Re: Layout basics

Hi Kevin

Nice reply! :)
Thanks!

Kevin Spencer wrote:
Hi Samuel,

As an admitted newbie, I can certainly see why you would call the positioning issue an "absolute nightmare." In fact, it is a nightmare for many of us, and no piece of cake to those of us with quite a bit of experience. And I wish I had some simple rules for you to follow. But there are none. I'm going to start from the beginning, and please forgive me if I tell you anything you already know.

ASP.Net is a technology for developing web applications. A web application is an application in which the vast majority of the programming is on a server machine, but the user interface is presented via a "thin-client" HTML browser user interface.

I'm sure you've visited many web sites, and viewed many web pages, even as an end-user. What I'm not sure about is if you're at all familiar with HTML (HyperText Markup Language), which is the text-based language that provides the display in a browser. HTML started out as an invention of the Mosaic group, who created the first web browsers, and a language for formatting display in those browsers. It quickly caught on, and before you know it, there were several popular web browsers, and several different "flavors" of HTML floating around. Things began to get complicated. There were no standards, and the major players in the game were all trying to outdo each other with browsers that did more, which meant creating HTML that enabled browsers to do more. Thus began the infamous "browser wars" not so long ago, in a galaxy not so far away.

Thankfully, standards organizations like the W3C (World-Wide Web Consortium) and ISO (International Organization for Standards) began to get involved, to bring some order to the chaos, and make life simpler for everyone. And that goal is being realized, but is not yet fully realized. So, between "legacy" HTML, and the various flavors of browsers, perhaps most notably IE 6, which has long outlived its heyday, soon to be replaced by the standards-based IE7, which has been delayed for entirely too long, we have an "absolute nightmare" involved in doing layout that looks more or less the same in the major browsers.

HTML started off rather simply, with not much thought in the way of fancy layout, and the use of an ever-expanding list of inline attributes to handle layout properties. In the beginning, HTML was laid out in a "flow layout" in which various elements simply appeared in the browser in the order in which they existed in the markup language, some on new lines, and some inline. This was an increasingly troublesome situation. The first solution was the use of HTML tables to provide enhanced layout capabilities. But this was only a partial solution, and not extremely well-thought-out. Tables still used inline markup and were limited to a tabular format.

The advent of CSS (Cascading Style Sheets) changed all that. CSS could be written as inline style attributes, or in a single block in the head of an HTML document, or even as an external document that was linked to HTML elements via style names, element names, and id attributes. CSS was not limited to a tabular format; in fact, elements could be freely positioned in any variety of ways. Now CSS is the dominant layout methodology. But CSS is more complex than tables. CSS elements can be positioned absolutely (relative to the page) or relatively to other elements.

Getting back to ASP.Net now, ASP.Net was an evolution in web application development, which started with CGI, ASP, and other similar technologies. Microsoft decided that ASP should behave in a familiar way, and thus introduced the concept of the "WebForm," which is intended to behave much like a Windows Form, both to the developer and to the user. Of course, it can't really, but it does a decent job of approximating much of the look and feel.

Because Windows Forms use "absolute positioning" in a Form interface, the default layout "style" of a WebForm is called "grid layout." This uses CSS absolute positioning. However, because a browser with HTML is not a Windows Form application, and browsers are all different, well, it is only partially successful. WebControls and HtmlControls are actually server-side classes that present themselves as HTML elements or combinations thereof on the client browser.

Bottom line is, there are 2 basic paths you can take, and each has its plusses and minuses. You can use "flow layout" and HTML tables, which is simpler, but less flexible and extensible, or you can use "grid layout" and absolute positioning. Or, you can mix and match. But in any case, you're going to have to learn a good bit more about HTML, JavaScript and CSS to get any good at it. And test in a variety of browsers, screen resolutions, etc.

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