Recently I’ve been developing a remote assistance feature for macOS, which requires mapping keyboard events coming from Windows and simulating them as macOS NSEvents. Events on macOS are simulated through the underlying CoreGraphic classes. Here’s a snippet of the implementation.
- Import
#import <Carbon/Carbon.h> - Create a
CGEventSourceRefevent source object (note that it is not an OC object, so there’s no*in front of the object name, and you need to release its memory withCFRelease()). - Create a
CGEventRefusingCGEventCreateKeyboardEvent; the third parametertruemeanskeydown— the key is in the pressed state — andfalsemeanskeyup. Here I used thekVK_ANSI_AA key as an example CGEventTapLocationis the parameter required by the next function; it should be the physical key information of the hardware keyboard press (if I got this wrong, feel free to correct me and I’ll fix it right away)CGEventPost()posts theNSEventevent- Release memory
talk is cheap, show me the code –LINUS TORVALDS
Here’s the demo code
1
2
3
4
5
6
7
8
9
10
11
12
13
14
#import <Carbon/Carbon.h>
int main(int argc, const char * argv[]) {
@autoreleasepool {
CGEventSourceRef source = CGEventSourceCreate(kCGEventSourceStatePrivate);
CGEventRef A = CGEventCreateKeyboardEvent(source, kVK_ANSI_A, true);
CGEventTapLocation location = kCGHIDEventTap;
//Post the event
CGEventPost(location, A);
CFRelease(A);
CFRelease(source);
}
return 0;
}
CGEventSourceCreate() defines three enums
1
2
3
4
5
typedef CF_ENUM(int32_t, CGEventSourceStateID) {
kCGEventSourceStatePrivate = -1,
kCGEventSourceStateCombinedSessionState = 0,
kCGEventSourceStateHIDSystemState = 1
};
kCGEventSourceStatePrivaterepresents dedicated applications; for example, remote control programs can create and track event source state independently of other processes. These programs should use thekCGEventSourceStatePrivatevalue when creating their event sources.kCGEventSourceStateCombinedSessionStateThe state table reflects the combined state of all event sources posted to the current user login session. If your program posts events in a login session, you should use this source state when creating an event source.
kCGEventSourceStateHIDSystemStateThe state table reflects the combined hardware input sources for events posted from the HID system hardware layer. These are the generated events, i.e. events from external keyboards, the built-in MacBook keyboard, and some system-defined key clicks.
Here I used the first one, which happens to mention remote control
That’s the full logic for simulating system keyboard events I wanted to share today. If there are any mistakes, feel free to point them out, and I’ll gladly take good advice.
Appendix: macOS ANSI code **enums
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
/*
* Summary:
* Virtual keycodes
*
* Discussion:
* These constants are the virtual keycodes defined originally in
* Inside Mac Volume V, pg. V-191. They identify physical keys on a
* keyboard. Those constants with "ANSI" in the name are labeled
* according to the key position on an ANSI-standard US keyboard.
* For example, kVK_ANSI_A indicates the virtual keycode for the key
* with the letter 'A' in the US keyboard layout. Other keyboard
* layouts may have the 'A' key label on a different physical key;
* in this case, pressing 'A' will generate a different virtual
* keycode.
