I have been looking around to find a way to crop an image (imageView) inside ScrollView. What i need to achieve here is user pinch to zoom an image, (which is working great) and then able to crop ONLY the part of the image that is shown on the screen after the zoom. so in another words, if i have a series of number 1 to 10, user zoom it to see only number 4 and 5 and when user taps crop, i ONLY need image of 4 and 5 that was visible at the time of crop. I'm using this code...
- (UIImage *)croppedImageWithImage:(UIImage *)image zoom:(CGFloat)zoom
{
CGFloat zoomReciprocal = 1.0f / zoom;
CGRect croppedRect = CGRectMake(self.scrollView.contentOffset.x*zoom,
self.scrollView.contentOffset.y*zoom,
image.size.width * zoomReciprocal,
image.size.height * zoomReciprocal);
CGImageRef croppedImageRef = CGImageCreateWithImageInRect([image CGImage], croppedRect);
UIImage* croppedImage = [[UIImage alloc] initWithCGImage:croppedImageRef scale:[image scale] orientation:[image imageOrientation]];
CGImageRelease(croppedImageRef);
return croppedImage;
}
This method crops the image however, the x and y values are incorrect... What do i have to do to get the correct x and y of my crop area?
FYI.. the image i'm trying to crop is 2200 * 3200, not sure if that would make any difference?
I solved it!! here is the updated method for others who might come across this issue.
- (UIImage *)croppedImageWithImage:(UIImage *)image zoom:(CGFloat)zoom {
CGFloat zoomReciprocal = 1.0f / zoom;
CGFloat xOffset = image.size.width / self.scrollViewBackground.contentSize.width;
CGFloat yOffset = image.size.height / self.scrollViewBackground.contentSize.height;
CGRect croppedRect = CGRectMake(self.scrollViewBackground.contentOffset.x * xOffset,
self.scrollViewBackground.contentOffset.y * yOffset,
image.size.width * zoomReciprocal,
image.size.height * zoomReciprocal);
CGImageRef croppedImageRef = CGImageCreateWithImageInRect([image CGImage], croppedRect);
UIImage *croppedImage = [[UIImage alloc] initWithCGImage:croppedImageRef scale:[image scale] orientation:[image imageOrientation]];
CGImageRelease(croppedImageRef);
return croppedImage;
}
Related
I need to crop UIImage which is loaded in UIScrollview with some rect of Another UIView which is also in UIScrollView
Following is View Hierarchy
--> View
--> UIScrollView
--> viewBase (UIView)
--> UIImageView -> (Zoomed & rotated )
--> UIView (Target View)(Movable User can move anywhere in scrollview to crop rect)
My Image is Rotated & Zoomed I need to get exact part of image in TargetView
I am drawing UIImage with rotation on context following is code
CGFloat angleCroppedImageRetreacted = atan2f(self.imgVPhoto.transform.b, self.imgVPhoto.transform.a);
angleCroppedImageRetreacted = angleCroppedImageRetreacted * (180 / M_PI);
UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, self.imgVPhoto.image.size.width, self.imgVPhoto.image.size.height)];
rotatedViewBox.transform = CGAffineTransformMakeRotation(-angleCroppedImageRetreacted);
CGSize rotatedSize = rotatedViewBox.frame.size;
UIGraphicsBeginImageContext(rotatedSize);
CGContextRef bitmap = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(bitmap, rotatedSize.width / 2.0f, rotatedSize.height / 2.0f);
CGContextRotateCTM(bitmap, -angleCroppedImageRetreacted);
CGContextScaleCTM(bitmap, 1.0f, -1.0f);
CGContextDrawImage(bitmap, CGRectMake(-self.imgVPhoto.image.size.width / 2.0f,
-self.imgVPhoto.image.size.height / 2.0f,
self.imgVPhoto.image.size.width,
self.imgVPhoto.image.size.height),
self.imgVPhoto.image.CGImage);
UIImage *resultImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
And it works fine . I am getting Rotated UIImage same as i can see in Simulator
For converting Point of Target View to UIImage I use following code which is NOT WORKING
CGPoint imageViewPoint = [self.viewBase convertPoint:self.targetImageview.center toView:self.imgVPhoto];
float percentX = imageViewPoint.x / self.imgVPhoto.frame.size.width;
float percentY = imageViewPoint.y / self.imgVPhoto.frame.size.height;
CGPoint imagePoint = CGPointMake(resultImage.size.width * percentX, resultImage.size.height * percentY);
rect.origin = imagePoint;
//rect.origin.x *= (self.imgVPhoto.image.size.width / self.imgVPhoto.frame.size.width);
//rect.origin.y *= (self.imgVPhoto.image.size.height / self.imgVPhoto.frame.size.height);
imageRef = CGImageCreateWithImageInRect([resultImage CGImage], rect);
img = [UIImage imageWithCGImage:imageRef scale:viewImage.scale orientation:viewImage.imageOrientation];
I think issue is we can't use Rect after Transform Apply
Please Help me to crop UIImage which is zoomed and rotated from rect on same Hierarchy
If you need more info pls ask
I am answering my own question .
