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dmtxregion.c
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/**
* libdmtx - Data Matrix Encoding/Decoding Library
* Copyright 2008, 2009 Mike Laughton. All rights reserved.
* Copyright 2012-2016 Vadim A. Misbakh-Soloviov. All rights reserved.
* Copyright 2016 Tim Zaman. All rights reserved.
*
* See LICENSE file in the main project directory for full
* terms of use and distribution.
*
* Contact:
* Vadim A. Misbakh-Soloviov <[email protected]>
* Mike Laughton <[email protected]>
*
* \file dmtxregion.c
* \brief Detect barcode regions
*/
#define DMTX_HOUGH_RES 180
/**
* \brief Create copy of existing region struct
* \param None
* \return Initialized DmtxRegion struct
*/
extern DmtxRegion *
dmtxRegionCreate(DmtxRegion *reg)
{
DmtxRegion *regCopy;
regCopy = (DmtxRegion *)malloc(sizeof(DmtxRegion));
if(regCopy == NULL)
return NULL;
memcpy(regCopy, reg, sizeof(DmtxRegion));
return regCopy;
}
/**
* \brief Destroy region struct
* \param reg
* \return void
*/
extern DmtxPassFail
dmtxRegionDestroy(DmtxRegion **reg)
{
if(reg == NULL || *reg == NULL)
return DmtxFail;
free(*reg);
*reg = NULL;
return DmtxPass;
}
/**
* \brief Find next barcode region
* \param dec Pointer to DmtxDecode information struct
* \param timeout Pointer to timeout time (NULL if none)
* \return Detected region (if found)
*/
extern DmtxRegion *
dmtxRegionFindNext(DmtxDecode *dec, DmtxTime *timeout)
{
DmtxScanConstraint constraint;
// Functionally these two branches do the same thing even
// if timeout were null, but we use the latter form in order
// to preserve the most short-circuit performance if the
// caller doesn't specify a timeout.
if(timeout != NULL) {
constraint.maxTimeout = timeout;
constraint.maxIterations = 0;
return dmtxRegionFindNextDeterministic(dec, &constraint);
} else {
return dmtxRegionFindNextDeterministic(dec, NULL);
}
}
/**
* \brief Find next barcode region
* \param dec Pointer to DmtxDecode information struct
* \param constraint Pointer to constraint (NULL if no constraints)
* Constraint is an input/output structure.
* Limits will be considered independently. Set to zero/null
* to indicate no-constraint. Actual runtime and iterations,
* as well as termination reason will be filled in upon return
* if constraint is non-null.
*
* \return Detected region (if found)
*/
extern DmtxRegion *
dmtxRegionFindNextDeterministic(DmtxDecode *dec, DmtxScanConstraint *constraint)
{
int locStatus;
int iterations = 0;
DmtxPixelLoc loc;
DmtxRegion *reg;
/* Continue until we find a region or run out of chances */
for(;;) {
locStatus = PopGridLocation(&(dec->grid), &loc);
if(locStatus == DmtxRangeEnd) {
if(constraint != NULL)
constraint->stopCause = DmtxScanNotFound;
break;
}
/* Iterations counts the number of calls to ScanPixel */
++iterations;
/* Scan location for presence of valid barcode region */
