Installing a Virtual Menu Scrolling Function

You might want to scroll other information along with the user's movement in a virtual menu, perhaps other virtual menus or help information within a window. To do this, install a virtual form scrolling function. The virtual form scrolling function is called whenever the user scrolls within the virtual form. The system passes to the function the change in the user's row position within the virtual form, the change in the user's column position, and the current form pointer.

Thus, the call for a scrolling function should be as follows:

int vscrl_fp(delta_rowq, delta_colq, fmp)

int delta_rowq;

/* Change in rows

*/

int delta_colq;

/* Change in column position

*/

FORMPTR fmp;

/* Pointer to current menu form

*/

A negative number passed for delta_rowq indicates that the user scrolled up. A negative delta_colq indicates that the user scrolled left.

The function should return TRUE if successful and FALSE if a fatal error occurred. A return of FALSE causes both menu processing and the program to be terminated.

Designer: You can install the virtual form scrolling function from within the Designer. See the Designer User's Guide for more information. You can also install the function in your code, by calling sfm_vscrlfp() as described below.

Code: To install the virtual form scrolling function for the form, call the set virtual form scroll function function, sfm_vscrlfp():

void sfm_vscrlfp(scrl_fp, mfmp)

int (*scrl_fp)();

/* Scrolling function to install

*/

MFORMPTR mfmp;

/* Pointer to menu form

*/