font.c

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/*
 * Copyright 2009 - 2014 Vincent Sanders <vince@netsurf-browser.org>
 * Copyright 2009 - 2013 Michael Drake <tlsa@netsurf-browser.org>
 *
 * 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/>.
 */
 
/**
 * \file
 * Windows font handling and character encoding implementation.
 */
 
#include "utils/config.h"
#include <assert.h>
#include <windows.h>
 
#include "netsurf/inttypes.h"
#include "utils/log.h"
#include "utils/nsoption.h"
#include "utils/utf8.h"
#include "netsurf/layout.h"
#include "netsurf/utf8.h"
#include "netsurf/plot_style.h"
 
#include "windows/font.h"
 
HWND font_hwnd;
 
/* exported interface documented in windows/font.h */
nserror
utf8_to_font_encoding(const struct font_desc* font,
                      const char *string,
                      size_t len,
                      char **result)
{
        return utf8_to_enc(string, font->encoding, len, result);
}
 
 
/**
 * Convert a string to UCS2 from UTF8
 *
 * \param[in] string source string
 * \param[in] len source string length
 * \param[out] result The UCS2 string
 */
static nserror
utf8_to_local_encoding(const char *string, size_t len, char **result)
{
        return utf8_to_enc(string, "UCS-2", len, result);
}
 
 
/**
 * Convert a string to UTF8 from local encoding
 *
 * \param[in] string source string
 * \param[in] len source string length
 * \param[out] result The UTF8 string
 */
static nserror
utf8_from_local_encoding(const char *string, size_t len, char **result)
{
        assert(string && result);
 
        if (len == 0) {
                len = strlen(string);
        }
 
        *result = strndup(string, len);
        if (!(*result)) {
                return NSERROR_NOMEM;
        }
 
        return NSERROR_OK;
}
 
 
/* exported interface documented in windows/font.h */
HFONT get_font(const plot_font_style_t *style)
{
        char *face = NULL;
        DWORD family;
        int nHeight;
        HDC hdc;
        HFONT font;
 
        switch(style->family) {
        case PLOT_FONT_FAMILY_SERIF:
                face = strdup(nsoption_charp(font_serif));
                family = FF_ROMAN | DEFAULT_PITCH;
                break;
 
        case PLOT_FONT_FAMILY_MONOSPACE:
                face = strdup(nsoption_charp(font_mono));
                family = FF_MODERN | DEFAULT_PITCH;
                break;
 
        case PLOT_FONT_FAMILY_CURSIVE:
                face = strdup(nsoption_charp(font_cursive));
                family = FF_SCRIPT | DEFAULT_PITCH;
                break;
 
        case PLOT_FONT_FAMILY_FANTASY:
                face = strdup(nsoption_charp(font_fantasy));
                family = FF_DECORATIVE | DEFAULT_PITCH;
                break;
 
        case PLOT_FONT_FAMILY_SANS_SERIF:
        default:
                face = strdup(nsoption_charp(font_sans));
                family = FF_SWISS | DEFAULT_PITCH;
                break;
        }
 
        nHeight = -10;
 
        hdc = GetDC(font_hwnd);
        nHeight = -MulDiv(style->size, GetDeviceCaps(hdc, LOGPIXELSY), 72 * PLOT_STYLE_SCALE);
        ReleaseDC(font_hwnd, hdc);
 
        font = CreateFont(nHeight, /* height */
                          0, /* width */
                          0, /* escapement*/
                          0, /* orientation */
                          style->weight,
                          (style->flags & FONTF_ITALIC) ? TRUE : FALSE,
                          FALSE, /* underline */
                          FALSE, /* strike */
                          DEFAULT_CHARSET, /* for locale */
                          OUT_DEFAULT_PRECIS, /* general 'best match' */
                          CLIP_DEFAULT_PRECIS,
                          DEFAULT_QUALITY,
                          family,
                          face); /* name of font face */
 
        if (face != NULL) {
                free(face);
        }
 
        if (font == NULL) {
                if (style->family == PLOT_FONT_FAMILY_MONOSPACE) {
                        font = (HFONT) GetStockObject(ANSI_FIXED_FONT);
                } else {
                        font = (HFONT) GetStockObject(ANSI_VAR_FONT);
                }
        }
 
        if (font == NULL) {
                font = (HFONT) GetStockObject(SYSTEM_FONT);
        }
 
        return font;
}
 
/* size of temporary wide character string for computing string width */
#define WSTRLEN 4096
 