reg = dmtxRegionScanPixel(dec, loc.X, loc.Y);
if(reg != NULL) {
if(constraint != NULL) {
constraint->iterations = iterations;
constraint->stopCause = DmtxScanSuccess;
}
return reg;
}
/* Ran out of iterations? */
if(constraint != NULL && constraint->maxIterations != 0 && constraint->maxIterations <= iterations) {
constraint->stopCause = DmtxScanIterLimit;
break;
}
/* Ran out of time? */
if(constraint != NULL && constraint->maxTimeout != NULL && dmtxTimeExceeded(*constraint->maxTimeout)) {
constraint->stopCause = DmtxScanTimeLimit;
break;
}
}
if(constraint)
constraint->iterations = iterations;
return NULL;
}
/**
* \brief Scan individual pixel for presence of barcode edge
* \param dec Pointer to DmtxDecode information struct
* \param loc Pixel location
* \return Detected region (if any)
*/
extern DmtxRegion *
dmtxRegionScanPixel(DmtxDecode *dec, int x, int y)
{
unsigned char *cache;
DmtxRegion reg;
DmtxPointFlow flowBegin;
DmtxPixelLoc loc;
loc.X = x;
loc.Y = y;
cache = dmtxDecodeGetCache(dec, loc.X, loc.Y);
if(cache == NULL)
return NULL;
if((int)(*cache & 0x80) != 0x00)
return NULL;
/* Test for presence of any reasonable edge at this location */
flowBegin = MatrixRegionSeekEdge(dec, loc);
if(flowBegin.mag < (int)(dec->edgeThresh * 7.65 + 0.5))
return NULL;
memset(®, 0x00, sizeof(DmtxRegion));
/* Determine barcode orientation */
if(MatrixRegionOrientation(dec, ®, flowBegin) == DmtxFail)
return NULL;
if(dmtxRegionUpdateXfrms(dec, ®) == DmtxFail)
return NULL;
/* Define top edge */
if(MatrixRegionAlignCalibEdge(dec, ®, DmtxEdgeTop) == DmtxFail)
return NULL;
if(dmtxRegionUpdateXfrms(dec, ®) == DmtxFail)
return NULL;
/* Define right edge */
if(MatrixRegionAlignCalibEdge(dec, ®, DmtxEdgeRight) == DmtxFail)
return NULL;
if(dmtxRegionUpdateXfrms(dec, ®) == DmtxFail)
return NULL;
CALLBACK_MATRIX(®);
/* Calculate the best fitting symbol size */
if(MatrixRegionFindSize(dec, ®) == DmtxFail)
return NULL;
/* Found a valid matrix region */
return dmtxRegionCreate(®);
}
/**
*
*
*/
static DmtxPointFlow
MatrixRegionSeekEdge(DmtxDecode *dec, DmtxPixelLoc loc)
{
int i;
int strongIdx;
int channelCount;
DmtxPointFlow flow, flowPlane[3];
DmtxPointFlow flowPos, flowPosBack;
DmtxPointFlow flowNeg, flowNegBack;
channelCount = dec->image->channelCount;
/* Find whether red, green, or blue shows the strongest edge */
strongIdx = 0;
for(i = 0; i < channelCount; i++) {
flowPlane[i] = GetPointFlow(dec, i, loc, dmtxNeighborNone);
if(i > 0 && flowPlane[i].mag > flowPlane[strongIdx].mag)
strongIdx = i;
}
if(flowPlane[strongIdx].mag < 10)
return dmtxBlankEdge;
flow = flowPlane[strongIdx];
flowPos = FindStrongestNeighbor(dec, flow, +1);
flowNeg = FindStrongestNeighbor(dec, flow, -1);
if(flowPos.mag != 0 && flowNeg.mag != 0) {
flowPosBack = FindStrongestNeighbor(dec, flowPos, -1);
flowNegBack = FindStrongestNeighbor(dec, flowNeg, +1);
if(flowPos.arrive == (flowPosBack.arrive+4)%8 &&
