crop a zoomed image in ImageView inside scrollView - iphone

Question

I already do Lot of efforts from my Side. finally I need help. thanks
Goal :
1) How I fit imageView inside ScrollView
2) How I crop a zoomed Image in inside scrollView.
I have a imageView inside Scroll View. I wants crop image after zoomed which is display inside scrollview boundary. I cropped image already but it not exactly same which i wants.
Here I set backgroundColor Black to my scrollView. And when I place imageView inside it, it's not fit.
after zoom image inside scroll view is
and after crop image is
and my code is here :
- (void)viewDidLoad
{
[super viewDidLoad];
CGRect frame1 = CGRectMake(50,50,200,200);
CGRect frame2 = CGRectMake(50,50,200,200);
imageView1=[[UIImageView alloc]initWithFrame:frame1];
imageView1.image= [UIImage imageNamed:#"back.jpeg"];
imageView1.backgroundColor=[UIColor brownColor];
imageView1.contentMode = UIViewContentModeScaleAspectFit;
scroll=[[UIScrollView alloc]initWithFrame:frame2];
scroll.backgroundColor=[UIColor blackColor];
[scroll addSubview:imageView1];
scroll.delegate=self;
[self.view addSubview:scroll];
[self setContentSizeForScrollView];
self.imageView1.userInteractionEnabled = YES;
}
setting scroll view contentSize
-(void)setContentSizeForScrollView
{
// scroll.contentSize = CGSizeMake(imageView1.frame.size.width,imageView1.frame.size.height);
scroll.contentSize = CGSizeMake(200, 200);
scroll.minimumZoomScale = .50;
scroll.maximumZoomScale = 1.5;
}
and my crop logic is
-(IBAction)cropButtonClicked
{
//Calculate the required area from the scrollview
CGRect rect = CGRectMake(50, 50, 200,200);
UIImage *image = [self imageByCropping:imageView1.image toRect:rect];
imageView1.image=image;
imageView1.contentMode = UIViewContentModeScaleAspectFit;
}
And this method crop image :
- (UIImage*)imageByCropping:(UIImage *)myImage toRect:(CGRect)cropToArea{
CGImageRef cropImageRef = CGImageCreateWithImageInRect(myImage.CGImage, cropToArea);
UIImage* cropped = [UIImage imageWithCGImage:cropImageRef];
CGImageRelease(cropImageRef);
return cropped;
}

Answer 1

Answer of my own Question : After many efforts i found the answer of both of my questions.
and it work good for me. I share here, may be it help someone. :)
1) Fit image View inside Scroll View. I use this link
- (void)centerScrollViewContents {
CGSize boundsSize = scroll.bounds.size;
CGRect contentsFrame = self.imageView1.frame;
if (contentsFrame.size.width < boundsSize.width) {
contentsFrame.origin.x = (boundsSize.width - contentsFrame.size.width) / 2.0f;
}
else {
contentsFrame.origin.x = 0.0f;
}
if (contentsFrame.size.height < boundsSize.height) {
contentsFrame.origin.y = (boundsSize.height - contentsFrame.size.height) / 2.0f;
}
else {
contentsFrame.origin.y = 0.0f;
}
self.imageView1.frame = contentsFrame;
}
2) Crop a zoomed Image in inside scrollView. I use this link
UIGraphicsBeginImageContext(CGSizeMake(200, 200));
[scroll.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *fullScreenshot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
imageView1.contentMode = UIViewContentModeScaleAspectFill;
UIImageWriteToSavedPhotosAlbum(fullScreenshot, nil, nil, nil);
return fullScreenshot;

Answer 2

I had a similar problem recently, I got the solution using the relative idea ( Xa,b = Xa,c - Xb,c )
-(IBAction)crop:(id)sender{
// F = frame
// i = image
// iv = imageview
// sv = self.view
// of = offset
//Frame Image in imageView coordinates
CGRect Fi_iv = [self frameForImage:self.image inImageViewAspectFit:self.imageView];
//Frame ImageView in self.view coordinates
CGRect Fiv_sv = self.imageView.frame;
//Frame Image in self.view coordinates
CGRect Fi_sv = CGRectMake(Fi_iv.origin.x + Fiv_sv.origin.x
,Fi_iv.origin.y + Fiv_sv.origin.y,
Fi_iv.size.width, Fi_iv.size.height);
//ScrollView offset
CGPoint offset = self.scrollView.contentOffset;
//Frame Image in offset coordinates
CGRect Fi_of = CGRectMake(Fi_sv.origin.x - offset.x,
Fi_sv.origin.y - offset.y,
Fi_sv.size.width,
Fi_sv.size.height);
CGFloat scale = self.imageView.image.size.width/Fi_of.size.width;
//the crop frame in image offset coordinates
CGRect Fcrop_iof = CGRectMake((self.cropView.frame.origin.x - Fi_of.origin.x)*scale,
(self.cropView.frame.origin.y - Fi_of.origin.y)*scale,
self.cropView.frame.size.width*scale,
self.cropView.frame.size.height*scale);
UIImage *image = [self image:self.imageView.image cropRect:Fcrop_iof];
// Use this crop image...
You can crop the image using:
//Use this code to crop when you have the right frame
-(UIImage*)image:(UIImage *)image cropRect:(CGRect)frame
{
// Create a new UIImage
CGImageRef imageRef = CGImageCreateWithImageInRect(image.CGImage, frame);
UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
return croppedImage;
}
Since you are using the ImageView in Aspect Fit, you need to calculate the image frame inside the imageView
-(CGRect)frameForImage:(UIImage*)image inImageViewAspectFit:(UIImageView*)imageView
{
float imageRatio = image.size.width / image.size.height;
float viewRatio = imageView.frame.size.width / imageView.frame.size.height;
if(imageRatio < viewRatio)
{
float scale = imageView.frame.size.height / image.size.height;
float width = scale * image.size.width;
float topLeftX = (imageView.frame.size.width - width) * 0.5;
return CGRectMake(topLeftX, 0, width, imageView.frame.size.height);
}
else
{
float scale = imageView.frame.size.width / image.size.width;
float height = scale * image.size.height;
float topLeftY = (imageView.frame.size.height - height) * 0.5;
return CGRectMake(0, topLeftY, imageView.frame.size.width, height);
}
}
I hope this code can work for you as it worked for me.
Best,
Rafael.