Adding, Deleting, and Replacing Resources

Applications must frequently add, delete, or replace resources in executable files. Two methods can be used to accomplish these tasks. The first is to edit the resource-definition file, recompile the resources, and add the recompiled resources to the application's executable file. The second method is to copy the resource data directly into the application's executable file.

For example, to localize an English-language application for use in Norway, it may be necessary to replace the English dialog box with one using Norwegian. A developer creates an appropriate dialog box by using a dialog box editor or by writing a template in the resource-definition file. The developer then recompiles the resources and adds the new resources to the application's executable file.

If an appropriate dialog box exists in binary form, however, the developer can copy the data directly to the executable file being localized by using three Windows functions. The BeginUpdateResource function creates an update handle for the executable file whose resources are to be changed. The UpdateResource function uses this handle to add, delete, or replace a resource in the executable file. The EndUpdateResource function closes the handle.

After an update handle to an executable file is created by BeginUpdateResource, an application can use UpdateResource repeatedly to make changes to the resource data. Each call to UpdateResource contributes to an internal list of additions, deletions, and replacements but does not actually write the data to the executable file. Immediately before closing the update handle, EndUpdateResource writes the accumulated changes to the executable file.

Sometimes, an application must copy resources or find resource sizes. The LoadLibrary function provides a module handle to an executable file whose resources are to be copied, and the LockResource function provides a pointer to the resource data in the specified module. The SizeofResource function returns the size, in bytes, of a specified resource.