twin_font.c

/*
 * Twin - A Tiny Window System
 * Copyright © 2004 Keith Packard <keithp@keithp.com>
 * All rights reserved.
 *
 * This Library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This Library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with the Twin Library; see the file COPYING.  If not,
 * write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include "twinint.h"

#if 0
#include <stdio.h>
#define F(x) twin_fixed_to_double(x)
#define S(x) twin_sfixed_to_double(x)
#define G(x) ((double) (x))
#define DBGMSG(x)	printf x
#else
#define DBGMSG(x)
#endif

#define SNAPI(p)	(((p) + 0x8000) & ~0xffff)
#define SNAPH(p)	(((p) + 0x4000) & ~0x7fff)
#define FX(g,i)		(((g) * (i)->scale.x) >> 6)
#define FY(g,i)		(((g) * (i)->scale.y) >> 6)

typedef struct _twin_text_info {
    twin_point_t    scale;
    twin_point_t    pen;
    twin_point_t    margin;
    twin_point_t    reverse_scale;
    twin_bool_t	    snap;
    twin_matrix_t   matrix;
    twin_matrix_t   pen_matrix;
    int		    n_snap_x;
    twin_fixed_t    snap_x[TWIN_GLYPH_MAX_SNAP_X];
    int		    n_snap_y;
    twin_fixed_t    snap_y[TWIN_GLYPH_MAX_SNAP_Y];
} twin_text_info_t;

static void _twin_text_compute_info (twin_path_t	*path,
				     twin_font_t	*font,
				     twin_text_info_t	*info)
{
    twin_spoint_t   origin = _twin_path_current_spoint (path);
    
    /*
     * Only hint axis aligned text 
     */
    if ((path->state.font_style & TWIN_TEXT_UNHINTED) == 0 &&
	((path->state.matrix.m[0][1] == 0 &&
	  path->state.matrix.m[1][0] == 0) ||
	 (path->state.matrix.m[0][0] == 0 &&
	  path->state.matrix.m[1][1] == 0)))
    {
	int		xi, yi;
	twin_fixed_t    margin_x;

	if (path->state.matrix.m[0][0] != 0)
	    xi = 0;
	else
	    xi = 1;
	yi = 1-xi;
	info->matrix.m[xi][0] = TWIN_FIXED_ONE;
	info->matrix.m[xi][1] = 0;
	info->matrix.m[yi][0] = 0;
	info->matrix.m[yi][1] = TWIN_FIXED_ONE;
	if (font->type == TWIN_FONT_TYPE_STROKE) {
	    info->snap = TWIN_TRUE;
	    info->matrix.m[2][0] = SNAPI(twin_sfixed_to_fixed (origin.x));
	    info->matrix.m[2][1] = SNAPI(twin_sfixed_to_fixed (origin.y));
	} else {
	    info->snap = TWIN_FALSE;
	    info->matrix.m[2][0] = twin_sfixed_to_fixed (origin.x);
	    info->matrix.m[2][1] = twin_sfixed_to_fixed (origin.y);
	}
	info->scale.x = twin_fixed_mul (path->state.font_size, 
					path->state.matrix.m[0][xi]);
	info->reverse_scale.x = twin_fixed_div (TWIN_FIXED_ONE,
						path->state.matrix.m[0][xi]);
	if (info->scale.x < 0)
	{
	    info->scale.x = -info->scale.x;
	    info->reverse_scale.x = -info->reverse_scale.x;
	    info->matrix.m[0][xi] = -info->matrix.m[0][xi];
	    info->matrix.m[1][xi] = -info->matrix.m[1][xi];
	}
	info->scale.y = twin_fixed_mul (path->state.font_size,
					path->state.matrix.m[1][yi]);
	info->reverse_scale.y = twin_fixed_div (TWIN_FIXED_ONE,
						path->state.matrix.m[1][yi]);
	if (info->scale.y < 0)
	{
	    info->scale.y = -info->scale.y;
	    info->reverse_scale.y = -info->reverse_scale.y;
	    info->matrix.m[0][yi] = -info->matrix.m[0][yi];
	    info->matrix.m[1][yi] = -info->matrix.m[1][yi];
	}

