Alternating Row Colors (iTunes ListBox Redux) by Seth Willits 10-01-05 Printer Version

iTunes ListBox
Over three years ago, Erick Tejkowski posted a tutorial on alternating row colors to get the same style as iTunes. Times have changed apparently and his project no longer is... optimal. Now while the current solution is very simple, maaany people still ask how to do it, and I actually had someone ask me this morning so I figure I might as well post the answer. You know what they say, if one person asks, several more people have the same question...

Create the Class
Because code reusability is a good thing, we're going to create a simple class to do this. Add a ListBox subclass named "ARListBox". Add one property, "AlternateRows as Boolean" and make sure it is Public. The code to alternate the rows is:

Function CellBackgroundPaint(g As Graphics, row As Integer, column As Integer) As Boolean
  if AlternateRows and row mod 2 = 0 then
    g.ForeColor = RGB(237, 243, 254)
    g.FillRect 0, 0, g.Width, g.Height
  end if
End Function

row mod 2 will equal 0 on every other row (0 mod 2 is 0, 2 mod 2 is 0, 4 mod 2 is 0...) so that's our switch for alternating between blue and white. AlternateRows is a boolean property which can allow you to use the same class for both alternating and non-alternating lists. To make it show up in t he properties list in the window editor, go to the project tab and Right/Control-Click on the ARListBox class and select "Window Editor Behavior..."

Here you'll see a list of the public properties of the ARListBox class and checkbox next to each one. If the box is checked, that property will be displayed in the properties list in the window editor. This is the new home of the "Show in Properties List" checkbox that was in REALbaisc 5.5 and earlier when you created a property. So check that...

...and now when you add an ARListBox to the window in the window editor, you'll see the AlternateRows property way down at the bottom of the list. Check that box to have the alternating colors appear.

After that, we just need a little bit of test code that will just add rows to the listbox to test it.

Sub Open()
  dim i as Integer
  for i = 1 to 15
    me.AddRow "Row " + str(i)
    me.Cell(i - 1, 1) = "Cell (" + str(i) + ", 1)"
    me.Cell(i - 1, 2) = "Cell (" + str(i) + ", 2)"
  next
End Sub

Finished
Like I said, it's very simple, but many people do ask how to do this. If you already knew, congrats! If you didn't, congrats! Now you do! One thing to note is that the alternating rows go all the way to the bottom of the list even though there aren't actual rows there. This is a new feature in REALbasic 2005. In 5.5 and earlier the CellxPaint events were only called for each row in the listbox, but now it's called for each potential row that would fit in the visual bounds of the list. Handy! Download the project.