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OC中关于图片的处理 压和缩处理

OC中关于图片的处理 压和缩处理

作者: Augus_man | 来源:发表于2017-10-26 17:36 被阅读17次

    最近公司处理图片 前端上传的时候 总是会出现图片上传失败  我们用的是base64和后台交互的,但是base64有大小限制 大约在750--800k之间,超过这个就会无法跟后台进行正常的请求交互.而我们的客户群体又是比较广泛,谁也不知道上帝会给你传多大的照片,而我作为开发,背锅那是肯定的了.为了解决上帝的烦恼呢,就不停地筛选查看文献,最终在俩位大神的文章帮助下自己综合了一下(http://www.jb51.net/article/89491.htm和http://blog.csdn.net/u012603758/article/details/52787225).

    代码如下(自己写了个分类扩展)

    .h

    #import<UIKit/UIKit.h>

    @interface UIImage (YZJImageScale)

    //image: 处理的图片  

    //kb:处理后的大小 单位kb

    //size:处理后的尺寸(压之后 还大于kb的话才会缩)

    +(NSData*)scaleImage:(UIImage *)image toKb:(NSInteger)kb withSize:(CGSize )size;

    @end

    .m

    #import "UIImage+YZJImageScale.h"

    @implementation UIImage (YZJImageScale)

    +(NSData *)scaleImage:(UIImage *)image toKb:(NSInteger)kb withSize:(CGSize )size{

    //压

    if (kb<1) {

    return nil;

    }

    kb*=1024;

    CGFloat compression = 0.4f;

    CGFloat maxCompression = 0.1f;

    NSData *imageData = UIImageJPEGRepresentation(image, compression);

    while ([imageData length] > kb && compression > maxCompression) {

    compression -= 0.1;

    imageData = UIImageJPEGRepresentation(image, compression);

    }

    //缩

    if ([imageData length]>kb&&compression<0.1) {

    UIImage *newImage=[UIImage imageWithData:imageData];

    UIImage *targetImg=[[self new] imageByScalingAndCroppingForSize:size withSourceImage:newImage];

    imageData= UIImageJPEGRepresentation(targetImg, 0.7f);

    }

    return imageData;

    }

    - (UIImage*)imageByScalingAndCroppingForSize:(CGSize)targetSize withSourceImage:(UIImage *)sourceImage

    {

    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;

    }

    @end

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