Android C/C++獲取屏觸屏輸入設備、屏幕分辨率

前言

如果在Android 的C/C++層或者JNI層有獲取屏幕分辨率的需求，或者需要獲取設備的觸屏設備用來做點事情，可以參考一下代碼

代碼示例

#include <stdlib.h>
#include <stdio.h>
#include <gui/ISurfaceComposer.h>
#include <gui/Surface.h>
#include <gui/SurfaceComposerClient.h>
#include <ui/DisplayInfo.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <linux/input.h>
#include <unistd.h>
#include <dirent.h>

#define test_bit(bit, array)    (array[bit/8] & (1<<(bit%8)))
#define sizeof_bit_array(bits)  ((bits + 7) / 8)

using namespace android;

bool containsNonZeroByte(const uint8_t* array, uint32_t startIndex, uint32_t endIndex) {
    const uint8_t* end = array + endIndex;
    array += startIndex;
    while (array != end) {
        if (*(array++) != 0) {
            return true;
        }
    }
    return false;

}


int getTouchDevice()
{
    char          name[64];           /*  RATS: Use ok, but could be better */
    char          buf[256] = { 0,  };  /*  RATS: Use ok */
    int           fd = 0;
    int           i;
    uint8_t keyBitmask[(KEY_MAX + 1) / 8];
    uint8_t absBitmask[(ABS_MAX + 1) / 8];
    char devname[PATH_MAX];
    char *filename;
    char *dirname = "/dev/input/";
    DIR *dir;
    struct dirent *de;
    dir = opendir(dirname);
    if(dir == NULL)
        return -1;
    strcpy(devname, dirname);
    filename = devname + strlen(devname);
    *filename++ = '/';
    while((de = readdir(dir))) {
        if(de->d_name[0] == '.' &&
            (de->d_name[1] == '\0' ||
            (de->d_name[1] == '.' && de->d_name[2] == '\0'))) {
            continue;
        }
        strcpy(filename, de->d_name);

        if ((fd = open(devname, O_RDONLY, 0)) >= 0)
        {
            ioctl(fd, EVIOCGNAME(sizeof(buf)), buf);
            ioctl(fd, EVIOCGBIT(EV_KEY, sizeof(keyBitmask)), keyBitmask);
            ioctl(fd, EVIOCGBIT(EV_ABS, sizeof(absBitmask)), absBitmask);

            bool haveGamepadButtons = containsNonZeroByte(keyBitmask, sizeof_bit_array(BTN_MISC),
                                        sizeof_bit_array(BTN_MOUSE))
                            || containsNonZeroByte(keyBitmask, sizeof_bit_array(BTN_JOYSTICK),
                                                        sizeof_bit_array(BTN_DIGI));
            if (test_bit(ABS_MT_POSITION_X, absBitmask)
                    && test_bit(ABS_MT_POSITION_Y, absBitmask)) {
                if (test_bit(BTN_TOUCH, keyBitmask) || !haveGamepadButtons) {
                    printf("MT TOPUCH DeviceL: %s\n",  devname);
                }
                // Is this an old style single-touch driver?
                else if (test_bit(BTN_TOUCH, keyBitmask)
                        && test_bit(ABS_X, absBitmask)
                        && test_bit(ABS_Y, absBitmask)) {
                    printf("Old TOPUCH DeviceL: ",  devname);
                    // Is this a BT stylus?
                }
            }
            printf("name: %s\n\n\n", buf);
            close(fd);
        }
    }
    closedir(dir);
    return 0;
}

int main(){

    getTouchDevice();
    sp<IBinder> dtoken(SurfaceComposerClient::getBuiltInDisplay(
            ISurfaceComposer::eDisplayIdMain));
    DisplayInfo dinfo;
    status_t status = SurfaceComposerClient::getDisplayInfo(dtoken, &dinfo);
    if (status)
        return -1;

    printf("h:%d, w:%d\n", dinfo.h, dinfo.w);
    return 0;
}