Wayland开发入门教程12：鼠标操作

之前文章中我们创建了一个空白窗口，接下来我们处理一下窗口上的鼠标操作。

先把新建窗口的代码复制过来。然后把seat的部分代码复制过来，在注册函数中添加seat处理部分。

Wayland只提供了wl_pointer_listener，要想获取鼠标相关的消息需要首先设置监听器。

wl_pointer的消息有：

enter 进入窗口范围
leave 离开窗口范围
motion 鼠标移动
button 鼠标点击，鼠标按键id定义位于文件<linux/input.h>中，例如BTN_LEFT表示鼠标左键。

static void
global_registry_handler(void *data, struct wl_registry *registry,
						uint32_t id, const char *interface, uint32_t version)
{
	printf("Got a registry event for %s id %d\n", interface, id);
	if (strcmp(interface, "wl_compositor") == 0)
	{
		compositor = wl_registry_bind(registry, id, &wl_compositor_interface, version);
	}
	else if (strcmp(interface, xdg_wm_base_interface.name) == 0)
	{
		xdg_shell = wl_registry_bind(registry, id, &xdg_wm_base_interface, version);
	}
	else if (strcmp(interface, "wl_shm") == 0)
	{
		shm = wl_registry_bind(registry, id, &wl_shm_interface, version);
		wl_shm_add_listener(shm, &shm_listener, NULL);
	}
	else if (strcmp(interface, "wl_seat") == 0)
	{
		seat = wl_registry_bind(registry, id, &wl_seat_interface, 1);
		wl_seat_add_listener(seat, &seat_listener, NULL);
	}
}

添加一个seat_listener结构体

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static const struct wl_seat_listener seat_listener = {
    seat_handle_capabilities,
};

添加seat_listener的回调函数

static void
seat_handle_capabilities(void *data, struct wl_seat *seat,
                         enum wl_seat_capability caps)
{
    if ((caps & WL_SEAT_CAPABILITY_POINTER) && !pointer)
    {
        pointer = wl_seat_get_pointer(seat);
        wl_pointer_add_listener(pointer, &pointer_listener, NULL);
    }else if (!(caps & WL_SEAT_CAPABILITY_POINTER) && pointer){
        wl_pointer_destroy(pointer);
        pointer = NULL;
    }
}

分两种情况，第一种是输入设备是鼠标并且指针不为空那么就表示当前状态有效，第二种是输入设备为鼠标但是指针为空表示鼠标已经离开窗口了。

添加pointer_listener函数。

static const struct wl_pointer_listener pointer_listener = {
    pointer_handle_enter,
    pointer_handle_leave,
    pointer_handle_motion,
    pointer_handle_button,
    pointer_handle_axis,
};

有四种情况：进入、离开、移动、点击、坐标系。四种情况对应的函数为：

static void
pointer_handle_enter(void *data, struct wl_pointer *pointer,
                     uint32_t serial, struct wl_surface *surface,
                     wl_fixed_t sx, wl_fixed_t sy)
{
    fprintf(stderr, "Pointer entered surface %p at %d %d\n", surface, sx, sy);
}

static void
pointer_handle_leave(void *data, struct wl_pointer *pointer,
                     uint32_t serial, struct wl_surface *surface)
{
    fprintf(stderr, "Pointer left surface %p\n", surface);
}

static void
pointer_handle_motion(void *data, struct wl_pointer *pointer,
                      uint32_t time, wl_fixed_t sx, wl_fixed_t sy)
{
    printf("Pointer moved at %d %d\n", sx, sy);
}

static void
pointer_handle_button(void *data, struct wl_pointer *wl_pointer,
                      uint32_t serial, uint32_t time, uint32_t button,
                      uint32_t state)
{
    printf("Pointer button\n");
    if (button == BTN_LEFT && state == WL_POINTER_BUTTON_STATE_PRESSED)
        wl_shell_surface_move(shell_surface, seat, serial);
}

static void
pointer_handle_axis(void *data, struct wl_pointer *wl_pointer,
                    uint32_t time, uint32_t axis, wl_fixed_t value)
{
    printf("Pointer handle axis\n");
}