Notes on Changing Look and Feel

Not to say unimportant--look and feel is very important--just orthogonal.

We can change one without affecting the other.

Pluggable L&F

• Pluggable Look and Feel
  • There are two setLookAndFeel methods. One takes an object, the other a class name.
  • You can also get a list of the available Look and Feels.
  • MetalLookAndFeel is the cross-platform "Java" Look and Feel.
  • public static void main is the entry point of any Java app.
    This is where we set the Look and Feel--before we create a single component.
  
  
• Catalyst Theme
  
  • We have two ways to modify the Metal L&F.
    • We can extend it, and override the parts we want to change
      or easier still
    • We can install a MetalTheme.
  • At a minimum, we create our own theme by defining six colors.
  • We can also set a few fonts.
  • To do more, we need to implement the addCustomEntriesToTable method.
  • Here's where we override default borders, colors, and fonts on specific component types.
  • We can also install our own UI (as we do for ComboBoxUI).
  • Some little things (such as menu item accelerator delimiter) can be set here and nowhere else.
  
  
• Catalyst Combo Box UI
  
  • We got the buttons we wanted simply by overriding Metal's button border.
  • Metal's combo box was so completely wrong, we had no choice but to plug in our own ComboBoxUI.
  • We had to add our own arrow buttons, re-work the layout, and add a default list cell renderer.
  • This just provides the default renderer--you can still call setRenderer when you need something different.
  • The power you have when you write your own UI is just absolutely awesome.

Full Custom UI

• Writing Custom UIs
  
  • Always assume with any programming problem that at least a hundred other programmers have had the same problem.
  • Further assume that at least one of those programmers has written an article bragging about how he solved it.
  • Finally assume that the article he wrote is posted on Sun's Java site. All you have to do is find it.
  • This fellow Ralph Rar works for SAP and had to create a custom L&F. In this article he weighs the options.
  
  
• Borrowing Code
  
  • I read a lot of code. A lot of code.
  • Sun provides the source for all the Java libraries. It's packed with the JDK in a zip file.
  • Before you start hacking your own solution look at Sun's code. You might get some ideas.
  • You may even get the impression you can improve on it. (You probably can.)
  • Don't forget to run up the Jolly Roger while you're doing this.
  • Oh, man, look at this pathetic code to draw a triangle on the arrow buttons...
    (Proof, if you needed it, that Sun uses contractors.)
  
  
• Custom by Composition
  
  • When you don't need global changes, you can do a lot just by plugging in to the Swing API.
  • Virtually everything about a component can be customized, frequently by composition.
  • A combo box is not one object; rather it is composed of many objects, such as borders, lists, editors, and renderers.
  • You modify it by swapping out the objects that compose it.
  • The distinction between composition and property setting is a fuzzy one.

Component Factories

• Factories for Properties
  
  • When we need a bunch of custom components we naturally think of sub-classing.
  • A better option in many cases is a factory method.
  • Factory methods don't clutter up the name space.
    Also, they tend to be easier to read and modify.
  • As always the goal is to avoid duplicating code.
  
  
• Extending for Behavior
  
  • Sometimes you have no choice but to extend a component to get the behavior you want.
  • Even so, you can do it inside a factory method using an anonymous inner class.
  
  
• Summary of L&F Options
  
  • Here are your options for modifying the Look and Feel of your application.
  • I list these in order of increasing complexity.
  • Coincidentally, they also appear in order from local (one or two components) to global (every component in the program).