About the DHTML Sample

The Dynamic HTML Sample consists of two Web pages, a series of GIF images, and the Clip1.asf file. The Default.htm page contains a Windows Media Player control, which starts playing Clip1.asf as soon as the page is opened, and various other frames and controls for displaying text and the DHTML events. A row along the lower section of the page displays your progress through the content. Click the Details buttons, which pop up in the row, to open a second page that displays the scripting used to implement the DHTML shown on the Default.htm page.

As Clip1.asf is played back, the Windows Media Player control reads script commands contained in the file, and sends them to the browser at the appropriate times. Each script command contains two text strings. The first string is passed to the browser in a ScriptCommand event as the variable bstrType; the second is passed as bstrParam.

When you click a Details button, one of the first lines in the JavaScript code is similar to if (bstrType = = “eventnumber1”). An If statement is the mechanism that is almost always used when handling script commands in a Web page. In this case, when bstrType is equal to eventnumber1, then the code within that If statement is executed.

The DHTML Sample also demonstrates how you can enhance the look of your Web page by the creative placement and graphic treatment of Windows Media Player. In this case, the Windows Media Player display and controls are hidden, and transport control methods are sent to it using JavaScript and a custom button bar.

Expanding on this Sample

DHTML provides you with a powerful tool for enhancing your Web site. For example, with Windows Media Technologies components and DHTML, you can do the following:

Send code. Both the script type string and command string are capable of holding over 100 ASCII characters. In most cases, script commands are used for sending display and URL text, but they can also be used for sending chunks of executable code or even a small program, such as a JavaScript applet. In the DHTML Sample, the following script command is sent as Clip1.asf is played back. The script command type string is:
```
eventnumber3
```
The command in the script command is:
```
document.all.DHTMLTitle.style.visibility = 
"hidden";document.all.slide2.style.visibility = 
"hidden";move(dlogo,20,20,5);
```
In JavaScript on the Web page, Default.htm, the command text in the script command becomes the argument in an eval function. The script command runs the move() function and changes the visibility attribute of two images. The following is a portion of Default.htm:
```
else if (bstrType == "eventnumber3")
            {
                eval(bstrparam);
                document.all.descript.innerText = "In this third event, the code is embedded in the .asf file to run the move(); function as well as the code to change the 'visibility' attibute of two images.";
                …
            }
```
Integrate Microsoft® PowerPoint® 2000. The latest version of PowerPoint has many new features that make it especially useful for creating Web-based presentations using Windows Media components and DHTML. PowerPoint 2000 presentations can be saved as Web pages. allowing users to view them in Microsoft® Internet Explorer version 4.01 or later on the Internet or an internal network. An online broadcast wizard in PowerPoint 2000 makes it easy to set up live presentations that look similar to the DHTML Sample. The wizard helps you schedule and plan the live event, send e-mail announcements, set up servers, and configure Microsoft® Windows Media™ Encoder for live audio and video.

For more information, see Windows Media Presenter and Enhancing ASF content in the Windows Media Tools Documentation.

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