Page:NBS Technical Note 11176 (1983) (IAutilityprogramsf1176dick).djvu/18

 Lines 4000-4070: DISPLAY THE FONT DRIVING ROUTINES

The routines of this section are used to display the fonts on the hires graphics pages. In line 4000, a jump is made to the disk access routine at 7000 to input the font from the disk if a new filename is used to access the data. The routine of line 4010 displays the font, N$, character by character, if the memory flag, MF, is not set. If the memory flag is set, then the font has been saved on hires page 2, and a call to the memory flip routines at 11000- recalls it for display. Line 4030 returns control to the calling routine if the font input flag, FI, is set. Otherwise, the remainder of the routine allows the user to either write the font to the disk, or return to the main menu.

Lines 5000-5460: THE CHARACTER EDIT ROUTINE

These routines allow the user to edit a character by entering either the Hershey coordinates or by using a hires cursor input. Line 5040 displays the entire font and the user is prompted (line 5060), to enter the number of the character to be changed. This character is then displayed in a magnified version by the routine of lines 8000-. Figure 2 illustrates this display for the Gothic letter N. Lines 5070-5120 perform this display by determining the appropriate x and y coordinates by decoding the string describing the character. After the character display, line 5125 gives the user the option of returning to the start of the edit routine if the wrong character has been selected to edit. Otherwise, the user has the option of either entering the Hershey coordinates (lines 1000-), or redrawing the character using the cursor control. The cursor control input technique allows the generation of custom characters by manipulating a high resolution cursor on the high resolution display. Initially, the user is requested to enter the limits of the character by defining the left and right marker locations (lines 5150-5190). The cursor is then placed on the left marker, and may be moved to the appropriate location by use of the I, J, K, and M keys of the keyboard. The current status of the pen is given on the text display and may be changed at any time by striking the space bar. Rh