I have the exact problem as described here:
crop a rotated UIImage.
I need to crop a rotated UIImage, however, when I try the solution it doesn't crop the image
UIView *rotatedViewBox = [[UIView alloc] initWithFrame:videoPreviewView.frame];
NSLog(#"frame width: %f height:%f x:%f y:%f",videoPreviewView.frame.size.width, videoPreviewView.frame.size.height,videoPreviewView.frame.origin.x,videoPreviewView.frame.origin.y);
rotatedViewBox.transform = CGAffineTransformMakeRotation(90 * M_PI / 180);
CGSize rotatedSize = rotatedViewBox.frame.size;
UIGraphicsBeginImageContext(rotatedSize);
CGContextRef bitmap = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(bitmap, rotatedSize.width / 2.0f, rotatedSize.height / 2.0f);
CGContextRotateCTM(bitmap, 90 * M_PI / 180);
CGContextScaleCTM(bitmap, 1.0f, -1.0f);
CGContextDrawImage(bitmap, CGRectMake(-videoPreviewView.frame.size.width / 2.0f,
-videoPreviewView.frame.size.height / 2.0f,
videoPreviewView.frame.size.width,
videoPreviewView.frame.size.height),
image.CGImage);
UIImage *resultImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
The log is:
frame width:310 height:310 x:0 y: 69
The rotation works though but the new image is not cropped on 0,69,310,310 of the old image.
You are using a "solution" which, although accepted, also carries the OP comment "but it's not working."
The solution only claims to deal with the rotation part of the problem, not the crop. It's doing what it claims to do, but no more.
Here's a CG function that performs a crop:
CGImageRef CGImageCreateWithImageInRect (
CGImageRef image,
CGRect rect
);
Input you image and the rect of the region you want to crop to.
See the answer here for an example use:
Cropping an UIImage
Related
I am performing rotation on an UIImageView and then i try to crop a part of it and save it as an UIImage. The UIImageView rotates however it always crops the same part of the photo. So the cropping does not take into account the image rotation. What am i doing wrong?
//rotate image
CGRect new = CGRectMake(0, 0, 100, 50);
CGAffineTransform rotation = CGAffineTransformMakeRotation(5);
[photo setTransform:rotation];
// crop image
CGImageRef imageRef = CGImageCreateWithImageInRect([photo.image CGImage], new);
UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
// display crop bounds
UIView* faceBounds = [[UIView alloc] initWithFrame:new];
faceBounds.layer.borderWidth = 2;
faceBounds.layer.borderColor = [[UIColor redColor] CGColor];
Use the following snippet for rotating image data.
The input data is inAngle (angle in radians) and inImage (UIImage instance).
What this does, it creates an image context, applies the transformation to it and draws the original image into that context. The resulting image data will now be stored in resultImage.
The first three lines handle the calculation of the bounding result image frame.
UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, inImage.size.width, inImage.size.height)];
rotatedViewBox.transform = CGAffineTransformMakeRotation(inAngle);
CGSize rotatedSize = rotatedViewBox.frame.size;
UIGraphicsBeginImageContext(rotatedSize);
CGContextRef bitmap = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(bitmap, rotatedSize.width / 2.0f, rotatedSize.height / 2.0f);
CGContextRotateCTM(bitmap, inAngle);
CGContextScaleCTM(bitmap, 1.0f, -1.0f);
CGContextDrawImage(bitmap, CGRectMake(-inImage.size.width / 2.0f,
-inImage.size.height / 2.0f,
inImage.size.width,
inImage.size.height),
inImage.CGImage);
UIImage *resultImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
This is too late for now but For now someone can try this
This is a simple issue, which is bugging me ...
So, I have an object of UIImageView over which, I use
-(void)rotate {
// ...
CGAffineTransform transform = CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(180));
self.image.transform = transform; // image is a property.
}
So, when I call this method once, it rotates the object !. When I call the method again, I expect the object to be rotated again - but it is not rotating by another 180 degrees. After messing with the coordinates and moving the image, I can understand that the -perspective of the object has also be rotated by 180 degrees and all coordinates have been inverted as well.
