I am capturing CGRect with following code. But the resulting image is not the image what i want. Image has some transparent background. What to do for removing transparent background as suggesting the picture.
- (UIImage *)captureScreenInRect:(CGRect)captureFrame {
CALayer *layer;
layer = imageScrollview.layer;
UIGraphicsBeginImageContext(imageScrollview.bounds.size);
CGContextClipToRect (UIGraphicsGetCurrentContext(),captureFrame);
\[layer renderInContext:UIGraphicsGetCurrentContext()\];
UIImage *screenImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return screenImage;
}
Translate your context so that its origin matches your captureFrame:
UIGraphicsBeginImageContext(imageScrollview.bounds.size);
CGContextRef c = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(c, -captureFrame.origin.x, -captureFrame.origin.y);
[imageScrollView.layer renderInContext:c];
UIImage *screenImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
(written from memory, untested)
Additionally clipping the context is not necessary as the image is already clipped by the image context's bounds.
Try this one
CGRect cropRect = CGRectMake(imageScrollview.frame.origin.x+15, imageScrollview.frame.origin.y+15, WIDTH, HEIGHT);
Related
I want to draw image from transformed uiimageview - refer left side image,
Dragview = UIImageView that can be rotated or scaled using some controls, and I need to draw that transformed image at same position
I am facing problem with Transformation (CGContextConcatCTM),
It gives required output if
CGAffineTransform = CGAffineTransformIdentity
but I got wrong origin on output image with same transformation
below is my code to draw image same like original imageview
UIGraphicsBeginImageContext(CGSizeMake(1024, 768));
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextConcatCTM(context, dragView.originalTransform);
UIImage *curImage1 = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
try this:
UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.opaque, 0.0);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage * img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
I am using the following code for capture a view on the screen but it is not as sharp as on the screen. the imageView size is 200x200point but the scale is 2.0 (with retina screen). The saved img size is 200x200 px. how could i make the img as sharp as the original one? Any help will be appreciated!
- (UIImage*)captureView:(UIView *)theView {
CGRect rect = theView.frame;
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[theView.layer renderInContext:context];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
Try like that:
CGRect screenRect = [[UIScreen mainScreen] bounds];
UIGraphicsBeginImageContextWithOptions(screenRect.size, NO, 0.0);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
You are using the old way of creating the image context. Use this instead:
UIGraphicsBeginImageContextWithOptions(rect.size, YES, [UIScreen mainScreen].scale);
The older UIGraphicsBeginImageContext function always assumes a scale of 1.0.
Replace 'YES' with 'NO' if you need the alpha channel.
I am working on creating an image gallery which has thumbnails in different sizes. I want to convert these rectangle thumbnails to square size so that all of them could appear similar in size. I dont mind cropping it from extended portion but I am not sure how to do it. can anyone please help me?
Thanks
Pankaj
You need to use the image in rect method passing in the image and the required bounds...
CGImageRef imageRef = CGImageCreateWithImageInRect([anImage CGImage], requiredBounds);
UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
I have added this to a UIImage category (UIImage+Resize) in the following post, you can download the source code as well - Categories example
Well if you use an UIImageView to display your images (wich I am more than sure that you do) you can set it's contentMode property to UIViewContentModeScaleAspectFill. This should 'crop' your image to the boundaries of your UIImageView. In case your image will go out of the boundaries of the UIImageView make sure clipsToBounds is also set to YES.
Let me know if that helps.
I'm using the next method. The input are the UIImage to scale and the size of the UIImageView's frame where the UIImage is. It works when the frame's height and width are equal.
One important thing: I keep the image's ratio. I don't expand the image to cover the full square. If you want to do it you have to change the 'drawInRect' line for [self drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)]; and remove the if-else.
- (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
CGFloat scaleRatio;
if (image.size.width > image.size.height) {
scaleRatio = image.size.height/image.size.width;
}else{
scaleRatio = image.size.width/image.size.height;
}
CGAffineTransform scaleTransform = CGAffineTransformMakeScale(scaleRatio, scaleRatio);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextConcatCTM(context, scaleTransform);
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0);
if (image.size.width > image.size.height) {
[image drawInRect:CGRectMake(0, (newSize.height/2)-(newSize.height*scaleRatio/2), newSize.width, newSize.height*scaleRatio)];
}else{
[image drawInRect:CGRectMake((newSize.width/2)-(newSize.width*scaleRatio/2), 0, newSize.width*scaleRatio, newSize.height)];
}
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
I want to know, how can I erase a custom rect (with, for example, an UIView in IB or something else) of an UIImageView in order to display an other UIImageView positioned underneath.
I didn't manage to do it using some response in the forum...
This will clear a rect in an image:
- (UIImage *)clearRect:(CGRect)rect inImage:(UIImage *)image {
if (UIGraphicsBeginImageContextWithOptions != NULL)
UIGraphicsBeginImageContextWithOptions([image size], NO, 0.0);
else
UIGraphicsBeginImageContext([image size]);
CGContextRef context = UIGraphicsGetCurrentContext();
[image drawInRect:CGRectMake(0.0, 0.0, [image size].width, [image size].height)];
CGContextClearRect(context, rect);
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return result;
}
Just load your image and clear the rects before assigning it to the image view:
UIImage *image = [UIImage imageNamed:#"Image.png"];
UIImage *maskedImage = [self clearRect:CGRectMake(10.0, 10.0, 50.0, 50.0) inImage:image];
[imageView setImage:maskedImage];
probably not the best solution but you can do the other way and take the 4 parts around the rect separately and combine them afterwards without the inner rect. You would repeat this as long as you have rect's to crop out.
You cannot clear the UIImageView itself because this just draws the UIImage. So you have erase the rect in the UIImage. Create a bitmap context, draw the image into it. Erase the part you want to "see through" with CGContextClearRect. When create a new new image from the bitmap context.
I used the codes below to rotate an UIImage
double angle = -90;
NSData *imageData = [NSData dataWithContentsOfFile:sss];
UIImage *image =[UIImage imageWithData:imageData];
CGSize s = {image.size.width, image.size.height};
UIGraphicsBeginImageContext(s);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(ctx, 0,image.size.height);
CGContextScaleCTM(ctx, 1.0, -1.0);
CGContextRotateCTM(ctx, 2*M_PI*angle/360);
CGContextDrawImage(ctx,CGRectMake(0,0,image.size.width, image.size.height),image.CGImage);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[myUIImageView setImage:newImage];
but nothing displays on myUIImageView.
If there is anything wrong?
Welcome any comment
Thanks
interdev
If you're going to be rotating the image 90 degrees, you should swap the width and height when you create the image context:
CGSize s = {image.size.height, image.size.width};
This way, there's enough space to draw the fully-transformed image. Attempting to draw an image into a rectangle which exceeds the bounds of a graphics context will just result in nothing being drawn.
P.S. I recommend using a CGBitmapContext instead of UIGraphicsBeginImageContext(), as the former is thread-safe, which means you'd be able to do your image manipulations on a background thread if you so chose.