O'Reilly logo

REALBasic: TDG, 2nd Edition by Matt Neuburg

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Chapter 15.  Progress Bars, Sliders, and Scrollbars

The three built-in control classes, ProgressBar, Slider, and Scrollbar, are variations on a single theme: each provides a visual representation of a numeric value in terms of its position along a scale. They differ, however, in details of appearance and usage:[109]

  • A ProgressBar displays a “thermometer,” such as might provide the user with visual feedback as to the progress of a time-consuming task.

  • A Slider displays a horizontal or vertical “slot” with a “knob”; the user can slide the knob along the slot, like a sliding control on a piece of audio equipment, and can click in the slot to move the knob by a fixed amount.

  • A Scrollbar displays a standard horizontal or vertical scrollbar, with arrows at each end and a scroll box (or thumb) between. The user can slide the thumb, click the arrows to move the thumb by a small fixed amount, or click the gray areas on either side of the thumb to move the thumb by a larger fixed amount.

The numeric values for these controls must lie between -32768 and 32767. This is because, owing to the way they are implemented by the Macintosh Toolbox, the value is actually a short integer (two bytes).

A ProgressBar, Slider, or Scrollbar is a RectControl, and therefore receives all the events and has all the methods and properties listed in Chapter 10: Open and Close events; Visible, Enabled, and AutoDeactivate properties; Top, Left, Height, and Width properties; LockLeft, LockRight, LockTop, and LockBottom ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required