Add Caption for an Image

   
  
<Window x:Class="BitmapProgramming.AddCaption"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="BitmapProgramming" Height="300" Width="300"
    >
  <Image x:Name="imageElement" />
</Window>

//File:Window.xaml.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;

namespace BitmapProgramming
{
    public partial class AddCaption : System.Windows.Window
    {
        public AddCaption()
        {
            InitializeComponent();

            BitmapImage originalBmp = new BitmapImage();
            originalBmp.BeginInit();
            originalBmp.UriSource = new Uri("http://www.your host.com/a.jpeg");
            originalBmp.DownloadCompleted += delegate{
                Grid rootGrid = new Grid();
                Image img = new Image();
                img.Source = originalBmp;
                rootGrid.Children.Add(img);
                TextBlock caption = new TextBlock();
                caption.Text = "Ian&#039;s car";
                caption.VerticalAlignment = VerticalAlignment.Bottom;
                caption.HorizontalAlignment = HorizontalAlignment.Center;
                caption.Margin = new Thickness(5);
                caption.Padding = new Thickness(5);
                caption.TextAlignment = TextAlignment.Center;
                caption.TextWrapping = TextWrapping.Wrap;
                rootGrid.Children.Add(caption);

                RenderTargetBitmap bmp = new RenderTargetBitmap(originalBmp.PixelWidth, originalBmp.PixelHeight,originalBmp.DpiX, originalBmp.DpiY, PixelFormats.Pbgra32);
                rootGrid.Measure(new Size(originalBmp.Width, originalBmp.Height));
                rootGrid.Arrange(new Rect(0, 0, originalBmp.Width, originalBmp.Height));
                bmp.Render(rootGrid);

                imageElement.Source = bmp;
            };
            originalBmp.EndInit();
        }
    }
}