	if (font->type == TWIN_FONT_TYPE_STROKE) {
	    info->pen.x = SNAPH(info->scale.x / 24);
	    info->pen.y = SNAPH(info->scale.y / 24);
	    if (info->pen.x < TWIN_FIXED_HALF)
		info->pen.x = TWIN_FIXED_HALF;
	    if (info->pen.y < TWIN_FIXED_HALF)
		info->pen.y = TWIN_FIXED_HALF;
	} else {
	    info->pen.x = 0;
	    info->pen.y = 0;
	}
	info->margin.x = info->pen.x;
	info->margin.y = info->pen.y;
	if (font->type == TWIN_FONT_TYPE_STROKE &&
	    (path->state.font_style & TWIN_TEXT_BOLD))
	{
	    twin_fixed_t    pen_x_add;
	    twin_fixed_t    pen_y_add;

	    pen_x_add = SNAPH(info->pen.x >> 1);
	    pen_y_add = SNAPH(info->pen.y >> 1);

	    if (pen_x_add < TWIN_FIXED_HALF)
	        pen_x_add = TWIN_FIXED_HALF;
	    if (pen_y_add < TWIN_FIXED_HALF)
		pen_y_add = TWIN_FIXED_HALF;

	    info->pen.x += pen_x_add;
	    info->pen.y += pen_y_add;
	}
	DBGMSG (("pen: %9.4f %9.4f\n", F(info->pen.x), F(info->pen.y)));
	
	margin_x = info->snap ? SNAPI(info->margin.x) : info->margin.x;
	twin_matrix_translate (&info->matrix,
			       margin_x + info->pen.x,
			       -info->pen.y);
	info->pen_matrix = info->matrix;
    }
    else
    {
	info->snap = TWIN_FALSE;
	info->matrix = path->state.matrix;
	info->matrix.m[2][0] = twin_sfixed_to_fixed (origin.x);
	info->matrix.m[2][1] = twin_sfixed_to_fixed (origin.y);
	info->scale.x = path->state.font_size;
	info->scale.y = path->state.font_size;
	
	if (font->type != TWIN_FONT_TYPE_STROKE) {
	    info->pen.x = info->pen.y = 0;
	    info->margin.x = info->margin.y = 0;
	} else {
	    if (path->state.font_style & TWIN_TEXT_BOLD)
		info->pen.x = path->state.font_size / 16;
	    else
		info->pen.x = path->state.font_size / 24;
	    info->pen.y = info->pen.x;
	    info->margin.x = path->state.font_size / 24;
	    info->margin.y = info->margin.x;
	
	}

	info->pen_matrix = path->state.matrix;
	twin_matrix_translate (&info->matrix,
			       info->margin.x + info->pen.x, -info->pen.y);
    }
    info->pen_matrix.m[2][0] = 0; info->pen_matrix.m[2][1] = 0;
    twin_matrix_scale (&info->pen_matrix, info->pen.x, info->pen.y);
	
    if (path->state.font_style & TWIN_TEXT_OBLIQUE)
    {
	twin_matrix_t	m;
	
	m.m[0][0] = TWIN_FIXED_ONE;	    m.m[0][1] = 0;
	m.m[1][0] = -TWIN_FIXED_ONE / 4;    m.m[1][1] = TWIN_FIXED_ONE;
	m.m[2][0] = 0;			    m.m[2][1] = 0;
	twin_matrix_multiply (&info->matrix, &m, &info->matrix);
    }
    DBGMSG (("%9.4f %9.4f\n", F(info->matrix.m[0][0]), F(info->matrix.m[0][1])));
    DBGMSG (("%9.4f %9.4f\n", F(info->matrix.m[1][0]), F(info->matrix.m[1][1])));
    DBGMSG (("%9.4f %9.4f\n", F(info->matrix.m[2][0]), F(info->matrix.m[2][1])));
}

static void _twin_text_compute_snap (twin_text_info_t   *info,
				     const signed char  *b)
{
    int			s, n;
    const signed char	*snap;

    snap = twin_glyph_snap_x (b);
    n = twin_glyph_n_snap_x (b);
    info->n_snap_x = n;
    for (s = 0; s < n; s++)
	info->snap_x[s] = FX(snap[s], info);

    snap = twin_glyph_snap_y (b);
    n = twin_glyph_n_snap_y (b);
    info->n_snap_y = n;
    for (s = 0; s < n; s++)
	info->snap_y[s] = FY(snap[s], info);
}

static twin_path_t * _twin_text_compute_pen (twin_text_info_t *info)
{
    twin_path_t	*pen = twin_path_create ();

    twin_path_set_matrix (pen, info->pen_matrix);
    twin_path_circle (pen, 0, 0, TWIN_FIXED_ONE);
    return pen;
}

static twin_fixed_t _twin_snap (twin_fixed_t    v,
				twin_fixed_t    *snap,
				int	        n)
{
    int	s;

