BitmapFactory.decodeFile() returning null xamarin.android - xamarin.android

Question

When I am calling this function there is no image/string in _bitmap. In my application, I select image from the gallery and convert it to base64. I had debugged the app for the problem, so I found that the method BitmapFactory.decodeFile("image path") is returning null value even though the path which I am getting is totally fine.
private void _btnResimYolu_Click(object sender, System.EventArgs e)
{
var imageIntent = new Intent();
imageIntent.SetType("image/*");
imageIntent.SetAction(Intent.ActionGetContent);
StartActivityForResult(Intent.CreateChooser(imageIntent, "Select Image"), 0);
}
protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
{
base.OnActivityResult(requestCode, resultCode, data);
if (resultCode == Result.Ok)
{
var imageView = FindViewById<ImageView>(Resource.Id.img1);
imageView.SetImageURI(data.Data);
_imageTest.Text = data.DataString;
}
}
private void _gonder_Click(object sender, System.EventArgs e)
{
string uriString = _imageTest.Text;
_bitmap = BitmapFactory.DecodeFile(uriString);
MemoryStream stream = new MemoryStream();
_bitmap.Compress(Bitmap.CompressFormat.Jpeg, 100, stream);
byte[] ba = stream.ToArray();
string bal = Base64.EncodeToString(ba, Base64.Default);
}

Answer 1

BitmapFactory.decodeFile() returning null
The problem is that your get the wrong image path, so the BitmapFactory.DecodeFile(uriString) always return null. The data.DataString in OnActivityResult is my device is :
[0:] data.Data = content://com.miui.gallery.open/raw/%2Fstorage%2Femulated%2F0%2FDCIM%2FCamera%2FIMG_20171125_143057.jpg
Solution :
When you choose a picture, you should convert its Uri to a real path. You could refer to my answer : How to get actual path from Uri xamarin android. Then, modify your code like this :
protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
{
base.OnActivityResult(requestCode, resultCode, data);
if (requestCode == Result.Ok)
{
var uri = data.Data;
//You could find the GetActualPathFromFile() method code in the above link I have post.
string path = GetActualPathFromFile(uri);
_imageTest.Text = path ;
System.Diagnostics.Debug.WriteLine("data.Data = " + data.Data);
System.Diagnostics.Debug.WriteLine("path = " + path);
}
}
The image path :
[0:] path = /storage/emulated/0/DCIM/Camera/IMG_20171125_143057.jpg
Then you could BitmapFactory.DecodeFile() to implement your function.
Update :
Please make sure you have the WRITE_EXTERNAL_STORAGE permission, since Android 6.0, you have to Requesting Permissions at Run Time.