Suppose you want to convert an image named MyImage.png from Assets folder then below code will return the base64 string of that image.
private async Task DoWork()
{
var file = await StorageFile.GetFileFromApplicationUriAsync(new Uri("ms-appx:///Assets/MyImage.png"));
var b64 = await ConvertStorageFileToBase64String(file);
}
private async Task<string> ConvertStorageFileToBase64String(StorageFile File)
{
var stream = await File.OpenReadAsync();
using (var dataReader = new DataReader(stream))
{
var bytes = new byte[stream.Size];
await dataReader.LoadAsync((uint)stream.Size);
dataReader.ReadBytes(bytes);
return Convert.ToBase64String(bytes);
}
}