main.c

// --------------
// TextBar v0.1.0
// --------------
// Usage: <text generator> | textbar | <input handler>
//
// Shows the last two lines from stdin on a bar
// Every odd line is on the left
// Every even line is on the right
// Updating one side at a time is not possible
// Line buffered
// Prints all mouse clicks to stdout
// In the format of `X Y` (without the '`')

#include <pthread.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <stdbool.h>

#include <X11/Xlib.h>
#include <X11/Xatom.h>

#include <cairo.h>
#include <cairo-xlib.h>

Display* dpy;
Window win;
cairo_surface_t* sfc;
cairo_t* ctx;
char text[256] = {0};
char text_other[256] = {0};
int width;

//extern int errno;

// CONFIG
#define POSITION TOP
#define FONT "FiraCode Nerd Font"
#define FONT_SIZE 16
#define BG_COLOR 0.157, 0.165, 0.212
#define FG_COLOR 0.973, 0.973, 0.949

// COMPUTATION
#define HEIGHT FONT_SIZE*2
#define FONT_POS FONT_SIZE*1.4

void init() {
	XInitThreads();
	dpy = XOpenDisplay(NULL);
	int screen = DefaultScreen(dpy);
	width = DisplayWidth(dpy, screen);
	win = XCreateSimpleWindow(dpy, DefaultRootWindow(dpy), 0, 0, width, HEIGHT, 0, 0, 0);
	XSelectInput(dpy, win, ButtonPressMask | StructureNotifyMask | ExposureMask);
	Atom type = XInternAtom(dpy, "_NET_WM_WINDOW_TYPE", False);
	long value = XInternAtom(dpy, "_NET_WM_WINDOW_TYPE_DOCK", False);
	XChangeProperty(dpy, win, type,
			XA_ATOM, 32, PropModeReplace, (unsigned char *) &value, 1);
#if POSITION==BOTTOM
	XMoveWindow(dpy, win, 0, DisplayHeight(dpy, screen));
#elif POSITION==TOP
	XMoveWindow(dpy, win, 0, 0);
#endif
	XMapWindow(dpy, win);
	sfc = cairo_xlib_surface_create(dpy, win, DefaultVisual(dpy, screen), DisplayWidth(dpy, screen), HEIGHT);
	ctx = cairo_create(sfc);
}

pthread_mutex_t do_paint;
void paint() {
	pthread_mutex_lock(&do_paint);
	cairo_push_group(ctx);
	cairo_set_source_rgb(ctx, BG_COLOR);
	cairo_paint(ctx);
	cairo_move_to(ctx, FONT_SIZE / 2, FONT_POS);
	cairo_select_font_face(ctx, FONT, CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_NORMAL);
	cairo_set_font_size(ctx, FONT_SIZE);
	cairo_set_source_rgb(ctx, FG_COLOR);
	cairo_show_text(ctx, text);
	cairo_text_extents_t extents;
	cairo_text_extents (ctx, text_other, &extents);
	cairo_move_to(ctx, (width-extents.width) - FONT_SIZE / 2, FONT_POS);
	cairo_show_text(ctx, text_other);
	cairo_pop_group_to_source(ctx);
	cairo_paint(ctx);
	cairo_surface_flush(sfc);
	XFlush(dpy);
	pthread_mutex_unlock(&do_paint);
}

void update() {
	while(1) {
		fgets(text, 256, stdin);
		fgets(text_other, 256, stdin);
		text[strcspn(text, "\n")] = 0;
		text_other[strcspn(text_other, "\n")] = 0;
		paint();
	}
}

int main() {
	init();

	pthread_mutex_init(&do_paint, NULL);
	pthread_t update_thread_id;
	if(pthread_create(&update_thread_id, NULL, update, NULL)) {
		perror("pthread failed");
	}
	
	while(1) {
		XEvent e;
		XNextEvent(dpy, &e);
		if(e.type == ButtonPress) {
			printf("%d %d\n", e.xbutton.x, e.xbutton.y);
			fflush(stdout);
		} else
		if(e.type == ConfigureNotify) {
			pthread_mutex_lock(&do_paint);
			cairo_xlib_surface_set_size(sfc, e.xconfigure.width, e.xconfigure.height);
			pthread_mutex_unlock(&do_paint);
		} else
		if(e.type == Expose) {
			paint();
		}
	}
}