7.1 Mouse Properties

This chapter 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, the MS-DOS, Windows, and Windows NT 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 chapter describes which mouse features are automatic when you run your program with the ACUCOBOL-GT runtime. 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, such as DOS, the mouse pointer is invisible by default. In order to make use of the mouse, you'll need to enable it, as described on page 7-14 (ENABLE-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.

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.