图片的旋转、缩放操作的分类

UIImage+fixOrientation.h

#import <UIKit/UIKit.h>

@interface UIImage (fixOrientation)

/**
 将当前的图片旋转一下
 */
- (UIImage *)fixOrientation;

/**
 按当前屏幕的分辨率的倍数缩放图片大小
 */
- (UIImage *)imageCompress;

/**
 根据ImageView的Size进行缩放
 */
- (UIImage *)imageCompressWithImageViewSize:(CGSize)vSize;

/**
 根据ImageView的Size进行裁剪图片
 */
- (UIImage *)imageCompressWithImageViewNoAutoChangeWithSize:(CGSize)vSize;

@end

UIImage+fixOrientation.m

#import "UIImage+fixOrientation.h"

@implementation UIImage (fixOrientation)

- (UIImage *)fixOrientation{
    // No-op if the orientation is already correct
    if (self.imageOrientation == UIImageOrientationUp) return self;
    
    // We need to calculate the proper transformation to make the image upright.
    // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
    CGAffineTransform transform = CGAffineTransformIdentity;
    
    switch (self.imageOrientation) {
        case UIImageOrientationDown:
        case UIImageOrientationDownMirrored:
            transform = CGAffineTransformTranslate(transform, self.size.width, self.size.height);
            transform = CGAffineTransformRotate(transform, M_PI);
            break;
            
        case UIImageOrientationLeft:
        case UIImageOrientationLeftMirrored:
            transform = CGAffineTransformTranslate(transform, self.size.width, 0);
            transform = CGAffineTransformRotate(transform, M_PI_2);
            break;
            
        case UIImageOrientationRight:
        case UIImageOrientationRightMirrored:
            transform = CGAffineTransformTranslate(transform, 0, self.size.height);
            transform = CGAffineTransformRotate(transform, -M_PI_2);
            break;
        case UIImageOrientationUp:
        case UIImageOrientationUpMirrored:
            break;
    }
    
    switch (self.imageOrientation) {
        case UIImageOrientationUpMirrored:
        case UIImageOrientationDownMirrored:
            transform = CGAffineTransformTranslate(transform, self.size.width, 0);
            transform = CGAffineTransformScale(transform, -1, 1);
            break;
            
        case UIImageOrientationLeftMirrored:
        case UIImageOrientationRightMirrored:
            transform = CGAffineTransformTranslate(transform, self.size.height, 0);
            transform = CGAffineTransformScale(transform, -1, 1);
            break;
        case UIImageOrientationUp:
        case UIImageOrientationDown:
        case UIImageOrientationLeft:
        case UIImageOrientationRight:
            break;
    }
    
    // Now we draw the underlying CGImage into a new context, applying the transform
    // calculated above.
    CGContextRef ctx = CGBitmapContextCreate(NULL, self.size.width, self.size.height,
                                             CGImageGetBitsPerComponent(self.CGImage), 0,
                                             CGImageGetColorSpace(self.CGImage),
                                             CGImageGetBitmapInfo(self.CGImage));
    CGContextConcatCTM(ctx, transform);
    switch (self.imageOrientation) {
        case UIImageOrientationLeft:
        case UIImageOrientationLeftMirrored:
        case UIImageOrientationRight:
        case UIImageOrientationRightMirrored:
            // Grr...
            CGContextDrawImage(ctx, CGRectMake(0,0,self.size.height,self.size.width), self.CGImage);
            break;
            
        default:
            CGContextDrawImage(ctx, CGRectMake(0,0,self.size.width,self.size.height), self.CGImage);
            break;
    }
    
    // And now we just create a new UIImage from the drawing context
    CGImageRef cgimg = CGBitmapContextCreateImage(ctx);
    UIImage *img = [UIImage imageWithCGImage:cgimg];
    CGContextRelease(ctx);
    CGImageRelease(cgimg);
    return img;
}

- (UIImage *)imageCompress{
    
//    CGSize size = self.size;
//    CGFloat width = size.width;
//    CGFloat height = size.height;
    
//    NSInteger retinalMutipler = [UIScreen mainScreen].scale;
//    CGFloat scale = kAllWidth*1.0*retinalMutipler/width;
    
//    CGFloat scaleWidth = width*scale;
//    CGFloat scaleHeight = height*scale;
//    UIGraphicsBeginImageContext(size);//this will crop
//    [self drawInRect:CGRectMake(0, 0, scaleWidth, scaleHeight)];
//    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
//    UIGraphicsEndImageContext();
    
    
    UIImage *newImage = nil;
    
