source: mainline/uspace/lib/ui/src/paint.c@ 35cffea

/*
 * Copyright (c) 2022 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 libui
 * @{
 */
/**
 * @file Painting routines
 */

#include <errno.h>
#include <gfx/color.h>
#include <gfx/context.h>
#include <gfx/render.h>
#include <gfx/text.h>
#include <ui/accel.h>
#include <ui/paint.h>
#include <stdlib.h>
#include <str.h>
#include "../private/resource.h"

/** Single box characters */
static ui_box_chars_t single_box_chars = {
        {
                { "\u250c", "\u2500", "\u2510" },
                { "\u2502", " ",      "\u2502" },
                { "\u2514", "\u2500", "\u2518" }
        }
};

/** Double box characters */
static ui_box_chars_t double_box_chars = {
        {
                { "\u2554", "\u2550", "\u2557" },
                { "\u2551", " ",      "\u2551" },
                { "\u255a", "\u2550", "\u255d" }
        }
};

/** Single horizontal brace characters */
static ui_brace_chars_t single_hbrace_chars = {
        .start = "\u251c",
        .middle = "\u2500",
        .end = "\u2524"
};

/** Double horizontal brace characters */
static ui_brace_chars_t double_hbrace_chars = {
        .start = "\u2560",
        .middle = "\u2550",
        .end = "\u2563"
};

/** Paint bevel.
 *
 * @param gc Graphic context
 * @param rect Rectangle to paint into
 * @param tlcolor Top-left color
 * @param brcolor Bottom-right color
 * @param thickness Bevel thickness in pixels
 * @param inside Place to store rectangle of the interior or @c NULL
 * @return EOK on success or an error code
 */
errno_t ui_paint_bevel(gfx_context_t *gc, gfx_rect_t *rect,
    gfx_color_t *tlcolor, gfx_color_t *brcolor, gfx_coord_t thickness,
    gfx_rect_t *inside)
{
        gfx_rect_t frect;
        gfx_coord_t i;
        errno_t rc;

        /* Top left */

        rc = gfx_set_color(gc, tlcolor);
        if (rc != EOK)
                goto error;

        for (i = 0; i < thickness; i++) {
                frect.p0.x = rect->p0.x + i;
                frect.p0.y = rect->p0.y + i;
                frect.p1.x = rect->p1.x - i - 1;
                frect.p1.y = rect->p0.y + i + 1;
                rc = gfx_fill_rect(gc, &frect);
                if (rc != EOK)
                        goto error;

                frect.p0.x = rect->p0.x + i;
                frect.p0.y = rect->p0.y + i + 1;
                frect.p1.x = rect->p0.x + i + 1;
                frect.p1.y = rect->p1.y - i - 1;
                rc = gfx_fill_rect(gc, &frect);
                if (rc != EOK)
                        goto error;
        }

        /* Bottom right */

        rc = gfx_set_color(gc, brcolor);
        if (rc != EOK)
                goto error;

        for (i = 0; i < thickness; i++) {
                frect.p0.x = rect->p0.x + i;
                frect.p0.y = rect->p1.y - i - 1;
                frect.p1.x = rect->p1.x - i - 1;
                frect.p1.y = rect->p1.y - i;
                rc = gfx_fill_rect(gc, &frect);
                if (rc != EOK)
                        goto error;

                frect.p0.x = rect->p1.x - i - 1;
                frect.p0.y = rect->p0.y + i;
                frect.p1.x = rect->p1.x - i;
                frect.p1.y = rect->p1.y - i;
                rc = gfx_fill_rect(gc, &frect);
                if (rc != EOK)
                        goto error;
        }

        if (inside != NULL)
                ui_paint_get_bevel_inside(gc, rect, thickness, inside);

        return EOK;
error:
        return rc;
}

/** Get bevel interior rectangle.
 *
 * Get the bevel interior rectangle without painting it.
 *
 * @param gc Graphic context
 * @param rect Rectangle to paint into
 * @param thickness Bevel thickness in pixels
 * @param inside Place to store rectangle of the interior
 */
void ui_paint_get_bevel_inside(gfx_context_t *gc, gfx_rect_t *rect,
    gfx_coord_t thickness, gfx_rect_t *inside)
{
        inside->p0.x = rect->p0.x + thickness;
        inside->p0.y = rect->p0.y + thickness;
        inside->p1.x = rect->p1.x - thickness;
        inside->p1.y = rect->p1.y - thickness;
}

