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1.根据给定得图片，从其指定区域截取一张新得图片 -(UIImage *)getImageFromImage{ //大图bigImage //定义myImageRect，截图的区域 CGRect myImageRect = CGRectMake(10.0, 10.0, 57.0, 57.0); UIImage* bigImage= [UIImage imageNamed:@"k00030.jpg"]; CGImageRef imageRef = bigImage.CGImage; CGImageRef subImageRef = CGImageCreateWithImageInRect(imageRef, myImageRect); CGSize size; size.width = 57.0; size.height = 57.0; UIGraphicsBeginImageContext(size); CGContextRef context = UIGraphicsGetCurrentContext(); CGContextDrawImage(context, myImageRect, subImageRef); UIImage* smallImage = [UIImage imageWithCGImage:subImageRef]; UIGraphicsEndImageContext(); return smallImage; } 复制代码 2.针对ＵIImage得一些常用缩放得方法： -(UIImage*)resizedImage1:(UIImage*)inImage inRect:(CGRect)thumbRect { // Creates a bitmap-based graphics context and makes it the current context. UIGraphicsBeginImageContext(thumbRect.size); [inImage drawInRect:thumbRect]; return UIGraphicsGetImageFromCurrentImageContext(); } -(UIImage*)resizedImage2:(UIImage*)inImage inRect:(CGRect)thumbRect { CGImageRef imageRef = [inImage CGImage]; CGImageAlphaInfo alphaInfo = CGImageGetAlphaInfo(imageRef); /* There's a wierdness with kCGImageAlphaNone and CGBitmapContextCreate see Supported Pixel Formats in the Quartz 2D Programming Guide Creating a Bitmap Graphics Context section only RGB 8 bit images with alpha of kCGImageAlphaNoneSkipFirst, kCGImageAlphaNoneSkipLast, kCGImageAlphaPremultipliedFirst,and kCGImageAlphaPremultipliedLast, with a few other oddball image kinds are supported The images on input here are likely to be png or jpeg files*/ if (alphaInfo == kCGImageAlphaNone) alphaInfo = kCGImageAlphaNoneSkipLast; // Build a bitmap context that's the size of the thumbRect CGFloat bytesPerRow; if( thumbRect.size.width > thumbRect.size.height ) { bytesPerRow = 4 * thumbRect.size.width; } else { bytesPerRow = 4 * thumbRect.size.height; } CGContextRef bitmap = CGBitmapContextCreate(NULL, thumbRect.size.width, // width thumbRect.size.height, // height 8, //CGImageGetBitsPerComponent(imageRef), // really needs to always be 8 bytesPerRow, //4 * thumbRect.size.width, // rowbytes CGImageGetColorSpace(imageRef), alphaInfo ); // Draw into the context, this scales the image CGContextDrawImage(bitmap, thumbRect, imageRef); // Get an image from the context and a UIImage CGImageRef ref = CGBitmapContextCreateImage(bitmap); UIImage* result = [UIImage imageWithCGImage:ref]; CGContextRelease(bitmap); // ok if NULL CGImageRelease(ref); return result; } - (UIImage *)scaleImage:(UIImage *) image maxWidth:(float) maxWidth maxHeight:(float) maxHeight { CGImageRef imgRef = image.CGImage; CGFloat width = CGImageGetWidth(imgRef); CGFloat height = CGImageGetHeight(imgRef); if (width <= maxWidth && height <= maxHeight) { return image; } CGAffineTransform transform = CGAffineTransformIdentity; CGRect bounds = CGRectMake(0, 0, width, height); if (width > maxWidth || height > maxHeight) { CGFloat ratio = width/height; if (ratio > 1) { bounds.size.width = maxWidth; bounds.size.height = bounds.size.width / ratio; } else { bounds.size.height = maxHeight; bounds.size.width = bounds.size.height * ratio; } } CGFloat scaleRatio = bounds.size.width / width; UIGraphicsBeginImageContext(bounds.size); CGContextRef context = UIGraphicsGetCurrentContext(); CGContextScaleCTM(context, scaleRatio, -scaleRatio); CGContextTranslateCTM(context, 0, -height); CGContextConcatCTM(context, transform); CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, width, height), imgRef); UIImage *imageCopy = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return imageCopy; } 复制代码 3.