png transparent image file in android

Question

I want to save a png image to SD card and it should be without background. in the sd card I do not see any background but when attach it into telegram I see a white background. here is my code in android:

    File filepath = Environment.getExternalStorageDirectory();
    File dir = new File(filepath.getAbsolutePath() + "/background_eraser/");
    dir.mkdirs();
    mImagename = "image" + cal.getTimeInMillis() + ".png";
    file = new File(dir, mImagename);