I have an image with multiple icons, and I have the position and the size of the icon that I want to show.
The question is, how can I show just part of an image in a UIImageView so I can show only the icon that I want to?
Is it possible to show the icon correctly in 1x, 2x, and 3x, even if the image gets a bit pixelated?
You can crop a part of the image and create a new UIImage from it with CGImageCreateWithImageInRect:
CGRect cropRect = CGRectMake(x,y,width,height); //Calculate the rect you'd like to show
CGImageRef imageRef = CGImageCreateWithImageInRect(originalImage.CGImage, cropRect);
UIImage* outImage = [UIImage imageWithCGImage:imageRef scale:originalImage.scale orientation:originalImage.imageOrientation];
CGImageRelease(imageRef);
Related
I have an implementation of AVCaptureSession and my goal is for the user to take a photo and only save the part of the image within the red square border, as shown below:
AVCaptureSession's previewLayer (the camera) spans from (0,0) (top left) to the bottom of my camera controls bar (the bar just above the view that contains the shutter). My navigation bar and controls bar are semi-transparent, so the camera can show through.
I'm using [captureSession setSessionPreset:AVCaptureSessionPresetPhoto]; to ensure that the original image being saved to the camera roll is like Apple's camera.
The user will be able to take the photo in portrait, landscape left and right, so the cropping method must take this into account.
So far, I've tried to crop the original image using this code:
DDLogVerbose(#"%#: Image crop rect: (%f, %f, %f, %f)", THIS_FILE, self.imageCropRect.origin.x, self.imageCropRect.origin.y, self.imageCropRect.size.width, self.imageCropRect.size.height);
// Create new image context (retina safe)
UIGraphicsBeginImageContextWithOptions(CGSizeMake(self.imageCropRect.size.width, self.imageCropRect.size.width), NO, 0.0);
// Create rect for image
CGRect rect = self.imageCropRect;
// Draw the image into the rect
[self.captureManager.stillImage drawInRect:rect];
// Saving the image, ending image context
UIImage *croppedImage = UIGraphicsGetImageFromCurrentImageContext();
However, when I look at the cropped image in the camera roll, it seems that it has just squashed the original image, and not discarded the top and bottom parts of the image like I'd like. It also results in 53 pixels of white space at the top of the "cropped" image, likely because of the y position of my CGRect.
This is my logging output for the CGRect:
Image crop rect: (0.000000, 53.000000, 320.000000, 322.000000)
This also describes the frame of the red bordered view in the superview.
Is there something crucial I'm overlooking?
P.S. The original image size (taken with a camera in portrait mode) is:
Original image size: (2448.000000, 3264.000000)
You can crop images with CGImageCreateWithImageInRect:
CGImageRef imageRef = CGImageCreateWithImageInRect([uncroppedImage CGImage], bounds);
UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
Don't forget to add scale parameter otherwise you will get low resolution image
CGImageRef imageRef = CGImageCreateWithImageInRect([uncroppedImage CGImage], CGRectMake(0, 0, 30, 120));
[imageView setImage:[UIImage imageWithCGImage:imageRef scale:[[UIScreen mainScreen] scale] orientation:UIImageOrientationUp]];
CGImageRelease(imageRef);
Swift 3:
let imageRef:CGImage = uncroppedImage.cgImage!.cropping(to: bounds)!
let croppedImage:UIImage = UIImage(cgImage: imageRef)
I want to crop selected image from a gallery (Programmatically). I have done a lot of research and got the [tutor](http://iosdevelopertips.com/graphics/how-to-crop-an-image.html) gone through this.still getting confuse whether cropping of image can be done by using UIImagePickerController or UIImageView.I'm not getting from where to start or how to start?. please suggest me the right way any one.
Answer : CGImage Reference
1) Create a rectangle that represents a cropped image from the middle of the existing image :
CGRect rect = CGRectMake(size.width / 4, size.height / 4 ,
(size.width / 2), (size.height / 2));
2) Create bitmap image from original image data, using rectangle to specify desired crop area :
CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], rect);
UIImage *img = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
3) Create and show the new image from bitmap data :
imageView = [[UIImageView alloc] initWithImage:img];
Useful Links :
1) Working with UIGestureRecognizers.
2) Cropping and Resizing Images from Camera in iOS and Objective-C.
GoodLuck !!!
I can access image's by using [UIImage imageNamed:#"nameOfPng.png"]; if I have a single image in a .png file. But if we are having a multiple images in a .png file, how do we access sub images from a single UIImage ?
This is the single .png file. If i wanted to get the red button image or any other button image how can I do this.
What you are looking to do is to create a clipped UIImage from a section of your current image. I usually do it this way, changing the clip rect each time. Where srcImage is your original image.
//Set the clip rectangle
CGRect clipRect = CGRectMake(0, 0, 100, 100);
//Get sub image
CGImageRef drawImage = CGImageCreateWithImageInRect(srcImage.CGImage, clipRect);
UIImage *newImage = [UIImage imageWithCGImage:drawImage];
CGImageRelease(drawImage);
Yep as the title says I need to take a cropped snapshot of my app.
I want to cut top of the screenshot little bit (%20) I already have a code which I used to take a snapshot and send it to facebook and its working but its taking the photo of all of the screen so how can tell my code to ignore the %20 percent of the screen.Maybe with height and width also I looked some questions in the stack overflow and manage to slide my screenshot so I get rid of the unwanted part at the top but this time at the bottom huge white area appeared so it didnt solve my problem.
Here is my snapshot code
UIGraphicsBeginImageContext(self.ekran.bounds.size);
[self.ekran.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
A method to crop the image, that accepts any frame to crop the image against
- (UIImage *)cropImage:(UIImage *)imageToCrop toRect:(CGRect)rect
{
CGImageRef imageRef = CGImageCreateWithImageInRect([imageToCrop CGImage], rect);
UIImage *cropped = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
return cropped;
}
Use it as follows:
UIGraphicsBeginImageContext(self.ekran.bounds.size);
[self.ekran.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGFloat imgHight = resultingImage.size.height;
// Create a frame that crops the top 20% of the image
CGRect* imageFrame = CGRectMake(0, imgHight - (imgHight*0.8), width, imgHight*0.8);
resultingImage = [self cropImage:resultingImage toRect:imageFrame];
I have one UIImageView. Its content mode is set to AspectFit.
[imageView setContentMode:UIViewContentModeScaleAspectFit].
I need to crop a subImage from this image. This is the code which crops the image:
CGImageRef imageRef = CGImageCreateWithImageInRect([imageView.image CGImage], customRect);
UIImage *cropped = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
where customRect is the rectangle from which I need to crop the image.
This is how I calculate it:
CGRect customRect = CGRectMake((cropView.frame.origin.x/xFactor),
(cropView.frame.origin.y/yFactor),
(cropView.frame.size.width/xFactor),
(cropView.frame.size.height/yFactor));
The problem comes in cropping. CGImageCreateWithImageInRect crops the given area according to the actual image size which, in some cases, is larger than the image view size. I tried using other approaches such as UIGraphics:getImageFromCurrentImageContext but these do not keep the image quality as much as it degrades them.