Nunchuk-Mouse - Experimenting with Raspberry Pi - page 57

Posting EV_KEY Events
The following code snippet shows how to post a key down event, followed by a key up
event:

1 static void
2 uinput_postkey(int fd,unsigned key) {
3 struct input_event ev;
4 int rc;
5
6 memset(&ev,0,sizeof(ev));
7 ev.type = EV_KEY;
8 ev.code = key;
9 ev.value = 1;
10
11 rc = write(fd,&ev,sizeof(ev));
12 assert(rc == sizeof(ev));
13
14 ev.value = 0;
15 rc = write(fd,&ev,sizeof(ev));
16 assert(rc == sizeof(ev));
17 }

From this example, you see that each event is posted by writing a suitably initialized
input_event structure. The example illustrates that the member named type was set to
EV_KEY , code was set to the key code, and a keypress was indicated by setting the member
value to 1 (line 9).
To inject a key up event, value is reset to 0 (line 14) and the structure is written again.
Mouse button events work the same way, except that you supply mouse button codes
for the code member. For example:

memset(&ev,0,sizeof(ev));
ev.type = EV_KEY;
ev.code = BTN_RIGHT; / Right click /

∗ ∗

ev.value = 1;

Posting EV_REL Events
To post a relative mouse movement, we populate the input_event as a type EV_REL . The
member code is set to the type of event ( REL_X or REL_Y in this example), with the value
for the relative movement established in the member value :

static void
uinput_movement(int fd,int x,inty) {
struct input_event ev;
int rc;