*/
enum {
kVK_ANSI_A = 0x00,
kVK_ANSI_S = 0x01,
kVK_ANSI_D = 0x02,
kVK_ANSI_F = 0x03,
kVK_ANSI_H = 0x04,
kVK_ANSI_G = 0x05,
kVK_ANSI_Z = 0x06,
kVK_ANSI_X = 0x07,
kVK_ANSI_C = 0x08,
kVK_ANSI_V = 0x09,
kVK_ANSI_B = 0x0B,
kVK_ANSI_Q = 0x0C,
kVK_ANSI_W = 0x0D,
kVK_ANSI_E = 0x0E,
kVK_ANSI_R = 0x0F,
kVK_ANSI_Y = 0x10,
kVK_ANSI_T = 0x11,
kVK_ANSI_1 = 0x12,
kVK_ANSI_2 = 0x13,
kVK_ANSI_3 = 0x14,
kVK_ANSI_4 = 0x15,
kVK_ANSI_6 = 0x16,
kVK_ANSI_5 = 0x17,
kVK_ANSI_Equal = 0x18,
kVK_ANSI_9 = 0x19,
kVK_ANSI_7 = 0x1A,
kVK_ANSI_Minus = 0x1B,
kVK_ANSI_8 = 0x1C,
kVK_ANSI_0 = 0x1D,
kVK_ANSI_RightBracket = 0x1E,
kVK_ANSI_O = 0x1F,
kVK_ANSI_U = 0x20,
kVK_ANSI_LeftBracket = 0x21,
kVK_ANSI_I = 0x22,
kVK_ANSI_P = 0x23,
kVK_ANSI_L = 0x25,
kVK_ANSI_J = 0x26,
kVK_ANSI_Quote = 0x27,
kVK_ANSI_K = 0x28,
kVK_ANSI_Semicolon = 0x29,
kVK_ANSI_Backslash = 0x2A,
kVK_ANSI_Comma = 0x2B,
kVK_ANSI_Slash = 0x2C,
kVK_ANSI_N = 0x2D,
kVK_ANSI_M = 0x2E,
kVK_ANSI_Period = 0x2F,
kVK_ANSI_Grave = 0x32,
kVK_ANSI_KeypadDecimal = 0x41,
kVK_ANSI_KeypadMultiply = 0x43,
kVK_ANSI_KeypadPlus = 0x45,
kVK_ANSI_KeypadClear = 0x47,
kVK_ANSI_KeypadDivide = 0x4B,
kVK_ANSI_KeypadEnter = 0x4C,
kVK_ANSI_KeypadMinus = 0x4E,
kVK_ANSI_KeypadEquals = 0x51,
kVK_ANSI_Keypad0 = 0x52,
kVK_ANSI_Keypad1 = 0x53,
kVK_ANSI_Keypad2 = 0x54,
kVK_ANSI_Keypad3 = 0x55,
kVK_ANSI_Keypad4 = 0x56,
kVK_ANSI_Keypad5 = 0x57,
kVK_ANSI_Keypad6 = 0x58,
kVK_ANSI_Keypad7 = 0x59,
kVK_ANSI_Keypad8 = 0x5B,
kVK_ANSI_Keypad9 = 0x5C
};
/* keycodes for keys that are independent of keyboard layout*/
enum {
kVK_Return = 0x24,
kVK_Tab = 0x30,
kVK_Space = 0x31,
kVK_Delete = 0x33,
kVK_Escape = 0x35,
kVK_Command = 0x37,
kVK_Shift = 0x38,
kVK_CapsLock = 0x39,
kVK_Option = 0x3A,
kVK_Control = 0x3B,
kVK_RightCommand = 0x36,
kVK_RightShift = 0x3C,
kVK_RightOption = 0x3D,
kVK_RightControl = 0x3E,
kVK_Function = 0x3F,
kVK_F17 = 0x40,
kVK_VolumeUp = 0x48,
kVK_VolumeDown = 0x49,
kVK_Mute = 0x4A,
kVK_F18 = 0x4F,
kVK_F19 = 0x50,
kVK_F20 = 0x5A,
kVK_F5 = 0x60,
kVK_F6 = 0x61,
kVK_F7 = 0x62,
kVK_F3 = 0x63,
kVK_F8 = 0x64,
kVK_F9 = 0x65,
kVK_F11 = 0x67,
kVK_F13 = 0x69,
kVK_F16 = 0x6A,
kVK_F14 = 0x6B,
kVK_F10 = 0x6D,
kVK_F12 = 0x6F,
kVK_F15 = 0x71,
kVK_Help = 0x72,
kVK_Home = 0x73,
kVK_PageUp = 0x74,
kVK_ForwardDelete = 0x75,
kVK_F4 = 0x76,
kVK_End = 0x77,
kVK_F2 = 0x78,
kVK_PageDown = 0x79,
kVK_F1 = 0x7A,
kVK_LeftArrow = 0x7B,
kVK_RightArrow = 0x7C,
kVK_DownArrow = 0x7D,
kVK_UpArrow = 0x7E
};
End of article