st

/* See LICENSE for license details. */

#include <stdlib.h>
#include <stdio.h>
#include <hb.h>
#include <hb-ft.h>

#include "st.h"
#include "render.h"
#include "hb.h"

void hbtransformsegment(FT_Face, const Glyph *, hb_codepoint_t *, int, int);
hb_font_t *hbfindfont(FT_Face);

typedef struct {
	FT_Face face;
	hb_font_t *font;
} HbFontMatch;

static int hbfontslen = 0;
static HbFontMatch *hbfontcache = NULL;

void
hbunloadfonts(void)
{
	int i;

	for (i = 0; i < hbfontslen; i++)
		hb_font_destroy(hbfontcache[i].font);

	free(hbfontcache);
	hbfontcache = NULL;
	hbfontslen = 0;
}

hb_font_t *
hbfindfont(FT_Face face)
{
	int i;
	hb_font_t *font;

	for (i = 0; i < hbfontslen; i++)
		if (hbfontcache[i].face == face)
			return hbfontcache[i].font;

	hbfontcache = realloc(hbfontcache,
	                      sizeof(HbFontMatch) * (hbfontslen + 1));
	if (!hbfontcache)
		die("realloc: failed to grow HarfBuzz font cache\n");

	font = hb_ft_font_create(face, NULL);
	if (!font)
		die("Failed to load Harfbuzz font.\n");

	hbfontcache[hbfontslen].face = face;
	hbfontcache[hbfontslen].font = font;
	hbfontslen++;

	return font;
}

void
hbtransform(GlyphSpec *specs, const Glyph *glyphs, size_t len, int x, int y)
{
	int start = 0, length = 1, gstart = 0;
	hb_codepoint_t *codepoints;
	int idx, specidx;

	codepoints = calloc(len, sizeof(hb_codepoint_t));
	if (!codepoints)
		die("calloc: failed to allocate HarfBuzz buffer\n");

	for (idx = 1, specidx = 1; idx < (int)len; idx++) {
		if (glyphs[idx].mode & ATTR_WDUMMY) {
			length++;
			continue;
		}

		if (specs[specidx].font != specs[start].font ||
		    ATTRCMP(glyphs[gstart], glyphs[idx]) ||
		    selected(x + idx, y) != selected(x + gstart, y)) {
			hbtransformsegment((FT_Face)specs[start].font, glyphs,
			                   codepoints, gstart, length);

			length = 1;
			start = specidx;
			gstart = idx;
		} else {
			length++;
		}

		specidx++;
	}

	/* EOL. */
	hbtransformsegment((FT_Face)specs[start].font, glyphs, codepoints,
	                   gstart, length);

	/* Apply the transformation to glyph specs. */
	for (idx = 0, specidx = 0; idx < (int)len; idx++) {
		if (glyphs[idx].mode & ATTR_WDUMMY)
			continue;
		if (glyphs[idx].mode & ATTR_BOXDRAW) {
			specidx++;
			continue;
		}

		if (codepoints[idx] != specs[specidx].glyph)
			((Glyph *)glyphs)[idx].mode |= ATTR_LIGA;

		specs[specidx++].glyph = codepoints[idx];
	}

	free(codepoints);
}

void
hbtransformsegment(FT_Face face, const Glyph *string,
                   hb_codepoint_t *codepoints, int start, int length)
{
	hb_font_t *font = hbfindfont(face);
	hb_buffer_t *buffer;
	hb_glyph_info_t *info;
	unsigned int count, i;
	Rune rune;
	ushort mode;

	if (font == NULL)
		return;

	buffer = hb_buffer_create();
	hb_buffer_set_direction(buffer, HB_DIRECTION_LTR);

	/* Fill buffer with codepoints. */
	for (i = 0; i < (unsigned)length; i++) {
		rune = string[start + i].u;
		mode = string[start + i].mode;
		if (mode & ATTR_WDUMMY)
			rune = 0x0020;
		hb_buffer_add_codepoints(buffer, &rune, 1, 0, 1);
	}

	/* Shape the segment. */
	hb_shape(font, buffer, NULL, 0);

	/* Get new glyph info. */
	info = hb_buffer_get_glyph_infos(buffer, &count);

	/* Write new codepoints.  A ligature can collapse several cells into
	 * one glyph; leave the remaining cells with glyph 0, which wl.c skips. */
	for (i = 0; i < (unsigned)length; i++)
		codepoints[start + i] = i < count ? info[i].codepoint : 0;

	hb_buffer_destroy(buffer);
}