ios图片压缩

下面的例子是一个ios图片压缩的简单示例函数。可以压缩图片的分辨率和质量

在工程里新建category：UIImage+Compress， 拷贝以下代码到对应的文件。

UIImage+Compress.h文件

#import <Foundation/Foundation.h>

@interface UIImage (Compress)
/**
 * @description 按分辨率和质量压缩图片
 * @param newSize 压缩到的分辨率
 * @param quality 压缩到的质量
 * @return image data
 */
- (NSData *)dataByCompressToSize:(CGSize)size toQuality:(CGFloat)quality;

/**
 * @description 按分辨率和质量压缩图片
 * @param newSize 压缩到的分辨率
 * @param quality 压缩到的质量
 * @return image
 */
- (UIImage *)imageByCompressToSize:(CGSize)size toQuality:(CGFloat)quality;

/**
 * @description 按分辨率比例和质量压缩图片
 * @param scale 压缩到的分辨率比例
 * @param quality 压缩到的质量
 */
- (NSData *)dataByCompressToScale:(CGFloat)scale toQuality:(CGFloat)quality;

/**
 * @description 按分辨率比例和质量压缩图片
 * @param scale 压缩到的分辨率比例
 * @param quality 压缩到的质量
 */
- (UIImage *)imageByCompressToScale:(CGFloat)scale toQuality:(CGFloat)quality;


@end

UIImage+Compress.m文件

#import "UIImage+Compress.h"
#import <ImageIO/ImageIO.h>

@implementation UIImage (Compress)
- (NSData *)dataByCompressToSize:(CGSize)size toQuality:(CGFloat)quality {
    UIImage *compressedImage = self;
    if (!CGSizeEqualToSize(size, CGSizeZero)) {
        UIGraphicsBeginImageContext(size);
        [self drawInRect:CGRectMake(0, 0, size.width, size.height)];
        compressedImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
    }
    if (quality == 1) {
        return UIImagePNGRepresentation(compressedImage);
    } else {
        return UIImageJPEGRepresentation(compressedImage, quality);
    }
}

- (UIImage *)imageByCompressToSize:(CGSize)size toQuality:(CGFloat)quality {
    UIImage *compressedImage = self;
    if (!CGSizeEqualToSize(size, CGSizeZero)) {
        UIGraphicsBeginImageContext(size);
        [self drawInRect:CGRectMake(0, 0, size.width, size.height)];
        compressedImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
    }
    if (quality == 1) {
        return compressedImage;
    } else {
        return [UIImage imageWithData:UIImageJPEGRepresentation(compressedImage, quality)];
    }
}

- (NSData *)dataByCompressToScale:(CGFloat)scale toQuality:(CGFloat)quality {
    return [self dataByCompressToSize:CGSizeMake(self.size.width * scale, self.size.height * scale) toQuality:quality];
}

- (UIImage *)imageByCompressToScale:(CGFloat)scale toQuality:(CGFloat)quality {
    return [self imageByCompressToSize:CGSizeMake(self.size.width * scale, self.size.height * scale) toQuality:quality];
}

@end

Android图片压缩

首先需要引入**BitmapUtils**类。

import com.alibaba.sdk.android.media.utils.BitmapUtils

1 压缩指定路径的文件

通过指定文件的路径filePath，设置压缩分辨率width和height，并指定压缩的质量quality，完成文件压缩。如下所示：

byte[] BitmapUtils.getSmallBitmapBytes(String filePath, int width, int height, int quality)

2 byte[]压缩到Bitmap

设置压缩分辨率width和height，将图片数据byte[]压缩到Bitmap。

Bitmap BitmapUtils.createBitmap(byte[] data, int maxWidh, int maxHeight)

3 Bitmap转换到byte[]

将Bitmap对象转换成byte[]。

byte[] BitmapUtils.toBytes(Bitmap bm)

4 Bitmap压缩到Bitmap

设置压缩的质量quality，将Bitmap压缩到Bitmap。

Bitmap BitmapUtils.compressBitmap(Bitmap bitmap, int compress)

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