Developing a GUI in C++ and DirectX

· Static Text, Icon, and Group Boxes - vital. These controls label and group the other controls in a dialog box. The static control is crucial; the frame control we could probably live without, but it’s fairly simple, and in some cases can go a long way towards making a dialog box easy to navigate, so I’m including it. Icon controls should be simple, but should be able to animate, providing cool background animations in our dialogs and menus (ala Theif: The Dark Project).

· Buttons and Checkboxes - vital. Weird button types (flat buttons, pushbutton-style radio buttons) we can do without, but most games can’t live without a basic button and checkbox.

· List control - important. I’ve found list controls, especially multi-column list controls, indispensable when creating game GUIs. They’re used everywhere. You’re going to want a very intelligent, heavyweight list control, as good or better than the Windows List Control. For me, the list control was the most difficult control to implement.

· Sliders and scrollbars - Important. Famous for controlling sound and music volume. The bad news is that we’ll probably need horizontal and vertical flavors of these guys; the good news is that they’re so similar you can implement them very easily.

· Textboxes - Vital. You have to be able to enter your mega-3l33t, super-kewl player handle somewhere, right?

· Progress Bars - Essential for displaying hit points, “I’m almost done loading!”, etc.

Noticeably absent from this list are the spin button controls (which aren’t crucial, and irritate me to no end anyway), radio buttons (we can get by with a single selection listbox instead), and the drop-down combo box (again, we can just use a list box), and tree control. By making the listbox control smart enough to indent certain items, we can incorporate the functionality of the tree control

Tab controls aren’t included simply because my game doesn’t have enough of a GUI to warrant them, though your needs may differ.

Even with all the omissions, the “minimum” list might seem daunting at first, but we can simplify it quite a bit…

Breaking It Down: Complex Controls As Combinations of Simple Ones

The list becomes much more manageable when we realize that the more complex controls are just clever combinations of other, more simple controls. For example, a scrollbar is basically just two buttons and a slider control. A checkbox is a static control and two buttons (one “off” button, and one “on” button). A plain old button could be implemented using three static icon controls (just show/hide the appropriate ones to get the button to “press”), so that you can reuse your drawing code. If you were really strapped for time, you could even implement a progress bar as a slider that’s moved by the computer, though I prefer having a separate control for this.

There are, however, disadvantages to this - namely, your GUI controls are going to take up more system resources than they really need. Think about it - each control is a window. Let’s say you’ve gone with the reuse philosophy, and have created a button control that’s really just three different statics. That’s three windows per button. Now, you build a scrollbar control, using two button controls. That’s six windows per scrollbar control. Build a List control using horizontal and vertical scrollbars, and you’re sitting at twelve windows per list. It adds up quickly.

So it’s really just another example of the classic tradeoff between “how fast can I develop it” and “how little resources can I get it to use?” If you need a very high performance, no-waste GUI, implement each control from the ground up. If you would instead a quick implementation, and don’t mind the performance hit, you might choose to implement your controls so that the only control that would actually draw to the screen would be the static, and all other controls would be made up of combinations of statics.

When building my GUI, I tried to create a good balance between these two extremes.

Now, let’s dive into the actual implementation of each control, starting with everyone’s favorite, the static label.

The Static Controls

There are three kinds of static controls we’ll be looking at: static text controls, static icon controls, and frame controls. All three of these controls are very easy, because they take no messages - all they do is draw themselves at certain positions.