I want the object's perspective to be restored (although it's been rotated by some angle) such that, I can continue to rotate and move it just like before !
Any ideas ?
Anyways, this code works:
UIImage* rotateUIImage(const UIImage* src, float angleDegrees) {
UIView* rotatedViewBox = [[UIView alloc] initWithFrame: CGRectMake(0, 0, src.size.width, src.size.height)];
float angleRadians = angleDegrees * ((float)M_PI / 180.0f);
CGAffineTransform t = CGAffineTransformMakeRotation(angleRadians);
rotatedViewBox.transform = t;
CGSize rotatedSize = rotatedViewBox.frame.size;
UIGraphicsBeginImageContext(rotatedSize);
CGContextRef bitmap = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);
CGContextRotateCTM(bitmap, angleRadians);
CGContextScaleCTM(bitmap, 1.0, -1.0);
CGContextDrawImage(bitmap, CGRectMake(-src.size.width / 2, -src.size.height / 2, src.size.width, src.size.height), [src CGImage]);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
Solved the problem with CABasicAnimation !
I want to rotate an UIImage (not UIImageView) in custom degree
I followed this post but it didn't work for me.
Anyone can help? Thanks.
UPDATE:
The code below does some of the job, but I lose some of the image after rotating it:
What should I change to get it right? (btw the yellow color in the screenshots is my UIImageView bg)
- (UIImage *) rotate: (UIImage *) image
{
double angle = 20;
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();
return newImage;
}
This method return you image on your angle of rotate
#pragma mark -
#pragma mark Rotate Image
- (UIImage *)scaleAndRotateImage:(UIImage *)image {
CGImageRef imgRef = image.CGImage;
CGFloat width = CGImageGetWidth(imgRef);
CGFloat height = CGImageGetHeight(imgRef);
CGAffineTransform transform = CGAffineTransformIdentity;
CGRect bounds = CGRectMake(0, 0, width, height);
CGFloat boundHeight;
boundHeight = bounds.size.height;
bounds.size.height = bounds.size.width;
bounds.size.width = boundHeight;
transform = CGAffineTransformMakeScale(-1.0, 1.0);
transform = CGAffineTransformRotate(transform, M_PI / 2.0); //use angle/360 *MPI
UIGraphicsBeginImageContext(bounds.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextConcatCTM(context, transform);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), imgRef);
UIImage *imageCopy = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return imageCopy;
}
- (UIImage *)rotate:(UIImage *)image radians:(float)rads
{
float newSide = MAX([image size].width, [image size].height);
CGSize size = CGSizeMake(newSide, newSide);
UIGraphicsBeginImageContext(size);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(ctx, newSide/2, newSide/2);
CGContextRotateCTM(ctx, rads);
CGContextDrawImage(UIGraphicsGetCurrentContext(),CGRectMake(-[image size].width/2,-[image size].height/2,size.width, size.height),image.CGImage);
//CGContextTranslateCTM(ctx, [image size].width/2, [image size].height/2);
UIImage *i = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return i;
}
this function rotates any image on its center, but the image becomes a square so I would suggest referencing the image center when drawing it after this function.
You need to address two things to make this work.
You are rotating about the bottom corner of the image instead of the centre
The bounding rectangle of the resulting image needs to be larger now the image is rotated for it to fit in.
To solve the rotation about the centre, first perform a translate to the centre, then rotate, then translate back.
