source: mainline/uspace/lib/gfxfont/src/text.c@ a0aeb8f

/*
 * Copyright (c) 2021 Jiri Svoboda
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup libgfxfont
 * @{
 */
/**
 * @file Text rendering
 */

#include <errno.h>
#include <gfx/bitmap.h>
#include <gfx/color.h>
#include <gfx/font.h>
#include <gfx/glyph.h>
#include <gfx/render.h>
#include <gfx/text.h>
#include <io/pixelmap.h>
#include <mem.h>
#include <str.h>
#include "../private/font.h"
#include "../private/typeface.h"

/** Initialize text formatting structure.
 *
 * Text formatting structure must always be initialized using this function
 * first.
 *
 * @param fmt Text formatting structure
 */
void gfx_text_fmt_init(gfx_text_fmt_t *fmt)
{
        memset(fmt, 0, sizeof(gfx_text_fmt_t));
}

/** Compute text width.
 *
 * @param font Font
 * @param str String
 * @return Text width
 */
gfx_coord_t gfx_text_width(gfx_font_t *font, const char *str)
{
        gfx_glyph_metrics_t gmetrics;
        size_t stradv;
        const char *cp;
        gfx_glyph_t *glyph;
        gfx_coord_t width;
        errno_t rc;

        if ((font->finfo->props.flags & gff_text_mode) != 0)
                return str_width(str);

        width = 0;
        cp = str;
        while (*cp != '\0') {
                rc = gfx_font_search_glyph(font, cp, &glyph, &stradv);
                if (rc != EOK) {
                        ++cp;
                        continue;
                }

                gfx_glyph_get_metrics(glyph, &gmetrics);

                cp += stradv;
                width += gmetrics.advance;
        }

        return width;
}

/** Print string using text characters in text mode.
 *
 * @param font Font
 * @param pos Position of top-left corner of text
 * @param color Text color
 * @param str String
 * @return EOK on success or an error code
 */
static errno_t gfx_puttext_textmode(gfx_font_t *font, gfx_coord2_t *pos,
    gfx_color_t *color, const char *str)
{
        gfx_context_t *gc = font->typeface->gc;
        gfx_bitmap_params_t params;
        gfx_bitmap_t *bitmap;
        gfx_bitmap_alloc_t alloc;
        uint8_t attr;
        pixelmap_t pmap;
        gfx_coord_t x;
        pixel_t pixel;
        char32_t c;
        size_t off;
        errno_t rc;

        /*
         * NOTE: Creating and destroying bitmap each time is not probably
         * the most efficient way.
         */

        gfx_color_get_ega(color, &attr);

        gfx_bitmap_params_init(&params);
        params.rect.p0.x = 0;
        params.rect.p0.y = 0;
        params.rect.p1.x = str_width(str);
        params.rect.p1.y = 1;

        if (params.rect.p1.x == 0) {
                /* Nothing to do. Avoid creating bitmap of zero width. */
                return EOK;
        }

        rc = gfx_bitmap_create(gc, &params, NULL, &bitmap);
        if (rc != EOK)
                return rc;

        rc = gfx_bitmap_get_alloc(bitmap, &alloc);
        if (rc != EOK) {
                gfx_bitmap_destroy(bitmap);
                return rc;
        }

        pmap.width = params.rect.p1.x;
        pmap.height = 1;
        pmap.data = alloc.pixels;

        off = 0;
        for (x = 0; x < params.rect.p1.x; x++) {
                c = str_decode(str, &off, STR_NO_LIMIT);
                pixel = PIXEL(attr,
                    (c >> 16) & 0xff,
                    (c >> 8) & 0xff,
                    c & 0xff);
                pixelmap_put_pixel(&pmap, x, 0, pixel);
        }

        rc = gfx_bitmap_render(bitmap, NULL, pos);

        gfx_bitmap_destroy(bitmap);
        return rc;
}

/** Get text starting position.
 *
 * @param font Font
 * @param pos Anchor position
 * @param fmt Text formatting
 * @param str String
 * @param spos Place to store starting position
 */
void gfx_text_start_pos(gfx_font_t *font, gfx_coord2_t *pos,
    gfx_text_fmt_t *fmt, const char *str, gfx_coord2_t *spos)
{
        gfx_font_metrics_t fmetrics;
        gfx_coord_t width;

        *spos = *pos;

        /* Adjust position for horizontal alignment */
        if (fmt->halign != gfx_halign_left) {
                width = gfx_text_width(font, str);
                switch (fmt->halign) {
                case gfx_halign_center:
                        spos->x -= width / 2;
                        break;
                case gfx_halign_right:
                        spos->x -= width;
                        break;
                default:
                        break;
                }
        }

        /* Adjust position for vertical alignment */
        gfx_font_get_metrics(font, &fmetrics);

        if (fmt->valign != gfx_valign_baseline) {
                switch (fmt->valign) {
                case gfx_valign_top:
                        spos->y += fmetrics.ascent;
                        break;
                case gfx_valign_center:
                        spos->y += fmetrics.ascent / 2;
                        break;
                case gfx_valign_bottom:
                        spos->y -= fmetrics.descent + 1;
                        break;
                default:
                        break;
                }
        }
}

