uibar: Colored bar indicator (like a waitbar) that can be placed in a figure.

Multi-purpose variable-length colored bar indicator.

This is a class that implements a colored bar indicator, very much like a waitbar, that you can embed in any figure. It mimics built-in MATLAB UI elements with the following properties and their default values:
BackgroundColor = [1 1 1]
BorderColor = [0 0 0]
CurrentMouseValue (Read-only)
Direction = 'east' or 'north' depending on Position and DirectionMode
DirectionMode = 'auto'
ForegroundColor = [1 0 0]
LineWidth = 0.5
Max = 1
Min = 0
Position = [20 20 200 15]
Units = 'pixels'
Value = 0
ButtonDownFcn
DeleteFcn
HitTest = 'on'
Parent
Selected = 'off'
SelectionHighlight = 'on'
Type = 'uibar' (Read-only)
UIContextMenu
UserData
Visible = 'on'
You change the length of the bar simply by setting the Value property of the instantiated object.
mybar = uibar;
mybar.Value = 0.5;