其他缩放uiimage的size，有需要的可以看看 -(UIImage*) scaleAndRotateImage:(UIImage*)photoimage:(CGFloat)bounds_width:(CGFloat)bounds_height { //int kMaxResolution = 300; CGImageRef imgRef =photoimage.CGImage; CGFloat width = CGImageGetWidth(imgRef); CGFloat height = CGImageGetHeight(imgRef); CGAffineTransform transform = CGAffineTransformIdentity; CGRect bounds = CGRectMake(0, 0, width, height); /*if (width > kMaxResolution || height > kMaxResolution) { CGFloat ratio = width/height; if (ratio > 1) { bounds.size.width = kMaxResolution; bounds.size.height = bounds.size.width / ratio; } else { bounds.size.height = kMaxResolution; bounds.size.width = bounds.size.height * ratio; } }*/ bounds.size.width = bounds_width; bounds.size.height = bounds_height; CGFloat scaleRatio = bounds.size.width / width; CGFloat scaleRatioheight = bounds.size.height / height; CGSize imageSize = CGSizeMake(CGImageGetWidth(imgRef), CGImageGetHeight(imgRef)); CGFloat boundHeight; UIImageOrientation orient =photoimage.imageOrientation; switch(orient) { case UIImageOrientationUp: //EXIF = 1 transform = CGAffineTransformIdentity; break; case UIImageOrientationUpMirrored: //EXIF = 2 transform = CGAffineTransformMakeTranslation(imageSize.width, 0.0); transform = CGAffineTransformScale(transform, -1.0, 1.0); break; case UIImageOrientationDown: //EXIF = 3 transform = CGAffineTransformMakeTranslation(imageSize.width, imageSize.height); transform = CGAffineTransformRotate(transform, M_PI); break; case UIImageOrientationDownMirrored: //EXIF = 4 transform = CGAffineTransformMakeTranslation(0.0, imageSize.height); transform = CGAffineTransformScale(transform, 1.0, -1.0); break; case UIImageOrientationLeftMirrored: //EXIF = 5 boundHeight = bounds.size.height; bounds.size.height = bounds.size.width; bounds.size.width = boundHeight; transform = CGAffineTransformMakeTranslation(imageSize.height, imageSize.width); transform = CGAffineTransformScale(transform, -1.0, 1.0); transform = CGAffineTransformRotate(transform, 3.0 * M_PI / 2.0); break; case UIImageOrientationLeft: //EXIF = 6 boundHeight = bounds.size.height; bounds.size.height = bounds.size.width; bounds.size.width = boundHeight; transform = CGAffineTransformMakeTranslation(0.0, imageSize.width); transform = CGAffineTransformRotate(transform, 3.0 * M_PI / 2.0); break; case UIImageOrientationRightMirrored: //EXIF = 7 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); break; case UIImageOrientationRight: //EXIF = 8 boundHeight = bounds.size.height; bounds.size.height = bounds.size.width; bounds.size.width = boundHeight; transform = CGAffineTransformMakeTranslation(imageSize.height, 0.0); transform = CGAffineTransformRotate(transform, M_PI / 2.0); break; default: [NSException raise:NSInternalInconsistencyException format:@"Invalid?image?orientation"]; break; } UIGraphicsBeginImageContext(bounds.size); CGContextRef context = UIGraphicsGetCurrentContext(); if (orient == UIImageOrientationRight || orient == UIImageOrientationLeft) { CGContextScaleCTM(context, -scaleRatio, scaleRatioheight); CGContextTranslateCTM(context, -height, 0); } else { CGContextScaleCTM(context, scaleRatio, -scaleRatioheight); CGContextTranslateCTM(context, 0, -height); } CGContextConcatCTM(context, transform); CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, width, height), imgRef); UIImage *imageCopy = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return imageCopy; } 本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/ymqqqqdx/archive/2011/04/29/6371529.aspx 1.根据给定得图片，从其指定区域截取一张新得图片
