1 | srecord noeq G22RegionThinner_v2<Img extends WidthAndHeight>(IImageRegion<Img> originalRegion) is Steppable { |
2 | Rect bounds; |
3 | IImageRegion<Img> region; |
4 | bool phase1done; |
5 | |
6 | settable bool debug; |
7 | settable bool doFinalStep = true; |
8 | settable int lastPhaseThreshold1 = 2; |
9 | settable int lastPhaseThreshold = 5; |
10 | |
11 | settable byte[] lookupTable; |
12 | |
13 | // 0 = outside of region |
14 | // 1 = inner pixel |
15 | // 2 = border pixel |
16 | // index is in bounds coordinates |
17 | byte[] pixels; |
18 | |
19 | int idx(int x, int y) { |
20 | ret (y-bounds.y)*bounds.w+x-bounds.x; |
21 | } |
22 | int idx(Pt p) { ret idx(p.x, p.y); } |
23 | |
24 | Pt idxToPt(int idx) { |
25 | ret pt(bounds.x+(idx % bounds.w), bounds.y+idx/bounds.w); |
26 | } |
27 | |
28 | byte getPixel(Pt p) { |
29 | ret !containsPt(bounds, p) ? 0 : pixels[idx(p)]; |
30 | } |
31 | |
32 | byte getPixel(int x, int y) { |
33 | ret !containsPt(bounds, x, y) ? 0 : pixels[idx(x, y)]; |
34 | } |
35 | |
36 | bool contains(int x, int y) { |
37 | ret getPixel(x, y) != 0; |
38 | } |
39 | |
40 | bool clearPixel(int x, int y) { |
41 | if (!region.contains(x, y)) false; |
42 | pixels[idx(x, y)] = 0; |
43 | true; |
44 | } |
45 | |
46 | void init { |
47 | if (bounds != null) ret; |
48 | bounds = originalRegion.bounds(); |
49 | pixels = new byte[area(bounds)]; |
50 | for (Pt p : originalRegion.pixelIterator()) |
51 | pixels[idx(p.x, p.y)] = 1; |
52 | |
53 | region = new ThinnedRegion; |
54 | } |
55 | |
56 | class ThinnedRegion is IImageRegion<Img> { |
57 | public Img image() { ret originalRegion.image(); } |
58 | public Rect bounds() { ret bounds; } |
59 | |
60 | public bool contains(int x, int y) { |
61 | ret containsPt(bounds, x, y) && pixels[idx(x, y)] > 0; |
62 | } |
63 | |
64 | public ItIt<Pt> pixelIterator() { |
65 | ret iff_null(new IF0<Pt> { |
66 | int idx = 0; |
67 | |
68 | public Pt get() { |
69 | for (; idx < pixels.length; idx++) |
70 | if (pixels[idx] > 0) |
71 | ret idxToPt(idx++); |
72 | null; |
73 | } |
74 | }); |
75 | } |
76 | } |
77 | |
78 | public bool step() { |
79 | init(); |
80 | |
81 | if (phase1done) |
82 | ret finalStep(); |
83 | |
84 | L<PtBuffer> traces = g22_allBorderTraces_withDiagonals(region); |
85 | for (points : traces) |
86 | for (p : points) |
87 | pixels[idx(p)] = 2; |
88 | |
89 | new PtBuffer toDelete; |
90 | |
91 | for (points : traces) { |
92 | int nPoints = l(points); |
93 | BitSet deletable = emptyBitSet(nPoints); |
94 | for i to nPoints: { |
95 | if (deletableBorderPoint(points, i)) |
96 | deletable.set(i); |
97 | } |
98 | |
99 | // handle special cases |
100 | for i to nPoints: |
101 | if (cyclicGet(deletable, nPoints, i-1) |
102 | && !deletable.get(i) |
103 | && cyclicGet(deletable, nPoints, i+1)) { |
104 | Pt p = points.get(i); |
105 | Pt prev = ptMinus(cyclicGet(points, i-1), p); |
106 | Pt next = ptMinus(cyclicGet(points, i+1), p); |
107 | int dir1 = onePathLookupDirection(prev); |
108 | int dir2 = onePathLookupDirection(next); |
109 | int diff = mod(dir2-dir1, 8); |
110 | if (debug) printVars("special case", +p, +prev, +next, +dir1, +dir2, +diff); |
111 | if (diff == 1 || diff == 7) |
112 | deletable.set(i); |
113 | } |
114 | |
115 | for i to nPoints: |
116 | if (deletable.get(i)) |
