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  • 缩小 UIImage 的代码

    这段“许靖昕”先生分享的代码将示范如何缩小 UIImage

    @implementation UIImage (Extras)  

    #pragma mark -  

    #pragma mark Scale and crop image  

    - (UIImage*)imageByScalingAndCroppingForSize:(CGSize)targetSize  

    {  

    UIImage *sourceImage = self;  

    UIImage *newImage = nil;          

    CGSize imageSize = sourceImage.size;  

    CGFloat width = imageSize.width;  

    CGFloat height = imageSize.height;  

    CGFloat targetWidth = targetSize.width;  

    CGFloat targetHeight = targetSize.height;  

    CGFloat scaleFactor = 0.0;  

    CGFloat scaledWidth = targetWidth;  

    CGFloat scaledHeight = targetHeight;  

    CGPoint thumbnailPoint = CGPointMake(0.0,0.0);  

    if (CGSizeEqualToSize(imageSize, targetSize) == NO)   

            {  

            CGFloat widthFactor = targetWidth / width;  

            CGFloat heightFactor = targetHeight / height;  

            if (widthFactor > heightFactor)   

                    scaleFactor = widthFactor; // scale to fit height  

            else  

                    scaleFactor = heightFactor; // scale to fit width  

            scaledWidth  = width * scaleFactor;  

            scaledHeight = height * scaleFactor;  

            // center the image  

            if (widthFactor > heightFactor)  

                    {  

                    thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;   

                    }  

            else   

                    if (widthFactor < heightFactor)  

                            {  

                            thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;  

                            }  

            }         

    UIGraphicsBeginImageContext(targetSize); // this will crop  

    CGRect thumbnailRect = CGRectZero;  

    thumbnailRect.origin = thumbnailPoint;  

    thumbnailRect.size.width  = scaledWidth;  

    thumbnailRect.size.height = scaledHeight;  

    [sourceImage drawInRect:thumbnailRect];  

    newImage = UIGraphicsGetImageFromCurrentImageContext();  

    if(newImage == nil)   

            NSLog(@"could not scale image");  

    //pop the context to get back to the default  

    UIGraphicsEndImageContext();  

    return newImage;  

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  • 原文地址:https://www.cnblogs.com/greywolf/p/2615392.html
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