousLocationInView:self];
CGPoint curPoint1 = [[[touches allObjects] objectAtIndex:0] locationInView:self];
CGPoint curPoint2 = [[[touches allObjects] objectAtIndex:1] locationInView:self];
float prevDistance = [self distanceBetweenPoint1:prevPoint1 andPoint2:prevPoint2];
float newDistance = [self distanceBetweenPoint1:curPoint1 andPoint2:curPoint2];
float sizeDifference = (newDistance / prevDistance);
CGAffineTransform newTransform1 = CGAffineTransformTranslate(self.transform, difx, dify);
self.transform = newTransform1;
CGAffineTransform newTransform2 = CGAffineTransformScale(self.transform, sizeDifference, sizeDifference);
self.transform = newTransform2;
float prevAngle = [self angleBetweenPoint1:prevPoint1 andPoint2:prevPoint2];
float curAngle = [self angleBetweenPoint1:curPoint1 andPoint2:curPoint2];
float angleDifference = curAngle - prevAngle;
CGAffineTransform newTransform3 = CGAffineTransformRotate(self.transform, angleDifference);
self.transform = newTransform3;
}
}
- (NSInteger)distanceBetweenPoint1:(CGPoint)point1 andPoint2:(CGPoint)point2 {
CGFloat deltaX = fabsf(point1.x - point2.x);
CGFloat deltaY = fabsf(point1.y - point2.y);
CGFloat distance = sqrt((deltaY*deltaY)+(deltaX*deltaX));
return distance;
}
- (CGFloat)angleBetweenPoint1:(CGPoint)point1 andPoint2:(CGPoint)point2
{
CGFloat deltaY = point1.y - point2.y;
CGFloat deltaX = point1.x - point2.x;
CGFloat angle = atan2(deltaY, deltaX);
return angle;
}
You might also look at Erica Sadun's example from the iphone dev cookbook (oreilly). It's in chapter 8 on gestures and touches.
http://github.com/erica/iphone-3.0-cookbook-/tree/master/C08-Gestures/14-Resize%20And%20Rotate/