117 | toDelete.add(points.get(i)); |
118 | } |
119 | |
120 | for (p : toDelete) |
121 | pixels[idx(p)] = 0; |
122 | |
123 | if (empty(toDelete)) |
124 | set phase1done; |
125 | true; |
126 | } |
127 | |
128 | bool deletableBorderPoint(PtBuffer points, int i) { |
129 | L<Pt> range = cyclicSubList_incl(points, i-3, i+3); |
130 | Pt p = points.get(i); |
131 | |
132 | // special case |
133 | if (eq(range.get(1), p) || eq(range.get(5), p)) false; |
134 | |
135 | int surroundingBorderPixels = 0, surroundingInnerPixels = 0; |
136 | for (int dir = 1; dir <= 8; dir++) { |
137 | Pt p2 = ptPlus(p, onePathDirection(dir)); |
138 | byte value = getPixel(p2); |
139 | if (value == 2 && !range.contains(p2)) |
140 | surroundingBorderPixels++; |
141 | else if (value == 1) |
142 | surroundingInnerPixels++; |
143 | } |
144 | |
145 | bool deletable = surroundingInnerPixels > 0 && surroundingBorderPixels == 0; |
146 | |
147 | printVars ifdef G22RegionThinner_debug(+p, +surroundingInnerPixels, +surroundingBorderPixels, +deletable, +range); |
148 | ret deletable; |
149 | } |
150 | |
151 | IImageRegion region aka get() { ret or(region, originalRegion); } |
152 | |
153 | // go from 2 pixels wide to 1 pixel wide (TODO) |
154 | bool finalStep() { |
155 | if (!doFinalStep) false; |
156 | |
157 | if (lookupTable == null) |
158 | lookupTable = new G22RegionThinner_LookupTable() |
159 | .lastPhaseThreshold(lastPhaseThreshold) |
160 | .lastPhaseThreshold1(lastPhaseThreshold1)!; |
161 | |
162 | bool change; |
163 | int x1 = bounds.x, x2 = bounds.x2(); |
164 | int y1 = bounds.y, y2 = bounds.y2(); |
165 | printVars ifdef G22RegionThinner_lastPhase_debug("finalStep", +x1, +y1, +x2, +y2); |
166 | |
167 | var pingSource = pingSource(); |
168 | |
169 | for (int y = y1; y < y2; y++) { |
170 | ping(pingSource); |
171 | for (int x = x1; x < x2; x++) { |
172 | // need a set pixel |
173 | if (!contains(x, y)) continue; |
174 | |
175 | // check if this pixel is essential to hold the structure |
176 | // together by doing a floodfill in the 3x3 neighborhood |
177 | // (simulating the pixel being cleared already) |
178 | |
179 | var imgPattern = ubyteFromBits( |
180 | contains(x-1, y-1), |
181 | contains(x, y-1), |
182 | contains(x+1, y-1), |
183 | contains(x-1, y), |
184 | contains(x+1, y), |
185 | contains(x-1, y+1), |
186 | contains(x, y+1), |
187 | contains(x+1, y+1)); |
188 | |
189 | bool delete = getBit(lookupTable, imgPattern); |
190 | |
191 | printVars ifdef G22RegionThinner_lastPhase_debug( |
192 | +x, +y, +imgPattern, +pixels, +delete); |
193 | |
194 | if (delete) |
195 | change |= clearPixel(x, y); |
196 | } |
197 | } |
198 | ret change; |
199 | } |
200 | } |
Began life as a copy of #1034983
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Snippet ID: | #1035054 |
Snippet name: | G22RegionThinner_v2 - thin a region to 1 pixel wide [backup] |
Eternal ID of this version: | #1035054/1 |
Text MD5: | 99493fe26989d941813764994be20c8e |
Author: | stefan |
Category: | javax |
Type: | JavaX fragment (include) |
Public (visible to everyone): | Yes |
Archived (hidden from active list): | No |
Created/modified: | 2022-03-26 02:53:29 |
Source code size: | 5693 bytes / 200 lines |
Pitched / IR pitched: | No / No |
Views / Downloads: | 179 / 165 |
Referenced in: | [show references] |