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/* Libart_LGPL - library of basic graphic primitives
* Copyright (C) 1998 Raph Levien
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "config.h"
#include "art_rgb_rgba_affine.h"
#include <math.h>
#include "art_misc.h"
#include "art_point.h"
#include "art_affine.h"
#include "art_rgb_affine_private.h"
/* This module handles compositing of affine-transformed rgba images
over rgb pixel buffers. */
/* Composite the source image over the destination image, applying the
affine transform. */
/**
* art_rgb_rgba_affine: Affine transform source RGBA image and composite.
* @dst: Destination image RGB buffer.
* @x0: Left coordinate of destination rectangle.
* @y0: Top coordinate of destination rectangle.
* @x1: Right coordinate of destination rectangle.
* @y1: Bottom coordinate of destination rectangle.
* @dst_rowstride: Rowstride of @dst buffer.
* @src: Source image RGBA buffer.
* @src_width: Width of source image.
* @src_height: Height of source image.
* @src_rowstride: Rowstride of @src buffer.
* @affine: Affine transform.
* @level: Filter level.
* @alphagamma: #ArtAlphaGamma for gamma-correcting the compositing.
*
* Affine transform the source image stored in @src, compositing over
* the area of destination image @dst specified by the rectangle
* (@x0, @y0) - (@x1, @y1). As usual in libart, the left and top edges
* of this rectangle are included, and the right and bottom edges are
* excluded.
*
* The @alphagamma parameter specifies that the alpha compositing be
* done in a gamma-corrected color space. In the current
* implementation, it is ignored.
*
* The @level parameter specifies the speed/quality tradeoff of the
* image interpolation. Currently, only ART_FILTER_NEAREST is
* implemented.
**/
void
art_rgb_rgba_affine (art_u8 *dst,
gint x0, gint y0, gint x1, gint y1, gint dst_rowstride,
const art_u8 *src,
gint src_width, gint src_height, gint src_rowstride,
const gdouble affine[6],
ArtFilterLevel level,
ArtAlphaGamma *alphagamma)
{
/* Note: this is a slow implementation, and is missing all filter
levels other than NEAREST. It is here for clarity of presentation
and to establish the interface. */
gint x, y;
gdouble inv[6];
art_u8 *dst_p, *dst_linestart;
const art_u8 *src_p;
ArtPoint pt, src_pt;
gint src_x, src_y;
gint alpha;
art_u8 bg_r, bg_g, bg_b;
art_u8 fg_r, fg_g, fg_b;
gint tmp;
gint run_x0, run_x1;
dst_linestart = dst;
art_affine_invert (inv, affine);
for (y = y0; y < y1; y++)
{
pt.y = y + 0.5;
run_x0 = x0;
run_x1 = x1;
art_rgb_affine_run (&run_x0, &run_x1, y, src_width, src_height,
inv);
dst_p = dst_linestart + (run_x0 - x0) * 3;
for (x = run_x0; x < run_x1; x++)
{
pt.x = x + 0.5;
art_affine_point (&src_pt, &pt, inv);
src_x = floor (src_pt.x);
src_y = floor (src_pt.y);
src_p = src + (src_y * src_rowstride) + src_x * 4;
if (src_x >= 0 && src_x < src_width &&
src_y >= 0 && src_y < src_height)
{
alpha = src_p[3];
if (alpha)
{
if (alpha == 255)
{
dst_p[0] = src_p[0];
dst_p[1] = src_p[1];
dst_p[2] = src_p[2];
}
else
{
bg_r = dst_p[0];
bg_g = dst_p[1];
bg_b = dst_p[2];
tmp = (src_p[0] - bg_r) * alpha;
fg_r = bg_r + ((tmp + (tmp >> 8) + 0x80) >> 8);
tmp = (src_p[1] - bg_g) * alpha;
fg_g = bg_g + ((tmp + (tmp >> 8) + 0x80) >> 8);
tmp = (src_p[2] - bg_b) * alpha;
fg_b = bg_b + ((tmp + (tmp >> 8) + 0x80) >> 8);
dst_p[0] = fg_r;
dst_p[1] = fg_g;
dst_p[2] = fg_b;
}
}
} else { dst_p[0] = 255; dst_p[1] = 0; dst_p[2] = 0; }
dst_p += 3;
}
dst_linestart += dst_rowstride;
}
}
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