Reference An Image Imbedded In A Wpf Application From Within An Html File Used As Help Content

October 02, 2024 Post a Comment

I have a WPF desktop application. In it I have a menu option that shows a help window. The help window simply wraps a System.Windows.Controls.WebBrowser control. Now I can create

Solution 1:

Specifying an absolute path to the image will work. For example, in the HTML

<imgalt="My Logo"src="file:///C:/Images/MyLogo_3115-2935.jpg"width="500"/>

This solution would not work with an application resource. You would have to create a file locally from the resource, at least temporarily. Or alternatively copy the file locally with the app.

Another, more complex solution would be to embed a webserver into your application, or somewhere else that responds to web request. For more information see HttpListener

Solution 2:

I thank user2509738 for his reply, however, I wanted to use an image that was embedded instead of deploying a separate file. I came up with my own solution and I'll post it here for completeness.

I used the HtmlAgilityPack found at http://htmlagilitypack.codeplex.com to make parsing a little easier.

Here is the HelpWindow.Xaml

<Windowx:Class="POC_WpfHelpWindowUsingHtml.HelpWindow"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"Title="HelpWindow"Height="600"Width="800"><Grid><Grid.RowDefinitions><RowDefinition/><RowDefinitionHeight="50"/></Grid.RowDefinitions><WebBrowserx:Name="helpBrowser"/><StackPanelx:Name="controlPanel"Grid.Row="1"Orientation="Horizontal"HorizontalAlignment="Right"><Buttonx:Name="closeButton"Margin="0,10,20,10"Width="100"Content="Close"Click="closeButton_Click"/></StackPanel></Grid></Window>

Here is the HTML content in the form of a file: HelpContent.html

<!DOCTYPE html><htmllang="en"xmlns="http://www.w3.org/1999/xhtml"><head><metacharset="utf-8" /><title></title></head><body><tablestyle="width: 100%;"><tr><td>&nbsp;</td><tdstyle="align-content:center"><imgid="imgMyLogo"alt="My Logo"src="Images/MyLogo.png"width="100"/></td><td>&nbsp;</td></tr></table></body></html>

Here is the HelpWindow.xaml.cs file with most of the magic

using System;
using System.IO;
using System.Windows;
using HtmlAgilityPack;
using System.Reflection;

namespacePOC_WpfHelpWindowUsingHtml
{
    ///<summary>/// Interaction logic for HelpWindow.xaml///</summary>publicpartialclassHelpWindow : Window
    {
        publicHelpWindow()
        {
            InitializeComponent();
            Uri uri = new Uri(@"/HelpContent.html", UriKind.Relative);
            System.Windows.Resources.StreamResourceInfo info
                = System.Windows.Application.GetContentStream(uri);
            Stream streamOriginalPage = info.Stream;
            Stream streamModifiedPage = new MemoryStream();
            StreamWriter streamWriter = new StreamWriter(streamModifiedPage);

            // this is from HtmlAgilityPack
            HtmlDocument doc = new HtmlDocument();
            doc.Load(streamOriginalPage);
            // find all the img elementsforeach (HtmlNode node in doc.DocumentNode.SelectNodes("//img"))
            {
                // change the image reference to an embedded stringstring src = node.GetAttributeValue("src", "");
                src = ConvertImageToEmbeddedString(src);
                if (!string.IsNullOrWhiteSpace(src))
                {
                    node.SetAttributeValue("src", src);
                }
            }
            // save the changes
            doc.Save(streamWriter);
            streamWriter.Flush();
            streamModifiedPage.Position = 0;

            // send the Html content to the WebBrowser component
            helpBrowser.NavigateToStream(streamModifiedPage);
        }

        privatevoidcloseButton_Click(object sender, RoutedEventArgs e)
        {
            this.Close();
        }

        privatestringConvertImageToEmbeddedString(string source)
        {
            // find the image typestring imageType = "png";
            if (source.ToLower().IndexOf("jpg") > -1) imageType = "jpg";
            if (source.ToLower().IndexOf("ico") > -1) imageType = "ico";
            // initialize the return valuestring ret = "";

            if (source.Length > 4)
            {
                if (!source.StartsWith("/"))
                {
                    source = "/" + source;
                }

                // get the embedded image as a stream
                Stream stream = Application.GetResourceStream(
                    new Uri("pack://application:,,," + source)).Stream;
                if (stream != null)
                {
                    // put the image into an Image object
                    System.Drawing.Image image = System.Drawing.Image.FromStream(stream);
                    if (image != null)
                    {
                        // prepend the text for Data URI scheme
                        ret = "data:image/" + imageType + ";base64,";
                        using (MemoryStream ms = new MemoryStream())
                        {
                            // convert the image into a MemoryStream
                            image.Save(ms, image.RawFormat);
                            // convert the image to base64 encoding
                            ret += Convert.ToBase64String(ms.ToArray());
                        }
                    }
                }
            }

            return ret;
        }
    }
}

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Reference An Image Imbedded In A Wpf Application From Within An Html File Used As Help Content

Solution 1:

Solution 2:

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