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如何使用Linux获取触摸屏原始数据的坐标

本文介绍了如何使用Linux获取触摸屏原始数据的坐标的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

具有3m的触摸显示屏.它通过USB连接到我的debian系统，并重新识别为人机界面(hid).我正在尝试访问和推送实时信息...如果被触摸，我想知道(x，y)的位置，并将其通过netcat通过管道传递到另一台主机.

wie have a 3m microtouch display. Its connected to my debian system via usb and recongnized as human interface (hid). I am trying to access and push realtime information... if its getting touched I want to know where (x,y) and pipe it throught netcat to another host.

不幸的是，我只能使用

cat /dev/input/event2 | hexdump

或evtest

您得到的十六进制代码似乎无处记载...

You get hexcode that seem nowhere documented...

有人知道如何获取这些信息吗?必须有一种从十六进制代码中提取它的方法.不幸的是，我不知道如何解释十六进制代码.我找不到它记录的任何来源...

Does anybody have a clue how to get those information? There must be a way to extract it from the hexcode. Unfortunately I have no idea how to interpret the hexcode. I couldnt find any source where its documented...

内核是否可以实时向我提供这些所需信息?作为一个工作环境，也许可以找到X-Server可以告诉我的解决方案?触摸屏的行为就像X中的鼠标.实际上，我已经准备好尝试通过xlib获取鼠标的x，y位置.但这太慢了，无法告诉我是否有人在触摸……

Is there a way the Kernel could provide me those desired information in realtime?As a workarround is there maybe a solution Where the X-Server could tell me? The touchscreen behaves like a mouse in X. I actually allready tried to get x,y-position of the mouse via xlib. But it was too slow and wouldnt tell me if somebody is touching or not...

提前谢谢！

evtest示例输出:

evtest sample output: 

