1 #define __NR_PIXBLOCK_SCALER_CPP__
3 /*
4 * Functions for blitting pixblocks using matrix transformation
5 *
6 * Author:
7 * Niko Kiirala <niko@kiirala.com>
8 *
9 * Copyright (C) 2006 Niko Kiirala
10 *
11 * Released under GNU GPL, read the file 'COPYING' for more information
12 */
14 #include <glib.h>
15 #include <cmath>
16 using std::floor;
18 #include "libnr/nr-pixblock.h"
19 #include "libnr/nr-matrix.h"
21 namespace NR {
23 struct RGBA {
24 int r, g, b, a;
25 };
27 /**
28 * Sanity check function for indexing pixblocks.
29 * Catches reading and writing outside the pixblock area.
30 * When enabled, decreases filter rendering speed massively.
31 */
32 inline void _check_index(NRPixBlock const * const pb, int const location, int const line)
33 {
34 if(false) {
35 int max_loc = pb->rs * (pb->area.y1 - pb->area.y0);
36 if (location < 0 || (location + 4) > max_loc)
37 g_warning("Location %d out of bounds (0 ... %d) at line %d", location, max_loc, line);
38 }
39 }
41 void transform_nearest(NRPixBlock *to, NRPixBlock *from, Matrix &trans)
42 {
43 if (NR_PIXBLOCK_BPP(from) != 4 || NR_PIXBLOCK_BPP(to) != 4) {
44 g_warning("A non-32-bpp image passed to transform_nearest: scaling aborted.");
45 return;
46 }
48 // Precalculate sizes of source and destination pixblocks
49 int from_width = from->area.x1 - from->area.x0;
50 int from_height = from->area.y1 - from->area.y0;
51 int to_width = to->area.x1 - to->area.x0;
52 int to_height = to->area.y1 - to->area.y0;
54 Matrix itrans = trans.inverse();
56 // Loop through every pixel of destination image, a line at a time
57 for (int to_y = 0 ; to_y < to_height ; to_y++) {
58 for (int to_x = 0 ; to_x < to_width ; to_x++) {
59 RGBA result = {0,0,0,0};
61 int from_x = (int)round(itrans[0] * (to_x + to->area.x0)
62 + itrans[2] * (to_y + to->area.y0)
63 + itrans[4]);
64 from_x -= from->area.x0;
65 int from_y = (int)round(itrans[1] * (to_x + to->area.x0)
66 + itrans[3] * (to_y + to->area.y0)
67 + itrans[5]);
68 from_y -= from->area.y0;
70 if (from_x >= 0 && from_x < from_width
71 && from_y >= 0 && from_y < from_height) {
72 _check_index(from, from_y * from->rs + from_x * 4, __LINE__);
73 result.r = NR_PIXBLOCK_PX(from)[from_y * from->rs + from_x * 4];
74 result.g = NR_PIXBLOCK_PX(from)[from_y * from->rs + from_x * 4 + 1];
75 result.b = NR_PIXBLOCK_PX(from)[from_y * from->rs + from_x * 4 + 2];
76 result.a = NR_PIXBLOCK_PX(from)[from_y * from->rs + from_x * 4 + 3];
77 }
79 _check_index(to, to_y * to->rs + to_x * 4, __LINE__);
80 NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4] = result.r;
81 NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 1] = result.g;
82 NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 2] = result.b;
83 NR_PIXBLOCK_PX(to)[to_y * to->rs + to_x * 4 + 3] = result.a;
84 }
85 }
86 }
88 } /* namespace NR */
89 /*
90 Local Variables:
91 mode:c++
92 c-file-style:"stroustrup"
93 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
94 indent-tabs-mode:nil
95 fill-column:99
96 End:
97 */
98 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :