Hosting IE in your application is a relatively straight forward process, provided your development environment supports the use of ActiveX controls. Each language/framework has its own way of doing it: VB works directly with the WebBrowser control, MFC has its CHtmlView wrapper classes, Delphi has the TWebBrowser wrapper and C++Builder uses TCppWebBrowser. Create one of these somewhere in your application and your on your way to displaying HTML pages.
Before I go any further, I want to point you to the MSDN documentation of reusing the WebBrowser control. It will be an invaluable reference to you.
The WebBrowser control is really made up of a command interface (IWebBrowser2) and event interfaces (DWebBrowserEvents and DWebBrowserEvents2). Unless you are writing code against the raw control (please don’t), your wrapper component will expose both of these sides to you automatically. The event names may be slightly different between components. Here are the most useful methods and events:
- Document – This property is your means to gain access to the IHTMLDocument2 MSHTML interface. More on this in later posts, I just wanted to point it out now.
- Navigate / Navigate2 – Provides a simple way to tell the WebBrowser to display a page from a given file or URL. Remember to specify the full URL (including http://). Navigate is the simpler method. Both support functionality such as passing in flags to keep the page from displaying in IE’s cache list.
- GoHome / GoBack / GoForward / Refresh – Allow you to mimic the IE functionality with the respective names.
- ExecWB – Provides a way to get the WebBrowser to execute commands (listed here), such as Print, Print Preview, Save As, Copy and Find.
- OnBeforeNavigate2 – Event that is called before the WebBrowser actually navigates to a given page. This event allows you to cancel or redirect the navigation. Many embedded browser applications use this event to implement “custom protocols” where clicking on a link will display your dialog, for example.
- OnDocumentComplete – Event that is called when a page is fully loaded into the browser. Use this event as a trigger for hooking up other functionality that can only be done after a page is completely in the browser.
- OnNavigateComplete2 – Event that is fired as individual pieces of the page are loaded. Many people assume this event will only be called once per page load. Not true, it is called once for each frame and then for the page. It is usually safer to use OnDocumentComplete, unless you need to be notified for each frame.
Using these methods and events, it is very easy to create a nicely featured web browser. Next time we can look at ways to make WebBrowser seem less like a web browser and more like a custom HTML display control you can use inside your application.