Cropping UIimage in IOS - ios

Question

I am very new to IOS and the first task given to me is Image cropping. means If I am using an image as banner image and the given frame size is more then or smaller thn the size of the image . my code should automatically resize image in respective aspect ratio of the image and then set image in that frame.
I have done so much R&D and after that i have written code.
-(UIImage *)MyScaleNEwMethodwithImage:(UIImage *)image andframe:(CGRect)frame{
float bmHeight= image.size.height;
float bmWidth= image.size.width;
UIImage *RecievedImage=image;
if (bmHeight>bmWidth) {
float ratio = frame.size.height/frame.size.width;
float newbmHeight = ratio*bmWidth;
float cropedHeight= (bmHeight-newbmHeight)/2;
if (cropedHeight<0) {
float ratio1= frame.size.width/frame.size.height;
float newbmHeight1= (ratio1*bmHeight);
float cropedimageHeight1 = (bmWidth- newbmHeight1)/2;
CGRect cliprect = CGRectMake(cropedimageHeight1, 0,bmWidth-cropedimageHeight1,bmHeight);
CGImageRef imref = CGImageCreateWithImageInRect([image CGImage],cliprect);
UIImage *newSubImage = [UIImage imageWithCGImage:imref];
return newSubImage;
}
else
{
CGRect cliprect = CGRectMake(0,cropedHeight,bmWidth,bmHeight-cropedHeight);
CGImageRef imref = CGImageCreateWithImageInRect([image CGImage],cliprect);
UIImage *newSubImage = [UIImage imageWithCGImage:imref];
return newSubImage;
}
}
else
{
float ratio = frame.size.height/frame.size.width;
float newbmHeight = ratio*bmHeight;
float cropedHeight= (bmHeight-newbmHeight)/4;
if (cropedHeight<0) {
float ratio1= frame.size.width/frame.size.height;
float newbmHeight1= (ratio1*bmWidth);
float cropedimageHeight1 = (bmWidth- newbmHeight1)/2;
UIImageView *DummyImage=[[UIImageView alloc]initWithFrame:CGRectMake(0,cropedimageHeight1,bmWidth,(bmHeight-cropedimageHeight1))];
[DummyImage setImage:RecievedImage];
CGImageRef imageRef = CGImageCreateWithImageInRect([DummyImage.image CGImage], CGRectMake(0,cropedimageHeight1/2,bmWidth/2,(bmHeight-cropedimageHeight1)/2));
// or use the UIImage wherever you like
[DummyImage setImage:[UIImage imageWithCGImage:imageRef]];
CGImageRelease(imageRef);
UIImage *ScaledImage=[UIImage imageWithCGImage:imageRef];
return ScaledImage;
} else {
UIImageView *DummyImage=[[UIImageView alloc]initWithFrame:CGRectMake(cropedHeight,0,bmWidth-cropedHeight,bmHeight)];
[DummyImage setImage:RecievedImage];
CGImageRef imageRef = CGImageCreateWithImageInRect([DummyImage.image CGImage],CGRectMake(cropedHeight,2*cropedHeight,(bmWidth-cropedHeight),bmHeight/2));
// or use the UIImage wherever you like
[DummyImage setImage:[UIImage imageWithCGImage:imageRef]];
CGImageRelease(imageRef);
UIImage *ScaledImage=[UIImage imageWithCGImage:imageRef];
return ScaledImage;
}
}
}
In my frame i am getting required image but when screen changes i can see full image. i want to cut the unwanted image.

Answer 1

Thise piece of code may help you out
-(CGRect) cropImage:(CGRect)frame
{
NSAssert(self.contentMode == UIViewContentModeScaleAspectFit, #"content mode should be aspect fit");
CGFloat wScale = self.bounds.size.width / self.image.size.width;
CGFloat hScale = self.bounds.size.height / self.image.size.height;
float x, y, w, h, offset;
if (wScale<hScale) {
offset = (self.bounds.size.height - (self.image.size.height*widthScale))/2;
x = frame.origin.x / wScale;
y = (frame.origin.y-offset) / wScale;
w = frame.size.width / wScale;
h = frame.size.height / wScale;
} else {
offset = (self.bounds.size.width - (self.image.size.width*heightScale))/2;
x = (frame.origin.x-offset) / hScale;
y = frame.origin.y / hScale;
w = frame.size.width / hScale;
h = frame.size.height / hScale;
}
return CGRectMake(x, y, w, h);
}