/** Paint inset frame.
 *
 * @param resource UI resource
 * @param rect Rectangle to paint onto
 * @param inside Place to store inside rectangle or @c NULL
 * @return EOK on success or an error code
 */
errno_t ui_paint_inset_frame(ui_resource_t *resource, gfx_rect_t *rect,
    gfx_rect_t *inside)
{
        gfx_rect_t frame;
        errno_t rc;

        rc = ui_paint_bevel(resource->gc, rect,
            resource->wnd_shadow_color, resource->wnd_highlight_color,
            1, &frame);
        if (rc != EOK)
                goto error;

        rc = ui_paint_bevel(resource->gc, &frame,
            resource->wnd_frame_sh_color, resource->wnd_frame_hi_color,
            1, inside);
        if (rc != EOK)
                goto error;

        return EOK;
error:
        return rc;
}

/** Get inset frame interior rectangle.
 *
 * This allows one to get the interior rectangle without actually painting
 * the inset frame.
 *
 * @param resource UI resource
 * @param rect Rectangle to paint onto
 * @param inside Place to store inside rectangle or @c NULL
 */
void ui_paint_get_inset_frame_inside(ui_resource_t *resource, gfx_rect_t *rect,
    gfx_rect_t *inside)
{
        ui_paint_get_bevel_inside(resource->gc, rect, 2, inside);
}

/** Paint outset frame.
 *
 * @param resource UI resource
 * @param rect Rectangle to paint onto
 * @param inside Place to store inside rectangle or @c NULL
 * @return EOK on success or an error code
 */
errno_t ui_paint_outset_frame(ui_resource_t *resource, gfx_rect_t *rect,
    gfx_rect_t *inside)
{
        gfx_rect_t frame;
        errno_t rc;

        rc = ui_paint_bevel(resource->gc, rect,
            resource->wnd_frame_hi_color, resource->wnd_frame_sh_color,
            1, &frame);
        if (rc != EOK)
                goto error;

        rc = ui_paint_bevel(resource->gc, &frame,
            resource->wnd_highlight_color, resource->wnd_shadow_color,
            1, inside);
        if (rc != EOK)
                goto error;

        return EOK;
error:
        return rc;
}

/** Paint filled circle vertical scanline.
 *
 * @param gc Graphic context
 * @param center Coordinates of the center of the circle
 * @param x X-coordinate of the scanline
 * @param y0 Lowest Y coordinate of the scanline (inclusive)
 * @param y1 Highest Y coordinate of the scanline (inclusive)
 * @param part Which part(s) of cicle to paint
 * @return EOK on success or an error code
 */
static errno_t ui_paint_fcircle_line(gfx_context_t *gc, gfx_coord2_t *center,
    gfx_coord_t x, gfx_coord_t y0, gfx_coord_t y1, ui_fcircle_part_t part)
{
        gfx_rect_t rect;
        gfx_rect_t trect;

        rect.p0.x = x;
        rect.p0.y = y0;
        rect.p1.x = x + 1;
        rect.p1.y = y1;

        /* Clip to upper-left/lower-right half of circle, if required */

        if ((part & ui_fcircle_upleft) == 0) {
                if (rect.p0.y < -rect.p1.x)
                        rect.p0.y = -rect.p1.x;
        }

        if ((part & ui_fcircle_lowright) == 0) {
                if (rect.p1.y > -rect.p1.x)
                        rect.p1.y = -rect.p1.x;
        }