    @autoreleasepool {
        NSInteger retinalMutipler = [UIScreen mainScreen].scale;
        CGSize targetSize = CGSizeMake(0, 0);
        
        //判断长宽
        if (self.size.height>=self.size.width) {
            //高度长宽度短的图片
            //计算宽度占高度的比例
            CGFloat widthHeightRate = self.size.width*1.0/self.size.height;
            CGFloat scaleHeight = kAllHeight*1.0*retinalMutipler;
            CGFloat scaleWidth = scaleHeight*widthHeightRate;
            targetSize = CGSizeMake(scaleWidth, scaleHeight);
        }else{
            //宽度长高度短的图片
            //计算高度占宽度的比例
            CGFloat heightWidthRate = self.size.height*1.0/self.size.width;
            CGFloat scaleWidth = kAllWidth*1.0*retinalMutipler;
            CGFloat scaleHeight = scaleWidth*heightWidthRate;
            targetSize = CGSizeMake(scaleWidth, scaleHeight);
        }
        
        //CGSize targetSize = CGSizeMake(retinalMutipler*kAllWidth, retinalMutipler*kAllHeight);
        UIGraphicsBeginImageContext(targetSize);
        [self drawInRect:CGRectMake(0, 0, targetSize.width, targetSize.height)];
        newImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
    }
    
    return newImage;
    
}

- (UIImage *)imageCompressWithImageViewSize:(CGSize)vSize{
    
    if (CGSizeEqualToSize(vSize, CGSizeZero)) {
        return [self imageCompress];
    }
    
    UIImage *newImage = nil;
    
    @autoreleasepool {
        //源文件大小
        CGSize sourceSize = self.size;
        
        //屏幕的缩放比例
        NSInteger retinalMutipler = [UIScreen mainScreen].scale;
        //设置画板的Size
        vSize = CGSizeMake(retinalMutipler*vSize.width, retinalMutipler*vSize.height);
        
        //获取宽度和高度的缩放比例
        CGFloat widthRate = vSize.width*1.0/sourceSize.width;
        CGFloat heightRate = vSize.height*1.0/sourceSize.height;
        
        //判断哪个比例最小,就用哪个比例进行缩放
        CGSize targetSize = CGSizeZero;
        if (widthRate <= heightRate) {
            targetSize.width = sourceSize.width * widthRate;
            targetSize.height = sourceSize.height * widthRate;
        }else{
            targetSize.width = sourceSize.width * heightRate;
            targetSize.height = sourceSize.height * heightRate;
        }
        
        //获取绘制图片的X和Y
        CGFloat targetX = floorf((vSize.width - targetSize.width)/2.0);
        CGFloat targetY = floorf((vSize.height - targetSize.height)/2.0);
        
        UIGraphicsBeginImageContext(vSize);
        [self drawInRect:CGRectMake(targetX, targetY, targetSize.width, targetSize.height)];
        newImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
    }
    
    return newImage;
}

- (UIImage *)imageCompressWithImageViewNoAutoChangeWithSize:(CGSize)vSize{
    if (CGSizeEqualToSize(vSize, CGSizeZero)) {
        return [self imageCompress];
    }
    
    UIImage *newImage = nil;
    
    @autoreleasepool {
        //源文件大小
        CGSize sourceSize = self.size;
        
        //屏幕的缩放比例
        NSInteger retinalMutipler = [UIScreen mainScreen].scale;
        //设置画板的Size
        vSize = CGSizeMake(retinalMutipler*vSize.width, retinalMutipler*vSize.height);
        
        //获取宽度和高度的缩放比例
        CGFloat widthRate = vSize.width*1.0/sourceSize.width;
        CGFloat heightRate = vSize.height*1.0/sourceSize.height;
        
        //判断哪个比例较大,就用哪个比例进行缩放
        CGSize targetSize = CGSizeZero;
        if (widthRate >= heightRate) {
            targetSize.width = sourceSize.width * widthRate;
            targetSize.height = sourceSize.height * widthRate;
        }else{
            targetSize.width = sourceSize.width * heightRate;
            targetSize.height = sourceSize.height * heightRate;
        }
        
        //获取绘制图片的X和Y
        CGFloat targetX = floorf((vSize.width - targetSize.width)/2.0);
        CGFloat targetY = floorf((vSize.height - targetSize.height)/2.0);
        
        UIGraphicsBeginImageContext(vSize);
        [self drawInRect:CGRectMake(targetX, targetY, targetSize.width, targetSize.height)];
        newImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
    }
    
    return newImage;
}

@end