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.
Related
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);
I've got an image that I need crop. To do this, I wanted to use the contentMode (set it to Top/TopLeft instead of Aspect Fit) but when I'm doing this, the image go back to it's real size (and not the size I gave to it). So my question is :
How to crop the bottom of my image retaining its size ?
Thanks a lot.
May be you have to set the rect for the imageView
imageView is the instance of UIImageView
Let the rectangle to be cropped is croppedRect
CGImageRef imageRef = CGImageCreateWithImageInRect([imageView.image CGImage], croppedRect);
[imageView setImage:[UIImage imageWithCGImage:imageRef]];
CGImageRelease(imageRef);
The generic problem I'm facing is this:
I have a stretchable 50x50 PNG. I'm stretching it to 300x100. I want to get three UIImages of size 100x100 cut from the stretched image, A, B & C in the picture below:
I'm trying to do it like this:
// stretchedImage is the 50x50 UIImage, abcImageView is the 300x100 UIImageView
UIImage *stretchedImage = [abcImageView.image stretchableImageWithLeftCapWidth:25 topCapHeight:25];
CGImageRef image = CGImageCreateWithImageInRect(stretchedImage.CGImage, bButton.frame);
UIImage *result = [UIImage imageWithCGImage:image];
[bButton setBackgroundImage:result forState:UIControlStateSelected];
CGImageRelease(image);
I'm trying to crop the middle 100 ("B") using CGImageCreateWithImageInRect, but this is not right, since stretchedImage is 50x50, not 300x100. How do I get the 300x100 image to crop from? If the original image was 300x100 there would be no problem, but then I would lose the advantage of stretchable image.
I guess to generalize the problem even more, the question would be as simple as: if you scale or stretch an image to a bigger image view, how do you get the scaled/stretched image?
Background for the specific task I'd like to apply the solution for (if you can come up with an alternative solution):
I'm trying to implement a UI that's similar to the one you see during a call in native iPhone call application: a plate containing buttons for mute, speaker, hold, etc. Some of them are toggle type buttons with a different background color for selected state.
I have two graphics for the whole plate, for non-selected and selected states. I'm stretching both images to the desired size. For the buttons in selected state I want to get a piece of the stretched selected graphic.
You should be able to do this by rendering abcImageView to a UIImage
UIGraphicsBeginImageContextWithOptions(abcImageView.bounds.size, NO, 0.f);
[abcImageView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Then, you can crop the image like this (given cropRect):
CGImageRef cgImage = CGImageCreateWithImageInRect(image.CGImage, cropRect);
UIImage *croppedImage = [UIImage imageWithCGImage:cgImage];
// Do something with the image.
CGImageRelease(cgImage);
I have a UIImage that is reading from a transparent PNG (500px by 500px). Somewhere in the image, there is a picture that I want to crop out and save as a separate UIImage. I also want to store the X and Y coordinates based on how many transparent pixels there were on the left and top of the newly cropped rectangle.
I was able to crop an image with this code:
- (UIImage *)cropImage:(UIImage *)image atRect:(CGRect)rect
{
double scale = image.scale;
CGRect scaledRect = CGRectMake(rect.origin.x*scale,rect.origin.y*scale,rect.size.width*scale,rect.size.height*scale);
CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], scaledRect);
UIImage *cropped = [UIImage imageWithCGImage:imageRef scale:scale orientation:image.imageOrientation];
CGImageRelease(imageRef);
return cropped;
}
Which actually cuts off the transparent pixels on the top and left :S (this would be great if I was able to crop the pixels on right and bottom too!). It then resizes the rest of the image to the rectangle I specified. Unfortunately though I need to cut a picture that is in the middle of the image and I need the size to be able to be dynamic.
Been struggling with this for several hours now. Any ideas?
To crop an image, draw it into a smaller graphics context.
For example, let's say you have a 600x600 image. And let's say that you want to crop 200 pixels off all four sides. That leaves a 200x200 rectangle.
So you would make a 200x200 graphics context, using UIGraphicsBeginImageContextWithOptions. Then you would draw the image into it using drawAtPoint:, drawing at the point (-200,-200). If you think about it, you will see that that offset causes just the 200x200 from the middle of the original to be drawn into the actual bounds of the context. Thus you have cropped the image by 200 pixels on all four sides, which is what we wanted to do.
Thus here is a generalized version, assuming that we know the amount to crop from the left, right, top, and bottom:
UIImage* original = [UIImage imageNamed:#"original.png"];
CGSize sz = [original size];
CGFloat cropLeft = ...;
CGFloat cropRight = ...;
CGFloat cropTop = ...;
CGFloat cropBottom = ...;
UIGraphicsBeginImageContextWithOptions(
CGSizeMake(sz.width - cropLeft - cropRight, sz.height - cropTop - cropBottom),
NO, 0);
[original drawAtPoint:CGPointMake(-cropLeft, -cropTop)];
UIImage* cropped = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
After that, cropped is your cropped image.
Image Size captured using Camera return's image of size 720*960.
The captured Image is displayed in a UIImageView of 320*436, like this.
UIImageView *imgView=[[UIImageView alloc] initWithFrame:CGRectMake(0.0,0.0,320.0,436.0)];
imgView.image=img;//Image received from camera.
[self.view addSubView:imgView];
This, works fine image 720*960 is scaled to 320*436 and displayed.
Now, from here actual problem starts. I have another image of size 72*72. This image is overlapped with the image received from camera at some arbitrary coordinates.
CGRectMake(0.0,0.0,72.0,72.0);
I am not able to find a better way to handle scaling and applying a overlay of another Image, at the same time maintain its quality.
The image needs to be send to a server.
Use the following code to scale images:
-(UIImage*) imageWithImage:(UIImage*)image scaledToSize:(CGSize)newSize
{
UIGraphicsBeginImageContext(newSize);
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}