Into the Arc

This month's Into the Arc deals with selecting colours in Basic programs. There are five programs that illustrate the principles discussed in the article. Clicking on the icon above will open a window showing these programs.

COL01
This program displays the standard 16-colour mode palette as a strip near the bottom of the screen.

COL02
This program redefines the palette so that the top eight colours are the same as the bottom eight but in reverse order. It then displays a strip showing the colours.

COL03
This program creates a palette identical to the one used by the RISC OS Desktop. It then displays the available colours.

COL04
In order to run this program succesfully, you must double-click on the file Run COL04. If you copy the program to another place, you should copy Run COL04 to the same place and run it from there.

This loads a palette file as saved by the Desktop Palette utility, so that you can use palettes that have been defined using that program. Any palette that you load using this program will also affect the colours used by the Desktop, so if you use an unusual colour set, you may have to use the Default option in the Palette menu to return things to normal.

Palette
This draws a screen similar to the colour selector used by Draw and Paint. The mouse can be used to drag the red, green and blue colour bars to alter the colour displayed in the box at the bottom of the screen. The numbers at the right of the screen show the intensities of the different colour components. Unlike the Desktop colour selector, the box at the bottom of the screen will always show the nearest approximation to the colour that can be achieved on the machine it is being run on.

Escape can be pressed to leave each program.

 Copyright RISC User 1994