Event: time 1425319271.595631, type 3 (EV_ABS), code 57 (ABS_MT_TRACKING_ID), value 51
Event: time 1425319271.595631, type 3 (EV_ABS), code 53 (ABS_MT_POSITION_X), value 10304
Event: time 1425319271.595631, type 3 (EV_ABS), code 54 (ABS_MT_POSITION_Y), value 30629
Event: time 1425319271.595631, type 3 (EV_ABS), code 48 (ABS_MT_TOUCH_MAJOR), value 893
Event: time 1425319271.595631, type 3 (EV_ABS), code 49 (ABS_MT_TOUCH_MINOR), value 414
Event: time 1425319271.595631, type 1 (EV_KEY), code 330 (BTN_TOUCH), value 1
Event: time 1425319271.595631, type 3 (EV_ABS), code 0 (ABS_X), value 10304
Event: time 1425319271.595631, type 3 (EV_ABS), code 1 (ABS_Y), value 30629
Event: time 1425319271.595631, -------------- SYN_REPORT ------------
Event: time 1425319271.601632, type 3 (EV_ABS), code 53 (ABS_MT_POSITION_X), value 10306
Event: time 1425319271.601632, type 3 (EV_ABS), code 54 (ABS_MT_POSITION_Y), value 30625
Event: time 1425319271.601632, type 3 (EV_ABS), code 48 (ABS_MT_TOUCH_MAJOR), value 962
Event: time 1425319271.601632, type 3 (EV_ABS), code 49 (ABS_MT_TOUCH_MINOR), value 421
Event: time 1425319271.601632, type 3 (EV_ABS), code 47 (ABS_MT_SLOT), value 1
Event: time 1425319271.601632, type 3 (EV_ABS), code 57 (ABS_MT_TRACKING_ID), value 52
Event: time 1425319271.601632, type 3 (EV_ABS), code 53 (ABS_MT_POSITION_X), value 15416
Event: time 1425319271.601632, type 3 (EV_ABS), code 54 (ABS_MT_POSITION_Y), value 24159
Event: time 1425319271.601632, type 3 (EV_ABS), code 48 (ABS_MT_TOUCH_MAJOR), value 649
Event: time 1425319271.601632, type 3 (EV_ABS), code 49 (ABS_MT_TOUCH_MINOR), value 354
Event: time 1425319271.601632, type 3 (EV_ABS), code 0 (ABS_X), value 10306
Event: time 1425319271.601632, type 3 (EV_ABS), code 1 (ABS_Y), value 30625
Event: time 1425319271.601632, -------------- SYN_REPORT ------------
Event: time 1425319271.606626, type 3 (EV_ABS), code 47 (ABS_MT_SLOT), value 0
Event: time 1425319271.606626, type 3 (EV_ABS), code 53 (ABS_MT_POSITION_X), value 10318
Event: time 1425319271.606626, type 3 (EV_ABS), code 54 (ABS_MT_POSITION_Y), value 30609
Event: time 1425319271.606626, type 3 (EV_ABS), code 48 (ABS_MT_TOUCH_MAJOR), value 1014
Event: time 1425319271.606626, type 3 (EV_ABS), code 49 (ABS_MT_TOUCH_MINOR), value 426
Event: time 1425319271.606626, type 3 (EV_ABS), code 47 (ABS_MT_SLOT), value 1
Event: time 1425319271.606626, type 3 (EV_ABS), code 54 (ABS_MT_POSITION_Y), value 24161
Event: time 1425319271.606626, type 3 (EV_ABS), code 48 (ABS_MT_TOUCH_MAJOR), value 681
Event: time 1425319271.606626, type 3 (EV_ABS), code 49 (ABS_MT_TOUCH_MINOR), value 376
Event: time 1425319271.606626, type 3 (EV_ABS), code 0 (ABS_X), value 10318
Event: time 1425319271.606626, type 3 (EV_ABS), code 1 (ABS_Y), value 30609
Event: time 1425319271.606626, -------------- SYN_REPORT ------------
Event: time 1425319271.611629, type 3 (EV_ABS), code 47 (ABS_MT_SLOT), value 0
Event: time 1425319271.611629, type 3 (EV_ABS), code 53 (ABS_MT_POSITION_X), value 10320
Event: time 1425319271.611629, type 3 (EV_ABS), code 54 (ABS_MT_POSITION_Y), value 30605
Event: time 1425319271.611629, type 3 (EV_ABS), code 48 (ABS_MT_TOUCH_MAJOR), value 1053
Event: time 1425319271.611629, type 3 (EV_ABS), code 49 (ABS_MT_TOUCH_MINOR), value 430
Event: time 1425319271.611629, type 3 (EV_ABS), code 47 (ABS_MT_SLOT), value 1
Event: time 1425319271.611629, type 3 (EV_ABS), code 48 (ABS_MT_TOUCH_MAJOR), value 705
Event: time 1425319271.611629, type 3 (EV_ABS), code 49 (ABS_MT_TOUCH_MINOR), value 392
Event: time 1425319271.611629, type 3 (EV_ABS), code 0 (ABS_X), value 10320
Event: time 1425319271.611629, type 3 (EV_ABS), code 1 (ABS_Y), value 30605

推荐答案

基于控制台的解决方案

您可以使用evtest工具获取解析的坐标.

Console-based solution

You can obtain parsed coordinates using evtest tool.

  1. 如果只需要单点触摸坐标:查找ABS_X和ABS_Y字段:

type 3 (EV_ABS), code 0 (ABS_X), value 10306
type 3 (EV_ABS), code 1 (ABS_Y), value 30625

  • 如果您需要多点触摸坐标:

  • If you need multi-touch coordinates:

    • ABS_MT_SLOT代表手指的数量
    • ABS_MT_POSITION_X和ABS_MT_POSITION_Y-坐标
    • ABS_MT_SLOT represents number of finger
    • ABS_MT_POSITION_X and ABS_MT_POSITION_Y -- coordinates

    #0手指:

    type 3 (EV_ABS), code 47 (ABS_MT_SLOT), value 0
type 3 (EV_ABS), code 53 (ABS_MT_POSITION_X), value 10318
type 3 (EV_ABS), code 54 (ABS_MT_POSITION_Y), value 30609

    1号手指:

    type 3 (EV_ABS), code 47 (ABS_MT_SLOT), value 1
type 3 (EV_ABS), code 53 (ABS_MT_POSITION_X), value 20301
type 3 (EV_ABS), code 54 (ABS_MT_POSITION_Y), value 24161