-(UIImage *)getImageFromImage{ //大图bigImage //定义myImageRect，截图的区域 CGRect myImageRect = CGRectMake(10.0, 10.0, 57.0, 57.0); UIImage* bigImage= [UIImage imageNamed:@"k00030.jpg"]; CGImageRef imageRef = bigImage.CGImage; CGImageRef subImageRef = CGImageCreateWithImageInRect(imageRef, myImageRect); CGSize size; size.width = 57.0; size.height = 57.0; UIGraphicsBeginImageContext(size); CGContextRef context = UIGraphicsGetCurrentContext(); CGContextDrawImage(context, myImageRect, subImageRef); UIImage* smallImage = [UIImage imageWithCGImage:subImageRef]; UIGraphicsEndImageContext(); return smallImage; } 2.针对ＵIImage得一些常用缩放得方法： -(UIImage*)resizedImage1:(UIImage*)inImage inRect:(CGRect)thumbRect { // Creates a bitmap-based graphics context and makes it the current context. UIGraphicsBeginImageContext(thumbRect.size); [inImage drawInRect:thumbRect]; return UIGraphicsGetImageFromCurrentImageContext(); } -(UIImage*)resizedImage2:(UIImage*)inImage inRect:(CGRect)thumbRect { CGImageRef imageRef = [inImage CGImage]; CGImageAlphaInfo alphaInfo = CGImageGetAlphaInfo(imageRef); /* There's a wierdness with kCGImageAlphaNone and CGBitmapContextCreate see Supported Pixel Formats in the Quartz 2D Programming Guide Creating a Bitmap Graphics Context section only RGB 8 bit images with alpha of kCGImageAlphaNoneSkipFirst, kCGImageAlphaNoneSkipLast, kCGImageAlphaPremultipliedFirst,and kCGImageAlphaPremultipliedLast, with a few other oddball image kinds are supported The images on input here are likely to be png or jpeg files*/ if (alphaInfo == kCGImageAlphaNone) alphaInfo = kCGImageAlphaNoneSkipLast; // Build a bitmap context that's the size of the thumbRect CGFloat bytesPerRow; if( thumbRect.size.width > thumbRect.size.height ) { bytesPerRow = 4 * thumbRect.size.width; } else { bytesPerRow = 4 * thumbRect.size.height; } CGContextRef bitmap = CGBitmapContextCreate(NULL, thumbRect.size.width, // width thumbRect.size.height, // height 8, //CGImageGetBitsPerComponent(imageRef), // really needs to always be 8 bytesPerRow, //4 * thumbRect.size.width, // rowbytes CGImageGetColorSpace(imageRef), alphaInfo ); // Draw into the context, this scales the image CGContextDrawImage(bitmap, thumbRect, imageRef); // Get an image from the context and a UIImage CGImageRef ref = CGBitmapContextCreateImage(bitmap); UIImage* result = [UIImage imageWithCGImage:ref]; CGContextRelease(bitmap); // ok if NULL CGImageRelease(ref); return result; } - (UIImage *)scaleImage:(UIImage *) image maxWidth:(float) maxWidth maxHeight:(float) maxHeight { CGImageRef imgRef = image.CGImage; CGFloat width = CGImageGetWidth(imgRef); CGFloat height = CGImageGetHeight(imgRef); if (width <= maxWidth && height <= maxHeight) { return image; } CGAffineTransform transform = CGAffineTransformIdentity; CGRect bounds = CGRectMake(0, 0, width, height); if (width > maxWidth || height > maxHeight) { CGFloat ratio = width/height; if (ratio > 1) { bounds.size.width = maxWidth; bounds.size.height = bounds.size.width / ratio; } else { bounds.size.height = maxHeight; bounds.size.width = bounds.size.height * ratio; } } CGFloat scaleRatio = bounds.size.width / width; UIGraphicsBeginImageContext(bounds.size); CGContextRef context = UIGraphicsGetCurrentContext(); CGContextScaleCTM(context, scaleRatio, -scaleRatio); CGContextTranslateCTM(context, 0, -height); CGContextConcatCTM(context, transform); CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, width, height), imgRef); UIImage *imageCopy = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return imageCopy; } 复制代码 3.