        /* If coordinates are reversed, there is nothing to do */
        if (rect.p1.y <= rect.p0.y)
                return EOK;

        gfx_rect_translate(center, &rect, &trect);

        return gfx_fill_rect(gc, &trect);
}

/** Paint filled circle scanlines corresponding to octant point.
 *
 * Fills the four vertical scanlines lying between the eight reflections
 * of a circle point.
 *
 * @param gc Graphic context
 * @param center Coordinates of the center
 * @param r Radius in pixels
 * @param part Which part(s) of cicle to paint
 * @return EOK on success or an error code
 */
static int ui_paint_fcircle_point(gfx_context_t *gc, gfx_coord2_t *center,
    gfx_coord2_t *p, ui_fcircle_part_t part)
{
        errno_t rc;

        rc = ui_paint_fcircle_line(gc, center, +p->x, -p->y, p->y + 1, part);
        if (rc != EOK)
                return rc;
        rc = ui_paint_fcircle_line(gc, center, -p->x, -p->y, p->y + 1, part);
        if (rc != EOK)
                return rc;
        rc = ui_paint_fcircle_line(gc, center, +p->y, -p->x, p->x + 1, part);
        if (rc != EOK)
                return rc;
        rc = ui_paint_fcircle_line(gc, center, -p->y, -p->x, p->x + 1, part);
        if (rc != EOK)
                return rc;

        return EOK;
}

/** Paint a filled circle.
 *
 * @param gc Graphic context
 * @param center Coordinates of the center
 * @param r Radius in pixels
 * @param part Which part(s) of cicle to paint
 * @return EOK on success or an error code
 */
errno_t ui_paint_filled_circle(gfx_context_t *gc, gfx_coord2_t *center,
    gfx_coord_t r, ui_fcircle_part_t part)
{
        gfx_coord2_t p;
        gfx_coord_t f;
        errno_t rc;

        /* Run through one octant using circle midpoint algorithm */

        p.x = r;
        p.y = 0;
        f = 1 - r;

        rc = ui_paint_fcircle_point(gc, center, &p, part);
        if (rc != EOK)
                return rc;

        while (p.x > p.y) {
                if (f < 0) {
                        f = f + 2 * p.y + 3;
                } else {
                        f = f + 2 * (p.y - p.x) + 5;
                        --p.x;
                }
                ++p.y;

                rc = ui_paint_fcircle_point(gc, center, &p, part);
                if (rc != EOK)
                        return rc;
        }

        return EOK;
}

/** Paint upward pointing triangle.
 *
 * @param gc Graphic context
 * @param pos Center position
 * @param n Length of triangle side
 * @return EOK on success or an error code
 */
errno_t ui_paint_up_triangle(gfx_context_t *gc, gfx_coord2_t *pos,
    gfx_coord_t n)
{
        gfx_coord_t i;
        errno_t rc;
        gfx_rect_t rect;

        for (i = 0; i < n; i++) {
                rect.p0.x = pos->x - i;
                rect.p0.y = pos->y - n / 2 + i;
                rect.p1.x = pos->x + i + 1;
                rect.p1.y = pos->y - n / 2 + i + 1;
                rc = gfx_fill_rect(gc, &rect);
                if (rc != EOK)
                        return rc;
        }

        return EOK;
}

/** Paint downward pointing triangle.
 *
 * @param gc Graphic context
 * @param pos Center position
 * @param n Length of triangle side
 * @return EOK on success or an error code
 */
errno_t ui_paint_down_triangle(gfx_context_t *gc, gfx_coord2_t *pos,
    gfx_coord_t n)
{
        gfx_coord_t i;
        errno_t rc;
        gfx_rect_t rect;