    for (s = 0; s < n - 1; s++)
    {
	if (snap[s] <= v && v <= snap[s+1])
	{
	    twin_fixed_t    before = snap[s];
	    twin_fixed_t    after = snap[s+1];
	    twin_fixed_t    dist = after - before;
	    twin_fixed_t    snap_before = SNAPI(before);
	    twin_fixed_t    snap_after = SNAPI(after);
	    twin_fixed_t    move_before = snap_before - before;
	    twin_fixed_t    move_after = snap_after - after;
	    twin_fixed_t    dist_before = v - before;
	    twin_fixed_t    dist_after = after - v;
	    twin_fixed_t    move = ((int64_t) dist_before * move_after + 
				    (int64_t) dist_after * move_before) / dist;
	    DBGMSG (("%9.4f <= %9.4f <= %9.4f\n", F(before), F(v), F(after)));
	    DBGMSG (("before: %9.4f -> %9.4f\n", F(before), F(snap_before)));
	    DBGMSG (("after: %9.4f -> %9.4f\n", F(after), F(snap_after)));
	    DBGMSG (("v: %9.4f -> %9.4f\n", F(v), F(v+move)));
	    v += move;
	    break;
	}
    }
    return v;
}

static twin_bool_t twin_find_ucs4_page(twin_font_t *font, uint32_t page)
{
    int i;

    if (font->cur_page && font->cur_page->page == page)
	return TWIN_TRUE;

    for (i = 0; i < font->n_charmap; i++)
	if (font->charmap[i].page == page) {
	    font->cur_page = &font->charmap[i];
	    return TWIN_TRUE;
	}

    font->cur_page = &font->charmap[0];
    return TWIN_FALSE;
}

twin_bool_t twin_has_ucs4 (twin_font_t *font, twin_ucs4_t ucs4)
{
    return twin_find_ucs4_page(font, twin_ucs_page(ucs4));
}

#define SNAPX(p)	_snap (path, p, snap_x, nsnap_x)
#define SNAPY(p)	_snap (path, p, snap_y, nsnap_y)

static const signed char * _twin_g_base (twin_font_t *font, twin_ucs4_t ucs4)
{
    int		idx = twin_ucs_char_in_page(ucs4);

    if (!twin_find_ucs4_page(font, twin_ucs_page(ucs4)))
	idx = 0;

    return font->outlines + font->cur_page->offsets[idx];
}

static twin_fixed_t _twin_glyph_width (twin_text_info_t	 *info,
				       const signed char *b)
{
    twin_fixed_t    right = FX(twin_glyph_right(b), info) + info->pen.x * 2;
    twin_fixed_t    right_side_bearing;
    twin_fixed_t    width;

    if (info->snap)
	right = SNAPI(_twin_snap (right, info->snap_x, info->n_snap_x));
	
    right_side_bearing = right + info->margin.x;
    width = right_side_bearing + info->margin.x;

    DBGMSG(("gw: g_right=%d right=%f, rsb=%f, margin_x=%f, width=%f\n",
	   twin_glyph_right(b), F(right), F(right_side_bearing), F(info->margin.x), F(width)));
    return width;
}

void twin_text_metrics_ucs4 (twin_path_t	    *path, 
			     twin_ucs4_t	    ucs4, 
			     twin_text_metrics_t    *m)
{
    twin_font_t		*font = g_twin_font;
    const signed char	*b = _twin_g_base (font, ucs4);
    twin_text_info_t	info;
    twin_fixed_t	left, right, ascent, descent;
    twin_fixed_t	font_spacing;
    twin_fixed_t	font_descent;
    twin_fixed_t	font_ascent;
    twin_fixed_t	margin_x, margin_y;

    _twin_text_compute_info (path, font, &info);
    if (info.snap)
	_twin_text_compute_snap (&info, b);

    left = FX(twin_glyph_left(b), &info);
    right = FX(twin_glyph_right(b), &info) + info.pen.x * 2;
    ascent = FY(twin_glyph_ascent(b), &info) + info.pen.y * 2;
    descent = FY(twin_glyph_descent(b), &info);
    margin_x = info.margin.x;
    margin_y = info.margin.y;
    
    font_spacing = FY(TWIN_GFIXED_ONE, &info);
    font_descent = font_spacing / 3;
    font_ascent = font_spacing - font_descent;
    if (info.snap)
    {
	left = SNAPI(_twin_snap (left, info.snap_x, info.n_snap_x));
	right = SNAPI(_twin_snap (right, info.snap_x, info.n_snap_x));
	ascent = SNAPI(_twin_snap (ascent, info.snap_y, info.n_snap_y));
	descent = SNAPI(_twin_snap (descent, info.snap_y, info.n_snap_y));
	font_descent = SNAPI(font_descent);
	font_ascent = SNAPI(font_ascent);
	