其他缩放uiimage的size，有需要的可以看看 -(UIImage*) scaleAndRotateImage:(UIImage*)photoimage:(CGFloat)bounds_width:(CGFloat)bounds_height { //int kMaxResolution = 300; CGImageRef imgRef =photoimage.CGImage; CGFloat width = CGImageGetWidth(imgRef); CGFloat height = CGImageGetHeight(imgRef); CGAffineTransform transform = CGAffineTransformIdentity; CGRect bounds = CGRectMake(0, 0, width, height); /*if (width > kMaxResolution || height > kMaxResolution) { CGFloat ratio = width/height; if (ratio > 1) { bounds.size.width = kMaxResolution; bounds.size.height = bounds.size.width / ratio; } else { bounds.size.height = kMaxResolution; bounds.size.width = bounds.size.height * ratio; } }*/ bounds.size.width = bounds_width; bounds.size.height = bounds_height; CGFloat scaleRatio = bounds.size.width / width; CGFloat scaleRatioheight = bounds.size.height / height; CGSize imageSize = CGSizeMake(CGImageGetWidth(imgRef), CGImageGetHeight(imgRef)); CGFloat boundHeight; UIImageOrientation orient =photoimage.imageOrientation; switch(orient) { case UIImageOrientationUp: //EXIF = 1 transform = CGAffineTransformIdentity; break; case UIImageOrientationUpMirrored: //EXIF = 2 transform = CGAffineTransformMakeTranslation(imageSize.width, 0.0); transform = CGAffineTransformScale(transform, -1.0, 1.0); break; case UIImageOrientationDown: //EXIF = 3 transform = CGAffineTransformMakeTranslation(imageSize.width, imageSize.height); transform = CGAffineTransformRotate(transform, M_PI); break; case UIImageOrientationDownMirrored: //EXIF = 4 transform = CGAffineTransformMakeTranslation(0.0, imageSize.height); transform = CGAffineTransformScale(transform, 1.0, -1.0); break; case UIImageOrientationLeftMirrored: //EXIF = 5 boundHeight = bounds.size.height; bounds.size.height = bounds.size.width; bounds.size.width = boundHeight; transform = CGAffineTransformMakeTranslation(imageSize.height, imageSize.width); transform = CGAffineTransformScale(transform, -1.0, 1.0); transform = CGAffineTransformRotate(transform, 3.0 * M_PI / 2.0); break; case UIImageOrientationLeft: //EXIF = 6 boundHeight = bounds.size.height; bounds.size.height = bounds.size.width; bounds.size.width = boundHeight; transform = CGAffineTransformMakeTranslation(0.0, imageSize.width); transform = CGAffineTransformRotate(transform, 3.0 * M_PI / 2.0); break; case UIImageOrientationRightMirrored: //EXIF = 7 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); break; case UIImageOrientationRight: //EXIF = 8 boundHeight = bounds.size.height; bounds.size.height = bounds.size.width; bounds.size.width = boundHeight; transform = CGAffineTransformMakeTranslation(imageSize.height, 0.0); transform = CGAffineTransformRotate(transform, M_PI / 2.0); break; default: [NSException raise:NSInternalInconsistencyException format:@"Invalid?image?orientation"]; break; } UIGraphicsBeginImageContext(bounds.size); CGContextRef context = UIGraphicsGetCurrentContext(); if (orient == UIImageOrientationRight || orient == UIImageOrientationLeft) { CGContextScaleCTM(context, -scaleRatio, scaleRatioheight); CGContextTranslateCTM(context, -height, 0); } else { CGContextScaleCTM(context, scaleRatio, -scaleRatioheight); CGContextTranslateCTM(context, 0, -height); } CGContextConcatCTM(context, transform); CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, width, height), imgRef); UIImage *imageCopy = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return imageCopy; } 本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/ymqqqqdx/archive/2011/04/29/6371529.aspx |
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