font.c

这是一个开放源代码的与WINNT/WIN2K/WIN2003兼容的操作系统

        const WCHAR *str_on_entry = start_str;
        assert (max >= n);
        max -= n;
        while (n--)
            if (*start_str++ == PREFIX && max--)
                start_str++;
            else;
        start_count -= (start_str - str_on_entry);
    }
    else
    {
        start_str += n;
        start_count -= n;
    }
    *new_str = start_str;
    *new_count = start_count;
}

/*********************************************************************
 *                      TEXT_Reprefix
 *
 *  Reanalyse the text to find the prefixed character.  This is called when
 *  wordbreaking or ellipsification has shortened the string such that the
 *  previously noted prefixed character is no longer visible.
 *
 * Parameters
 *   str        [in] The original string segment (including all characters)
 *   ns         [in] The number of characters in str (including prefixes)
 *   pe         [in] The ellipsification data
 *
 * Return Values
 *   The prefix offset within the new string segment (the one that contains the
 *   ellipses and does not contain the prefix characters) (-1 if none)
 */

static int TEXT_Reprefix (const WCHAR *str, unsigned int ns,
                          const ellipsis_data *pe)
{
    int result = -1;
    unsigned int i = 0;
    unsigned int n = pe->before + pe->under + pe->after;
    assert (n <= ns);
    while (i < n)
    {
        if (i == (unsigned int) pe->before)
        {
            /* Reached the path ellipsis; jump over it */
            if (ns < (unsigned int) pe->under) break;
            str += pe->under;
            ns -= pe->under;
            i += pe->under;
            if (!pe->after) break; /* Nothing after the path ellipsis */
        }
        if (!ns) break;
        ns--;
        if (*str++ == PREFIX)
        {
            if (!ns) break;
            if (*str != PREFIX)
                result = (i < (unsigned int) pe->before || pe->under == 0) ? i : i - pe->under + pe->len;
                /* pe->len may be non-zero while pe_under is zero */
            str++;
            ns--;
        }
        else;
        i++;
    }
    return result;
}

/*********************************************************************
 *  Returns true if and only if the remainder of the line is a single
 *  newline representation or nothing
 */

static int remainder_is_none_or_newline (int num_chars, const WCHAR *str)
{
    if (!num_chars) return TRUE;
    if (*str != LF && *str != CR) return FALSE;
    if (!--num_chars) return TRUE;
    if (*str == *(str+1)) return FALSE;
    str++;
    if (*str != CR && *str != LF) return FALSE;
    if (--num_chars) return FALSE;
    return TRUE;
}

/*********************************************************************
 *  Return next line of text from a string.
 *
 * hdc - handle to DC.
 * str - string to parse into lines.
 * count - length of str.
 * dest - destination in which to return line.
 * len - dest buffer size in chars on input, copied length into dest on output.
 * width - maximum width of line in pixels.
 * format - format type passed to DrawText.
 * retsize - returned size of the line in pixels.
 * last_line - TRUE if is the last line that will be processed
 * p_retstr - If DT_MODIFYSTRING this points to a cursor in the buffer in which
 *            the return string is built.
 * tabwidth - The width of a tab in logical coordinates
 * pprefix_offset - Here is where we return the offset within dest of the first
 *                  prefixed (underlined) character.  -1 is returned if there
 *                  are none.  Note that there may be more; the calling code
 *                  will need to use TEXT_Reprefix to find any later ones.
 * pellip - Here is where we return the information about any ellipsification
 *          that was carried out.  Note that if tabs are being expanded then
 *          this data will correspond to the last text segment actually
 *          returned in dest; by definition there would not have been any
 *          ellipsification in earlier text segments of the line.
 *
 * Returns pointer to next char in str after end of the line
 * or NULL if end of str reached.
 */
static const WCHAR *TEXT_NextLineW( HDC hdc, const WCHAR *str, int *count,
                                 WCHAR *dest, int *len, int width, DWORD format,
                                 SIZE *retsize, int last_line, WCHAR **p_retstr,
                                 int tabwidth, int *pprefix_offset,
                                 ellipsis_data *pellip)
{
    int i = 0, j = 0;
    int plen = 0;
    SIZE size = {0, 0};
    int maxl = *len;
    int seg_i, seg_count, seg_j;
    int max_seg_width;
    int num_fit;
    int word_broken;
    int line_fits;
    unsigned int j_in_seg;
    int ellipsified;
    *pprefix_offset = -1;

    /* For each text segment in the line */

    retsize->cy = 0;
    while (*count)
    {

        /* Skip any leading tabs */

        if (str[i] == TAB && (format & DT_EXPANDTABS))
        {
            plen = ((plen/tabwidth)+1)*tabwidth;
            (*count)--; if (j < maxl) dest[j++] = str[i++]; else i++;
            while (*count && str[i] == TAB)
            {
                plen += tabwidth;
                (*count)--; if (j < maxl) dest[j++] = str[i++]; else i++;
            }
        }


