像在whatsapp上一样在iPhone上压缩图像 [英] Compression of an image on an iPhone like on whatsapp

问题描述

我正试图在Swift编程语言中找到一个图像压缩算法，就像在WhatsApp信使中一样。在OS下编程语言Java下我发现很快，并且在iOS平台下有困难。 
 
以下是适用于Android的图像压缩算法：

  public   static 文件saveBitmapToFile（文件文件）{
 尝试 {
  //  缩小图像的BitmapFactory选项 
 BitmapFactory .Options o =  new  BitmapFactory.Options（）; 
 o.inJustDecodeBounds = true; 
 o.inSampleSize =  6 ; 
  //  缩小图像的因素 
 
 FileInputStream inputStream =  new  FileInputStream（file）; 
  //   Bitmap selectedBitmap = null;  
 BitmapFactory.decodeStream（inputStream，null ，o）; 
 inputStream.close（）; 
 
  //  我们想要扩展到的新尺寸 
  final   int  REQUIRED_SIZE = 75; 
 
  //  找到正确的比例值。应该是2的幂。 
  int  scale =  1 ; 
  while （o.outWidth / scale /  2 > = REQUIRED_SIZE&& 
 o.outHeight / scale /  2 > = REQUIRED_SIZE）{
 scale * =  2 ; 
} 
 
 BitmapFactory.Options o2 =  new  BitmapFactory.Options（）; 
 o2.inSampleSize = scale; 
 inputStream =  new  FileInputStream（file）; 
 
 Bitmap selectedBitmap = BitmapFactory.decodeStream（inputStream，null，o2）; 
 inputStream.close（）; 
 
  //  这里我覆盖原始图像文件 
 file .createNewFile（）; 
 FileOutputStream outputStream =  new  FileOutputStream（file）; 
 
 selectedBitmap.compress（Bitmap.CompressFormat.JPEG， 70 ，outputStream）; 
 
  return 文件; 
}  catch （例外e）{
  return  null; 
} 
} 

此算法将图像压缩为100 KB。如果您能告诉我如何将此代码复制到Swift编程语言中，我将非常感激。

什么我试过了：

我研究了很多文章，试图使用不同的算法（遗憾的是我无法发布它们，因为我不记得网站），但我找不到必要的解决方案。

解决方案

Quote：

此算法将图像压缩为100 KB。

否，此代码不会将图像压缩为给定大小，它会缩小图片。缩小尺寸只是次要影响。

引用：

我正在尝试查找图像压缩算法

您不是在寻找压缩算法jpeg图像已被压缩。

您正在寻找的是一个允许您调整图像大小的库。

I'm trying to find an image compression algorithm in the Swift programming language, as in the WhatsApp messenger. In the programming language Java under OS Android I found quickly, and under the platform iOS have difficulties.

Here is the image compression algorithm for Android:

public static File saveBitmapToFile(File file){
    try {
        // BitmapFactory options to downsize the image
        BitmapFactory.Options o = new BitmapFactory.Options();
        o.inJustDecodeBounds = true;
        o.inSampleSize = 6;
        // factor of downsizing the image

        FileInputStream inputStream = new FileInputStream(file);
        //Bitmap selectedBitmap = null;
        BitmapFactory.decodeStream(inputStream, null, o);
        inputStream.close();

        // The new size we want to scale to
        final int REQUIRED_SIZE=75;

        // Find the correct scale value. It should be the power of 2.
        int scale = 1;
        while(o.outWidth / scale / 2 >= REQUIRED_SIZE &&
                o.outHeight / scale / 2 >= REQUIRED_SIZE) {
            scale *= 2;
        }

        BitmapFactory.Options o2 = new BitmapFactory.Options();
        o2.inSampleSize = scale;
        inputStream = new FileInputStream(file);

        Bitmap selectedBitmap = BitmapFactory.decodeStream(inputStream, null, o2);
        inputStream.close();

        // here i override the original image file
        file.createNewFile();
        FileOutputStream outputStream = new FileOutputStream(file);

        selectedBitmap.compress(Bitmap.CompressFormat.JPEG, 70 , outputStream);

        return file;
    } catch (Exception e) {
        return null;
    }
}

This algorithm compresses the image to 100 KB. If you can tell me how to duplicate this code into the Swift programming language, I'll be very grateful.

What I have tried:

I have studied many articles, tried to use different algorithms (unfortunately I can not publish them, because I do not remember the sites), but I did not find the necessary solution.

解决方案

Quote:

This algorithm compresses the image to 100 KB.

No, this code do not compress the image to given size, it downscale the image. The reduced size is only a secondary effect.

Quote:

I'm trying to find an image compression algorithm

You are not looking for a compression algorithm jpeg images are already compressed.
What you are looking for is a library that will allow you to resize the images.

这篇关于像在whatsapp上一样在iPhone上压缩图像的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！