font_internal.c

Go to the documentation of this file.

/*
 * Copyright 2005 James Bursa <bursa@users.sourceforge.net>
 *           2008 Vincent Sanders <vince@simtec.co.uk>
 *
 * This file is part of NetSurf, http://www.netsurf-browser.org/
 *
 * NetSurf 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; version 2 of the License.
 *
 * NetSurf 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include <inttypes.h>
#include <string.h>
#include <assert.h>
#include <stdlib.h>
 
#include "utils/nsoption.h"
#include "utils/utils.h"
#include "utils/utf8.h"
#include "netsurf/utf8.h"
#include "netsurf/layout.h"
#include "netsurf/plot_style.h"
 
#include "framebuffer/gui.h"
#include "framebuffer/font.h"
 
#include <font-ns-sans.h>
 
#define GLYPH_LEN               16
 
uint8_t code_point[GLYPH_LEN];
uint8_t glyph_x2[GLYPH_LEN * 4];
 
#define SEVEN_SET       ((1 << 0) | (1 << 1) | (1 << 2) | (1 << 3) |    \
                         (1 << 4) | (1 << 5) | (1 << 6))
 
#define THREE_SSS        ((1 << 0) | (1 << 1) | (1 << 2))
#define THREE_S_S        ((1 << 0) |            (1 << 2))
#define THREE__SS        ((1 << 0) | (1 << 1)           )
#define THREE_SS_        (           (1 << 1) | (1 << 2))
#define THREE_S__                               (1 << 2)
#define THREE__S_                    (1 << 1)
#define THREE___S         (1 << 0)
 
uint8_t frag[16][5] = {
        { THREE_SSS,
          THREE_S_S,
          THREE_S_S,
          THREE_S_S,
          THREE_SSS },
 
        { THREE__S_,
          THREE_SS_,
          THREE__S_,
          THREE__S_,
          THREE_SSS },
 
        { THREE_SS_,
          THREE___S,
          THREE__S_,
          THREE_S__,
          THREE_SSS },
 
        { THREE_SS_,
          THREE___S,
          THREE_SS_,
          THREE___S,
          THREE_SS_ },
 
        { THREE_S_S,
          THREE_S_S,
          THREE_SSS,
          THREE___S,
          THREE___S },
 
        { THREE_SSS,
          THREE_S__,
          THREE_SSS,
          THREE___S,
          THREE_SSS },
 
        { THREE__SS,
          THREE_S__,
          THREE_SSS,
          THREE_S_S,
          THREE_SSS },
 
        { THREE_SSS,
          THREE___S,
          THREE__S_,
          THREE__S_,
          THREE__S_ },
 
        { THREE_SSS,
          THREE_S_S,
          THREE_SSS,
          THREE_S_S,
          THREE_SSS },
 
        { THREE_SSS,
          THREE_S_S,
          THREE_SSS,
          THREE___S,
          THREE___S },
 
        { THREE__S_,
          THREE_S_S,
          THREE_SSS,
          THREE_S_S,
          THREE_S_S },
 
        { THREE_SS_,
          THREE_S_S,
          THREE_SS_,
          THREE_S_S,
          THREE_SS_ },
 
        { THREE__S_,
          THREE_S_S,
          THREE_S__,
          THREE_S_S,
          THREE__S_ },
 
        { THREE_SS_,
          THREE_S_S,
          THREE_S_S,
          THREE_S_S,
          THREE_SS_ },
 
        { THREE_SSS,
          THREE_S__,
          THREE_SS_,
          THREE_S__,
          THREE_SSS },
 
        { THREE_SSS,
          THREE_S__,
          THREE_SS_,
          THREE_S__,
          THREE_S__ }
};
 
static uint8_t * get_codepoint(uint32_t id, bool italic)
{
        int shift = 0;
        int l;
        int r;
 
        if (!italic)
                shift = 1;
 
        l =       (id >> 12);
        r = 0xf & (id >>  8);
 
        code_point[ 0] = SEVEN_SET << shift;
 
        code_point[ 2] = (frag[l][0] << (4 + shift)) | (frag[r][0] << shift);
        code_point[ 3] = (frag[l][1] << (4 + shift)) | (frag[r][1] << shift);
        code_point[ 4] = (frag[l][2] << (4 + shift)) | (frag[r][2] << shift);
        code_point[ 5] = (frag[l][3] << (4 + shift)) | (frag[r][3] << shift);
        code_point[ 6] = (frag[l][4] << (4 + shift)) | (frag[r][4] << shift);
 
        shift = 1;
 
        l = 0xf & (id >>  4);
        r = 0xf & id;
 
