java - 上传到 FirebaseStorage 之前进行图像压缩

Question

我有一个应用，用户可以在其中创建事件并从其图库上传图像并将其上传到 FirebaseStorage。一切工作正常，但图像尺寸确实很大，我想优化加载/下载过程。我已经尝试过这个:

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

UploadTask uploadTask = mountainsRef.putBytes(data);
uploadTask.addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception exception) {
    // Handle unsuccessful uploads
}
}).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
@Override
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
    // taskSnapshot.getMetadata() contains file metadata such as size,  content-type
    Uri downloadUrl = taskSnapshot.getDownloadUrl();
}
});

并设置bitmap.compress(Bitmap.compressFormat.JPEG, 50, baos);这是可行的，但这基本上使每张图像都变得丑陋。有没有办法(如果可能的话，有指南)在不完全破坏质量的情况下减小图像的尺寸？

Answer 1

What helped me was i scaled down the image resolution after converting the captured image to 1280 x 720 and then it dropped my file size by more that 50%.

Here is an example method.

   /**
     * Compress the file and return the compressed photo
     *
     * @return photoFile
     */
    public File PhotoCompressor(File PhotoFile) {
        Bitmap b = BitmapFactory.decodeFile(photoFile.getAbsolutePath());


        int originalWidth = b.getWidth();
        int originalHeight = b.getHeight();
        int boundWidth = COMPRESSED_PHOTO_WIDTH;
        int boundHeight = COMPRESSED_PHOTO_HEIGHT;
        int newWidth = originalWidth;
        int newHeight = originalHeight;

        //check if the image needs to be scale width
        if (originalWidth > boundWidth) {
            //scale width to fit
            newWidth = boundWidth;
            //scale height to maintain aspect ratio
            newHeight = (newWidth * originalHeight) / originalWidth;
        }

        //now check if we need to scale even the new height
        if (newHeight > boundHeight) {
            //scale height to fit instead
            newHeight = boundHeight;
            //scale width to maintain aspect ratio
            newWidth = (newHeight * originalWidth) / originalHeight;
        }
        Log.i(TAG, "Original Image:" + originalHeight + " x" + originalWidth);
        Log.i(TAG, "New Image:" + newHeight + " x" + newWidth);
        try {
            Bitmap out = Bitmap.createScaledBitmap(b, newWidth, newHeight, true);
            FileOutputStream fOut;
            fOut = new FileOutputStream(photoFile);
            out.compress(Bitmap.CompressFormat.JPEG, 100, fOut);
            fOut.flush();
            fOut.close();
            b.recycle();
            out.recycle();
        } catch (OutOfMemoryError exception) {
            Log.e(TAG, "OutofMemory excpetion" + exception);
            exception.printStackTrace();
        } catch (FileNotFoundException e) {
            Log.e(TAG, "File not found excpetion" + e);
            e.printStackTrace();
        } catch (IOException e) {
            Log.e(TAG, "IO exception excpetion" + e);
            e.printStackTrace();
        }
        return photoFile;
    }