如何在将图像上传到服务器之前降低图像质量

Posted 2023-04-17

【中文标题】如何在将图像上传到服务器之前降低图像质量

【英文标题】：How to reduce image quality before uploading it on server

【发布时间】：2019-09-23 09:24:47

【问题描述】：

我正在从图库中获取图像并尝试在将其上传到服务器之前降低其质量，但我不知道如何正确执行。

下面是我的代码：

 openGallery.setOnClickListener(new View.OnClickListener() 

        @Override
        public void onClick(View v) 

            Intent i = new Intent();
            i.setType("image/*");
            i.setAction(Intent.ACTION_GET_CONTENT);
            startActivityForResult(Intent.createChooser(i,"Select picture"),GALLERY_IMAGE);
        
    );

      @Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) 
    super.onActivityResult(requestCode, resultCode, data);

    if(requestCode == GALLERY_IMAGE && resultCode == RESULT_OK && data != null)

        selectedImage = data.getData();

        Bitmap bitmap = null;

        try 

             bitmap = MediaStore.Images.Media.getBitmap(getContentResolver(),selectedImage);


         catch (IOException e) 
            e.printStackTrace();

        

          if(bitmap !=  null)

              bookImage.setImageBitmap(bitmap);
          

      

    else

        TastyToast.makeText(getApplicationContext(),"No image selected",TastyToast.LENGTH_SHORT,TastyToast.INFO).show();

    

请让我知道我应该在上面的代码中添加什么以获得结果任何帮助将不胜感激。

谢谢

【问题讨论】：

查看这篇文章***.com/questions/18545246/how-to-compress-image-size

【参考方案1】：

我使用如下代码来缩小和设置 JPG 质量。下面的代码将 JPG 流保存到文件中，但您应该能够将其发送到内存流和字节数组。

话虽如此，您还应该考虑让 android 向您返回缩小尺寸的图片。特别是对于较旧的设备，您的应用程序可能没有足够的内存来存储全尺寸图片。不过，我没有任何代码供您执行此操作，抱歉。

            // Shrink to fit picture in a max size
        Point newSize = util.fitSizeInBounds(new Point(rawBitmap.getWidth(), rawBitmap.getHeight()), new Point(_maxPicSize, _maxPicSize));
        if (rawBitmap.getWidth() > newSize.x || rawBitmap.getHeight() > newSize.y) 
            scaledBitmap = Bitmap.createScaledBitmap(rawBitmap, newSize.x, newSize.y, false);
            // Because I was concerned about memory leaks, I call recycle, but maybe this is not nessessary
            rawBitmap.recycle(); rawBitmap = null;
        
        else 
            scaledBitmap = rawBitmap; rawBitmap = null;
        

        // Save file
        try 
            FileOutputStream outStream = new FileOutputStream(_tempDir + fileName);
            if (ext.equals("png")) scaledBitmap.compress(Bitmap.CompressFormat.PNG, 100, outStream);
            else scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 70, outStream);  // Here you can compress JPG (70% quality here)
            outStream.close();
        
        catch (Exception e) 



public Point fitSizeInBounds(Point size, Point bounds) 

    // return size that can fit in bounds.  Result will keep same proportion as orig size
    int newWidth = size.x;
    int newHeight = size.y;

    if (newWidth > bounds.x) 
        newHeight = (newHeight * bounds.x) / newWidth;
        newWidth = bounds.x;
    
    if (newHeight > bounds.y) 
        newWidth = (newWidth * bounds.y) / newHeight;
        newHeight = bounds.y;
    
    return new Point(newWidth, newHeight);