        code_point[ 8] = (frag[l][0] << (4 + shift)) | (frag[r][0] << shift);
        code_point[ 9] = (frag[l][1] << (4 + shift)) | (frag[r][1] << shift);
        code_point[10] = (frag[l][2] << (4 + shift)) | (frag[r][2] << shift);
        code_point[11] = (frag[l][3] << (4 + shift)) | (frag[r][3] << shift);
        code_point[12] = (frag[l][4] << (4 + shift)) | (frag[r][4] << shift);
 
        code_point[14] = SEVEN_SET << shift;
 
        return (uint8_t *)code_point;
}
 
 
bool fb_font_init(void)
{
        return true;
}
 
bool fb_font_finalise(void)
{
        return true;
}
 
enum fb_font_style
fb_get_font_style(const plot_font_style_t *fstyle)
{
        enum fb_font_style style = FB_REGULAR;
 
        if (fstyle->weight >= 700)
                style |= FB_BOLD;
        if ((fstyle->flags & FONTF_ITALIC) || (fstyle->flags & FONTF_OBLIQUE))
                style |= FB_ITALIC;
 
        return style;
}
 
int
fb_get_font_size(const plot_font_style_t *fstyle)
{
        int size = fstyle->size * 10 /
                        (((nsoption_int(font_min_size) * 3 +
                           nsoption_int(font_size)) / 4) * PLOT_STYLE_SCALE);
        if (size > 2)
                size = 2;
        else if (size <= 0)
                size = 1;
 
        return size;
}
 
/** Lookup table to scale 4 bits to 8 bits, so e.g. 0101 --> 00110011 */
const uint8_t glyph_lut[16] = {
                0x00, 0x03, 0x0c, 0x0f,
                0x30, 0x33, 0x3c, 0x3f,
                0xc0, 0xc3, 0xcc, 0xcf,
                0xf0, 0xf3, 0xfc, 0xff
};
 
static const uint8_t *
glyph_scale_2(const uint8_t *glyph_data)
{
        const uint8_t *glyph_max = glyph_data + GLYPH_LEN;
        uint8_t *pos = glyph_x2;
 
        do {
                *pos++ = glyph_lut[*glyph_data >> 4];
                *pos++ = glyph_lut[*glyph_data & 0xf];
                *pos++ = glyph_lut[*glyph_data >> 4];
                *pos++ = glyph_lut[*glyph_data & 0xf];
        } while (++glyph_data < glyph_max);
 
        return glyph_x2;
}
 
const uint8_t *
fb_get_glyph(uint32_t ucs4, enum fb_font_style style, int scale)
{
        const uint8_t *glyph_data;
        unsigned int section;
        unsigned int offset;
        uint16_t g_offset;
 
        /* Internal font has no glyphs beyond U+FFFF and there isn't
         * space to render a >4 digit codepoint; just show replacement
         * character. */
        if (ucs4 > 0xffff)
                ucs4 = 0xfffd;
 
        switch (style) {
        case FB_BOLD_ITALIC:
                section = fb_bold_italic_section_table[ucs4 / 256];
                if (section != 0 || ucs4 / 256 == 0) {
                        offset = section * 256 + (ucs4 & 0xff);
                        g_offset = fb_bold_italic_sections[offset] * 16;
                        if (g_offset != 0) {
                                glyph_data = &font_glyph_data[g_offset];
                                break;
                        }
                }
                fallthrough;
 
        case FB_BOLD:
                section = fb_bold_section_table[ucs4 / 256];
                if (section != 0 || ucs4 / 256 == 0) {
                        offset = section * 256 + (ucs4 & 0xff);
                        g_offset = fb_bold_sections[offset] * 16;
                        if (g_offset != 0) {
                                glyph_data = &font_glyph_data[g_offset];
                                break;
                        }
                }
                fallthrough;
 
        case FB_ITALIC:
                section = fb_italic_section_table[ucs4 / 256];
                if (section != 0 || ucs4 / 256 == 0) {
                        offset = section * 256 + (ucs4 & 0xff);
                        g_offset = fb_italic_sections[offset] * 16;
                        if (g_offset != 0) {
                                glyph_data = &font_glyph_data[g_offset];
                                break;
                        }
                }
                fallthrough;
 
        case FB_REGULAR:
                section = fb_regular_section_table[ucs4 / 256];
                if (section != 0 || ucs4 / 256 == 0) {
                        offset = section * 256 + (ucs4 & 0xff);
                        g_offset = fb_regular_sections[offset] * 16;
                        if (g_offset != 0) {
                                glyph_data = &font_glyph_data[g_offset];
                                break;
                        }
                }
                fallthrough;
 
        default:
                glyph_data = get_codepoint(ucs4, style & FB_ITALIC);
                break;
        }
 
        switch (scale) {
        case 1:
                break;
        case 2:
                glyph_data = glyph_scale_2(glyph_data);
                break;
        default:
                assert(scale >= 1 && scale <= 2);
                break;
        }
 
        return glyph_data;
}
 
static nserror utf8_to_local(const char *string,
                                       size_t len,
                                       char **result)
{
        return utf8_to_enc(string, "CP1252", len, result);
 
