androidmediastoreandroid-photo-picker

Permissions needed reading picture from gallery using MediaStore API

Consider implementing an app, that lets users pick images taken with a camera from Gallery, and then use those pics on the app.

Project settings are

targetSdk=34, compileSdk=34, minSdk=22

Using MediaStore API, picker can be launched

startActivityForResult(Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI) ,1);

and then acquire a picture in onActivityResult()

override fun onActivityResult(requestCode: Int, resultCode: Int, intent: Intent?) {
    super.onActivityResult(requestCode, resultCode, intent)
    val uri = intent!!.data!!
    val inputStream = contentResolver.openInputStream(uri)!!
    val bitmapBytes = inputStream.readBytes()
    val bitmap = BitmapFactory.decodeByteArray(bitmapBytes, 0, bitmapBytes.size)
}

Question 1: What permissions are needed to produce Bitmap? Reading specs it seems that READ_EXTERNAL_STORAGE would be needed. But the code works without any permission in SDK 34-24, and starts only requiring READ_EXTERNAL_STORAGE on <= SDK 23.

Question 2: Why READ_MEDIA_IMAGES is not needed on >= SDK 33? As it states on another specs, implementation needs that permission to read images other app produced on SDK 33 onwards.

Question 3: What would be the advantage of using PhotoPicker API (instead of MediaStore)?

Solution

  • What permissions are needed to produce Bitmap?

    If the Uri has a content scheme (and they all should on modern versions of Android), you should already have permission, courtesy of the user being involved in the selection via ACTION_PICK.

    starts only requiring READ_EXTERNAL_STORAGE on <= SDK 23

    Your Uri presumably has the file scheme on those older devices.

    Why READ_MEDIA_IMAGES is not needed on >= SDK 33?

    See above.

    What would be the advantage of using PhotoPicker API (instead of MediaStore)?

    You are not using MediaStore. You are using ACTION_PICK. What handles ACTION_PICK for a MediaStore-supplied Uri varies by OS version. On the most recent versions of Android, it might be the PhotoPicker — I have not used ACTION_PICK seriously in several years.

    The PhotoPicker API: