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/*

 * Copyright © 2004 Keith Packard

 *

 * Permission to use, copy, modify, distribute, and sell this software and its

 * documentation for any purpose is hereby granted without fee, provided that

 * the above copyright notice appear in all copies and that both that

 * copyright notice and this permission notice appear in supporting

 * documentation, and that the name of Keith Packard not be used in

 * advertising or publicity pertaining to distribution of the software without

 * specific, written prior permission.  Keith Packard makes no

 * representations about the suitability of this software for any purpose.  It

 * is provided "as is" without express or implied warranty.

 *

 * KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,

 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO

 * EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR

 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,

 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER

 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR

 * PERFORMANCE OF THIS SOFTWARE.

 */

#ifdef HAVE_CONFIG_H

#include 

#endif

#include 

#include "pixman-private.h"

/*

 * Compute the smallest value greater than or equal to y which is on a

 * grid row.

 */

PIXMAN_EXPORT pixman_fixed_t

pixman_sample_ceil_y (pixman_fixed_t y, int n)

{

    pixman_fixed_t f = pixman_fixed_frac (y);

    pixman_fixed_t i = pixman_fixed_floor (y);

    f = DIV (f - Y_FRAC_FIRST (n) + (STEP_Y_SMALL (n) - pixman_fixed_e), STEP_Y_SMALL (n)) * STEP_Y_SMALL (n) +

	Y_FRAC_FIRST (n);

    if (f > Y_FRAC_LAST (n))

    {

	if (pixman_fixed_to_int (i) == 0x7fff)

	{

	    f = 0xffff; /* saturate */

	}

	else

	{

	    f = Y_FRAC_FIRST (n);

	    i += pixman_fixed_1;

	}

    }

    return (i | f);

}

/*

 * Compute the largest value strictly less than y which is on a

 * grid row.

 */

PIXMAN_EXPORT pixman_fixed_t

pixman_sample_floor_y (pixman_fixed_t y,

                       int            n)

{

    pixman_fixed_t f = pixman_fixed_frac (y);

    pixman_fixed_t i = pixman_fixed_floor (y);

    f = DIV (f - pixman_fixed_e - Y_FRAC_FIRST (n), STEP_Y_SMALL (n)) * STEP_Y_SMALL (n) +

	Y_FRAC_FIRST (n);

    if (f < Y_FRAC_FIRST (n))

    {

	if (pixman_fixed_to_int (i) == 0x8000)

	{

	    f = 0; /* saturate */

	}

	else

	{

	    f = Y_FRAC_LAST (n);

	    i -= pixman_fixed_1;

	}

    }

    return (i | f);

}

/*

 * Step an edge by any amount (including negative values)

 */

PIXMAN_EXPORT void

pixman_edge_step (pixman_edge_t *e,

                  int            n)

{

    pixman_fixed_48_16_t ne;

    e->x += n * e->stepx;

    ne = e->e + n * (pixman_fixed_48_16_t) e->dx;

    if (n >= 0)

    {

	if (ne > 0)

	{

	    int nx = (ne + e->dy - 1) / e->dy;

	    e->e = ne - nx * (pixman_fixed_48_16_t) e->dy;

	    e->x += nx * e->signdx;

	}

    }

    else

    {

	if (ne <= -e->dy)

	{

	    int nx = (-ne) / e->dy;

	    e->e = ne + nx * (pixman_fixed_48_16_t) e->dy;

	    e->x -= nx * e->signdx;

	}

    }

}

/*

 * A private routine to initialize the multi-step

 * elements of an edge structure

 */

static void

_pixman_edge_multi_init (pixman_edge_t * e,

                         int             n,

                         pixman_fixed_t *stepx_p,

                         pixman_fixed_t *dx_p)

{

    pixman_fixed_t stepx;

    pixman_fixed_48_16_t ne;

    ne = n * (pixman_fixed_48_16_t) e->dx;

    stepx = n * e->stepx;

    if (ne > 0)

    {

	int nx = ne / e->dy;

	ne -= nx * e->dy;

	stepx += nx * e->signdx;

    }

    *dx_p = ne;

    *stepx_p = stepx;

}

/*

 * Initialize one edge structure given the line endpoints and a

 * starting y value

 */

PIXMAN_EXPORT void

pixman_edge_init (pixman_edge_t *e,

                  int            n,

                  pixman_fixed_t y_start,

                  pixman_fixed_t x_top,

                  pixman_fixed_t y_top,

                  pixman_fixed_t x_bot,

                  pixman_fixed_t y_bot)

{

    pixman_fixed_t dx, dy;

    e->x = x_top;

    e->e = 0;

    dx = x_bot - x_top;

    dy = y_bot - y_top;

    e->dy = dy;

    e->dx = 0;

    if (dy)

    {

	if (dx >= 0)

	{

	    e->signdx = 1;

	    e->stepx = dx / dy;

	    e->dx = dx % dy;

	    e->e = -dy;

	}

	else

	{

	    e->signdx = -1;

	    e->stepx = -(-dx / dy);

	    e->dx = -dx % dy;

	    e->e = 0;

	}

	_pixman_edge_multi_init (e, STEP_Y_SMALL (n),

				 &e->stepx_small, &e->dx_small);

	_pixman_edge_multi_init (e, STEP_Y_BIG (n),

				 &e->stepx_big, &e->dx_big);

    }

    pixman_edge_step (e, y_start - y_top);

