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res: Protocol Embedding HTML files in an EXE or DLL resource file
Page: 10 Dec 2001
 
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Introduction

When distributing an application that uses a web based interface or information pages you may not want your pages available to the end user.  The res: protocol allows you to embed your html and other objects into the resource file of an exe or dll file.

A good example of the res: protocol is "about:blank".  This is a blank embedded page.

In developing the project it is probably wiser to work directly with the HTML files so that adjustments to layout can be made during the development process.  Once your interface and application work you can embed the files into a resource file - either using the VB 6 Resource Editor or the Resource Compiler (rc.exe - usually found in the '..Microsoft Visual Studio\Common\Vb\Resources' folder.

You can include the Resource file in your project exe or have a separate ActiveX dll file.

The Res: Protocol
Format:

res://path and filename[/resource type]/resource ID
Path and filename: The path and file name of the EXE or DLL holding the resource.
Resource Type: [Optional] If the resource is a recognised Type (e.g. BITMAP) then the Type can be omitted.  If the resource is a custom resource (e.g. GIF) it should be labeled in the RC (resource compiler script file) and referenced in the res: information.  See the examples below.
Resource ID: This is the identifier of the resource in the resource file.  Often in the VB Resource Editor the first resource is 100 or 101.  If you have experience with defining names for resources you can use the definition term.

The resource type and ID can be referenced as numbers.  The format then requires a # (hash) inserted before the number - however as hash is an 'HTML special character' an escape sequence should be used:  The escape sequence for # (hash) is %23.  This can make the path look complicated especially as the Resource Type value for HTML is 23.

To load an HTML document from a resource file in Visual Basic use:

WebBrowser.Navigate2 "res://myres.dll/%2323/%23101"

Where 101 is the resource ID.

The table below shows examples of referencing elements in a resource file within the HTML source code and how to add a reference to the information in the VB6 Resource editor.

HTML Files
Type: 23 - this is the numerical value for the resource type HTML
HTML CODE:

src="res://myresource.dll/%2323/%23101"

RC Definition:

101 HTML "C:\Example\index.htm"

VB 6 Resource Editor: Click the Resource Editor Custom button 'Add Custom' button, find the htm file and click 'Open'.  The resource will appear in a Folder named "CUSTOM" and will most likely be numbered 101.  Double click the resource and change 'CUSTOM' to 23 in the Type box.  Renumber the resource as required.  Click OK.
Bitmap Files
Type: 2 - this is the numerical value for the resource type BITMAP
HTML CODE:

src="res://myresource.dll/%232/%23102"

RC Definition:

102 BITMAP "C:\Example\example.bmp"

VB 6 Resource Editor: Click the Resource Editor Bitmap button'Add Bitmap' button, find the bmp file and click 'Open'.  The Resource Editor will place the resource in a Folder named "Bitmap".  Double click the resource to change its ID if required.
Custom Types - e.g. GIF and JPG Files
Type: GIF is a custom format, there is no equivalent numerical type.  Note that rather than a numerical reference in the HTML CODE, we state the custom format 'GIF'.  For Jpegs or other formats, replace 'GIF' with the chosen custom name.
HTML CODE:

src="res://myresource.dll/GIF/%23103"

RC Definition:

103 GIF "C:\Example\picture.gif"

VB 6 Resource Editor: Click the Resource Editor Custom button 'Add Custom' button, find the GIF file and click 'Open'.  The resource will appear in a Folder named "CUSTOM".  Double click the resource and change the type from 'CUSTOM' to 'GIF'.  Renumber the resource as required.  Click OK.

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