Android 中input学习--取得input事件

 

有的时候我们并不希望起个View，从画面上得到各种输入事件。

怎么从底层得到各种input事件呢？

 

首先android下有个工具getevent，输出结果如下：

$ adb shell getevent
add device 1: /dev/input/event7
  name:     "proximity"
add device 2: /dev/input/event6
  name:     "lightsensor-level"
add device 3: /dev/input/event5
  name:     "compass"
add device 4: /dev/input/event4
  name:     "saga-keypad"
add device 5: /dev/input/event3
  name:     "atmel-touchscreen"
add device 6: /dev/input/event2
  name:     "projector-Keypad"
add device 7: /dev/input/event1
  name:     "projector_input"
add device 8: /dev/input/event0
  name:     "h2w headset"
/dev/input/event4: 0001 0074 00000001
/dev/input/event6: 0003 0028 ffffffff
/dev/input/event6: 0000 0000 00000000
/dev/input/event6: 0003 0028 00000005
/dev/input/event6: 0000 0000 00000000
/dev/input/event3: 0003 0030 00000000
/dev/input/event3: 0000 0000 00000000
/dev/input/event3: 0003 0030 00000000
/dev/input/event3: 0000 0000 00000000
/dev/input/event4: 0001 0074 00000000

/dev/input/event？都是一些输入设备，

比如event3是触摸屏的，event5是罗盘的，event4是物理键盘的，等等。

 

既然getevent能取到这些信息，那我们能不能自己写程序获得这些事件呢，

当然可以，以event3（触摸屏事件）为例：

#include <fcntl.h>
#include <linux/input.h>
#include <errno.h>
#include <poll.h>
static char TOUCH_DEVICE[256] = "/dev/input/event3";
int touchfd = -1;
struct pollfd fds[1];
static void init_touch()
{
        if((touchfd = open(TOUCH_DEVICE, O_RDWR)) == -1)
        {
                printf("cannot open touch device %s\n", TOUCH_DEVICE);
//                exit(-1);
        }
	fds[0].fd = touchfd;
	fds[0].events = POLLIN;
}

int getevent()
{
    struct input_event event;
	int res = 0;

	res = poll(fds, 1, -1);
	while(true) {
		if(fds[0].revents) {
			if(fds[0].revents & POLLIN) {
				res = read(touchfd, &event, sizeof(event));
				if(res < (int)sizeof(event)) {
				    fprintf(stderr, "could not get event\n");
				    return 1;
				}
				printf("getevent: %04x %04x %08x\n", event.type, event.code, event.value);
			}
		}
	}
	return 0;
}

能取到了，怎么用就不说了