	left = twin_fixed_mul (left, info.reverse_scale.x);
	right = twin_fixed_mul (right, info.reverse_scale.x);
	ascent = twin_fixed_mul (ascent, info.reverse_scale.y);
	descent = twin_fixed_mul (descent, info.reverse_scale.y);
	font_descent = twin_fixed_mul (font_descent, info.reverse_scale.y);
	font_ascent = twin_fixed_mul (font_ascent, info.reverse_scale.y);
	margin_x = twin_fixed_mul (margin_x, info.reverse_scale.x);
	margin_y = twin_fixed_mul (margin_y, info.reverse_scale.y);
    }
    m->left_side_bearing = left + margin_x;
    m->right_side_bearing = right + margin_x;
    m->ascent = ascent;
    m->descent = descent;
    m->width = m->right_side_bearing + margin_x;
    m->font_ascent = font_ascent + margin_y;
    m->font_descent = font_descent + margin_y;
}

static const signed char *twin_glyph_draw(twin_font_t	    *font,
					  const signed char *b)
{
	if (font->type == TWIN_FONT_TYPE_STROKE)
	    return twin_glyph_snap_y(b) + twin_glyph_n_snap_y(b);
	return b + 4;
}

void twin_path_ucs4 (twin_path_t *path, twin_ucs4_t ucs4)
{
    twin_font_t		*font = g_twin_font;
    const signed char	*b = _twin_g_base (font, ucs4);
    const signed char	*g = twin_glyph_draw(font, b);
    twin_spoint_t	origin;
    twin_fixed_t	x1, y1, x2, y2, x3, y3, _x1, _y1;
    twin_path_t		*stroke;
    twin_path_t		*pen = NULL;
    twin_fixed_t	width;
    twin_text_info_t	info;
    signed char		op;

    _twin_text_compute_info (path, font, &info);
    if (info.snap)
	_twin_text_compute_snap (&info, b);

    origin = _twin_path_current_spoint (path);
    
    stroke = twin_path_create ();
    twin_path_set_matrix (stroke, info.matrix);

    if (font->type == TWIN_FONT_TYPE_STROKE)
	pen = _twin_text_compute_pen (&info);

    x1 = y1 = 0;
    for (;;) {
	switch ((op = *g++)) {
	case 'm':
	    x1 = FX(*g++, &info);
	    y1 = FY(*g++, &info);
	    if (info.snap)
	    {
		x1 = _twin_snap (x1, info.snap_x, info.n_snap_x);
		y1 = _twin_snap (y1, info.snap_y, info.n_snap_y);
	    }
	    DBGMSG (("m %9.4f %9.4f\n",
		    S(_twin_matrix_x (&stroke->state.matrix, x1, y1)),
		    S(_twin_matrix_y (&stroke->state.matrix, x1, y1))));
	    twin_path_move (stroke, x1, y1);
	    continue;
	case 'l':
	    x1 = FX(*g++, &info);
	    y1 = FY(*g++, &info);
	    if (info.snap)
	    {
		x1 = _twin_snap (x1, info.snap_x, info.n_snap_x);
		y1 = _twin_snap (y1, info.snap_y, info.n_snap_y);
	    }
	    DBGMSG (("l %9.4f %9.4f\n",
		    S(_twin_matrix_x (&stroke->state.matrix, x1, y1)),
		    S(_twin_matrix_y (&stroke->state.matrix, x1, y1))));
	    twin_path_draw (stroke, x1, y1);
	    continue;
	case 'c':
	    x3 = FX(*g++, &info);
	    y3 = FY(*g++, &info);
	    x2 = FX(*g++, &info);
	    y2 = FY(*g++, &info);
	    x1 = FX(*g++, &info);
	    y1 = FY(*g++, &info);
	    if (info.snap)
	    {
		x3 = _twin_snap (x3, info.snap_x, info.n_snap_x);
		y3 = _twin_snap (y3, info.snap_y, info.n_snap_y);
		x2 = _twin_snap (x2, info.snap_x, info.n_snap_x);
		y2 = _twin_snap (y2, info.snap_y, info.n_snap_y);
		x1 = _twin_snap (x1, info.snap_x, info.n_snap_x);
		y1 = _twin_snap (y1, info.snap_y, info.n_snap_y);
	    }
	    twin_path_curve (stroke, x3, y3, x2, y2, x1, y1);
	    continue;
	case '2':
	    _x1 = FX(*g++, &info);
	    _y1 = FY(*g++, &info);
	    x3 = x1 + 2 * (_x1 - x1) / 3;
	    y3 = y1 + 2 * (_y1 - y1) / 3;
	    x1 = FX(*g++, &info);
	    y1 = FY(*g++, &info);
	    x2 = x1 + 2 * (_x1 - x1) / 3;
	    y2 = y1 + 2 * (_y1 - y1) / 3;
	    twin_path_curve (stroke, x3, y3, x2, y2, x1, y1);
	    continue;
	case 'e':
	    break;
	default:
	    DBGMSG (("unknown font op 0x%02x '%c'\n", op, op));
	}
	break;
    }

