Crop enlarged image in ImageView inside scrollView

Question

I already do a lot of effort on my part. finally i need help. thanks

Purpose: 1) How do I map imageView inside ScrollView

2) How do I crop the enlarged image inside scrollView.

I have a View image inside Scroll View. I want a cropping image after scaling that displays inside the scroll border. I cropped the image already, but this is not quite what I need.

Here I set the backgroundColor Black to my scrollView. And when I put an imageView in it, it doesn't fit.

after viewing the enlarged image inside the scroll

and after cropping image

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

 -(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 the 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 to my question: After many efforts, I found the answer to both of my questions.

and it works well for me. I share here, maybe this helps someone. :)

1) Fit image View inside Scroll View. I use the 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 the enlarged image inside scrollView. I use the 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

Recently, I had a similar problem, I got a 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 ImageView in Aspect Fit, you need to calculate the frame of the image 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

Raphael.