如何调整相机或画廊照片的大小

Question

我从图库或相机中选择一个文件。然后我将它们上传到服务器。但我不能减小它们的大小。图像质量无关紧要。你能告诉我最好的方法吗？我是初学者，我不知道如何使用代码。所以请提供详细信息。

  private File createImageFile() throws IOException {
    // Create an image file name
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    String imageFileName = "JPEG_" + timeStamp + "_";
    File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
    File image = File.createTempFile(
            imageFileName,  /* prefix */
            ".jpg",         /* suffix */
            storageDir      /* directory */
    );

    // Save a file: path for use with ACTION_VIEW intents
    currentPhotoPath = image.getAbsolutePath();
    return image;
}

 private void dispatchTakePictureIntent() {
    Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    // Ensure that there's a camera activity to handle the intent
    if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
        // Create the File where the photo should go
        File photoFile = null;
        try {
            photoFile = createImageFile();
        } catch (IOException ex) {
            // Error occurred while creating the File

        }
        // Continue only if the File was successfully created
        if (photoFile != null) {
            Uri photoURI = FileProvider.getUriForFile(this,
                    "com.example.myapplication.fileprovider",
                    photoFile);
            takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
            startActivityForResult(takePictureIntent, REQUEST_TAKE_PHOTO);
        }
    }
}

protected void onActivityResult(int requestCode, int resultCode, Intent data) {

    if (requestCode == REQUEST_TAKE_PHOTO && resultCode == RESULT_OK) {
        Glide.with(this).load(currentPhotoPath).into(iv);

    } else if (requestCode == SELECT_A_PHOTO && resultCode == RESULT_OK){

        selectedPhoto = data.getData();
        Glide.with(this).load(selectedPhoto).into(iv);

    }

 private void galleryIntent()
{
    Intent i = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
    startActivityForResult(i,SELECT_A_PHOTO);
}

My file sizes look like this

Answer 1

我找到了答案。这个方法可以让你缩小尺寸。

// Get the data from an ImageView as bytes
imageView.setDrawingCacheEnabled(true);
imageView.buildDrawingCache();
Bitmap bitmap = ((BitmapDrawable) imageView.getDrawable()).getBitmap();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos);
byte[] data = baos.toByteArray();

New image size

Answer 2

此函数接受图像路径并转换为位图。 700 是我在这里设置的高度/宽度的基本阈值。您可以相应地更改它并创建缩放位图（数字越小，图像尺寸越小）。 while 循环的每次迭代都将图像缩小到一半。您可以根据需要对其进行修改。

private Bitmap reduce_image_to_bitmap(String file_path){
    Bitmap bit_map = BitmapFactory.decodeFile(file_path);
    int h = bit_map.getHeight();
    int w = bit_map.getWidth();
    while(h > 700 || w > 700){
        h = h/2;
        w = w/2;
    }
    Bitmap out = Bitmap.createScaledBitmap(bit_map, w, h, false);
    return out;
}

确保将位图转换为文件，然后继续将文件发送到您的服务器。

Answer 3

使用这个库：Compressor

• Compressor 是一个轻量级且功能强大的安卓图像压缩库。 Compressor 将允许您将大照片压缩成更小尺寸的照片，而图像质量的损失非常少或可以忽略不计。

Answer 4

首先，您需要处理此图像，以便您可以减小尺寸但可以保持质量。您需要运行后台任务，以便在大图像处理期间设备不会发出嘶嘶声。

然后您可以在此过程中显示一个进度对话框，只需将此代码添加到您的 onCreate 活动中。

  public ProgressDialog progressDialog;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    progressDialog = new ProgressDialog(MyProfileEidtActivity.this);
    progressDialog.setMessage("Loading ...");


    // just execute this process

    new ImageProcessing().execute("YOUR IMAGE PATH");

  }


 public class ImageProcessing extends AsyncTask<String, Void, String> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        progressDialog.setMessage("Image Processing");
        progressDialog.setCancelable(false);
        progressDialog.show();
    }

    @Override
    protected String doInBackground(String... strings) {
        Bitmap mainImage = null;
        Bitmap converetdImage = null;
        ByteArrayOutputStream bos = null;
        byte[] bt = null;
        String encodeString = null;
        try {
            mainImage = BitmapFactory.decodeFile(strings[0]);

        /// 500 means image size will be maximum 500 kb

            converetdImage = getResizedBitmap(mainImage, 500);
            bos = new ByteArrayOutputStream();
            converetdImage.compress(Bitmap.CompressFormat.JPEG, 50, bos);
            bt = bos.toByteArray();
            encodeString = Base64.encodeToString(bt, Base64.DEFAULT);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return encodeString;
    }

    @Override
    protected void onPostExecute(String image) {
        super.onPostExecute(s);
        progressDialog.dismiss();

     // this image will be your reduced image path

    }
}

public Bitmap getResizedBitmap(Bitmap image, int maxSize) {
    int width = image.getWidth();
    int height = image.getHeight();

    float bitmapRatio = (float) width / (float) height;
    if (bitmapRatio > 1) {
        width = maxSize;
        height = (int) (width / bitmapRatio);
    } else {
        height = maxSize;
        width = (int) (height * bitmapRatio);
    }
    return Bitmap.createScaledBitmap(image, width, height, true);
}