/* 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 #include "art_misc.h" #include "art_point.h" #include "art_affine.h" #include "art_rgb_affine_private.h" #include "art_rgb_a_affine.h" /* This module handles compositing of affine-transformed alpha only images over rgb pixel buffers. */ /* Composite the source image over the destination image, applying the affine transform. */ /** * art_rgb_a_affine: Affine transform source Alpha 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 alpha buffer. * @src_width: Width of source image. * @src_height: Height of source image. * @src_rowstride: Rowstride of @src buffer. * @rgb: RGB foreground color, in 0xRRGGBB. * @affine: Affine transform. * @level: Filter level. * @alphagamma: #ArtAlphaGamma for gamma-correcting the compositing. * * Affine transform the solid color rgb with alpha specified by 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_a_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, art_u32 rgb, 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; art_u8 r, g, b; r = (rgb>>16)&0xff; g = (rgb>>8)&0xff; b = (rgb)&0xff; 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; if (src_x >= 0 && src_x < src_width && src_y >= 0 && src_y < src_height) { alpha = *src_p; if (alpha) { if (alpha == 255) { dst_p[0] = r; dst_p[1] = g; dst_p[2] = b; } else { bg_r = dst_p[0]; bg_g = dst_p[1]; bg_b = dst_p[2]; tmp = (r - bg_r) * alpha; fg_r = bg_r + ((tmp + (tmp >> 8) + 0x80) >> 8); tmp = (g - bg_g) * alpha; fg_g = bg_g + ((tmp + (tmp >> 8) + 0x80) >> 8); tmp = (b - 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; } }