一种 Android 用户事件的自适应分发方法
2020-10-15 本文已影响0人
hanpfei
Android 设备的远程操作控制中，用户可以在控制端看到远程 Android 设备的屏幕，并通过在控制端执行操作，控制远端 Android 上应用程序及系统的行为。控制端可以是任意的系统及平台，如 Windows，Android 等。
控制端捕获用户操作的事件，将事件传输到远端的 Android 系统中，控制远端的 Android 系统。
控制端和远程 Android 设备之间的通信中，用户事件通过事件的类型和点击/触摸事件的归一化屏幕坐标描述。在控制端支持多点触控的情况下，用户事件可能同时产生于两个不同的坐标上。用户事件的定义如下面这样：
message TouchEvent{
required ActionMode actionMode = 1;
required float x1Ratio = 2;
required float y1Ratio = 3;
optional float x2Ratio = 4;
optional float y2Ratio = 5;
enum ActionMode{
ACTION_DOWN = 1;
ACTION_UP = 2;
ACTION_MOVE = 3;
ACTION_MOVE2 = 4;
ACTION_POINTER_DOWN = 5;
ACTION_POINTER_UP0 = 6;
ACTION_POINTER_UP1 = 7;
}
}
(x1Ratio, y1Ratio) 和 (x2Ratio, y2Ratio) 分别是事件发生的两个归一化坐标。
在被控制的 Android 设备端接收到事件之后，需要将事件派发进系统，进而传递给应用程序，控制系统及应用程序的行为。将事件派发给系统的一种比较方便的方法是，将事件写入 Android 的输入设备文件中。
Android 设备上事件的派发进程首先需要根据屏幕的尺寸，将事件的归一化坐标转化为该 Android 设备上的实际屏幕坐标，然后写入 Android 设备的输入设备文件中。
Android 系统中的输入设备分为多种不同的类型，分别称为类型 A 与类型 B。即使经过了前面对归一化事件坐标的屏幕坐标转换，转换后的事件坐标依然不能直接写入 Android 的输入设备文件，而是需要按照不同输入设备类型的协议将事件写入 Anroid 的输入设备文件。
Android 系统提供了一个系统应用程序 getevent，可以帮助开发者获取 Android 系统中所有输入设备文件支持的输入事件类型等信息，并据此判断输入设备文件的类型。具体而言，可以根据 Android 输入设备支持的 ABS 事件类型来判断输入设备文件的类型，支持如下 ABS 输入事件类型的输入设备文件为类型 A 的输入设备文件：
ABS_MT_TOUCH_MAJOR (0x30)
ABS_MT_WIDTH_MAJOR (0x32)
ABS_MT_WIDTH_MINOR (0x33)
ABS_MT_POSITION_X (0x35)
ABS_MT_POSITION_Y (0x36)
ABS_MT_PRESSURE (0x3a)
支持如下 ABS 输入事件类型的输入设备文件为类型 B 的输入设备文件：
ABS_MT_SLOT (0x2f)
ABS_MT_TOUCH_MAJOR (0x30)
ABS_MT_POSITION_X (0x35)
ABS_MT_POSITION_Y (0x36)
ABS_MT_TRACKING_ID (0x39)
ABS_MT_PRESSURE (0x3a)
如 adb shell 进入 Android 6.0 的 X86 版模拟器，执行 getevent -p 可以看到如下信息：
root@generic_x86:/ # getevent -p
add device 1: /dev/input/event0
name: "Power Button"
events:
KEY (0001): 0074
input props:
<none>
add device 2: /dev/input/event1
name: "qwerty2"
events:
KEY (0001): 0001 0002 0003 0004 0005 0006 0007 0008
. . . . . .