        for (i = 0; i < n; i++) {
                rect.p0.x = pos->x - i;
                rect.p0.y = pos->y + n / 2 - i;
                rect.p1.x = pos->x + i + 1;
                rect.p1.y = pos->y + n / 2 - i + 1;
                rc = gfx_fill_rect(gc, &rect);
                if (rc != EOK)
                        return rc;
        }

        return EOK;
}

/** Paint left pointing triangle.
 *
 * @param gc Graphic context
 * @param pos Center position
 * @param n Length of triangle side
 * @return EOK on success or an error code
 */
errno_t ui_paint_left_triangle(gfx_context_t *gc, gfx_coord2_t *pos,
    gfx_coord_t n)
{
        gfx_coord_t i;
        errno_t rc;
        gfx_rect_t rect;

        for (i = 0; i < n; i++) {
                rect.p0.x = pos->x - n / 2 + i;
                rect.p0.y = pos->y - i;
                rect.p1.x = pos->x - n / 2 + i + 1;
                rect.p1.y = pos->y + i + 1;
                rc = gfx_fill_rect(gc, &rect);
                if (rc != EOK)
                        return rc;
        }

        return EOK;
}

/** Paint right pointing triangle.
 *
 * @param gc Graphic context
 * @param pos Center position
 * @param n Length of triangle side
 * @return EOK on success or an error code
 */
errno_t ui_paint_right_triangle(gfx_context_t *gc, gfx_coord2_t *pos,
    gfx_coord_t n)
{
        gfx_coord_t i;
        errno_t rc;
        gfx_rect_t rect;

        for (i = 0; i < n; i++) {
                rect.p0.x = pos->x + n / 2 - i;
                rect.p0.y = pos->y - i;
                rect.p1.x = pos->x + n / 2 - i + 1;
                rect.p1.y = pos->y + i + 1;
                rc = gfx_fill_rect(gc, &rect);
                if (rc != EOK)
                        return rc;
        }

        return EOK;
}

/** Paint diagonal cross (X).
 *
 * @param gc Graphic context
 * @param pos Center position
 * @param n Length of each leg
 * @param w Pen width
 * @param h Pen height
 * @return EOK on success or an error code
 */
errno_t ui_paint_cross(gfx_context_t *gc, gfx_coord2_t *pos,
    gfx_coord_t n, gfx_coord_t w, gfx_coord_t h)
{
        gfx_coord_t i;
        gfx_rect_t rect;
        errno_t rc;

        rect.p0.x = pos->x;
        rect.p0.y = pos->y;
        rect.p1.x = pos->x + w;
        rect.p1.y = pos->y + h;
        rc = gfx_fill_rect(gc, &rect);
        if (rc != EOK)
                return rc;

        for (i = 1; i < n; i++) {
                rect.p0.x = pos->x - i;
                rect.p0.y = pos->y - i;
                rect.p1.x = pos->x - i + w;
                rect.p1.y = pos->y - i + h;
                rc = gfx_fill_rect(gc, &rect);
                if (rc != EOK)
                        return rc;

                rect.p0.x = pos->x - i;
                rect.p0.y = pos->y + i;
                rect.p1.x = pos->x - i + w;
                rect.p1.y = pos->y + i + h;
                rc = gfx_fill_rect(gc, &rect);
                if (rc != EOK)
                        return rc;

                rect.p0.x = pos->x + i;
                rect.p0.y = pos->y - i;
                rect.p1.x = pos->x + i + w;
                rect.p1.y = pos->y - i + h;
                rc = gfx_fill_rect(gc, &rect);
                if (rc != EOK)
                        return rc;

                rect.p0.x = pos->x + i;
                rect.p0.y = pos->y + i;
                rect.p1.x = pos->x + i + w;
                rect.p1.y = pos->y + i + h;
                rc = gfx_fill_rect(gc, &rect);
                if (rc != EOK)
                        return rc;
        }