Thanks to Matic for giving a idea
I changed a logic
I have achieved same functionality what i looking for
CGPoint locationInImageView = [self.viewBase convertPoint:self.targetImageview.center toView:self.view]; // received from touch
locationInImageView = [self.view convertPoint:locationInImageView toView:self.imgVPhoto];
// I GOT LOCATION IN UIIMAGEVIEW OF TOUCH POINT
UIGraphicsBeginImageContextWithOptions(self.view.frame.size, NO, 0);
[self.imgVPhoto.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *img1 = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// I GOT UIIMAGE FROM CURRENT CONTEXT
CGFloat width = self.targetImageview.frame.size.width * self.zoomScale ;
CGFloat height = self.targetImageview.frame.size.height * self.zoomScale ;
//2 IS SCALE FACTOR
CGFloat xPos = (locationInImageView.x * 2) - width / 2;
CGFloat yPos = (locationInImageView.y * 2) - height / 2;
CGRect rect1 = CGRectMake(xPos, yPos, width, height);
CGImageRef imageRef = CGImageCreateWithImageInRect([img1 CGImage], rect1);
// YAHHH YOU HAVE EXACT IMAGE
UIImage *img = [UIImage imageWithCGImage:imageRef scale:img1.scale orientation:img1.imageOrientation];
I am working in iOS application where I want to select card rectangle from captured image using camera. So if anybody knows any solution please let me know. Thank you.
My code is below:
/**
* Cut out a image to a new image with the rect
*
* #param image UIImage image origin image
* #param rect CGRect rect the rect area you want
*
* #return UIImage
*/
+ (UIImage *)ct_imageFromImage:(UIImage *)image inRect:(CGRect)rect{
CGFloat scale = [UIScreen mainScreen].scale;
CGFloat x= rect.origin.x*scale,y=rect.origin.y *scale,w=rect.size.width*scale,h=rect.size.height*scale;
CGRect dianRect = CGRectMake(x, y, w, h);
//cut the image with the rect area
CGImageRef sourceImageRef = [image CGImage];
CGImageRef newImageRef = CGImageCreateWithImageInRect(sourceImageRef, dianRect);
UIImage *newImage = [UIImage imageWithCGImage:newImageRef scale:[UIScreen mainScreen].scale orientation:UIImageOrientationUp];
return newImage;
}
I am using the following crop method to crop a uiimage that's sitting in a UIImageView which is then sitting in a UIScrollView.
-(UIImage *)cropImage:(UIImage *)image
{
float scale = 1.0f/_scrollView.zoomScale;
NSLog(#"Oh and heres that zoomScale: %f", _scrollView.zoomScale);
CGRect visibleRect;
visibleRect.origin.x = _scrollView.contentOffset.x * scale;
visibleRect.origin.y = _scrollView.contentOffset.y * scale;
visibleRect.size.width = _scrollView.bounds.size.width * scale;
visibleRect.size.height = _scrollView.bounds.size.height * scale;
NSLog(#"Oh and here's that CGRect: %f", visibleRect.origin.x);
NSLog(#"Oh and here's that CGRect: %f", visibleRect.origin.y);
NSLog(#"Oh and here's that CGRect: %f", visibleRect.size.width);
NSLog(#"Oh and here's that CGRect: %f", visibleRect.size.height);
CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], visibleRect);
UIImage *croppedImage = [[UIImage alloc] initWithCGImage:imageRef];
CGImageRelease(imageRef);
return croppedImage;
}
I need the image to be cropped to a CGSize of (321,115). Upon cropping the image and seeing the print results, I can see that visibleRect is (0,0,321,115) - what it is supposed to be, the croppedImage UIImage then has width:321 and height:115. for some reason however the image appears to be zoomed in entirely too far (the method cropped a smaller portion of the original image to a size of 321x115).