}
 
static nserror utf8_from_local(const char *string,
                                        size_t len,
                                        char **result)
{
        *result = malloc(len + 1);
        if (*result == NULL) {
                return NSERROR_NOMEM;
        }
 
        memcpy(*result, string, len);
 
        (*result)[len] = '\0';
 
        return NSERROR_OK;
}
 
 
/* exported interface documented in framebuffer/freetype_font.h */
nserror
fb_font_width(const plot_font_style_t *fstyle,
              const char *string,
              size_t length,
              int *width)
{
        size_t nxtchr = 0;
 
        *width = 0;
        while (nxtchr < length) {
                uint32_t ucs4;
                ucs4 = utf8_to_ucs4(string + nxtchr, length - nxtchr);
                if (codepoint_displayable(ucs4)) {
                        *width += FB_FONT_WIDTH;
                }
 
                nxtchr = utf8_next(string, length, nxtchr);
        }
 
        *width *= fb_get_font_size(fstyle);
        return NSERROR_OK;
}
 
 
/* exported interface documented in framebuffer/freetype_font.h */
nserror
fb_font_position(const plot_font_style_t *fstyle,
                 const char *string,
                 size_t length,
                 int x,
                 size_t *char_offset,
                 int *actual_x)
{
        const int width = fb_get_font_size(fstyle) * FB_FONT_WIDTH;
        size_t nxtchr = 0;
        int x_pos = 0;
 
        while (nxtchr < length) {
                uint32_t ucs4;
                if (abs(x_pos - x) <= (width / 2))
                        break;
 
                ucs4 = utf8_to_ucs4(string + nxtchr, length - nxtchr);
                if (codepoint_displayable(ucs4)) {
                        x_pos += width;
                }
 
                nxtchr = utf8_next(string, length, nxtchr);
        }
 
        *actual_x = x_pos;
 
        *char_offset = nxtchr;
        return NSERROR_OK;
}
 
 
/**
 * Find where to split a string to make it fit a width.
 *
 * \param  fstyle       style for this text
 * \param  string       UTF-8 string to measure
 * \param  length       length of string, in bytes
 * \param  x            width available
 * \param  char_offset  updated to offset in string of actual_x, [1..length]
 * \param  actual_x     updated to x coordinate of character closest to x
 * \return  true on success, false on error and error reported
 *
 * On exit, char_offset indicates first character after split point.
 *
 * Note: char_offset of 0 should never be returned.
 *
 *   Returns:
 *     char_offset giving split point closest to x, where actual_x <= x
 *   else
 *     char_offset giving split point closest to x, where actual_x > x
 *
 * Returning char_offset == length means no split possible
 */
static nserror
fb_font_split(const plot_font_style_t *fstyle,
              const char *string,
              size_t length,
              int x,
              size_t *char_offset,
              int *actual_x)
{
        const int width = fb_get_font_size(fstyle) * FB_FONT_WIDTH;
        size_t nxtchr = 0;
        int last_space_x = 0;
        int last_space_idx = 0;
 
        *actual_x = 0;
        while (nxtchr < length) {
                uint32_t ucs4;
 
                if (string[nxtchr] == ' ') {
                        last_space_x = *actual_x;
                        last_space_idx = nxtchr;
                }
 
                ucs4 = utf8_to_ucs4(string + nxtchr, length - nxtchr);
                if (codepoint_displayable(ucs4)) {
                        *actual_x += width;
                }
 
                if (*actual_x > x && last_space_idx != 0) {
                        /* string has exceeded available width and we've
                         * found a space; return previous space */
                        *actual_x = last_space_x;
                        *char_offset = last_space_idx;
                        return NSERROR_OK;
                }
 
                nxtchr = utf8_next(string, length, nxtchr);
        }
 
        *char_offset = nxtchr;
 
        return NSERROR_OK;
}
 
 
static struct gui_layout_table layout_table = {
        .width = fb_font_width,
        .position = fb_font_position,
        .split = fb_font_split,
};
 
struct gui_layout_table *framebuffer_layout_table = &layout_table;
 
 
static struct gui_utf8_table utf8_table = {
        .utf8_to_local = utf8_to_local,
        .local_to_utf8 = utf8_from_local,
};
 
struct gui_utf8_table *framebuffer_utf8_table = &utf8_table;
 
 
/*
 * Local Variables:
 * c-basic-offset:8
 * End:
 */