Mouse Control

Pascal, being a language that is now reaching several decades in its incarnation as Pascal 6.0, is a language that has no basic facility for mouse control. In the modern computing world the mouse is all important, and surplants the keyboard whereever the more simple visual input device can be used appropriately. It is therefore necessary, particularly when writing application program in pascal, to include mouse control in order to avoid the severe frustration of a user that is forced to learn a serious of tedious and laborious keyboard shortcuts. Fortunately, with these units, adding mouse control is not as difficult as it may seem to the beginner. Although to read and recognise movements of the mouse an interupt must be set up, that runs every time the mouse is manipulated, once this is established the actual code for the drawing of the pointer is remarkably simple, and only slightly more complex in SVGA. Even this is not necessary, however: there are numerous high quality mouse units available accross the internet, and I present two of the best of them here for your experimentation. The first, designed for use with MCGA, was my mouse unit of choice when writing many of my early applications such as Canvas 2.4 and the Trooper II level editor, and was originally part of the excellent graphical units by Kevin A. Lee. The second, scripted purely by myself, uses assembler routines coded into the interupt to provide a very rapid, entirely reliable mouse pointer for much with SVGA. In my unit, the pointer can be changed at will to any configuration by assigning variables to arrays of bytes representing the pointer. In both the units, the mouse can be shown and hidden (vital for drawing processes - if the mouse is drawn on top of then the drawn section will be disturbed when the mouse is next moved), confined to a certain bounded region on the screen, moved around automatically, and all importantly, its position on the screen detected as well as the state of any of its buttons. Both the units are totally compatible with the existing MCGA and SVGA graphics libraries, and can simply can added to programs by invoking the initialize routines after the graphics engine has been started. All mouse pointers are drawn in palette colour 15, so the colour of the mouse can also be changed without disturbing the mouse unit. The MCGA download contains an exemplar program that demonstrates the basics (which is effectively everything) of mouse control, but since the program isn't actually mine I've omitted the source code. The SVGA unit has no exemplar program, but has full and completely transparent source. Both of these mouse units are desgined for use with the corresponding graphics engines. Have fun, Jon

Download the mouse unit for MCGA (7 Kb, zipped) | Back to Tools & Units
Download the mouse unit for SVGA (4 Kb, zipped)