flowNeg.arrive == (flowNegBack.arrive+4)%8) {
flow.arrive = dmtxNeighborNone;
CALLBACK_POINT_PLOT(flow.loc, 1, 1, 1);
return flow;
}
}
return dmtxBlankEdge;
}
/**
*
*
*/
static DmtxPassFail
MatrixRegionOrientation(DmtxDecode *dec, DmtxRegion *reg, DmtxPointFlow begin)
{
int cross;
int minArea;
int scale;
int symbolShape;
int maxDiagonal;
DmtxPassFail err;
DmtxBestLine line1x, line2x;
DmtxBestLine line2n, line2p;
DmtxFollow fTmp;
if(dec->sizeIdxExpected == DmtxSymbolSquareAuto ||
(dec->sizeIdxExpected >= DmtxSymbol10x10 &&
dec->sizeIdxExpected <= DmtxSymbol144x144))
symbolShape = DmtxSymbolSquareAuto;
else if(dec->sizeIdxExpected == DmtxSymbolRectAuto ||
(dec->sizeIdxExpected >= DmtxSymbol8x18 &&
dec->sizeIdxExpected <= DmtxSymbol16x48))
symbolShape = DmtxSymbolRectAuto;
else
symbolShape = DmtxSymbolShapeAuto;
if(dec->edgeMax != DmtxUndefined) {
if(symbolShape == DmtxSymbolRectAuto)
maxDiagonal = (int)(1.23 * dec->edgeMax + 0.5); /* sqrt(5/4) + 10% */
else
maxDiagonal = (int)(1.56 * dec->edgeMax + 0.5); /* sqrt(2) + 10% */
}
else {
maxDiagonal = DmtxUndefined;
}
/* Follow to end in both directions */
err = TrailBlazeContinuous(dec, reg, begin, maxDiagonal);
if(err == DmtxFail || reg->stepsTotal < 40) {
TrailClear(dec, reg, 0x40);
return DmtxFail;
}
/* Filter out region candidates that are smaller than expected */
if(dec->edgeMin != DmtxUndefined) {
scale = dmtxDecodeGetProp(dec, DmtxPropScale);
if(symbolShape == DmtxSymbolSquareAuto)
minArea = (dec->edgeMin * dec->edgeMin)/(scale * scale);
else
minArea = (2 * dec->edgeMin * dec->edgeMin)/(scale * scale);
if((reg->boundMax.X - reg->boundMin.X) * (reg->boundMax.Y - reg->boundMin.Y) < minArea) {
TrailClear(dec, reg, 0x40);
return DmtxFail;
}
}
line1x = FindBestSolidLine(dec, reg, 0, 0, +1, DmtxUndefined);
if(line1x.mag < 5) {
TrailClear(dec, reg, 0x40);
return DmtxFail;
}
err = FindTravelLimits(dec, reg, &line1x);
if(line1x.distSq < 100 || line1x.devn * 10 >= sqrt((double)line1x.distSq)) {
TrailClear(dec, reg, 0x40);
return DmtxFail;
}
assert(line1x.stepPos >= line1x.stepNeg);
fTmp = FollowSeek(dec, reg, line1x.stepPos + 5);
line2p = FindBestSolidLine(dec, reg, fTmp.step, line1x.stepNeg, +1, line1x.angle);
fTmp = FollowSeek(dec, reg, line1x.stepNeg - 5);
line2n = FindBestSolidLine(dec, reg, fTmp.step, line1x.stepPos, -1, line1x.angle);
if(max(line2p.mag, line2n.mag) < 5)
return DmtxFail;
if(line2p.mag > line2n.mag) {
line2x = line2p;
err = FindTravelLimits(dec, reg, &line2x);
if(line2x.distSq < 100 || line2x.devn * 10 >= sqrt((double)line2x.distSq))
return DmtxFail;
cross = ((line1x.locPos.X - line1x.locNeg.X) * (line2x.locPos.Y - line2x.locNeg.Y)) -
((line1x.locPos.Y - line1x.locNeg.Y) * (line2x.locPos.X - line2x.locNeg.X));
if(cross > 0) {
/* Condition 2 */
reg->polarity = +1;
reg->locR = line2x.locPos;
reg->stepR = line2x.stepPos;
reg->locT = line1x.locNeg;
