/*
 * text.c - FIG text object
 *
 * Written 2016 by Werner Almesberger
 * Copyright 2016 by Werner Almesberger
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */


#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>

#include "util.h"
#include "fig.h"
#include "text.h"


void text_init(struct text *txt)
{
	txt->s = NULL;
	txt->size = 0;
	txt->x = txt->y = 0;
	txt->rot = 0;
	txt->hor = text_mid;
	txt->vert = text_mid;
}


void text_free(struct text *txt)
{
	free((void *) txt->s);
	txt->s = NULL;
}


void text_set(struct text *txt, const char *s)
{
	free((void *) txt->s);
	txt->s = stralloc(s);
}


static int rx(int x, int y, int rot)
{
	float a = rot / 180.0 * M_PI;

	return cos(a) * x + sin(a) * y;
}


static int ry(int x, int y, int rot)
{
	float a = rot / 180.0 * M_PI;

	return -sin(a) * x + cos(a) * y;
}


static int align(int dim, enum text_align align)
{
	switch (align) {
	case text_min:
		return 0;
	case text_mid:
		return dim / 2;
	case text_max:
		return dim;
	default:
		abort();
	}
}


void text_fig(const struct text *txt, int color, unsigned layer)
{
	int x = txt->x;
	int y = txt->y;

	x += rx(0, align(txt->size, txt->vert), txt->rot);
	y += ry(0, align(txt->size, txt->vert), txt->rot);
	fig_text(x, y, txt->s, txt->size, txt->hor, txt->rot, color, layer);
}


static unsigned guess_width(const struct text *txt)
{
	/*
	 * Note that fig.c stretches the text size, so the ratio is larger than
	 * expressed here.
	 */
	return strlen(txt->s) * txt->size * 1.0;
}


void text_rel(const struct text *txt, enum text_align xr, enum text_align yr,
    int dx, int dy, int *res_x, int *res_y)
{
	dx -= align(guess_width(txt), txt->hor);
	dy += align(txt->size, txt->vert);
	dx += align(guess_width(txt), xr);
	dy -= align(txt->size, yr);
	if (res_x)
		*res_x = txt->x + rx(dx, dy, txt->rot);
	if (res_y)
		*res_y = txt->y + ry(dx, dy, txt->rot);
}


void text_shift(struct text *txt, enum text_align xr, enum text_align yr,
    int dx, int dy)
{
	text_rel(txt, xr, yr, dx, dy, &txt->x, &txt->y);
}


int text_rel_x(const struct text *txt, enum text_align xr, enum text_align yr,
    int dx, int dy)
{
	int x;

	text_rel(txt, xr, yr, dx, dy, &x, NULL);
	return x;
}


int text_rel_y(const struct text *txt, enum text_align xr, enum text_align yr,
    int dx, int dy)
{
	int y;

	text_rel(txt, xr, yr, dx, dy, NULL, &y);
	return y;
}