ABS (0003): 0000 : value 0, min 0, max 32767, fuzz 0, flat 0, resolution 0
0001 : value 0, min 0, max 32767, fuzz 0, flat 0, resolution 0
0002 : value 0, min 0, max 1, fuzz 0, flat 0, resolution 0
002f : value 0, min 0, max 9, fuzz 0, flat 0, resolution 0
0030 : value 0, min 0, max 2147483647, fuzz 0, flat 0, resolution 0
0035 : value 0, min 0, max 32767, fuzz 0, flat 0, resolution 0
0036 : value 0, min 0, max 32767, fuzz 0, flat 0, resolution 0
0039 : value 0, min 0, max 10, fuzz 0, flat 0, resolution 0
003a : value 0, min 0, max 256, fuzz 0, flat 0, resolution 0
SW (0005): 0000 0002 0004
input props:
<none>
could not get driver version for /dev/input/mice, Not a typewriter
在判断出输入设备文件的类型之后，即可执行相应的逻辑来派发输入事件。对于类型 A 的输入设备文件，将事件写入输入设备文件并派发的方法如下：
static void single_touch_proto_a(int fd, int pressure, int coord_x, int coord_y) {
struct timeval tv;
gettimeofday(&tv, 0);
struct input_event event;
memset(&event, 0, sizeof(event));
event.type = EV_ABS;
event.code = ABS_MT_PRESSURE;
event.value = pressure;
event.time = tv;
write(fd, &event, sizeof(event));
event.type = EV_ABS;
event.code = ABS_MT_POSITION_X;
event.value = coord_x;
event.time = tv;
write(fd, &event, sizeof(event));
event.type = EV_ABS;
event.code = ABS_MT_POSITION_Y;
event.value = coord_y;
event.time = tv;
write(fd, &event, sizeof(event));
event.type = EV_SYN;
event.code = SYN_MT_REPORT;
event.value = 0;
event.time = tv;
write(fd, &event, sizeof(event));
}
static void sys_report_proto_a(int fd) {
struct timeval tv;
gettimeofday(&tv, 0);
struct input_event event;
memset(&event, 0, sizeof(event));
event.type = EV_SYN;
event.code = SYN_REPORT;
event.value = 0;
event.time = tv;
write(fd, &event, sizeof(event));
}
//单点触摸
static int write_single_touch_proto_a(int fd, int slot, int coord_x, int coord_y) {
single_touch_proto_a(fd, 1, coord_x, coord_y);
sys_report_proto_a(fd);
return 0;
}
//多点触摸
static int write_multi_touch_proto_a(int fd, int coord_x1, int coord_y1, int coord_x2,
int coord_y2) {
single_touch_proto_a(fd, 1, coord_x1, coord_y1);
single_touch_proto_a(fd, 2, coord_x2, coord_y2);
sys_report_proto_a(fd);
return 0;
}
//释放触摸
static int write_up_proto_a(int fd, int slot) {
struct timeval tv;
gettimeofday(&tv, 0);
struct input_event event;
memset(&event, 0, sizeof(event));
event.type = EV_SYN;
event.code = SYN_MT_REPORT;
event.value = 0;
event.time = tv;
write(fd, &event, sizeof(event));
event.type = EV_SYN;
event.code = SYN_REPORT;
event.value = 0;
event.time = tv;
write(fd, &event, sizeof(event));
return 0;
}
struct touch_event_ops {
int (*write_single_touch)(int fd, int slot, int x, int y);
int (*write_up)(int fd, int slot);
int (*write_multi_touch)(int fd, int x1, int y1, int x2, int y2);
};
static struct touch_event_ops proto_a_ops = {
.write_single_touch = write_single_touch_proto_a,
.write_up = write_up_proto_a,
.write_multi_touch = write_multi_touch_proto_a,
};
对于类型 B 的输入设备文件，事件写入输入设备文件并派发的方法如下：
static int single_touch_proto_b(int fd, int slot, int x, int y) {
struct timeval tv;
gettimeofday(&tv, 0);
struct input_event event;
memset(&event, 0, sizeof(event));
event.type = EV_ABS;
event.code = ABS_MT_SLOT;
event.value = slot;
event.time = tv;
