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1# mtdev - Multitouch Protocol Translation Library
2
3The mtdev is a stand-alone library which transforms all variants of kernel MT events to the slotted type B protocol. The events put into mtdev may be from any MT device, specifically type A without contact tracking, type A with contact tracking, or type B with contact tracking.
4
5The bulk of the mtdev code has been out there since 2008, as part of the Multitouch X Driver. With this package, finger tracking and seamless MT protocol handling is available under a free license.
6
7
8## Directory structure
9
10```
11README.md                   English description
12README_zh.md                Chinese description
13include/                    API Definition
14src/                        Encapsulation layer implementation
15README.OpenSource           Open Source Description
16```
17
18## How OpenHarmony integrates mtdev
19### 1.Header file import
20```c
21#include <mtdev.h>
22```
23### 2.BUILD.gn add Reference
24```c
25public_deps += ["//third_party/mtdev:libmtdev"]
26```
27### 3.Example of calling mtdev function
28```c
29//year-proof millisecond event time
30typedef uint64_t mstime_t;
31
32static int use_event(const struct input_event *ev)
33{
34#if 0
35	return ev->type == EV_ABS && mtdev_is_absmt(ev->code);
36#else
37	return 1;
38#endif
39}
40
41//print events
42static void print_event(const struct input_event *ev)
43{
44	static const mstime_t ms = 1000;
45	static int slot;
46	mstime_t evtime = ev->input_event_usec / ms + ev->input_event_sec * ms;
47	if (ev->type == EV_ABS && ev->code == ABS_MT_SLOT)
48		slot = ev->value;
49	fprintf(stderr, "%012llx %02d %01d %04x %d\n",
50		evtime, slot, ev->type, ev->code, ev->value);
51}
52
53#define CHECK(dev, name)			\
54	if (mtdev_has_mt_event(dev, name))	\
55		fprintf(stderr, "   %s\n", #name)
56
57//check prop
58static void show_props(const struct mtdev *dev)
59{
60	fprintf(stderr, "supported mt events:\n");
61	CHECK(dev, ABS_MT_SLOT);
62	CHECK(dev, ABS_MT_TOUCH_MAJOR);
63	CHECK(dev, ABS_MT_TOUCH_MINOR);
64	CHECK(dev, ABS_MT_WIDTH_MAJOR);
65	CHECK(dev, ABS_MT_WIDTH_MINOR);
66	CHECK(dev, ABS_MT_ORIENTATION);
67	CHECK(dev, ABS_MT_POSITION_X);
68	CHECK(dev, ABS_MT_POSITION_Y);
69	CHECK(dev, ABS_MT_TOOL_TYPE);
70	CHECK(dev, ABS_MT_BLOB_ID);
71	CHECK(dev, ABS_MT_TRACKING_ID);
72	CHECK(dev, ABS_MT_PRESSURE);
73	CHECK(dev, ABS_MT_DISTANCE);
74}
75
76//Create mtdev, check prop, get and print mt events
77static void loop_device(int fd)
78{
79	struct mtdev dev;
80	struct input_event ev;
81	int ret = mtdev_open(&dev, fd);
82	if (ret) {
83		fprintf(stderr, "error: could not open device: %d\n", ret);
84		return;
85	}
86	show_props(&dev);
87	//while the device has not been inactive for five seconds
88	while (!mtdev_idle(&dev, fd, 5000)) {
89		//extract all available processed events
90		while (mtdev_get(&dev, fd, &ev, 1) > 0) {
91			if (use_event(&ev))
92				print_event(&ev);
93		}
94	}
95	mtdev_close(&dev);
96}
97
98//main function
99int main(int argc, char *argv[])
100{
101	int fd;
102	if (argc < 2) {
103		fprintf(stderr, "Usage: mtdev <device>\n");
104		return -1;
105	}
106	fd = open(argv[1], O_RDONLY | O_NONBLOCK);
107	if (fd < 0) {
108		fprintf(stderr, "error: could not open device\n");
109		return -1;
110	}
111	if (ioctl(fd, EVIOCGRAB, 1)) {
112		fprintf(stderr, "error: could not grab the device\n");
113		return -1;
114	}
115	loop_device(fd);
116	ioctl(fd, EVIOCGRAB, 0);
117	close(fd);
118	return 0;
119}
120```
121
122## mtdev Working with documents
123
124
125Official API http://bitmath.org/code/mtdev/
126
127
128## License
129
130见 [LICENSE](MIT(X11)License).
131
132---
133
134The mtdev library was released under the MIT licence in collaboration with Canonical, Ltd.