With the box drawing characters that 9th column is a copy of the 8th column, and therefore does not cut the pointer in half. It is important to use box drawing characters, because normally VGA displays fonts as 9x16, adding an empty 9th column, which would cause a 'gap' in the pointer. Then when the mouse moved, the original 4 bytes are restored on screen, and the whole procedure repeated on the new position. The basic principle is to store 4 bytes (2x2) from the screen, copy their VGA Fonts to some unused box drawing characters (0xC0 - 0xDF), OR mask the arrow onto then write those 2x2 box drawing characters on screen. Here's another example from the Screenshots forum TUI with 8x8 characters and pointing finger-shaped cursor How to implement You can easily spot this font altering cursor by the cursor color: as only the fonts are altered and the attribute bytes are untouched, the pointer changes color as you move it around. This technique was used in Norton Utilities or the DOS version of Norton Diskedit for example. Uint16_t get_cursor_position ( void ) Font based 'graphical' cursor Used byīack in the DOS days it was quite common not to use the hardware VGA cursor at all, instead overriding the VGA fonts to create an arrow pointer just like in graphical modes. Without BIOS access, manipulating the cursor requires sending data directly to the hardware. BH = display page (usually, if not always 0).CH = 0x3F (bits 0-7 unused, bit 5 disables cursor, bits 0-4 control cursor shape).The highest scanline is 0 and the lowest scanline is the maximum scanline (usually 15). To manipulate the cursor with the BIOS, use int 0x10, the interrupt for screen functions.Įnabling the cursor also allows you to set the start and end scanlines, the rows where the cursor starts and ends.

Html input change cursor color