Transpiled version (13958L) is out of date.
srecord noeq G22RegionThinner_v2<Img extends WidthAndHeight>(IImageRegion<Img> originalRegion) is Steppable { Rect bounds; IImageRegion<Img> region; bool phase1done; settable bool debug; settable bool doFinalStep = true; settable int lastPhaseThreshold1 = 2; settable int lastPhaseThreshold = 5; settable byte[] lookupTable; // 0 = outside of region // 1 = inner pixel // 2 = border pixel // index is in bounds coordinates byte[] pixels; int idx(int x, int y) { ret (y-bounds.y)*bounds.w+x-bounds.x; } int idx(Pt p) { ret idx(p.x, p.y); } Pt idxToPt(int idx) { ret pt(bounds.x+(idx % bounds.w), bounds.y+idx/bounds.w); } byte getPixel(long p) { ret getPixel(firstIntFromLong(p), secondIntFromLong(p)); } byte getPixel(Pt p) { ret !containsPt(bounds, p) ? 0 : pixels[idx(p)]; } byte getPixel(int x, int y) { ret !containsPt(bounds, x, y) ? 0 : pixels[idx(x, y)]; } bool contains(int x, int y) { ret getPixel(x, y) != 0; } bool clearPixel(int x, int y) { if (!region.contains(x, y)) false; pixels[idx(x, y)] = 0; true; } void init { if (bounds != null) ret; bounds = originalRegion.bounds(); pixels = new byte[area(bounds)]; for (Pt p : originalRegion.pixelIterator()) pixels[idx(p.x, p.y)] = 1; region = new ThinnedRegion; } class ThinnedRegion is IImageRegion<Img> { public Img image() { ret originalRegion.image(); } public Rect bounds() { ret bounds; } public bool contains(int x, int y) { ret containsPt(bounds, x, y) && pixels[idx(x, y)] > 0; } public ItIt<Pt> pixelIterator() { ret iff_null(new IF0<Pt> { int idx = 0; public Pt get() { for (; idx < pixels.length; idx++) if (pixels[idx] > 0) ret idxToPt(idx++); null; } }); } } public bool step() { init(); if (phase1done) ret finalStep(); L<PtBuffer> traces = g22_allBorderTraces_withDiagonals(region); for (points : traces) for (p : points) pixels[idx(p)] = 2; new PtBuffer toDelete; for (points : traces) { int nPoints = l(points); BitSet deletable = emptyBitSet(nPoints); for i to nPoints: { bool del = deletableBorderPoint(points, i); /*bool del2 = deletableBorderPoint_old(points, i); if (del != del2) failWithVars("deletableBorderPoint", +i, +nPoints, +del);*/ if (del) deletable.set(i); } // handle special cases // (preventing single isolated pixels from being left standing) for i to nPoints: if (cyclicGet(deletable, nPoints, i-1) && !deletable.get(i) && cyclicGet(deletable, nPoints, i+1)) { Pt p = points.get(i); Pt prev = ptMinus(cyclicGet(points, i-1), p); Pt next = ptMinus(cyclicGet(points, i+1), p); int dir1 = onePathLookupDirection(prev); int dir2 = onePathLookupDirection(next); int diff = mod(dir2-dir1, 8); if (debug) printVars("special case", +p, +prev, +next, +dir1, +dir2, +diff); if (diff == 1 || diff == 7) deletable.set(i); } for i to nPoints: if (deletable.get(i)) toDelete.add(points.get(i)); } for (p : toDelete) pixels[idx(p)] = 0; if (empty(toDelete)) set phase1done; true; } bool deletableBorderPoint(PtBuffer points, int i) { //L<Pt> range = cyclicSubList_incl(points, i-3, i+3); LongBuffer pointsBuf = points.buf; long p_long = pointsBuf.get(i); // special case (sharp corner) if (p_long == cyclicGet(pointsBuf, i-2) || p_long == cyclicGet(pointsBuf, i+2)) { printVars ifdef G22RegionThinner_debug("special case", p := ptFromLong(p_long)); false; } // Basic logic: // a pixel is deletable if at least one inner pixel is next to it // and no "foreign" border pixels are next to it. // This leaves diagonal lines two pixels wide though // which can lead to them eventually shrinking down to nothing // (the "k" problem). // Idea to fix: Ignore foreign border pixels in certain directions int /*surroundingBorderPixels = 0,*/ surroundingInnerPixels = 0; int foreignBorderPixels = 0; for (int dir = 1; dir <= 8; dir++) { long p2_long = onePathDirection_long(p_long, dir); byte value = getPixel(p2_long); if (value == 2 && !rangeContains(pointsBuf, i, p2_long)) { // found a "foreign" border pixel //surroundingBorderPixels++; bool fix = dir == 5 || dir == 7; printVars ifdef G22RegionThinner_debug("surroundingBorderPixel", p := ptFromLong(p_long), +dir, p2 := ptFromLong(p2_long), +fix); // FIX (dev.) //if (dir < 4) false; if (!fix) false; ifdef G22RegionThinner_debug foreignBorderPixels |= 1 << dir; endifdef } else if (value == 1) { printVars ifdef G22RegionThinner_debug("surroundingInnerPixel", p := ptFromLong(p_long), +dir, p2 := ptFromLong(p2_long)); surroundingInnerPixels++; } } bool deletable = /*foreignBorderPixels == 0 &&*/ surroundingInnerPixels > 0; // Fixes for certain problems follow. // Generally, if it's a certain pattern, the pixel must not be deleted. int imgPattern = neighborhoodPattern(firstIntFromLong(p_long), secondIntFromLong(p_long)); if (imgPattern == 0b10011100 // "E" problem || imgPattern == 0b01000111 // "ae" problem || imgPattern == 0b00111001 // "a" problem || imgPattern == 0b00111111 // "a" problem 2 || imgPattern == 0b10111101 // "k" problem ) deletable = false; // These are fixes to delete a pixel. else if (imgPattern == 0b11010110 // "&" problem (2x3 block) ) deletable = true; printVars ifdef G22RegionThinner_debug(p := ptFromLong(p_long), +foreignBorderPixels, +surroundingInnerPixels, +deletable, imgPattern := ubyteToBinary(imgPattern)); // FIX v2 /*if (foreignBorderPixels == ((1 << 4) | (1 << 5) | (1 << 6))) true;*/ ret deletable; } bool rangeContains(LongBuffer pointsBuf, int i, long p2_long) { for (int j = i-3; j <= i+3; j++) if (cyclicGet(pointsBuf, j) == p2_long) true; false; } bool deletableBorderPoint_old(PtBuffer points, int i) { L<Pt> range = cyclicSubList_incl(points, i-3, i+3); Pt p = points.get(i); // special case if (eq(range.get(1), p) || eq(range.get(5), p)) false; int surroundingBorderPixels = 0, surroundingInnerPixels = 0; for (int dir = 1; dir <= 8; dir++) { Pt p2 = ptPlus(p, onePathDirection(dir)); byte value = getPixel(p2); if (value == 2 && !range.contains(p2)) surroundingBorderPixels++; else if (value == 1) surroundingInnerPixels++; } bool deletable = surroundingInnerPixels > 0 && surroundingBorderPixels == 0; printVars ifdef G22RegionThinner_debug(+p, +surroundingInnerPixels, +surroundingBorderPixels, +deletable, +range); ret deletable; } IImageRegion region aka get() { ret or(region, originalRegion); } // go from 2 pixels wide to 1 pixel wide (TODO) bool finalStep() { if (!doFinalStep) false; if (lookupTable == null) lookupTable = new G22RegionThinner_LookupTable() .lastPhaseThreshold(lastPhaseThreshold) .lastPhaseThreshold1(lastPhaseThreshold1)!; bool change; int x1 = bounds.x, x2 = bounds.x2(); int y1 = bounds.y, y2 = bounds.y2(); printVars ifdef G22RegionThinner_lastPhase_debug("finalStep", +x1, +y1, +x2, +y2); var pingSource = pingSource(); for (int y = y1; y < y2; y++) { ping(pingSource); for (int x = x1; x < x2; x++) { // need a set pixel if (!contains(x, y)) continue; int imgPattern = neighborhoodPattern(x, y); // check if this pixel is essential to hold the structure // together by doing a floodfill in the 3x3 neighborhood // (simulating the pixel being cleared already) bool delete = getBit(lookupTable, imgPattern); printVars ifdef G22RegionThinner_lastPhase_debug( +x, +y, +imgPattern, +pixels, +delete); if (delete) change |= clearPixel(x, y); } } ret change; } int neighborhoodPattern(int x, int y) { ret ubyteFromBits( contains(x-1, y-1), contains(x, y-1), contains(x+1, y-1), contains(x-1, y), contains(x+1, y), contains(x-1, y+1), contains(x, y+1), contains(x+1, y+1)); } }
Began life as a copy of #1034965
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Travelled to 4 computer(s): bhatertpkbcr, ekrmjmnbrukm, mowyntqkapby, mqqgnosmbjvj
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