[Objective-C Tip] UImage 이미지 리사이징

프로젝트 하실때, UIImage를 많이 사용합니다.

이번 시간에는 UIImage의 관련된 팁을 드리고자 합니다.

* 크기 변경

- (UIImage *)resizeImage:(UIImage *)image width:(int)width height:(int)height

{

    

    CGImageRef imageRef = [image CGImage];

    CGImageAlphaInfo alphaInfo = CGImageGetAlphaInfo(imageRef);

    

    //if (alphaInfo == kCGImageAlphaNone)

    alphaInfo = kCGImageAlphaNoneSkipLast;

    

    CGContextRef bitmap = CGBitmapContextCreate(NULL, width, height, CGImageGetBitsPerComponent(imageRef), 4 * width, CGImageGetColorSpace(imageRef), alphaInfo);

    CGContextDrawImage(bitmap, CGRectMake(0, 0, width, height), imageRef);

    CGImageRef ref = CGBitmapContextCreateImage(bitmap);

    UIImage *result = [UIImageimageWithCGImage:ref];

    

    CGContextRelease(bitmap);

    CGImageRelease(ref);

    

    return result;    

}

* 이미지 자르기

- (UIImage*)imageByCropping:(UIImage *)imageToCrop toRect:(CGRect)rect

{

UIGraphicsBeginImageContext(rect.size);

CGContextRef currentContext = UIGraphicsGetCurrentContext();

CGContextTranslateCTM(currentContext, 0.0, rect.size.height);

CGContextScaleCTM(currentContext, 1.0, -1.0);

CGRect clippedRect = CGRectMake(0, 0, rect.size.width, rect.size.height);

CGContextClipToRect( currentContext, clippedRect);

CGRect drawRect = CGRectMake(rect.origin.x * -1,rect.origin.y * -1,imageToCrop.size.width,imageToCrop.size.height);

CGContextDrawImage(currentContext, drawRect, imageToCrop.CGImage);

CGContextScaleCTM(currentContext, 1.0, -1.0);

UIImage *cropped = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return cropped;

}

* 이미지 마스킹

-(UIImage *)maskingImage:(UIImage *)image maskImage:(NSString)_maskImage{

CGImageRef imageRef = [image CGImage];

CGImageRef maskRef = [[UIImage imageNamed:_maskImage] CGImage];

    

CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef),

CGImageGetHeight(maskRef),

CGImageGetBitsPerComponent(maskRef),

CGImageGetBitsPerPixel(maskRef),

CGImageGetBytesPerRow(maskRef),

CGImageGetDataProvider(maskRef),

NULL, false);

    

CGImageRef masked = CGImageCreateWithMask(imageRef, mask);

CGImageRelease(mask);

    

UIImage *maskedImage = [UIImage imageWithCGImage:masked];

CGImageRelease(masked);

return maskedImage;

}

*이미지 합치기

- (UIImage*)makeImage{

    // 기본 이미지

    UIImage *image = [UIImage imageNamed:@"image.png"];

    // 사용할 글자

    NSString *string = [NSString stringWithFormat:@"%@", @"Steve"];

    CGFloat fontSize = 15;

    UIFont *font = [UIFont systemFontOfSize:fontSize];

    CGSize textSize = [string sizeWithFont:font];

   

    // 반환될 이미지 크기

    CGSize resultImageSize = CGSizeMake(image.size.width + textSize.width, image.size.height);

   

    // Creates a bitmap-based graphics context and makes it the current context.

    UIGraphicsBeginImageContext(resultImageSize);

   

    // Returns the current graphics context.

    CGContextRef contextRef = UIGraphicsGetCurrentContext();

   

    // 이미지 시작점

    CGPoint pt = CGPointZero;

     [image drawAtPoint:pt];

   

    // Sets the current fill color to a value in the DeviceRGB color space.

    CGContextSetRGBFillColor(contextRef, 1.0, 0.0, 0.0, 1.0);         

   

    CGPoint textPt = CGPointMake(image.size.width, 0);

    [string drawAtPoint:textPt withFont:font];

   

    // Returns an image based on the contents of the current bitmap-based graphics context.

    UIImage *resultImage = UIGraphicsGetImageFromCurrentImageContext();

    // Removes the current bitmap-based graphics context from the top of the stack.

    UIGraphicsEndImageContext();

   

    return resultImage;

}

*UIColor로 IImage를 만들기

 #import <quartzcore/quartzcore.h>

...

+ (UIImage *)image1x1WithColor:(UIColor *)color

{

    CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);

    UIGraphicsBeginImageContext(rect.size);

    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetFillColorWithColor(context, [color CGColor]);

    CGContextFillRect(context, rect);

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return image;

}