Why is this method not correctly cropping my image?
-As a side note: When I call this method, I am calling like so _croppedImage = [self cropImage:_imageView.image]; which sets a UIImage property of a custom UIView class to the cropped image.
Please try this function. It may help you.
Parameters:
UIImage
CGSize (321,115) or any size
// crop image - image will crop from full image
- (UIImage *)cropImageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
double ratio;
double delta;
CGPoint offset;
//make a new square size, that is the resized imaged width
CGSize sz = CGSizeMake(newSize.width, newSize.width);
//figure out if the picture is landscape or portrait, then
//calculate scale factor and offset
if (image.size.width > image.size.height) {
ratio = newSize.width / image.size.width;
delta = (ratio*image.size.width - ratio*image.size.height);
offset = CGPointMake(delta/2, 0);
}
else {
ratio = newSize.width / image.size.height;
delta = (ratio*image.size.height - ratio*image.size.width);
offset = CGPointMake(0, delta/2);
}
//make the final clipping rect based on the calculated values
CGRect clipRect = CGRectMake(-offset.x,
-offset.y,
(ratio * image.size.width) + delta,
(ratio * image.size.height) + delta);
//start a new context, with scale factor 0.0 so retina displays get
//high quality image
if ([[UIScreen mainScreen] respondsToSelector:#selector(scale)]) {
UIGraphicsBeginImageContextWithOptions(sz, YES, 0.0);
} else {
UIGraphicsBeginImageContext(sz);
}
UIRectClip(clipRect);
[image drawInRect:clipRect];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
To crop only selected portion of image
Please check this link
I'm trying to add a video player icon on top of a thumbnail of a video.
I get the image from the YouTube API, then crop it to be square, then resize it to be the proper size. I then add my player icon image on top of it.
The problem lies in the fact that the player icon is much smaller than it should be on the thumbnail (it's 28x28pt when on screen it's much smaller). See in the below image where I added it to the cell to show the size it should be, versus the thumbnail size:
I crop it to a square with this method:
/**
* Given a UIImage, return it with a square aspect ratio (via cropping, not smushing).
*/
- (UIImage *)createSquareVersionOfImage:(UIImage *)image {
CGFloat originalWidth = image.size.width;
CGFloat originalHeight = image.size.height;
float smallestDimension = fminf(originalWidth, originalHeight);
// Determine the offset needed to crop the center of the image out.
CGFloat xOffsetToBeCentered = (originalWidth - smallestDimension) / 2;
CGFloat yOffsetToBeCentered = (originalHeight - smallestDimension) / 2;
// Create the square, making sure the position and dimensions are set appropriately for retina displays.
CGRect square = CGRectMake(xOffsetToBeCentered * image.scale, yOffsetToBeCentered * image.scale, smallestDimension * image.scale, smallestDimension *image.scale);
CGImageRef squareImageRef = CGImageCreateWithImageInRect([image CGImage], square);
UIImage *squareImage = [UIImage imageWithCGImage:squareImageRef scale:image.scale orientation:image.imageOrientation];
CGImageRelease(squareImageRef);
return squareImage;
}
Resize it with this method:
/**
* Resize the given UIImage to a new size and return the newly resized image.
*/
- (UIImage *)resizeImage:(UIImage *)image toSize:(CGSize)newSize {
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
And add it on top of the other image with this method:
/**
* Adds a UIImage on top of another UIImage and returns the result. The top image is centered.
