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