問題描述
使用 CGAffineTransform 時限制 UIImageView 的大小 (Limitting UIImageView size while using CGAffineTransform)
I want to limit my uiimageview size while using CGAffineTransform. I am limitting scale but I can't limit the size of the my uiimageview. When I run the app I see it is limitted but in the background the size of my uiimageview keeps increasing. How can I make this?
Here is my code:
- (id)initWithFrame:(CGRect)frame
{
if ([super initWithFrame:frame] == nil) {
return nil;
}
originalTransform = CGAffineTransformIdentity;
touchBeginPoints = CFDictionaryCreateMutable(NULL, 0, NULL, NULL);
self.userInteractionEnabled = YES;
self.multipleTouchEnabled = YES;
self.exclusiveTouch = YES;
return self;
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
NSMutableSet *currentTouches = [[[event touchesForView:self] mutableCopy] autorelease];
[currentTouches minusSet:touches];
if ([currentTouches count] > 0) {
[self updateOriginalTransformForTouches:currentTouches];
[self cacheBeginPointForTouches:currentTouches];
}
[super touchesBegan:touches withEvent:event];
[self cacheBeginPointForTouches:touches];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
CGAffineTransform incrementalTransform = [self incrementalTransformWithTouches:[event touchesForView:self]];
self.transform = CGAffineTransformConcat(originalTransform, incrementalTransform);
CGAffineTransform transform = self.transform;
float scale = sqrt(transform.a*transform.a + transform.c*transform.c);
NSLog(@"%f",self.frame.size.height);
if (scale > SCALE_MAX){
self.transform = CGAffineTransformScale(transform, SCALE_MAX/scale, SCALE_MAX/scale);
}
else if (scale < SCALE_MIN){
self.transform = CGAffineTransformScale(transform, SCALE_MIN/scale, SCALE_MIN/scale);
}
[super touchesMoved:touches withEvent:event];
}
-(void)updateOriginalTransformForTouches:(NSSet *)touches{
CGAffineTransform transform = self.transform;
float scale = sqrt(transform.a*transform.a + transform.c*transform.c);
if (scale > SCALE_MAX){
self.transform = CGAffineTransformScale(transform, SCALE_MAX/scale, SCALE_MAX/scale);
}
else if (scale < SCALE_MIN){
self.transform = CGAffineTransformScale(transform, SCALE_MIN/scale, SCALE_MIN/scale);
}
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
for (UITouch *touch in touches) {
if (touch.tapCount >= 2) {
[self.superview bringSubviewToFront:self];
}
}
[self updateOriginalTransformForTouches:[event touchesForView:self]];
[self removeTouchesFromCache:touches];
NSMutableSet *remainingTouches = [[[event touchesForView:self] mutableCopy] autorelease];
[remainingTouches minusSet:touches];
[super touchesEnded:touches withEvent:event];
[self cacheBeginPointForTouches:remainingTouches];
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {
[self touchesEnded:touches withEvent:event];
}
參考解法
方法 1:
You can know CGRect of UIImagView before applying transform on it like below example :
//Create transform
CGAffineTransform scaleTransform = CGAffineTransformMakeScale(1.2, 1.2);
//Apply transform on UIImageView to get CGRect
CRect newRect = CGRectApplyAffineTransform(yourImgView.frame, scaleTransform);
//Check if rect is in valid limitation
if(newRect.size.height > 200 && newRect.size.width >200) //your condition to limit UIImageView's Size
{
//Valid so apply transform
yourImageView.transform = scaleTransform
}
else
{
//rect increases so no transform
// no transform to UIImageView
NSLog(@"%@",NSStringFromCGRect(yourImageView.frame))
}
方法 2:
I was facing the a similar problem, I have an image view that's rotating according to compass heading data and also has to move position according to device change in interface orientation
I created a tempImageView to help maintain frame, and kept reseting it with every change in device orientation
- (void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
// equal tempImageView to imageView
_tempImageView = [[UIImageView alloc] initWithFrame:CGRectMake(self.view.frame.size.width-75, 150, 64, 61)];
[_tempImageView setImage:[UIImage imageNamed:@"image.gif"]];
_tempImageView.transform = _imageView.transform;
// reset imageView
[_imageView removeFromSuperview];
_imageView = _tempImageView;
[self.view insertSubview:_imageView atIndex:1];
}
(by user1560010、Paresh Navadiya、Ahmed Elashker)