        /* Now copy as far as the next tab or cr/lf or eos */

        seg_i = i;
        seg_count = *count;
        seg_j = j;

        while (*count &&
               (str[i] != TAB || !(format & DT_EXPANDTABS)) &&
               ((str[i] != CR && str[i] != LF) || (format & DT_SINGLELINE)))
        {
	    if (str[i] == PREFIX && !(format & DT_NOPREFIX) && *count > 1)
            {
                (*count)--, i++; /* Throw away the prefix itself */
                if (str[i] == PREFIX)
                {
                    /* Swallow it before we see it again */
		    (*count)--; if (j < maxl) dest[j++] = str[i++]; else i++;
                }
		else if (*pprefix_offset == -1 || *pprefix_offset >= seg_j)
                {
                    *pprefix_offset = j;
                }
                /* else the previous prefix was in an earlier segment of the
                 * line; we will leave it to the drawing code to catch this
                 * one.
                 */
	    }
            else
            {
                (*count)--; if (j < maxl) dest[j++] = str[i++]; else i++;
            }
        }


        /* Measure the whole text segment and possibly WordBreak and
         * ellipsify it
         */

        j_in_seg = j - seg_j;
        max_seg_width = width - plen;
        GetTextExtentExPointW (hdc, dest + seg_j, j_in_seg, max_seg_width, &num_fit, NULL, &size);

        /* The Microsoft handling of various combinations of formats is weird.
         * The following may very easily be incorrect if several formats are
         * combined, and may differ between versions (to say nothing of the
         * several bugs in the Microsoft versions).
         */
        word_broken = 0;
        line_fits = (num_fit >= j_in_seg);
        if (!line_fits && (format & DT_WORDBREAK))
        {
            const WCHAR *s;
            unsigned int chars_used;
            TEXT_WordBreak (hdc, dest+seg_j, maxl-seg_j, &j_in_seg,
                            max_seg_width, format, num_fit, &chars_used, &size);
            line_fits = (size.cx <= max_seg_width);
            /* and correct the counts */
            TEXT_SkipChars (count, &s, seg_count, str+seg_i, i-seg_i,
                            chars_used, !(format & DT_NOPREFIX));
            i = s - str;
            word_broken = 1;
        }
        pellip->before = j_in_seg;
        pellip->under = 0;
        pellip->after = 0;
        pellip->len = 0;
        ellipsified = 0;
        if (!line_fits && (format & DT_PATH_ELLIPSIS))
        {
            TEXT_PathEllipsify (hdc, dest + seg_j, maxl-seg_j, &j_in_seg,
                                max_seg_width, &size, *p_retstr, pellip);
            line_fits = (size.cx <= max_seg_width);
            ellipsified = 1;
        }
        /* NB we may end up ellipsifying a word-broken or path_ellipsified
         * string */
        if ((!line_fits && (format & DT_WORD_ELLIPSIS)) ||
            ((format & DT_END_ELLIPSIS) &&
              ((last_line && *count) ||
               (remainder_is_none_or_newline (*count, &str[i]) && !line_fits))))
        {
            int before, len_ellipsis;
            TEXT_Ellipsify (hdc, dest + seg_j, maxl-seg_j, &j_in_seg,
                            max_seg_width, &size, *p_retstr, &before, &len_ellipsis);
            if (before > pellip->before)
            {
                /* We must have done a path ellipsis too */
                pellip->after = before - pellip->before - pellip->len;
                /* Leave the len as the length of the first ellipsis */
            }
            else
            {
                /* If we are here after a path ellipsification it must be
                 * because even the ellipsis itself didn't fit.
                 */
                assert (pellip->under == 0 && pellip->after == 0);
                pellip->before = before;
                pellip->len = len_ellipsis;
                /* pellip->after remains as zero as does
                 * pellip->under
                 */
            }
            line_fits = (size.cx <= max_seg_width);
            ellipsified = 1;
        }
        /* As an optimisation if we have ellipsified and we are expanding
         * tabs and we haven't reached the end of the line we can skip to it
         * now rather than going around the loop again.
         */
        if ((format & DT_EXPANDTABS) && ellipsified)
        {
            if (format & DT_SINGLELINE)
                *count = 0;
            else
            {
                while ((*count) && str[i] != CR && str[i] != LF)
                {
                    (*count)--, i++;
                }
            }
        }

        j = seg_j + j_in_seg;
        if (*pprefix_offset >= seg_j + pellip->before)
        {
            *pprefix_offset = TEXT_Reprefix (str + seg_i, i - seg_i, pellip);
            if (*pprefix_offset != -1)
                *pprefix_offset += seg_j;
        }

        plen += size.cx;
        if (size.cy > retsize->cy)
            retsize->cy = size.cy;

        if (word_broken)
            break;
        else if (!*count)
            break;
        else if (str[i] == CR || str[i] == LF)
        {
            (*count)--, i++;
            if (*count && (str[i] == CR || str[i] == LF) && str[i] != str[i-1])
            {
                (*count)--, i++;
            }
            break;
        }
        /* else it was a Tab and we go around again */
    }

    retsize->cx = plen;
    *len = j;
    if (*count)
        return (&str[i]);
    else
        return NULL;
}


/***********************************************************************
 *                      TEXT_DrawUnderscore
 *
 *  Draw the underline under the prefixed character
 *
 * Parameters
 *   hdc        [in] The handle of the DC for drawing
 *   x          [in] The x location of the line segment (logical coordinates)
 *   y          [in] The y location of where the underscore should appear
 *                   (logical coordinates)
 *   str        [in] The text of the line segment
 *   offset     [in] The offset of the underscored character within str
 *   rect       [in] Clipping rectangle (if not NULL)
 */
/* WINE synced 22-May-2006 */