    • 例如，如果您需要通过网络发送单点触摸坐标，则可以使用如下脚本:

    For example, if you need to send single-touch coordinates via network, you can use script like this:

    #!/bin/sh

# ---- Global variables ----

input=/dev/input/event0
code_prefix="ABS"
code="${code_prefix}_[XY]"
val_regex=".*(${code_prefix}_\(.\)), value \([-]\?[0-9]\+\)"
val_subst="\1=\2"

# ---- Functions ----

send_axis() {
    # 1. Convert axis value ($1) from device specific units
    # 2. Send this axis value via UDP packet
    echo $1
}

process_line() {
    while read line; do
        axis=$(echo $line | grep "^Event:" | grep $code | \
               sed "s/$val_regex/$val_subst/")

        if [ -n "$axis" ]; then
            send_axis $axis
        fi
    done
}

# ---- Entry point ----

if [ $(id -u) -ne 0 ]; then
    echo "This script must be run from root" >&2
    exit 1
fi

evtest $input | process_line

    基于程序的解决方案

    您可以编写将读取事件文件的C应用程序.可以很容易地解释获得的二进制数据，请参阅内核文档中的第5节.您可以使用select() syscall等待下一个数据部分.

    Program-based solution

    You can write C application that will read your event file. Obtained binary data can be easily interpreted, see section 5 in kernel documentation.You can wait for next data portion using select() syscall.

    #include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <linux/input.h>

#define EVENT_DEVICE    "/dev/input/event2"
#define EVENT_TYPE      EV_ABS
#define EVENT_CODE_X    ABS_X
#define EVENT_CODE_Y    ABS_Y

/* TODO: Close fd on SIGINT (Ctrl-C), if it's open */

int main(int argc, char *argv[])
{
    struct input_event ev;
    int fd;
    char name[256] = "Unknown";

    if ((getuid ()) != 0) {
        fprintf(stderr, "You are not root! This may not work...\n");
        return EXIT_SUCCESS;
    }

    /* Open Device */
    fd = open(EVENT_DEVICE, O_RDONLY);
    if (fd == -1) {
        fprintf(stderr, "%s is not a vaild device\n", EVENT_DEVICE);
        return EXIT_FAILURE;
    }

    /* Print Device Name */
    ioctl(fd, EVIOCGNAME(sizeof(name)), name);
    printf("Reading from:\n");
    printf("device file = %s\n", EVENT_DEVICE);
    printf("device name = %s\n", name);

    for (;;) {
        const size_t ev_size = sizeof(struct input_event);
        ssize_t size;

        /* TODO: use select() */

        size = read(fd, &ev, ev_size);
        if (size < ev_size) {
            fprintf(stderr, "Error size when reading\n");
            goto err;
        }

        if (ev.type == EVENT_TYPE && (ev.code == EVENT_CODE_X
                      || ev.code == EVENT_CODE_Y)) {
            /* TODO: convert value to pixels */
            printf("%s = %d\n", ev.code == EVENT_CODE_X ? "X" : "Y",
                    ev.value);
        }
    }

    return EXIT_SUCCESS;

err:
    close(fd);
    return EXIT_FAILURE;
}

    坐标单位

    首先，您需要了解接下来的事情:

    Coordinates units

    First of all you need to know next things:

    • 哪里是坐标原点(即[x=0;y=0])
    • 您的设备用来表示坐标的单位

    通常可以在设备的驱动程序代码中找到此信息.

    This information usually can be found in driver code for your device.

    这是您的驱动程序设备.

    This is the driver for your device.

    因此，似乎您需要将evtest的轴值除以65535，然后乘以设备的宽度或高度(以像素为单位).例如，如果您得到X = 30000，并且LCD面板的宽度为1080像素，则需要执行以下操作:

    So it seems like you need to divide your axis value from evtest by 65535 and multiply it by width or height of device (in pixels). For example, if you get X=30000, and width of your LCD panel is 1080 pixels, you need to do:

    X = round((30000 / 65535) * 1080) = 494 pixels

    这篇关于如何使用Linux获取触摸屏原始数据的坐标的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！

    08-28 21:02
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