afx_msg void OnKeyDown( UINT nChar, UINT nRepCnt, UINT nFlags );
nChar
Specifies the virtual-key code of the given key.
nRepCnt
Repeat count (the number of times the keystroke is repeated as a result of the user holding down the key).
nFlags
Specifies the scan code, key-transition code, previous key state, and context code, as shown in the following list:
| Value | Description |
| 0–7 | Scan code (OEM-dependent value). |
| 8 | Extended key, such as a function key or a key on the numeric keypad (1 if it is an extended key). |
| 9–10 | Not used. |
| 11–12 | Used internally by Windows. |
| 13 | Context code (1 if the ALT key is held down while the key is pressed, 0 otherwise). |
| 14 | Previous key state (1 if the key is down before the call, 0 if the key is up). |
| 15 | Transition state (1 if the key is being released, 0 if the key is being pressed). |
For a WM_KEYDOWN message, the key-transition bit (bit 15) is 0 and the context-code bit (bit 13) is 0.
Called when a nonsystem key is pressed. A nonsystem key is a keyboard key that is pressed when the ALT key is not pressed, or a keyboard key that is pressed when CWnd has the input focus.
Because of auto-repeat, more than one OnKeyDown call may occur before an OnKeyUp member function call is made. The bit indicating the previous key state can be used to determine whether the OnKeyDown call indicates the first down transition or a repeated down transition.
For IBM Enhanced 101- and 102-key keyboards, enhanced keys are the right ALT and the right CONTROL keys on the main section of the keyboard; the INSERT, DELETE, HOME, END, PAGE UP, PAGE DOWN, and ARROW keys in the clusters to the left of the numeric keypad; and the slash (/) and ENTER keys in the numeric keypad. Some other keyboards may support the extended-key bit in nFlags.
This message-handler member function calls the Default member function. Override this member function in your derived class to handle the WM_KEYDOWN message.
WM_CHAR, WM_KEYUP, CWnd::Default, WM_KEYDOWN