Visual FoxPro Key Codes (API Library Construction)

Article
10/23/2006

Most keyboard keys have a constant value even when combined with different modifier keys (SHIFT, CTRL and ALT). All regular keys on the keyboard (alphabet and special characters) have a key code of their ASCII value.

Key code and key modifier values are returned in the EventRec structure. The key code can be found in EventRec.message and the key modifiers can be found in EventRec.modifiers.

Visual FoxPro interprets some keys as having a different value depending on the modifier with which they are combined. For example, if SHIFT+F10 is pressed, the corresponding fields in the EventRec would be:

EventRec.message = 15D (Hex)
EventRec.modifier = 1000 (Hex)

Similarly, if CTRL+F10 is pressed, the EventRec values would be:

EventRec.message = 167 (Hex)
EventRec.modifiers = 2000 (Hex)

When more than one modifier is used with a key, the modifier values are added together. For example, if you press CTRL+SHIFT+F10, the following values are returned:

EventRec.message = 167 (Hex)
EventRec.modifiers = 3000 (Hex)

The EventRec.modifiers value in the preceding example is 0x3000 because both the CTRL and SHIFT modifiers were included in the key press. Thus, the SHIFT key modifier (0x1000) was added to the CTRL key modifier (0x2000) to produce a value of 0x3000.

Note The manner in which Visual FoxPro interprets keys (specifically keys with modifiers) is inherent to Visual FoxPro. Other programs may interpret keys differently. If a key is pressed in combination with one or multiple modifier keys (SHIFT, CTRL and ALT), the uppermost nibble represents the modifiers that were used.

The following table demonstrates that the F8 key has a different key code depending on the modifier used.

Keys pressed	Modifier	Key value of F8
F8	None	\x142
SHIFT+F8	SHIFT	\x15B
CTRL+F8	CTRL	\x165
ALT+F8	ALT	\x16F

Macintosh keyboard	MS-DOS/Windows equivalent
	CTRL
CTRL+OPTION	ALT

Each special key that can be combined with modifiers has a unique value when combined with each modifier. If a special key is combined with multiple modifiers, the unique value assigned to the key is its value for one of the modifiers according to the following rules:

First check to see if the key combination pressed includes the ALT key because the main key will be assigned its ALT key value.
If the key combination does not include ALT, check to see if the CTRL key modifier was used because the main key will be assigned its CTRL key value.
If no ALT or CTRL key modifier is used, check to see if the SHIFT key modifier was used because the main key will be assigned its SHIFT key value.
Finally, if no modifiers were used, the main key is assigned its value based on no modifiers.

Special Key Codes

The following table lists the key values assigned by Visual FoxPro to special keys on the keyboard.

