HTML The Definitive Guide by Chuck Musciano Bill Kennedy Page B

documents. They don't yet fully or gracefully handle multimedia.
    Today, there are few standards for the many types and formats of multimedia. Computer systems connected to the Web vary wildly in their abilities to display those sound and video formats. Except for some graphics images, standard HTML gives you no specific provision for display of multimedia

    documents except the ability to reference one in an anchor. The browser, which retrieves the multimedia document, must activate a special helper application, download and execute an associated applet , or have a plug-in accessory installed to decode and display it for the user right within the document's display.
    Although HTML and most web browsers currently avoid the confusion by sidestepping it, that doesn't mean you can't or shouldn't exploit multimedia in your HTML documents: just be aware of the limitations.
    2.6 HTML and Text
    2.8 Images Are Special

    Chapter 2
    HTML Quick Start
     
    2.8 Images Are Special
    Image files are multimedia elements you may reference with anchors in your HTML document for separate download and display by the browser. But, unlike other multimedia, standard HTML has an explicit provision for image display "in line" with the text,[ 5 ] and images can serve as intricate maps of hyperlinks. That's because there is some consensus in the industry concerning image file formats -
    specifically, GIF and JPEG - and the graphical browsers have built in decoders that integrate those image types into your document.
    [5] Some browsers support other multimedia besides GIF and JPEG graphics for inline display. Internet Explorer, for instance, supports a tag that plays background audio. In addition, the HTML 4.0 standard provides a way to display other types of multimedia inline with HTML document text through a general tag.
    2.8.1 Inline Images
    The HTML tag for inline images is ; its required src attribute is the URL of the GIF or JPEG
    image you want to insert in the document. [, 5.2]
    The browser separately loads images and places them into the text flow as if the image were some special, albeit sometimes very large, character. Normally, that means the browser aligns the bottom of the image to the bottom of the current line of text. You can change that with the special align attribute whose value you set to put the image at the top, middle, or bottom of adjacent text. Examine Figures Figure 2.2 through Figure 2.4 for the image alignment you prefer. Of course,
    wide images may take up the whole line, and hence break the text flow. Or you may place an image by itself, by including preceding and following division, paragraph, or line-break tags.
    Figure 2.2: An inline image aligned with the bottom of the text (default)

    Figure 2.3: An inline image specially aligned with the middle of the text Figure 2.4: An inline image specially aligned with the top of the text Experienced HTML authors use images not only as supporting illustrations, but also as quite small inline characters or glyphs, added to aid browsing readers' eyes and to highlight sections of the documents. Veteran HTML authors commonly add custom list bullets or more distinctive section dividers than the conventional horizontal rules. Images, too, may be included in a hyperlink, so that users may select an inline thumbnail sketch to download a full-screen image. The possibilities with inline images are endless.
    2.8.2 Image Maps
    Image maps are images within an anchor with a special attribute: they may contain more than one hyperlink.
    One way to enable an image map is by adding the ismap attribute to an tag placed inside an

    anchor tag (). When the user clicks somewhere in the image, the graphical browser sends the relative x,y coordinates of the mouse position to the server that is also designated in the anchor. A special server program then translates the image coordinates into some special action, such as downloading another HTML document. [Server-side considerations