initial commit

swaystick.c

@@ -0,0 +1,246 @@
+/*
+ * swaystick: control Sway with a DualSense gamepad
+ * Copyright (c) 2024 Jeremy Baxter.
+ */
+
+#include <sys/wait.h>
+#include <linux/joystick.h>
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+/* DualSense button mapping */
+enum DSButton {
+	DS_CROSS = 0,
+	DS_CIRCLE = 1,
+	DS_TRIANGLE = 2,
+	DS_SQUARE = 3,
+	DS_L1 = 4,
+	DS_R1 = 5,
+	DS_L2 = 6,
+	DS_R2 = 7,
+	DS_CREATE = 8,
+	DS_OPTIONS = 9,
+	DS_PLAYSTATION = 10,
+	DS_LSTICK = 11,
+	DS_RSTICK = 12
+};
+
+int
+read_event(int fd, struct js_event *event)
+{
+	ssize_t bytes;
+
+	bytes = read(fd, event, sizeof(*event));
+
+	if (bytes == sizeof(*event))
+		return 0;
+
+	return -1;
+}
+
+size_t
+get_axis_count(int fd)
+{
+	__u8 axes;
+
+	if (ioctl(fd, JSIOCGAXES, &axes) == -1)
+		return 0;
+
+	return axes;
+}
+
+size_t
+get_button_count(int fd)
+{
+	__u8 buttons;
+	if (ioctl(fd, JSIOCGBUTTONS, &buttons) == -1)
+		return 0;
+
+	return buttons;
+}
+
+char *
+make_move_command(int pos, int x)
+{
+	char *buffer;
+	size_t len;
+
+	len = 32;
+	buffer = malloc(len * sizeof(char));
+
+	snprintf(buffer, len, "move %s %d",
+			 x ? "right" : "down",
+			 pos / 2000);
+
+	return buffer;
+}
+
+char *
+make_resize_command(int pos, int x)
+{
+	char *buffer;
+	size_t len;
+
+	len = 32;
+	buffer = malloc(len * sizeof(char));
+
+	snprintf(buffer, len, "resize %s %s %d",
+			 pos > 0 ? "grow" : "shrink",
+			 x ? "width" : "height",
+			 pos / 2000);
+
+	return buffer;
+}
+
+void
+swaymsg(const char *msg)
+{
+	const char *prog = "swaymsg";
+	pid_t child;
+	int wstatus;
+
+	child = fork();
+	switch (child) {
+	case -1:
+		perror("fork");
+		break;
+	case 0:
+		if (execlp(prog, prog, msg, NULL) == -1)
+			perror("execlp");
+		break;
+	default:
+		if (wait(&wstatus) == -1)
+			perror("wait");
+	}
+}
+
+struct axis_state {
+	short x, y;
+};
+
+/**
+ * Keeps track of the current axis state.
+ *
+ * NOTE: This function assumes that axes are numbered starting from 0,
+ * and that the X axis is an even number, and the Y axis is an odd number.
+ * However, this is usually a safe assumption.
+ *
+ * Returns the axis that the event indicated.
+ */
+size_t
+get_axis_state(struct js_event *event, struct axis_state axes[3])
+{
+	size_t axis = event->number / 2;
+
+	if (axis < 3) {
+		if (event->number % 2 == 0)
+			axes[axis].x = event->value;
+		else
+			axes[axis].y = event->value;
+	}
+
+	return axis;
+}
+
+int
+main(int argc, char *argv[])
+{
+	struct axis_state axes[3] = {0};
+	struct js_event event;
+	const char *device;
+	size_t axis;
+	int js;
+	int moving;
+
+	moving = 0;
+
+	if (argc > 1)
+		device = argv[1];
+	else
+		device = "/dev/input/js0";
+
+	js = open(device, O_RDONLY);
+
+	if (js == -1)
+		perror(device);
+
+	/* This loop will exit if the controller is unplugged. */
+	while (read_event(js, &event) == 0) {
+		if (moving)
+			swaymsg("move position cursor");
+
+		switch (event.type) {
+		case JS_EVENT_BUTTON:
+			if (event.value) { /* pressed */
+				switch (event.number) {
+				case DS_CROSS:
+					swaymsg("kill");
+					break;
+				case DS_TRIANGLE:
+					moving = 1;
+					break;
+				case DS_LSTICK:
+					swaymsg("focus prev");
+					break;
+				case DS_RSTICK:
+					swaymsg("focus next");
+					break;
+				default: break;
+				}
+				break;
+			}
+			/* released */
+			switch (event.number) {
+			case DS_CIRCLE:
+				swaymsg("focus mode_toggle");
+				break;
+			case DS_TRIANGLE:
+				moving = 0;
+				break;
+			case DS_SQUARE:
+				swaymsg("floating toggle");
+				break;
+			case DS_L1:
+				swaymsg("workspace prev");
+				break;
+			case DS_R1:
+				swaymsg("workspace next");
+				break;
+			case DS_CREATE:
+				swaymsg("layout tabbed");
+				break;
+			case DS_OPTIONS:
+				swaymsg("layout toggle split");
+				break;
+			case DS_PLAYSTATION:
+				swaymsg("exec 'emacsclient -c'");
+				break;
+			default: break;
+			}
+			break;
+		case JS_EVENT_AXIS:
+			axis = get_axis_state(&event, axes);
+
+			if (axis > 2)
+				break;
+			/* no activity? */
+			if (axes[axis].x > -2000 && axes[axis].x < 2000
+				&& axes[axis].y > -2000 && axes[axis].y < 2000)
+				break;
+
+			if (axis == 0) { /* left X/Y */
+				swaymsg(make_move_command(axes[axis].x, 1));
+				swaymsg(make_move_command(axes[axis].y, 0));
+			}
+		default:
+			/* ignore init events */
+			break;
+		}
+	}
+
+	close(js);
+	return 0;
+}