This section describes how to activate and use a mouse with your COBOL applications.
ACUCOBOL-GT offers mouse support for both character-based and graphical environments. (Currently, Windows environments are
supported. Limited mouse support is provided for X terminals if you are using a curses-compatible mouse. Support for character-based
UNIX terminals with ANSI mouse support is also available, but limited. Support for other host systems may be added in the
future, when their support software becomes available.)
For many applications, ACUCOBOL-GT can provide automatic mouse handling that simplifies the amount of programming you must
do to use the mouse effectively.
This section describes which mouse features are automatic when you run your program with the ACUCOBOL-GT run-time system.
It also explains how to add other mouse controls — in your COBOL program and your COBOL configuration file — if you want them.
Note: In character-based environments, the mouse pointer is invisible by default. To make use of the mouse, you'll need to enable
it, as described in
W$MOUSE. Under graphical environments, such as Windows, the mouse is always enabled.
A mouse is a device that allows the user to position a pointer on the screen. A mouse has the following properties:
- The mouse pointer can be positioned anywhere on the physical screen. (Note that this can include regions outside of your application
window in a graphical environment.)
- Under graphical environments, the mouse pointer can have a variety of shapes. The default shape is typically an arrow. On
character-based systems, the mouse pointer is a square in reverse-video.
- The mouse itself has from one to three buttons on it. These buttons may be either
up or
down. We say that a mouse button has been
clicked if it has been pushed down and then quickly released. Also, a button may be
double-clicked (clicked twice in quick succession). (Note that
up and
down are states;
clicking and
double-clicking are transient actions.)
- The buttons are referred to as the
left,
right, and
middle buttons. A mouse with two buttons has only
left and
right buttons; a one-button mouse has only a
left button. Left-handed users typically exchange the meanings of the left and right buttons, but this is handled outside of the
application — your program refers to the primary mouse button as the
left button regardless of the actual button used.
- Some mouses, in addition to the buttons, have a wheel. The mouse wheel can be used to scroll a window, just like a scroll
bar. In the Windows environment, in the Mouse Properties applet of the
Control Panel, the user can configure mouse wheel action so that each click (or notch) of the mouse wheel is equivalent to a certain number
of mouse button clicks on the scroll bar.
- The mouse pointer is independent from the program’s text cursor. Typically, an application lets the user position the text
cursor on the screen by positioning the mouse pointer at the desired location and clicking the left button.