 
/**
 * Measure the width of a string.
 *
 * \param[in] style plot style for this text
 * \param[in] utf8str string encoded in UTF-8 to measure
 * \param[in] utf8len length of string, in bytes
 * \param[out] width updated to width of string[0..length)
 * \return NSERROR_OK on success otherwise appropriate error code
 */
static nserror
win32_font_width(const plot_font_style_t *style,
                 const char *utf8str,
                 size_t utf8len,
                 int *width)
{
        nserror ret = NSERROR_OK;
        HDC hdc;
        HFONT font;
        HFONT fontbak;
        SIZE sizl; /* size in logical units */
        BOOL wres;
        int wclen; /* wide char length */
        static WCHAR wstr[WSTRLEN]; /* temporary wide char string */
 
        if (utf8len == 0) {
                *width = 0;
                return ret;
        }
 
        hdc = GetDC(NULL);
        font = get_font(style);
        fontbak = SelectObject(hdc, font);
 
        wclen = MultiByteToWideChar(CP_UTF8, 0, utf8str, utf8len, wstr, WSTRLEN);
        if (wclen != 0) {
                wres = GetTextExtentPoint32W(hdc, wstr, wclen, &sizl);
                if (wres == FALSE) {
                        ret = NSERROR_INVALID;
                } else {
                        *width = sizl.cx;
                }
        } else {
                ret = NSERROR_NOSPACE;
        }
 
        font = SelectObject(hdc, fontbak);
        DeleteObject(font);
        ReleaseDC(NULL, hdc);
 
        return ret;
}
 
 
/**
 * Find the position in a string where an x coordinate falls.
 *
 * \param  style css_style for this text, with style->font_size.size ==
 *                      CSS_FONT_SIZE_LENGTH
 * \param  utf8str string to measure encoded in UTF-8
 * \param  utf8len length of string
 * \param  x coordinate to search for
 * \param  char_offset updated to offset in string of actual_x, [0..length]
 * \param  actual_x updated to x coordinate of character closest to x
 * \return NSERROR_OK on success otherwise appropriate error code
 */
static nserror
win32_font_position(const plot_font_style_t *style,
                    const char *utf8str,
                    size_t utf8len,
                    int x,
                    size_t *char_offset,
                    int *actual_x)
{
        HDC hdc;
        HFONT font;
        HFONT fontbak;
        SIZE s;
        int offset;
        nserror ret = NSERROR_OK;
 
        /* deal with zero length input or invalid search co-ordiate */
        if ((utf8len == 0) || (x < 1)) {
                *char_offset = 0;
                *actual_x = 0;
                return ret;
        }
 
        hdc = GetDC(NULL);
        font = get_font(style);
        fontbak = SelectObject(hdc, font);
 
        if ((GetTextExtentExPointA(hdc, utf8str, utf8len, x, &offset, NULL, &s) != 0) &&
            (GetTextExtentPoint32A(hdc, utf8str, offset, &s) != 0)) {
                *char_offset = (size_t)offset;
                *actual_x = s.cx;
        } else {
                ret = NSERROR_UNKNOWN;
        }
 
        font = SelectObject(hdc, fontbak);
        DeleteObject(font);
        ReleaseDC(NULL, hdc);
 
        return ret;
}
 
 
/**
 * Find where to split a string to make it fit a width.
 *
 * \param  style        css_style for this text, with style->font_size.size ==
 *                      CSS_FONT_SIZE_LENGTH
 * \param  string       UTF-8 string to measure
 * \param  length       length of string
 * \param  x            width available
 * \param[out] offset updated to offset in string of actual_x, [0..length]
 * \param  actual_x     updated to x coordinate of character closest to x
 * \return NSERROR_OK on success otherwise appropriate error code
 *
 * On exit, [char_offset == 0 ||
 *         string[char_offset] == ' ' ||
 *         char_offset == length]
 */
static nserror
win32_font_split(const plot_font_style_t *style,
                 const char *string,
                 size_t length,
                 int x,
                 size_t *offset,
                 int *actual_x)
{
        nserror res;
        int c_off;
 
        /* get the offset into teh string on the proposed position */
        res = win32_font_position(style, string, length, x, offset, actual_x);
        if (res != NSERROR_OK) {
                return res;
        }
 
        /* return the whole string fits in the proposed length */
        if (*offset == length) {
                return NSERROR_OK;
        }
 
        c_off = *offset;
 
        /* walk backwards through string looking for space to break on */
        while ((string[*offset] != ' ') &&
               (*offset > 0)) {
                (*offset)--;
        }
 
        /* walk forwards through string looking for space if back failed */
        if (*offset == 0) {
                *offset = c_off;
                while ((*offset < length) &&
                       (string[*offset] != ' ')) {
                        (*offset)++;
                }
        }
 
        /* find the actual string width of the break */
        res = win32_font_width(style, string, *offset, actual_x);
 
        NSLOG(netsurf, DEEPDEBUG,
              "ret %d Split %u chars at %ipx: Split at char %i (%ipx) - %.*s",
              res, length, x, *offset, *actual_x, *offset, string);
 
        return res;
}
 
 
/** win32 font operations table */
static struct gui_layout_table layout_table = {
        .width = win32_font_width,
        .position = win32_font_position,
        .split = win32_font_split,
};
 
struct gui_layout_table *win32_layout_table = &layout_table;
 
/** win32 utf8 encoding operations table */
static struct gui_utf8_table utf8_table = {
        .utf8_to_local = utf8_to_local_encoding,
        .local_to_utf8 = utf8_from_local_encoding,
};
 
struct gui_utf8_table *win32_utf8_table = &utf8_table;