*/
- (UIImage *)addImage:(UIImage *)additionalImage toImage:(UIImage *)backgroundImage {
UIGraphicsBeginImageContext(backgroundImage.size);
[backgroundImage drawInRect:CGRectMake(0, 0, backgroundImage.size.width, backgroundImage.size.height)];
[additionalImage drawInRect:CGRectMake((backgroundImage.size.width - additionalImage.size.width) / 2, (backgroundImage.size.height - additionalImage.size.height) / 2, additionalImage.size.width, additionalImage.size.height)];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return resultingImage;
}
And this is how it is implemented:
UIImage *squareThumbnail = [self resizeImage:[self createSquareVersionOfImage:responseObject] toSize:CGSizeMake(110.0, 110.0)];
UIImage *playerIcon = [UIImage imageNamed:#"video-thumbnail-overlay"];
UIImage *squareThumbnailWithPlayerIcon = [self addImage:playerIcon toImage:squareThumbnail];
But in the end, the icon is always too small. The sizing things confuse me when working with images, as I'm used to it figuring out retina screen related things automatically, and for example in the above code block, I'm not sure why I set it to 110.0, 110.0 as it's a 55x55 UIImageView and I thought it scales automatically (but if I put it to 55 it's stretched terribly).
The reason you have to put 110 in your resizeImage call is because you are creating a CGGraphics context with a scale of 1.0. The graphics context for views in a view hierarchy on retina displays have a scale of 2.0 (provided you did nothing to scale anything else).
I believe that new UIImage that you create is now a "normal" image (Sorry I can't remember the technical term). It is not an #2x image. So its size that you will get when you ask for size will not scale for #2x.
Note this answer:
UIGraphicsGetImageFromCurrentImageContext retina resolutions?
I haven't tested this, but it should work. If it doesn't it should at least be more straightforward to debug.
//images should be passed in with their original scales
-(UIImage*)compositedImageWithSize:(CGSize)newSize bg:(UIImage*)backgroundImage fgImage:(UIImage*)foregroundImage{
//match the scale of screen.
CGFloat scale = [[UIScreen mainScreen] scale];
UIGraphicsBeginImageContextWithOptions(newSize, NO, scale);
//instead of resizing the image ahead of time, we just draw it into the context at the appropriate size. The context will clip the image.
CGRect aspectFillRect = CGRectZero;
if(newSize.width/newSize.height > backgroundImage.size.width/backgroundImage.size.height){
aspectFillRect.y = 0;
aspectFillRect.height = newSize.height;
CGFloat scaledWidth = (newSize.height / backgroundImage.size.height) * newSize.width;
aspectFillRect.x = (newSize.width - scaledWidth)/2.0;
aspectFillRect.width = scaledWidth;
}else{
aspectFillRect.x = 0;
aspectFillRect.width = newSize.width;
CGFloat scaledHeight = (newSize.width / backgroundImage.size.width) * newSize.height;
aspectFillRect.y = (newSize.height - scaledHeight)/2.0;
aspectFillRect.height = scaledHeight;
}
[backgroundImage drawInRect:aspectFillRect];
//pass in the 2x image for the fg image so it provides a better resolution
[foregroundImage drawInRect:CGRectMake((newSize.width - additionalImage.size.width) / 2, (newSize.height - additionalImage.size.height) / 2, additionalImage.size.width, additionalImage.size.height)];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return resultingImage;
}
You would skip all those methods you were calling before and do:
UIImage *playerIcon = [UIImage imageNamed:#"video-thumbnail-overlay"];
//pass in the non-retina scale of the image
UIImage *result = [self compositedImageWithSize:CGSizeMake(55.0, 55.0)
bg:responseObject
fg:playerIcon];
Hope this helps!
I have method that zooming UIImage
- (UIImage*)croppedImageWithImage:(UIImage *)image zoom:(CGFloat)zoom
{
CGFloat zoomReciprocal = 1.0f / zoom;
CGPoint offset = CGPointMake(40, 40);
CGRect croppedRect = CGRectMake(offset.x, offset.y, image.size.width * zoomReciprocal, image.size.height * zoomReciprocal);
CGImageRef croppedImageRef = CGImageCreateWithImageInRect([image CGImage], croppedRect);
UIImage* croppedImage = [[UIImage alloc] initWithCGImage:croppedImageRef scale:[image scale] orientation:[image imageOrientation]];
CGImageRelease(croppedImageRef);
return croppedImage;
}
How to save image width and height after zooming?
To save zoomed image :
UIImageWriteToSavedPhotosAlbum(croppedImage, nil, nil, nil);
To save Image Size
CGSize imageSize = CGSizeMake(croppedImage.size.width, croppedImage.size.height);
If you want to save the image width and height just create CGSize variable and save like below
CGSize croppedSize = croppedImage.size