1/*
2 * Copyright 2005, Stephan Aßmus <superstippi@gmx.de>.
3 * Copyright 2008, Andrej Spielmann <andrej.spielmann@seh.ox.ac.uk>.
4 * All rights reserved. Distributed under the terms of the MIT License.
5 *
6 * DrawingMode implementing B_OP_SUBTRACT on B_RGBA32.
7 *
8 */
9
10#ifndef DRAWING_MODE_SUBTRACT_SUBPIX_H
11#define DRAWING_MODE_SUBTRACT_SUBPIX_H
12
13#include "DrawingMode.h"
14#include "GlobalSubpixelSettings.h"
15
16// BLEND_SUBTRACT_SUBPIX
17#define BLEND_SUBTRACT_SUBPIX(d, r, g, b, a1, a2, a3) \
18{ \
19	pixel32 _p; \
20	_p.data32 = *(uint32*)d; \
21	uint8 rt = max_c(0, _p.data8[2] - (r)); \
22	uint8 gt = max_c(0, _p.data8[1] - (g)); \
23	uint8 bt = max_c(0, _p.data8[0] - (b)); \
24	BLEND_SUBPIX(d, rt, gt, bt, a1, a2, a3); \
25}
26
27
28// blend_solid_hspan_subtract_subpix
29void
30blend_solid_hspan_subtract_subpix(int x, int y, unsigned len,
31	const color_type& c, const uint8* covers, agg_buffer* buffer,
32	const PatternHandler* pattern)
33{
34	uint8* p = buffer->row_ptr(y) + (x << 2);
35	const int subpixelL = gSubpixelOrderingRGB ? 2 : 0;
36	const int subpixelM = 1;
37	const int subpixelR = gSubpixelOrderingRGB ? 0 : 2;
38	do {
39		rgb_color color = pattern->ColorAt(x, y);
40		BLEND_SUBTRACT_SUBPIX(p, color.red, color.green, color.blue,
41			covers[subpixelL], covers[subpixelM], covers[subpixelR]);
42		covers += 3;
43		p += 4;
44		x++;
45		len -= 3;
46	} while (len);
47}
48
49#endif // DRAWING_MODE_SUBTRACT_SUBPIX_H
50
51