write(fd, &event, sizeof(event));
event.type = EV_ABS;
event.code = ABS_MT_TRACKING_ID;
event.value = slot;
event.time = tv;
write(fd, &event, sizeof(event));
event.type = EV_ABS;
event.code = ABS_MT_PRESSURE;
event.value = 1;
event.time = tv;
write(fd, &event, sizeof(event));
event.type = EV_ABS;
event.code = ABS_MT_TOUCH_MINOR;
event.value = 1;
event.time = tv;
write(fd, &event, sizeof(event));
event.type = EV_ABS;
event.code = ABS_MT_TOUCH_MAJOR;
event.value = 1;
event.time = tv;
write(fd, &event, sizeof(event));
event.type = EV_ABS;
event.code = ABS_MT_POSITION_X;
event.value = x;
event.time = tv;
write(fd, &event, sizeof(event));
event.type = EV_ABS;
event.code = ABS_MT_POSITION_Y;
event.value = y;
event.time = tv;
write(fd, &event, sizeof(event));
return 0;
}
static void sys_report_proto_b(int fd) {
struct timeval tv;
gettimeofday(&tv, 0);
struct input_event event;
memset(&event, 0, sizeof(event));
event.type = EV_SYN;
event.code = SYN_REPORT;
event.value = 0;
event.time = tv;
write(fd, &event, sizeof(event));
}
static int write_single_touch_proto_b(int fd, int slot, int x, int y) {
single_touch_proto_b(fd, slot, x, y);
sys_report_proto_b(fd);
return 0;
}
static int write_multi_touch_proto_b(int fd, int x1, int y1, int x2, int y2) {
single_touch_proto_b(fd, 0, x1, y1);
single_touch_proto_b(fd, 1, x2, y2);
sys_report_proto_b(fd);
return 0;
}
static int write_up_proto_b(int fd, int slot) {
struct timeval tv;
gettimeofday(&tv, 0);
struct input_event event;
memset(&event, 0, sizeof(event));
event.type = EV_SYN;
event.code = ABS_MT_SLOT;
event.value = slot;
event.time = tv;
write(fd, &event, sizeof(event));
event.type = EV_ABS;
event.code = ABS_MT_TRACKING_ID;
event.value = -1;
event.time = tv;
write(fd, &event, sizeof(event));
event.type = EV_SYN;
event.code = SYN_REPORT;
event.value = 0;
event.time = tv;
write(fd, &event, sizeof(event));
return 0;
}
struct touch_event_ops {
int (*write_single_touch)(int fd, int slot, int x, int y);
int (*write_up)(int fd, int slot);
int (*write_multi_touch)(int fd, int x1, int y1, int x2, int y2);
};
static struct touch_event_ops proto_b_ops = {
.write_single_touch = write_single_touch_proto_b,
.write_up = write_up_proto_b,
.write_multi_touch = write_multi_touch_proto_b,
};
其它无需支持多种不同类型设备的输入事件派发的应用，可以事先根据 getevent -p 的输出判断输入设备的类型，并编写相应的适用于该设备的输入事件派发程序，但这种方法适应性比较差，难以用于需要支持多种不同输入设备类型的应用中。
输入设备文件支持的事件类型信息，不仅仅可以通过 getevent -p 命令获得，还可以通过系统调用接口 ioctl() 获取。
本发明基于系统调用接口 ioctl()，先获得设备文件支持的输入事件类型信息，判断出输入设备的类型信息，并据输入设备的类型，选择不同的事件写入操作集，执行不同的事件派发逻辑。具体方法如下：
static const char *get_label(const struct label *labels, int value) {
while (labels->name && value != labels->value) {
labels++;
}
return labels->name;
}
static int get_input_props(int fd, uint8_t *bits, int bitsSize) {
int res = ioctl(fd, EVIOCGPROP(bitsSize), bits);
return res;
}
static bool has_prop(uint8_t *bits, int prop) {
int index = prop / 8;
int bitIndex = prop % 8;
return (bits[index] & (1 << bitIndex)) > 0;
}
static int get_abs_events(int fd, uint8_t *bits, int bits_size) {
int res = ioctl(fd, EVIOCGBIT(EV_ABS, bits_size), bits);
return res;
}
static bool support_event(uint8_t *bits, int event) {
int index = event / 8;
int bitIndex = event % 8;
return (bits[index] & (1 << bitIndex)) > 0;
}
static bool support_proto_a_touch_event(uint8_t *absbits) {
return support_event(absbits, ABS_MT_TOUCH_MAJOR)
&& support_event(absbits, ABS_MT_WIDTH_MAJOR)
&& support_event(absbits, ABS_MT_WIDTH_MINOR)
&& support_event(absbits, ABS_MT_POSITION_X)
&& support_event(absbits, ABS_MT_POSITION_Y)
&& support_event(absbits, ABS_MT_PRESSURE);
}
static bool support_proto_b_touch_event(uint8_t *absbits) {
return support_event(absbits, ABS_MT_SLOT)
&& support_event(absbits, ABS_MT_TOUCH_MAJOR)
&& support_event(absbits, ABS_MT_POSITION_X)
&& support_event(absbits, ABS_MT_POSITION_Y)
&& support_event(absbits, ABS_MT_TRACKING_ID)
&& support_event(absbits, ABS_MT_PRESSURE);
}
static bool is_touch_dev(const char *device, bool verbose = false) {
int fd = open(device, O_RDWR);
if (fd < 0) {
fprintf(stderr, "could not open %s, %s\n", device, strerror(errno));
return false;
}
if (verbose) {
print_device_basic_info(device, fd);
}
uint8_t bits[INPUT_PROP_CNT / 8];
bzero(bits, INPUT_PROP_CNT / 8);
int res = get_input_props(fd, bits, INPUT_PROP_CNT / 8);
if (verbose) {
print_input_props(bits, res);
}
uint8_t absbits[ABS_CNT / 8];
bzero(absbits, ABS_CNT / 8);
res = get_abs_events(fd, absbits, ABS_CNT / 8);
if (verbose) {
fprintf(stderr, "ABS event res for %s is %d\n", device, res);
print_abs_events(fd, absbits, res);
}
if (support_proto_a_touch_event(absbits)
|| support_proto_b_touch_event(absbits)) {
close(fd);
return true;
}
close(fd);
return false;
}
typedef bool (*check_dev)(const char *device, bool verbose);
static bool scan_dir(const char *dirname, char *devname, check_dev check_func) {
char *filename;
DIR *dir;
struct dirent *de;
dir = opendir(dirname);
if (dir == NULL)
return -1;
strcpy(devname, dirname);
filename = devname + strlen(devname);
*filename++ = '/';
bool found = false;
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 (check_func(devname, false)) {
found = true;
break;
}
}
closedir(dir);
return found;
}
static struct touch_event_ops proto_a_ops = {
.write_single_touch = write_single_touch_proto_a,
.write_up = write_up_proto_a,
.write_multi_touch = write_multi_touch_proto_a,
};
static struct touch_event_ops proto_b_ops = {
.write_single_touch = write_single_touch_proto_b,
.write_up = write_up_proto_b,
.write_multi_touch = write_multi_touch_proto_b,
};
//打开设备
struct touch_dev_ops * open_touch_dev() {
const char *device_path = "/dev/input";
char devname[PATH_MAX];
struct touch_dev_ops *dev_ops = NULL;
if (!scan_dir(device_path, devname, &is_touch_dev)) {
fprintf(stderr, "Can't find touch device.\n");
return dev_ops;
}
fprintf(stderr, "find touch dev %s\n", devname);
int fd_touch = open(devname, O_RDWR);
if (fd_touch <= 0) {
LOGE("open touch %s error:%s", devname, strerror(errno));
return dev_ops;
}
uint8_t absbits[ABS_CNT / 8];
bzero(absbits, ABS_CNT / 8);
int res = get_abs_events(fd_touch, absbits, ABS_CNT / 8);
dev_ops = new touch_dev_ops;
dev_ops->touch_dev_fd = fd_touch;
if (support_proto_a_touch_event(absbits)) {
dev_ops->event_ops = &proto_a_ops;
} else {
dev_ops->event_ops = &proto_b_ops;
}
return dev_ops;
}
本文介绍的 Android 用户事件自适应分发程序，可以同时支持多种不同类型的 Android 输入设备文件。