/** Render text.
 *
 * @param font Font
 * @param pos Anchor position
 * @param fmt Text formatting
 * @param str String
 * @return EOK on success or an error code
 */
errno_t gfx_puttext(gfx_font_t *font, gfx_coord2_t *pos,
    gfx_text_fmt_t *fmt, const char *str)
{
        gfx_glyph_metrics_t gmetrics;
        size_t stradv;
        const char *cp;
        gfx_glyph_t *glyph;
        gfx_coord2_t cpos;
        errno_t rc;

        gfx_text_start_pos(font, pos, fmt, str, &cpos);

        /* Text mode */
        if ((font->finfo->props.flags & gff_text_mode) != 0)
                return gfx_puttext_textmode(font, &cpos, fmt->color, str);

        rc = gfx_set_color(font->typeface->gc, fmt->color);
        if (rc != EOK)
                return rc;

        cp = str;
        while (*cp != '\0') {
                rc = gfx_font_search_glyph(font, cp, &glyph, &stradv);
                if (rc != EOK) {
                        ++cp;
                        continue;
                }

                gfx_glyph_get_metrics(glyph, &gmetrics);

                rc = gfx_glyph_render(glyph, &cpos);
                if (rc != EOK)
                        return rc;

                cp += stradv;
                cpos.x += gmetrics.advance;
        }

        return EOK;
}

/** Find character position in string by X coordinate.
 *
 * @param font Font
 * @param pos Anchor position
 * @param fmt Text formatting
 * @param str String
 * @param fpos Position for which we need to find offset
 *
 * @return Byte offset in @a str of character corresponding to position
 *         @a fpos. Note that the position is rounded, that is,
 *         if it is before the center of character A, it will return
 *         offset of A, if it is after the center of A, it will return
 *         offset of the following character.
 */
size_t gfx_text_find_pos(gfx_font_t *font, gfx_coord2_t *pos,
    gfx_text_fmt_t *fmt, const char *str, gfx_coord2_t *fpos)
{
        gfx_glyph_metrics_t gmetrics;
        size_t stradv;
        const char *cp;
        gfx_glyph_t *glyph;
        gfx_coord2_t cpos;
        size_t off;
        size_t strsize;
        errno_t rc;

        gfx_text_start_pos(font, pos, fmt, str, &cpos);

        /* Text mode */
        if ((font->finfo->props.flags & gff_text_mode) != 0) {
                off = 0;
                strsize = str_size(str);
                while (off < strsize) {
                        if (fpos->x <= cpos.x)
                                return off;
                        (void) str_decode(str, &off, strsize);
                        cpos.x++;
                }

                return off;
        }

        cp = str;
        off = 0;
        while (*cp != '\0') {
                rc = gfx_font_search_glyph(font, cp, &glyph, &stradv);
                if (rc != EOK) {
                        ++cp;
                        continue;
                }

                gfx_glyph_get_metrics(glyph, &gmetrics);

                if (fpos->x < cpos.x + gmetrics.advance / 2)
                        return off;

                cp += stradv;
                off += stradv;
                cpos.x += gmetrics.advance;
        }

        return off;
}

/** Get text continuation parameters.
 *
 * Return the anchor position and format needed to continue printing
 * text after the specified string. It is allowed for the sources
 * (@a pos, @a fmt) and destinations (@a cpos, @a cfmt) to point
 * to the same objects, respectively.
 *
 * @param font Font
 * @param pos Anchor position
 * @param fmt Text formatting
 * @param str String
 * @param cpos Place to store anchor position for continuation
 * @param cfmt Place to store format for continuation
 */
void gfx_text_cont(gfx_font_t *font, gfx_coord2_t *pos,
    gfx_text_fmt_t *fmt, const char *str, gfx_coord2_t *cpos,
    gfx_text_fmt_t *cfmt)
{
        gfx_coord2_t spos;
        gfx_text_fmt_t tfmt;

        /* Continuation should start where the current string ends */
        gfx_text_start_pos(font, pos, fmt, str, &spos);
        cpos->x = spos.x + gfx_text_width(font, str);
        cpos->y = spos.y;

        /*
         * Formatting is the same, except the text should be aligned
         * so that it starts at the anchor point.
         */
        tfmt = *fmt;
        tfmt.halign = gfx_halign_left;
        tfmt.valign = gfx_valign_baseline;

        *cfmt = tfmt;
}

/** Get text bounding rectangle.
 *
 * @param font Font
 * @param pos Anchor position
 * @param fmt Text formatting
 * @param str String
 * @param rect Place to store bounding rectangle
 */
void gfx_text_rect(gfx_font_t *font, gfx_coord2_t *pos,
    gfx_text_fmt_t *fmt, const char *str, gfx_rect_t *rect)
{
        gfx_coord2_t spos;

        gfx_text_start_pos(font, pos, fmt, str, &spos);

        rect->p0.x = spos.x;
        rect->p0.y = spos.y - font->metrics.ascent;
        rect->p1.x = spos.x + gfx_text_width(font, str);
        rect->p1.y = spos.y + font->metrics.descent + 1;
}

/** @}
 */