Answer 2

The code which I had referred to crop the image as per aspect ratio is :
typedef enum {
MGImageResizeCrop,
MGImageResizeCropStart,
MGImageResizeCropEnd,
MGImageResizeScale
} MGImageResizingMethod;
- (UIImage *)imageToFitSize:(CGSize)fitSize method:(MGImageResizingMethod)resizeMethod
{
float imageScaleFactor = 1.0;
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 40000
if ([self respondsToSelector:#selector(scale)]) {
imageScaleFactor = [self scale];
}
#endif
float sourceWidth = [self size].width * imageScaleFactor;
float sourceHeight = [self size].height * imageScaleFactor;
float targetWidth = fitSize.width;
float targetHeight = fitSize.height;
BOOL cropping = !(resizeMethod == MGImageResizeScale);
// Calculate aspect ratios
float sourceRatio = sourceWidth / sourceHeight;
float targetRatio = targetWidth / targetHeight;
// Determine what side of the source image to use for proportional scaling
BOOL scaleWidth = (sourceRatio <= targetRatio);
// Deal with the case of just scaling proportionally to fit, without cropping
scaleWidth = (cropping) ? scaleWidth : !scaleWidth;
// Proportionally scale source image
float scalingFactor, scaledWidth, scaledHeight;
if (scaleWidth) {
scalingFactor = 1.0 / sourceRatio;
scaledWidth = targetWidth;
scaledHeight = round(targetWidth * scalingFactor);
} else {
scalingFactor = sourceRatio;
scaledWidth = round(targetHeight * scalingFactor);
scaledHeight = targetHeight;
}
float scaleFactor = scaledHeight / sourceHeight;
// Calculate compositing rectangles
CGRect sourceRect, destRect;
if (cropping) {
destRect = CGRectMake(0, 0, targetWidth, targetHeight);
float destX, destY;
if (resizeMethod == MGImageResizeCrop) {
// Crop center
destX = round((scaledWidth - targetWidth) / 2.0);
destY = round((scaledHeight - targetHeight) / 2.0);
} else if (resizeMethod == MGImageResizeCropStart) {
// Crop top or left (prefer top)
if (scaleWidth) {
// Crop top
destX = 0.0;
destY = 0.0;
} else {
// Crop left
destX = 0.0;
destY = round((scaledHeight - targetHeight) / 2.0);
}
} else if (resizeMethod == MGImageResizeCropEnd) {
// Crop bottom or right
if (scaleWidth) {
// Crop bottom
destX = round((scaledWidth - targetWidth) / 2.0);
destY = round(scaledHeight - targetHeight);
} else {
// Crop right
destX = round(scaledWidth - targetWidth);
destY = round((scaledHeight - targetHeight) / 2.0);
}
}
sourceRect = CGRectMake(destX / scaleFactor, destY / scaleFactor,
targetWidth / scaleFactor, targetHeight / scaleFactor);
} else {
sourceRect = CGRectMake(0, 0, sourceWidth, sourceHeight);
destRect = CGRectMake(0, 0, scaledWidth, scaledHeight);
}
// Create appropriately modified image.
UIImage *image = nil;
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 40000
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 4.0) {
UIGraphicsBeginImageContextWithOptions(destRect.size, NO, 0.0); // 0.0 for scale means "correct scale for device's main screen".
CGImageRef sourceImg = CGImageCreateWithImageInRect([self CGImage], sourceRect); // cropping happens here.
image = [UIImage imageWithCGImage:sourceImg scale:0.0 orientation:self.imageOrientation]; // create cropped UIImage.
[image drawInRect:destRect]; // the actual scaling happens here, and orientation is taken care of automatically.
CGImageRelease(sourceImg);
image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
#endif
if (!image) {
// Try older method.
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, fitSize.width, fitSize.height, 8, (fitSize.width * 4),
colorSpace, kCGImageAlphaPremultipliedLast);
CGImageRef sourceImg = CGImageCreateWithImageInRect([self CGImage], sourceRect);
CGContextDrawImage(context, destRect, sourceImg);
CGImageRelease(sourceImg);
CGImageRef finalImage = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
image = [UIImage imageWithCGImage:finalImage];
CGImageRelease(finalImage);
}
return image;
}
Check if this helps you.