WindowManager The Icon Bar (changes)

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» The Icon BarTechnical Details

Overview

The iconbar is a window which is located at the bottom of the screen. Its purpose is three-fold.

It provides access by displaying an icon that represents the application, filing system or device icon.

If there are too many icons on the iconbar, then the Wimp will automatically scroll the iconbar whenever the mouse pointer is positioned close to either end of the bar.

An icon placed on the iconbar can also have text underneath it. It is up to the application to decide the purpose of the text.

Registering an Icon

When an application, filing system or device wishes to be registered on the iconbar, the Wimp_CreateIcon is used (with the appropriate window handle). It is the window handle that determines where on the iconbar the icon should be placed.

In adherence to the RISC OS Style Guide the icon used should be the sprite used within the Filer for the application itself. See for example; the !Edit application.

Mouse Clicks

When the mouse pointer is clicked on an icon, the Wimp returns the Mouse_Click event (with a window handle of -2) to the application which created the icon originally.

Also, calling Wimp_GetPointerInfo returns a window handle of -2 when the pointer is partially or completely over the iconbar.

Icon Dimensions

When the Wimp is called to place an icon on the bar (registering an icon), it uses the icon’s x co-ordinates (see Wimp_CreateIcon) only to determine its width. The Wimp then decides how best to position the icon.

However, the Wimp does use both the icon’s y co-ordinates to determine the icon’s vertical position. Consequently applications must be aware of the ‘standard’ dimensions of the iconbar, in order to position their icons correctly.

Icons that appear on the iconbar should have a width and height of 68 OS units square.

See also

For a full detailed description on how to position Icons can be found in the Positioning icons on the iconbar? section within the RISC OS Style Guide.