CGAffineTransform transform = CGAffineTransformIdentity;
transform = CGAffineTransformTranslate(transform, boundingRect.size.width/2, boundingRect.size.height/2);
transform = CGAffineTransformRotate(transform, angle);
transform = CGAffineTransformScale(transform, 1.0, -1.0);
CGContextConcatCTM(context, transform);
// Draw the image into the context
CGContextDrawImage(context, CGRectMake(-imageView.image.size.width/2, -imageView.image.size.height/2, imageView.image.size.width, imageView.image.size.height), imageView.image.CGImage);
// Get an image from the context
rotatedImage = [UIImage imageWithCGImage: CGBitmapContextCreateImage(context)];
To calculate the size of the bounding rectangle you'd need to fit the new rotated image into use this:
- (CGRect) getBoundingRectAfterRotation: (CGRect) rectangle byAngle: (CGFloat) angleOfRotation {
// Calculate the width and height of the bounding rectangle using basic trig
CGFloat newWidth = rectangle.size.width * fabs(cosf(angleOfRotation)) + rectangle.size.height * fabs(sinf(angleOfRotation));
CGFloat newHeight = rectangle.size.height * fabs(cosf(angleOfRotation)) + rectangle.size.width * fabs(sinf(angleOfRotation));
// Calculate the position of the origin
CGFloat newX = rectangle.origin.x + ((rectangle.size.width - newWidth) / 2);
CGFloat newY = rectangle.origin.y + ((rectangle.size.height - newHeight) / 2);
// Return the rectangle
return CGRectMake(newX, newY, newWidth, newHeight);
}
You can find these techniques in my previous posts and answers here:
Creating a UIImage from a rotated UIImageView
and here:
Saving 2 UIImages
Hope this helps,
Dave
for rotate image.. you can use this IBAction ... for each and every button click, the image will be rotate by 90 degree...
-(IBAction)rotateImageClick:(id)sender{
UIImage *image2=[[UIImage alloc]init];
image2 = [self imageRotatedByDegrees:self.roateImageView.image deg:(90)]; //Angle by 90 degree
self.roateImageView.image = image2;
imgData= UIImageJPEGRepresentation(image2,0.9f);
}
for rotating image u only have to pass UIimage and rotating degrees for the following method
- (UIImage *)imageRotatedByDegrees:(UIImage*)oldImage deg:(CGFloat)degrees
//------------------------------------------------------------------------
#pragma mark - imageRotatedByDegrees Method
- (UIImage *)imageRotatedByDegrees:(UIImage*)oldImage deg:(CGFloat)degrees{
// calculate the size of the rotated view's containing box for our drawing space
UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0,oldImage.size.width, oldImage.size.height)];
CGAffineTransform t = CGAffineTransformMakeRotation(degrees * M_PI / 180);
rotatedViewBox.transform = t;
CGSize rotatedSize = rotatedViewBox.frame.size;
// Create the bitmap context
UIGraphicsBeginImageContext(rotatedSize);
CGContextRef bitmap = UIGraphicsGetCurrentContext();
// Move the origin to the middle of the image so we will rotate and scale around the center.
CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);
// // Rotate the image context
CGContextRotateCTM(bitmap, (degrees * M_PI / 180));
// Now, draw the rotated/scaled image into the context
CGContextScaleCTM(bitmap, 1.0, -1.0);
CGContextDrawImage(bitmap, CGRectMake(-oldImage.size.width / 2, -oldImage.size.height / 2, oldImage.size.width, oldImage.size.height), [oldImage CGImage]);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
I think this link will be help.......! Rotate Original Image by clicking button in Objective C
http://adrianmobileapplication.blogspot.com/2015/03/rotate-original-image-by-clicking.html
You have to do some thing like this
YourContainer.transform = CGAffineTransformMakeRotation( 270.0/180*M_PI );
I think rest of the thing you can figured out..
I developing the simple UIApplication in which i want to crop the UIImage (in .jpg format) with help of CGContext. The developed code till now as follows,
CGImageRef graphicOriginalImage = [originalImage.image CGImage];
UIGraphicsBeginImageContext(originalImage.image.size);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGBitmapContextCreateImage(graphicOriginalImage);
CGFloat fltW = originalImage.image.size.width;
CGFloat fltH = originalImage.image.size.height;
CGFloat X = round(fltW/4);
CGFloat Y =round(fltH/4);
CGFloat width = round(X + (fltW/2));
CGFloat height = round(Y + (fltH/2));
CGContextTranslateCTM(ctx, 0, image.size.height);
CGContextScaleCTM(ctx, 1.0, -1.0);
CGRect rect = CGRectMake(X,Y ,width ,height);
CGContextDrawImage(ctx, rect, graphicOriginalImage);
croppedImage = UIGraphicsGetImageFromCurrentImageContext();
return croppedImage;
}
The above code is worked fine but it can't crop image.
The original image memory and cropped image memory i will got same(equal to original image memory).
The above code is right for cropping the image??????????????????
