Visual FoxPro Key Codes (API Library Construction)

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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:

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

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:

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

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:

  1. First check to see if the key combination pressed includes the ALT key because the main key will be assigned its ALT key value.

  2. 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.

  3. 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.

  4. 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

В Copy Code
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

See Also



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