        return EOK;
}

/** Paint maximize icon.
 *
 * @param resource UI resource
 * @param pos Center position
 * @param w Icon width
 * @param h Icon height
 * @return EOK on success or an error code
 */
errno_t ui_paint_maxicon(ui_resource_t *resource, gfx_coord2_t *pos,
    gfx_coord_t w, gfx_coord_t h)
{
        gfx_rect_t rect;
        errno_t rc;

        rc = gfx_set_color(resource->gc, resource->btn_text_color);
        if (rc != EOK)
                return rc;

        rect.p0.x = pos->x - w / 2;
        rect.p0.y = pos->y - h / 2;
        rect.p1.x = rect.p0.x + w;
        rect.p1.y = rect.p0.y + h;
        rc = gfx_fill_rect(resource->gc, &rect);
        if (rc != EOK)
                return rc;

        rc = gfx_set_color(resource->gc, resource->btn_face_color);
        if (rc != EOK)
                return rc;

        rect.p0.x += 1;
        rect.p0.y += 2;
        rect.p1.x -= 1;
        rect.p1.y -= 1;
        rc = gfx_fill_rect(resource->gc, &rect);
        if (rc != EOK)
                return rc;

        return EOK;
}

/** Paint unmaximize icon.
 *
 * Unmaximize icon consists of two overlapping window icons.
 *
 * @param resource UI resource
 * @param pos Center position
 * @param w Window icon width
 * @param h Window icon height
 * @param dw Horizontal distance between window icon centers
 * @param dh Vertical distance between window icon centers
 * @return EOK on success or an error code
 */
errno_t ui_paint_unmaxicon(ui_resource_t *resource, gfx_coord2_t *pos,
    gfx_coord_t w, gfx_coord_t h, gfx_coord_t dw, gfx_coord_t dh)
{
        gfx_coord2_t p;
        errno_t rc;

        p.x = pos->x + dw / 2;
        p.y = pos->y - dh / 2;
        rc = ui_paint_maxicon(resource, &p, w, h);
        if (rc != EOK)
                return rc;

        p.x = pos->x - dw / 2;
        p.y = pos->y + dh / 2;
        rc = ui_paint_maxicon(resource, &p, w, h);
        if (rc != EOK)
                return rc;

        return EOK;
}

/** Paint a text box.
 *
 * @param resource UI resource
 * @param rect Rectangle inside which to paint the box
 * @param style Box style
 * @param color Color
 * @return EOK on success or an error code
 */
errno_t ui_paint_text_box(ui_resource_t *resource, gfx_rect_t *rect,
    ui_box_style_t style, gfx_color_t *color)
{
        errno_t rc;
        gfx_text_fmt_t fmt;
        gfx_rect_t srect;
        gfx_coord2_t pos;
        gfx_coord2_t dim;
        size_t bufsz;
        size_t off;
        int i;
        gfx_coord_t y;
        char *str = NULL;
        ui_box_chars_t *boxc = NULL;

        gfx_rect_points_sort(rect, &srect);
        gfx_rect_dims(&srect, &dim);

        /* Is rectangle large enough to hold box? */
        if (dim.x < 2 || dim.y < 2)
                return EOK;

        switch (style) {
        case ui_box_single:
                boxc = &single_box_chars;
                break;
        case ui_box_double:
                boxc = &double_box_chars;
                break;
        }

        if (boxc == NULL)
                return EINVAL;

        gfx_text_fmt_init(&fmt);
        fmt.font = resource->font;
        fmt.color = color;

        bufsz = str_size(boxc->c[0][0]) +
            str_size(boxc->c[0][1]) * (dim.x - 2) +
            str_size(boxc->c[0][2]) + 1;

        str = malloc(bufsz);
        if (str == NULL)
                return ENOMEM;

