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Diffstat (limited to 'art_rgb_rgba_affine.c')
| -rw-r--r-- | art_rgb_rgba_affine.c | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/art_rgb_rgba_affine.c b/art_rgb_rgba_affine.c new file mode 100644 index 0000000..41c7397 --- /dev/null +++ b/art_rgb_rgba_affine.c @@ -0,0 +1,142 @@ +/* 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, + int x0, int y0, int x1, int y1, int dst_rowstride, + const art_u8 *src, + int src_width, int src_height, int src_rowstride, + const double 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. */ + int x, y; + double inv[6]; + art_u8 *dst_p, *dst_linestart; + const art_u8 *src_p; + ArtPoint pt, src_pt; + int src_x, src_y; + int alpha; + art_u8 bg_r, bg_g, bg_b; + art_u8 fg_r, fg_g, fg_b; + int tmp; + int 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; + } +} |