Q58024: BASIC 7.00 MousePoll Gives Screen, Not Window Coordinates

Article: Q58024
Product(s): See article
Version(s): 7.00
Operating System(s): MS-DOS
Keyword(s): ENDUSER | SR# S891108-92 | mspl13_basic
Last Modified: 2-FEB-1990

The MousePoll routine of the MOUSE.BAS file that comes with the User
Interface (UI) Toolbox in Microsoft BASIC Professional Development
System (PDS) Version 7.00 for MS-DOS returns the absolute screen
coordinates of the mouse text cursor as well as the status of the left
and right mouse buttons.

Using the window routines of the WINDOW.BAS toolbox file (also
included) does not make the MousePoll routine return coordinates that
are relative to the top-left corner of the current window. They are
always relative to the top-left corner of the screen. This may not be
apparent because the documentation presents all the toolbox files as
being part of a user-interface unit; therefore, it may appear that the
MousePoll routine returns coordinates that are relative to the current
window.

Included with Microsoft BASIC PDS is a toolbox source file called
MOUSE.BAS. There is a routine in this module called MousePoll, which
when called returns the vertical and horizontal coordinates of the
mouse text cursor plus the status of the left and right mouse buttons.

The coordinates returned are absolute screen coordinates. That is, if
the mouse cursor is at the top-left corner of the screen, the
coordinate pair (vertical, horizontal) returned is (1,1).

This may lead to some confusion for those who are using another of the
toolbox source files, WINDOW.BAS. This module contains (among many
other things) routines used to open, resize, move, and print to
windows. When addressing locations in these windows, relative (not
absolute) coordinates are used. That is, the top-left corner of the
window has coordinates (1,1) even if it is not in the same position as
the screen's top-left corner (1,1).

Therefore, it is important to note that the MousePoll subprogram does
not return coordinates relative to any window's top-left corner, but
always returns coordinates relative to the screen's top-left corner.

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