        /* Top edge and corners */

        str_cpy(str, bufsz, boxc->c[0][0]);
        off = str_size(boxc->c[0][0]);

        for (i = 1; i < dim.x - 1; i++) {
                str_cpy(str + off, bufsz - off, boxc->c[0][1]);
                off += str_size(boxc->c[0][1]);
        }

        str_cpy(str + off, bufsz - off, boxc->c[0][2]);
        off += str_size(boxc->c[0][2]);
        str[off] = '\0';

        pos = rect->p0;
        rc = gfx_puttext(&pos, &fmt, str);
        if (rc != EOK)
                goto error;

        /* Vertical edges */
        for (y = rect->p0.y + 1; y < rect->p1.y - 1; y++) {
                pos.y = y;

                pos.x = rect->p0.x;
                rc = gfx_puttext(&pos, &fmt, boxc->c[1][0]);
                if (rc != EOK)
                        goto error;

                pos.x = rect->p1.x - 1;
                rc = gfx_puttext(&pos, &fmt, boxc->c[1][2]);
                if (rc != EOK)
                        goto error;
        }

        /* Bottom edge and corners */

        str_cpy(str, bufsz, boxc->c[2][0]);
        off = str_size(boxc->c[2][0]);

        for (i = 1; i < dim.x - 1; i++) {
                str_cpy(str + off, bufsz - off, boxc->c[2][1]);
                off += str_size(boxc->c[2][1]);
        }

        str_cpy(str + off, bufsz - off, boxc->c[2][2]);
        off += str_size(boxc->c[2][2]);
        str[off] = '\0';

        pos.x = rect->p0.x;
        pos.y = rect->p1.y - 1;
        rc = gfx_puttext(&pos, &fmt, str);
        if (rc != EOK)
                goto error;

        free(str);
        return EOK;
error:
        if (str != NULL)
                free(str);
        return rc;
}

/** Paint a text horizontal brace.
 *
 * @param resource UI resource
 * @param rect Rectangle inside which to paint the brace (height should
 *             be 1).
 * @param style Box style
 * @param color Color
 * @return EOK on success or an error code
 */
errno_t ui_paint_text_hbrace(ui_resource_t *resource, gfx_rect_t *rect,
    ui_box_style_t style, gfx_color_t *color)
{
        errno_t rc;
        gfx_text_fmt_t fmt;
        gfx_rect_t srect;
        gfx_coord2_t pos;
        gfx_coord2_t dim;
        size_t bufsz;
        size_t off;
        int i;
        char *str = NULL;
        ui_brace_chars_t *hbc = NULL;

        gfx_rect_points_sort(rect, &srect);
        gfx_rect_dims(&srect, &dim);

        /* Is rectangle large enough to hold brace? */
        if (dim.x < 2 || dim.y < 1)
                return EOK;

        switch (style) {
        case ui_box_single:
                hbc = &single_hbrace_chars;
                break;
        case ui_box_double:
                hbc = &double_hbrace_chars;
                break;
        }

        if (hbc == NULL)
                return EINVAL;

        gfx_text_fmt_init(&fmt);
        fmt.font = resource->font;
        fmt.color = color;

        bufsz = str_size(hbc->start) +
            str_size(hbc->middle) * (dim.x - 2) +
            str_size(hbc->end) + 1;

        str = malloc(bufsz);
        if (str == NULL)
                return ENOMEM;

        str_cpy(str, bufsz, hbc->start);
        off = str_size(hbc->start);

        for (i = 1; i < dim.x - 1; i++) {
                str_cpy(str + off, bufsz - off, hbc->middle);
                off += str_size(hbc->middle);
        }

        str_cpy(str + off, bufsz - off, hbc->end);
        off += str_size(hbc->end);
        str[off] = '\0';

        pos = rect->p0;
        rc = gfx_puttext(&pos, &fmt, str);
        if (rc != EOK)
                goto error;

        free(str);
        return EOK;
error:
        if (str != NULL)
                free(str);
        return rc;
}