Here is a good way to crop an image to a CGRect:
- (UIImage*)imageByCropping:(UIImage *)imageToCrop toRect:(CGRect)rect
{
//create a context to do our clipping in
UIGraphicsBeginImageContext(rect.size);
CGContextRef currentContext = UIGraphicsGetCurrentContext();
//create a rect with the size we want to crop the image to
//the X and Y here are zero so we start at the beginning of our
//newly created context
CGRect clippedRect = CGRectMake(0, 0, rect.size.width, rect.size.height);
CGContextClipToRect( currentContext, clippedRect);
//create a rect equivalent to the full size of the image
//offset the rect by the X and Y we want to start the crop
//from in order to cut off anything before them
CGRect drawRect = CGRectMake(rect.origin.x * -1,
rect.origin.y * -1,
imageToCrop.size.width,
imageToCrop.size.height);
//draw the image to our clipped context using our offset rect
CGContextDrawImage(currentContext, drawRect, imageToCrop.CGImage);
//pull the image from our cropped context
UIImage *cropped = UIGraphicsGetImageFromCurrentImageContext();
//pop the context to get back to the default
UIGraphicsEndImageContext();
//Note: this is autoreleased
return cropped;
}
Or another way:
- (UIImage *)imageByCropping:(UIImage *)imageToCrop toRect:(CGRect)rect
{
CGImageRef imageRef = CGImageCreateWithImageInRect([imageToCrop CGImage], rect);
UIImage *cropped = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
return cropped;
}
From http://www.hive05.com/2008/11/crop-an-image-using-the-iphone-sdk/.
The context you create to draw the image has the same size that the original image. That's why they have the same size.
If you don't want to re-invent the wheel, take a look at the TouchCode project on Google Code. You will find UIImage categories that do the job (see UIImage_ThumbnailExtensions.m).
After I load an image from the device, I need to rotate it 37.8 degrees then display it on a View.
Is there an function in Objective-C that can do the image rotation?
Ian
To rotate the view:
imageView.transform = CGAffineTransformMakeRotation(37.8°);
To rotate the image,
Calculate the width and height will be occupied by the image after rotation.
Create a CGContext by UIGraphicsBeginImageContext.
CGContextRotateCTM(UIGraphicsGetCurrentContext(), 37.8°);
[yourImage drawAtPoint:...];
UIGraphicsGetImageFromCurrentImageContext(); and use this image instead.
Release the context.
Yes, see my answer to this question: Question about rotating a slider
To convert degrees to radians (for the positionInRadians arg) use this function:
CGFloat DegreesToRadians(CGFloat degrees) {return degrees * M_PI / 180;};
To rotate the image, try this:
-(IBAction)rotateImageClick:(id)sender{
UIImage *image2=[[UIImage alloc]init];
image2 = [self imageRotatedByDegrees:self.roateImageView.image deg:(90)]; //Angle by 90 degree
self.roateImageView.image = image2;
imgData= UIImageJPEGRepresentation(image2,0.9f);
}
This method allows you to rotate an image an arbitrary amount:
- (UIImage *)imageRotatedByDegrees:(UIImage*)oldImage deg:(CGFloat)degrees{
// calculate the size of the rotated view's containing box for our drawing space
UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0,oldImage.size.width, oldImage.size.height)];
CGAffineTransform t = CGAffineTransformMakeRotation(degrees * M_PI / 180);
rotatedViewBox.transform = t;
CGSize rotatedSize = rotatedViewBox.frame.size;
// Create the bitmap context
UIGraphicsBeginImageContext(rotatedSize);
CGContextRef bitmap = UIGraphicsGetCurrentContext();
// Move the origin to the middle of the image so we will rotate and scale around the center.
CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);
// // Rotate the image context
CGContextRotateCTM(bitmap, (degrees * M_PI / 180));
// Now, draw the rotated/scaled image into the context
CGContextScaleCTM(bitmap, 1.0, -1.0);
CGContextDrawImage(bitmap, CGRectMake(-oldImage.size.width / 2, -oldImage.size.height / 2, oldImage.size.width, oldImage.size.height), [oldImage CGImage]);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
See this link for more information.