getImageSource property

Called when the user clicks the addImageIcon.

If null, the user will be prompted to select an image from the gallery by default.

Example:

getImageSource: () {
    return showDialog<ImageSource>(
      context: context,
      builder: (context) {
        return SimpleDialog(
          children: [
            SimpleDialogOption(
              child: const Text("Camera"),
              onPressed: () {
                Navigator.of(context).pop(ImageSource.camera);
              },
            ),
            SimpleDialogOption(
                child: const Text("Gallery"),
                onPressed: () {
                  Navigator.of(context).pop(ImageSource.gallery);
                }),
          ],
        );
      },
    ).then((value) {
      return value ?? ImageSource.gallery;
    });
  },
),