/** Fill rectangle with text character.
 *
 * @param resource UI resource
 * @param rect Rectangle
 * @param color Color
 * @param gchar Character to fill with
 * @return EOK on success or an error code
 */
errno_t ui_paint_text_rect(ui_resource_t *resource, gfx_rect_t *rect,
    gfx_color_t *color, const char *gchar)
{
        gfx_coord2_t pos;
        gfx_text_fmt_t fmt;
        gfx_rect_t srect;
        gfx_coord_t w, i;
        char *buf;
        size_t gcharsz;
        errno_t rc;

        gfx_rect_points_sort(rect, &srect);

        gfx_text_fmt_init(&fmt);
        fmt.font = resource->font;
        fmt.color = color;
        fmt.halign = gfx_halign_left;
        fmt.valign = gfx_valign_top;

        w = srect.p1.x - srect.p0.x;
        if (w == 0)
                return EOK;

        gcharsz = str_size(gchar);

        buf = malloc(w * gcharsz + 1);
        if (buf == NULL)
                return ENOMEM;

        for (i = 0; i < w; i++)
                str_cpy(buf + i * gcharsz, (w - i) * gcharsz + 1, gchar);
        buf[w * gcharsz] = '\0';

        pos.x = srect.p0.x;
        for (pos.y = srect.p0.y; pos.y < srect.p1.y; pos.y++) {
                rc = gfx_puttext(&pos, &fmt, buf);
                if (rc != EOK)
                        goto error;
        }

        free(buf);
        return EOK;
error:
        free(buf);
        return rc;
}

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

/** Compute UI text width.
 *
 * @param font Font
 * @param str String
 * @return Text width
 */
gfx_coord_t ui_text_width(gfx_font_t *font, const char *str)
{
        gfx_coord_t w;
        gfx_coord_t tw;
        const char *sp;

        /* Text including tildes */
        w = gfx_text_width(font, str);
        tw = gfx_text_width(font, "~");

        /* Subtract width of singular tildes */
        sp = str;
        while (*sp != '\0') {
                if (*sp == '~' && sp[1] != '~')
                        w -= tw;
                ++sp;
        }

        return w;
}

/** Paint text (with highlighting markup).
 *
 * Paint some text with highlighted sections enclosed with tilde characters
 * ('~'). A literal tilde can be printed with "~~". Text can be highlighted
 * with an underline or different color, based on display capabilities.
 *
 * @param pos Anchor position
 * @param fmt Text formatting
 * @param str String containing '~' markup
 *
 * @return EOK on success or an error code
 */
errno_t ui_paint_text(gfx_coord2_t *pos, ui_text_fmt_t *fmt, const char *str)
{
        gfx_coord2_t tpos;
        gfx_text_fmt_t tfmt;
        char *buf;
        char *endptr;
        const char *sp;
        errno_t rc;

        /* Break down string into list of (non)highlighted parts */
        rc = ui_accel_process(str, &buf, &endptr);
        if (rc != EOK)
                return rc;

        gfx_text_fmt_init(&tfmt);
        tfmt.font = fmt->font;
        tfmt.color = fmt->color;
        tfmt.halign = fmt->halign;
        tfmt.justify_width = fmt->justify_width;
        tfmt.valign = fmt->valign;
        tfmt.underline = false;

        tpos = *pos;
        sp = buf;
        while (sp != endptr) {
                /* Print the current string */
                rc = gfx_puttext(&tpos, &tfmt, sp);
                if (rc != EOK)
                        goto error;

                gfx_text_cont(&tpos, &tfmt, sp, &tpos, &tfmt);
                tfmt.underline = !tfmt.underline;
                tfmt.color = tfmt.underline ? fmt->hgl_color : fmt->color;

                /* Skip to the next string */
                while (*sp != '\0')
                        ++sp;
                ++sp;
        }

        free(buf);
        return EOK;
error:
        free(buf);
        return rc;
}

/** @}
 */