Key	Key code (Hex)	Key modifier
LEFTMOUSE	100	None
F1	13B	None
F2	13C	None
F3	13D	None
F4	13E	None
F5	13F	None
F6	140	None
F7	141	None
F8	142	None
F9	143	None
F10	144	None
HOME	147	None
UPARROW	148	None
PGUP	149	None
LEFTARROW	14B	None
RIGHTARROW	14D	None
END	14F	None
DNARROW	150	None
PGDN	151	None
INS	152	None
DEL	153	None
F11	185	None
F12	186	None
BACKTAB	10F	shiftKey
SHIFT+F1	154	shiftKey
SHIFT+F2	155	shiftKey
SHIFT+F3	156	shiftKey
SHIFT+F4	157	shiftKey
SHIFT+F5	158	shiftKey
SHIFT+F6	159	shiftKey
SHIFT+F7	15A	shiftKey
SHIFT+F8	15B	shiftKey
SHIFT+F9	15C	shiftKey
SHIFT+F10	15D	shiftKey
SHIFT+F11	187	shiftKey
SHIFT+F12	188	shiftKey
CTRL+A	001	ctrlKey
CTRL+B	002	ctrlKey
CTRL+C	003	ctrlKey
CTRL+D	004	ctrlKey
CTRL+E	005	ctrlKey
CTRL+F	006	ctrlKey
CTRL+G	007	ctrlKey
CTRL+H	008	ctrlKey
CTRL+I	009	ctrlKey
CTRL+ENTER	00A	ctrlKey
CTRL+J	00A	ctrlKey
CTRL+K	00B	ctrlKey
CTRL+L	00C	ctrlKey
CTRL+M	00D	ctrlKey
CTRL+N	00E	ctrlKey
CTRL+O	00F	ctrlKey
CTRL+P	010	ctrlKey
CTRL+Q	011	ctrlKey
CTRL+R	012	ctrlKey
CTRL+S	013	ctrlKey
CTRL+T	014	ctrlKey
CTRL+U	015	ctrlKey
CTRL+V	016	ctrlKey
CTRL+W	017	ctrlKey
CTRL+X	018	ctrlKey
CTRL+Y	019	ctrlKey
CTRL+Z	01A	ctrlKey
CTRL+LBRACKET	01B	ctrlKey
CTRL+BACKSLASH	01C	ctrlKey
CTRL+RBRACKET	01D	ctrlKey
CTRL+CARET	01E	ctrlKey+shiftKey
CTRL+HYPHEN	01F	ctrlKey
CTRL+SPACEBAR	020	ctrlKey
CTRL+F1	15E	ctrlKey
CTRL+F2	15F	ctrlKey
CTRL+F3	160	ctrlKey
CTRL+F4	161	ctrlKey
CTRL+F5	162	ctrlKey
CTRL+F6	163	ctrlKey
CTRL+F7	164	ctrlKey
CTRL+F8	165	ctrlKey
CTRL+F9	166	ctrlKey
CTRL+F10	167	ctrlKey
CTRL+LEFTARROW	173	ctrlKey
CTRL+RIGHTARROW	174	ctrlKey
CTRL+END	175	ctrlKey
CTRL+PGDN	176	ctrlKey
CTRL+HOME	177	ctrlKey
CTRL+PGUP	184	ctrlKey
CTRL+F11	189	ctrlKey
CTRL+F12	18A	ctrlKey
CTRL+UPARROW	18D	ctrlKey
CTRL+DNARROW	191	ctrlKey
CTRL+INS	192	ctrlKey
CTRL+DEL	193	ctrlKey
CTRL+TAB	194	ctrlKey
ALT+Q	110	altKey
ALT+W	111	altKey
ALT+E	112	altKey
ALT+R	113	altKey
ALT+T	114	altKey
ALT+Y	115	altKey
ALT+U	116	altKey
ALT+I	117	altKey
ALT+O	118	altKey
ALT+P	119	altKey
ALT+A	11E	altKey
ALT+S	11F	altKey
ALT+D	120	altKey
ALT+F	121	altKey
ALT+G	122	altKey
ALT+H	123	altKey
ALT+J	124	altKey
ALT+K	125	altKey
ALT+L	126	altKey
ALT+Z	12C	altKey
ALT+X	12D	altKey
ALT+C	12E	altKey
ALT+V	12F	altKey
ALT+B	130	altKey
ALT+N	131	altKey
ALT+M	132	altKey
ALT+F1	168	altKey
ALT+F2	169	altKey
ALT+F3	16A	altKey
ALT+F4	16B	altKey
ALT+F5	16C	altKey
ALT+F6	16D	altKey
ALT+F7	16E	altKey
ALT+F8	16F	altKey
ALT+F9	170	altKey
ALT+F10	171	altKey
ALT+1	178	altKey
ALT+2	179	altKey
ALT+3	17A	altKey
ALT+4	17B	altKey
ALT+5	17C	altKey
ALT+6	17D	altKey
ALT+7	17E	altKey
ALT+8	17F	altKey
ALT+9	180	altKey
ALT+0	181	altKey
ALT+F11	18B	altKey
ALT+F12	18C	altKey
ALT+HOME	197	altKey
ALT+UPARROW	198	altKey
ALT+PGUP	199	altKey
ALT+LEFTARROW	19B	altKey
ALT+RIGHTARROW	19D	altKey
ALT+END	19F	altKey
ALT+DNARROW	1A0	altKey
ALT+PGDN	1A1	altKey
ALT+INS	1A2	altKey
ALT+DEL	1A3	altKey

Example

FAR EventHandler(WHandle theWindow, EventRec FAR *ev) 
{
switch(ev->what)
{
case keyDownEvent:                  /* Check the keyDownEvent */
if (ev->modifiers & shiftCodeMask)      /* A modifier was pressed. */
{
if (ev->modifiers & altKey)            /* Check for the ALT Key */
_PutStr("ALT Key Code should be used.\n"); 
else
if (ev->modifiers & ctrlKey)         /* CTRL Key */
_PutStr("CTRL Key Code should be used.\n");
else
if (ev->modifiers & shiftKey)         /* SHIFT Key */
_PutStr("SHIFT Key Code should be used.\n");
}
else
_PutStr("Regular Key Code should be used.\n"); 
return NO;                        /* Let Visual FoxPro have Key also */ 
break;
default:
return NO;
}
}

Note shiftCodeMask, altKey, ctrlKey, and shiftKey are all defined in PRO_EXT.H and PRO_EXT.INC as follows:

#define shiftCodeMask 0xf000
#define shiftKey 0x1000
#define ctrlKey 0x2000
#define altKey 0x4000

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Visual FoxPro Key Codes (API Library Construction)

Special Key Codes

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