    if (font->type == TWIN_FONT_TYPE_STROKE) {
	twin_path_convolve (path, stroke, pen);
	twin_path_destroy (pen);
    } else
	twin_path_append(path, stroke);
    twin_path_destroy (stroke);
    
    width = _twin_glyph_width (&info, b);
    
    _twin_path_smove (path, 
		      origin.x + _twin_matrix_dx (&info.matrix, width, 0),
		      origin.y + _twin_matrix_dy (&info.matrix, width, 0));
}

twin_fixed_t twin_width_ucs4 (twin_path_t *path, twin_ucs4_t ucs4)
{
    twin_text_metrics_t	metrics;
    
    twin_text_metrics_ucs4 (path, ucs4, &metrics);
    return metrics.width;
}

static int _twin_utf8_to_ucs4 (const char	    *src_orig,
			       twin_ucs4_t	    *dst)
{
    const char	    *src = src_orig;
    char	    s;
    int		    extra;
    twin_ucs4_t	    result;

    s = *src++;
    if (!s)
	return 0;
    
    if (!(s & 0x80))
    {
	result = s;
	extra = 0;
    } 
    else if (!(s & 0x40))
    {
	return -1;
    }
    else if (!(s & 0x20))
    {
	result = s & 0x1f;
	extra = 1;
    }
    else if (!(s & 0x10))
    {
	result = s & 0xf;
	extra = 2;
    }
    else if (!(s & 0x08))
    {
	result = s & 0x07;
	extra = 3;
    }
    else if (!(s & 0x04))
    {
	result = s & 0x03;
	extra = 4;
    }
    else if ( ! (s & 0x02))
    {
	result = s & 0x01;
	extra = 5;
    }
    else
    {
	return -1;
    }
    
    while (extra--)
    {
	result <<= 6;
	s = *src++;
	if (!s)
	    return -1;
	
	if ((s & 0xc0) != 0x80)
	    return -1;
	
	result |= s & 0x3f;
    }
    *dst = result;
    return src - src_orig;
}

void twin_path_utf8 (twin_path_t *path, const char *string)
{
    int		len;
    twin_ucs4_t	ucs4;

    while ((len = _twin_utf8_to_ucs4(string, &ucs4)) > 0)
    {
	twin_path_ucs4 (path, ucs4);
	string += len;
    }
}

twin_fixed_t twin_width_utf8 (twin_path_t *path, const char *string)
{
    int		    len;
    twin_ucs4_t	    ucs4;
    twin_fixed_t    w = 0;

    while ((len = _twin_utf8_to_ucs4(string, &ucs4)) > 0)
    {
	w += twin_width_ucs4 (path, ucs4);
	string += len;
    }
    return w;
}

void twin_text_metrics_utf8 (twin_path_t	 *path, 
			     const char	    	 *string,
			     twin_text_metrics_t *m)
{
    int			len;
    twin_ucs4_t		ucs4;
    twin_fixed_t	w = 0;
    twin_text_metrics_t	c;
    twin_bool_t		first = TWIN_TRUE;

    while ((len = _twin_utf8_to_ucs4(string, &ucs4)) > 0)
    {
	twin_text_metrics_ucs4 (path, ucs4, &c);
	if (first)
	{
	    *m = c;
	    first = TWIN_FALSE;
	}
	else
	{
	    c.left_side_bearing += w;
	    c.right_side_bearing += w;
	    c.width += w;

	    if (c.left_side_bearing < m->left_side_bearing)
		m->left_side_bearing = c.left_side_bearing;
	    if (c.right_side_bearing > m->right_side_bearing)
		m->right_side_bearing = c.right_side_bearing;
	    if (c.width > m->width)
		m->width = c.width;
	    if (c.ascent > m->ascent)
		m->ascent = c.ascent;
	    if (c.descent > m->descent)
		m->descent = c.descent;
	}
	w = c.width;
	string += len;
    }
}