【IOS】旋转图片和截取图片

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// 图片旋转- (CGImageRef)createRotatedImage:(CGImageRef)original degrees:(float)degrees CF_RETURNS_RETAINED {    if (degrees == 0.0f) {        CGImageRetain(original);        return original;    } else {        double radians = degrees * M_PI / 180;        #if TARGET_OS_EMBEDDED || TARGET_IPHONE_SIMULATOR        radians = -1*radians;#endif                size_t _width = CGImageGetWidth(original);        size_t _height = CGImageGetHeight(original);                CGRect imgRect = CGRectMake(0, 0, _width, _height);        CGAffineTransform __transform = CGAffineTransformMakeRotation(radians);        CGRect rotatedRect = CGRectApplyAffineTransform(imgRect, __transform);                CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();        CGContextRef context = CGBitmapContextCreate(NULL,                                                     rotatedRect.size.width,                                                     rotatedRect.size.height,                                                     CGImageGetBitsPerComponent(original),                                                     0,                                                     colorSpace,                                                     kCGBitmapAlphaInfoMask & kCGImageAlphaPremultipliedFirst);        CGContextSetAllowsAntialiasing(context, FALSE);        CGContextSetInterpolationQuality(context, kCGInterpolationNone);        CGColorSpaceRelease(colorSpace);                CGContextTranslateCTM(context,                              +(rotatedRect.size.width/2),                              +(rotatedRect.size.height/2));        CGContextRotateCTM(context, radians);                CGContextDrawImage(context, CGRectMake(-imgRect.size.width/2,                                               -imgRect.size.height/2,                                               imgRect.size.width,                                               imgRect.size.height),                           original);                CGImageRef rotatedImage = CGBitmapContextCreateImage(context);        CFRelease(context);                return rotatedImage;    }}

/** * 图片截取 * 从图片中按指定的位置大小截取图片的一部分 * UIImage image 原始的图片 * CGRect rect 要截取的区域 */- (UIImage *)imageFromImage:(UIImage *)image inRect:(CGRect)rect {    float imageWidth =  image.size.width;    float imageHeight =  image.size.height;    //按图片和屏幕宽高比截取    float wcount = imageWidth/_videoPreviewView.frame.size.width;    float hcount = imageHeight/_videoPreviewView.frame.size.height;    CGRect tt = CGRectMake(rect.origin.x*wcount, rect.origin.y*hcount, rect.size.width*wcount, rect.size.height*hcount);    CGImageRef sourceImageRef = [image CGImage];    CGImageRef newImageRef = CGImageCreateWithImageInRect(sourceImageRef, tt);    UIImage *newImage = [UIImage imageWithCGImage:newImageRef];    return newImage;}

/** * 改变图片大小 */-(UIImage*)image:(UIImage*)image scaleToSize:(CGSize)size{    // 创建一个bitmap的context    // 并把它设置成为当前正在使用的context    UIGraphicsBeginImageContext(size);    // 绘制改变大小的图片    [image drawInRect:CGRectMake(0, 0, size.width, size.height)];    // 从当前context中创建一个改变大小后的图片    UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();    // 使当前的context出堆栈    UIGraphicsEndImageContext();    // 返回新的改变大小后的图片    return scaledImage;}

使用方法：

//旋转后的图片                UIImage *imageRef = [UIImage imageWithCGImage:[self createRotatedImage:image.CGImage degrees:90]];//旋转90度                //截取后的图片                UIImage *rectImage = [self imageFromImage:imageRef inRect:_scanImageRect];                //                UIImage *rotationImage = [UIImage imageWithCGImage:imageRef];                                _resultImage = [self image:rectImage scaleToSize:CGSizeMake(CAMERA_WIDTH, CAMERA_HEIGHT)];

PS：文章部分代码转载自ZXing源码

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