关于图片处理_siri图片处理-优快云博客

本文介绍iOS平台下图片压缩的方法，包括按宽度压缩、调整大小压缩、使用JPEG表示进行压缩等技术。此外还涉及了QBImagePickerController多选照片时可能出现的问题及解决方案。

1，图片尺寸压缩

//图片压缩，第二个参数为最终宽度
-(UIImage *) imageCompressForWidth:(UIImage *)sourceImage targetWidth:(CGFloat)defineWidth
{
    CGSize imageSize = sourceImage.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;
    CGFloat targetWidth = defineWidth;
    CGFloat targetHeight = (targetWidth / width) * height;
    UIGraphicsBeginImageContext(CGSizeMake(targetWidth, targetHeight));
    [sourceImage drawInRect:CGRectMake(0, 0, targetWidth, targetHeight)];
    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

//方法举例：
UIImage *newImage=[selfimageCompressForWidth:imagetargetWidth:image.size.width/2];

2，尺寸不变，大小压缩举例：ASI上传图片时，

NSData *data = UIImagePNGRepresentation(image);//未压缩
NSData *data =UIImageJPEGRepresentation(image,0.5);//压缩

3，QBImagePickerController多选照片出现的问题

QBImagePickerController.m中方法

- (NSDictionary *)mediaInfoFromAsset:(ALAsset *)asset

3.1，取照片后自动调整为尺寸不超过屏幕宽高：

[mediaInfo setObject:[UIImageimageWithCGImage:[[asset defaultRepresentation]fullScreenImage]] forKey:@"UIImagePickerControllerOriginalImage"];

3.2，取照片后为照片原图：

[mediaInfo setObject:[UIImageimageWithCGImage:[[asset defaultRepresentation]fullResolutionImage]] forKey:@"UIImagePickerControllerOriginalImage"];

3.3，3.2中照片较大会出现左转90度，解决方法为：

[mediaInfo setObject:[UIImage imageWithCGImage:[[asset defaultRepresentation] fullResolutionImage] scale:[asset defaultRepresentation].scale orientation:(UIImageOrientation)[asset defaultRepresentation].orientation] forKey:@"UIImagePickerControllerOriginalImage"];

/**
 *  调整图片尺寸和大小
 *
 *  @param sourceImage  原始图片
 *  @param maxImageSize 新图片最大尺寸
 *  @param maxSize      新图片最大存储大小
 *
 *  @return 新图片imageData
 */
+ (NSData *)reSizeImageData:(UIImage *)sourceImage maxImageSize:(CGFloat)maxImageSize maxSizeWithKB:(CGFloat) maxSize
{

    if (maxSize <= 0.0) maxSize = 1024.0;
    if (maxImageSize <= 0.0) maxImageSize = 1024.0;

    //先调整分辨率
    CGSize newSize = CGSizeMake(sourceImage.size.width, sourceImage.size.height);

    CGFloat tempHeight = newSize.height / maxImageSize;
    CGFloat tempWidth = newSize.width / maxImageSize;

    if (tempWidth > 1.0 && tempWidth > tempHeight) {
        newSize = CGSizeMake(sourceImage.size.width / tempWidth, sourceImage.size.height / tempWidth);
    }
    else if (tempHeight > 1.0 && tempWidth < tempHeight){
        newSize = CGSizeMake(sourceImage.size.width / tempHeight, sourceImage.size.height / tempHeight);
    }

    UIGraphicsBeginImageContext(newSize);
    [sourceImage drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    //调整大小
    NSData *imageData = UIImageJPEGRepresentation(newImage,1.0);
    CGFloat sizeOriginKB = imageData.length / 1024.0;

    CGFloat resizeRate = 0.9;
    while (sizeOriginKB > maxSize && resizeRate > 0.1) {
        imageData = UIImageJPEGRepresentation(newImage,resizeRate);
        sizeOriginKB = imageData.length / 1024.0;
        resizeRate -= 0.1;
    }

    return imageData;
}