}

/*

 * Initialize one edge structure given a line, starting y value

 * and a pixel offset for the line

 */

PIXMAN_EXPORT void

pixman_line_fixed_edge_init (pixman_edge_t *            e,

                             int                        n,

                             pixman_fixed_t             y,

                             const pixman_line_fixed_t *line,

                             int                        x_off,

                             int                        y_off)

{

    pixman_fixed_t x_off_fixed = pixman_int_to_fixed (x_off);

    pixman_fixed_t y_off_fixed = pixman_int_to_fixed (y_off);

    const pixman_point_fixed_t *top, *bot;

    if (line->p1.y <= line->p2.y)

    {

	top = &line->p1;

	bot = &line->p2;

    }

    else

    {

	top = &line->p2;

	bot = &line->p1;

    }

    pixman_edge_init (e, n, y,

                      top->x + x_off_fixed,

                      top->y + y_off_fixed,

                      bot->x + x_off_fixed,

                      bot->y + y_off_fixed);

}

PIXMAN_EXPORT void

pixman_add_traps (pixman_image_t * image,

                  int16_t          x_off,

                  int16_t          y_off,

                  int              ntrap,

                  pixman_trap_t *  traps)

{

    int bpp;

    int width;

    int height;

    pixman_fixed_t x_off_fixed;

    pixman_fixed_t y_off_fixed;

    pixman_edge_t l, r;

    pixman_fixed_t t, b;

    _pixman_image_validate (image);

    width = image->bits.width;

    height = image->bits.height;

    bpp = PIXMAN_FORMAT_BPP (image->bits.format);

    x_off_fixed = pixman_int_to_fixed (x_off);

    y_off_fixed = pixman_int_to_fixed (y_off);

    while (ntrap--)

    {

	t = traps->top.y + y_off_fixed;

	if (t < 0)

	    t = 0;

	t = pixman_sample_ceil_y (t, bpp);

	b = traps->bot.y + y_off_fixed;

	if (pixman_fixed_to_int (b) >= height)

	    b = pixman_int_to_fixed (height) - 1;

	b = pixman_sample_floor_y (b, bpp);

	if (b >= t)

	{

	    /* initialize edge walkers */

	    pixman_edge_init (&l, bpp, t,

	                      traps->top.l + x_off_fixed,

	                      traps->top.y + y_off_fixed,

	                      traps->bot.l + x_off_fixed,

	                      traps->bot.y + y_off_fixed);

	    pixman_edge_init (&r, bpp, t,

	                      traps->top.r + x_off_fixed,

	                      traps->top.y + y_off_fixed,

	                      traps->bot.r + x_off_fixed,

	                      traps->bot.y + y_off_fixed);

	    pixman_rasterize_edges (image, &l, &r, t, b);

	}

	traps++;

    }

}

#if 0

static void

dump_image (pixman_image_t *image,

            const char *    title)

{

    int i, j;

    if (!image->type == BITS)

	printf ("%s is not a regular image\n", title);

    if (!image->bits.format == PIXMAN_a8)

	printf ("%s is not an alpha mask\n", title);

    printf ("\n\n\n%s: \n", title);

    for (i = 0; i < image->bits.height; ++i)

    {

	uint8_t *line =

	    (uint8_t *)&(image->bits.bits[i * image->bits.rowstride]);

	for (j = 0; j < image->bits.width; ++j)

	    printf ("%c", line[j] ? '#' : ' ');

	printf ("\n");

    }

}

#endif

PIXMAN_EXPORT void

pixman_add_trapezoids (pixman_image_t *          image,

                       int16_t                   x_off,

                       int                       y_off,

                       int                       ntraps,

                       const pixman_trapezoid_t *traps)

{

    int i;

#if 0

    dump_image (image, "before");

#endif

    for (i = 0; i < ntraps; ++i)

    {

	const pixman_trapezoid_t *trap = &(traps[i]);

	if (!pixman_trapezoid_valid (trap))

	    continue;

	pixman_rasterize_trapezoid (image, trap, x_off, y_off);

    }

#if 0

    dump_image (image, "after");

#endif

}

PIXMAN_EXPORT void

pixman_rasterize_trapezoid (pixman_image_t *          image,

                            const pixman_trapezoid_t *trap,

                            int                       x_off,

                            int                       y_off)

{

    int bpp;

    int width;

    int height;

    pixman_fixed_t x_off_fixed;

    pixman_fixed_t y_off_fixed;

    pixman_edge_t l, r;

    pixman_fixed_t t, b;

    return_if_fail (image->type == BITS);

    _pixman_image_validate (image);

    if (!pixman_trapezoid_valid (trap))

	return;

    width = image->bits.width;

    height = image->bits.height;

    bpp = PIXMAN_FORMAT_BPP (image->bits.format);

    x_off_fixed = pixman_int_to_fixed (x_off);

    y_off_fixed = pixman_int_to_fixed (y_off);

    t = trap->top + y_off_fixed;

    if (t < 0)

	t = 0;

    t = pixman_sample_ceil_y (t, bpp);

    b = trap->bottom + y_off_fixed;

    if (pixman_fixed_to_int (b) >= height)

	b = pixman_int_to_fixed (height) - 1;

    b = pixman_sample_floor_y (b, bpp);

    if (b >= t)

    {

	/* initialize edge walkers */

	pixman_line_fixed_edge_init (&l, bpp, t, &trap->left, x_off, y_off);

	pixman_line_fixed_edge_init (&r, bpp, t, &trap->right, x_off, y_off);

	pixman_rasterize_edges (image, &l, &r, t, b);

    }

}