压缩图像以满足文件大小限制 (Android)

Question

我已经实现了下面的代码来缩小图像的纵横比（通过相对于彼此成比例地减小高度/宽度）。这肯定有助于减小上传到我后端的图像的大小，但这并没有考虑到图像的分辨率。我想设置一个硬图像限制，比如 800Kb，如果图像在调整大小后大于 800Kb，则压缩到小于 800Kb 的点。

任何人都有做这样的事情的经验？我很好奇传递给 Bitmap.Compress 方法的质量参数与每个质量百分比减少的文件大小之间有什么关系 - 如果我能获得这些信息，我相信我可以达到我的目标。

提前感谢您的任何帮助，我当前的代码如下，也许它会帮助其他人在未来朝着这个方向前进。

public static void uploadImage(String url, File file, Callback callback, Context context,
                               IMAGE_PURPOSE purpose) {

    BitmapFactory.Options options = new BitmapFactory.Options();
    options.inPreferredConfig = Bitmap.Config.ARGB_8888;
    Bitmap bitmap = BitmapFactory.decodeFile(file.getAbsolutePath(), options);

    int maxWidth = 0;
    int maxHeight = 0;
    int maxSize = 0;
    switch(purpose){
        case PROFILE:
            maxWidth = Constants.MAX_PROFILE_IMAGE_WIDTH;
            maxHeight = Constants.MAX_PROFILE_IMAGE_HEIGHT;
            maxSize = Constants.MAX_PROFILE_IMAGE_SIZE;
            break;
        case UPLOAD:
            maxWidth = Constants.MAX_UPLOAD_IMAGE_WIDTH;
            maxHeight = Constants.MAX_UPLOAD_IMAGE_HEIGHT;
            maxSize = Constants.MAX_UPLOAD_IMAGE_SIZE;
            break;
    }

    int newWidth = bitmap.getWidth();
    int newHeight = bitmap.getHeight();

    // Make sure the width is OK
    if(bitmap.getWidth() > maxWidth){

        // Find out how much the picture had to shrink to get to our max defined width
        float shrinkCoeff = ((float)(bitmap.getWidth() - maxWidth) / (float)bitmap.getWidth());
        newWidth = maxWidth;

        // Shrink the height by the same amount to maintain aspect ratio
        newHeight = bitmap.getHeight() - (int)((float)bitmap.getHeight() * shrinkCoeff);
    }

    // Make sure the height is OK
    if(newHeight > maxHeight){

        // Find out how much the picture had to shrink to get to our max defined width
        float shrinkCoeff = ((newHeight - maxHeight) / newHeight);
        newHeight = maxHeight;

        // Shrink the width by the same amount to maintain aspect ratio
        newWidth = newWidth - (int)((float)newWidth * shrinkCoeff);
    }

    Bitmap resized = Bitmap.createScaledBitmap(bitmap, newWidth, newHeight, true);

    // Get the image in bytes
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    resized.compress(Bitmap.CompressFormat.JPEG, 100, bos);
    byte[] imageBytes = bos.toByteArray();

    // If the size on disk is too big, reduce the quality
    if(imageBytes.length > maxSize){
        // Compress image here to get to maxSize
    }