reg->stepT = line1x.stepNeg;
reg->leftLoc = line1x.locBeg;
reg->leftAngle = line1x.angle;
reg->bottomLoc = line2x.locBeg;
reg->bottomAngle = line2x.angle;
reg->leftLine = line1x;
reg->bottomLine = line2x;
}
else {
/* Condition 3 */
reg->polarity = -1;
reg->locR = line1x.locNeg;
reg->stepR = line1x.stepNeg;
reg->locT = line2x.locPos;
reg->stepT = line2x.stepPos;
reg->leftLoc = line2x.locBeg;
reg->leftAngle = line2x.angle;
reg->bottomLoc = line1x.locBeg;
reg->bottomAngle = line1x.angle;
reg->leftLine = line2x;
reg->bottomLine = line1x;
}
}
else {
line2x = line2n;
err = FindTravelLimits(dec, reg, &line2x);
if(line2x.distSq < 100 || line2x.devn / sqrt((double)line2x.distSq) >= 0.1)
return DmtxFail;
cross = ((line1x.locNeg.X - line1x.locPos.X) * (line2x.locNeg.Y - line2x.locPos.Y)) -
((line1x.locNeg.Y - line1x.locPos.Y) * (line2x.locNeg.X - line2x.locPos.X));
if(cross > 0) {
/* Condition 1 */
reg->polarity = -1;
reg->locR = line2x.locNeg;
reg->stepR = line2x.stepNeg;
reg->locT = line1x.locPos;
reg->stepT = line1x.stepPos;
reg->leftLoc = line1x.locBeg;
reg->leftAngle = line1x.angle;
reg->bottomLoc = line2x.locBeg;
reg->bottomAngle = line2x.angle;
reg->leftLine = line1x;
reg->bottomLine = line2x;
}
else {
/* Condition 4 */
reg->polarity = +1;
reg->locR = line1x.locPos;
reg->stepR = line1x.stepPos;
reg->locT = line2x.locNeg;
reg->stepT = line2x.stepNeg;
reg->leftLoc = line2x.locBeg;
reg->leftAngle = line2x.angle;
reg->bottomLoc = line1x.locBeg;
reg->bottomAngle = line1x.angle;
reg->leftLine = line2x;
reg->bottomLine = line1x;
}
}
/* CALLBACK_POINT_PLOT(reg->locR, 2, 1, 1);
CALLBACK_POINT_PLOT(reg->locT, 2, 1, 1); */
reg->leftKnown = reg->bottomKnown = 1;
return DmtxPass;
}
/**
*
*
*/
static long
DistanceSquared(DmtxPixelLoc a, DmtxPixelLoc b)
{
long xDelta, yDelta;
xDelta = a.X - b.X;
yDelta = a.Y - b.Y;
return (xDelta * xDelta) + (yDelta * yDelta);
}
/**
*
*
*/
extern DmtxPassFail
dmtxRegionUpdateCorners(DmtxDecode *dec, DmtxRegion *reg, DmtxVector2 p00,
DmtxVector2 p10, DmtxVector2 p11, DmtxVector2 p01)
{
double xMax, yMax;
double tx, ty, phi, shx, scx, scy, skx, sky;
double dimOT, dimOR, dimTX, dimRX, ratio;
DmtxVector2 vOT, vOR, vTX, vRX, vTmp;
DmtxMatrix3 m, mtxy, mphi, mshx, mscx, mscy, mscxy, msky, mskx;
xMax = (double)(dmtxDecodeGetProp(dec, DmtxPropWidth) - 1);
yMax = (double)(dmtxDecodeGetProp(dec, DmtxPropHeight) - 1);
if(p00.X < 0.0 || p00.Y < 0.0 || p00.X > xMax || p00.Y > yMax ||
p01.X < 0.0 || p01.Y < 0.0 || p01.X > xMax || p01.Y > yMax ||
p10.X < 0.0 || p10.Y < 0.0 || p10.X > xMax || p10.Y > yMax)
return DmtxFail;
dimOT = dmtxVector2Mag(dmtxVector2Sub(&vOT, &p01, &p00)); /* XXX could use MagSquared() */
dimOR = dmtxVector2Mag(dmtxVector2Sub(&vOR, &p10, &p00));
dimTX = dmtxVector2Mag(dmtxVector2Sub(&vTX, &p11, &p01));
dimRX = dmtxVector2Mag(dmtxVector2Sub(&vRX, &p11, &p10));
/* Verify that sides are reasonably long */
if(dimOT <= 8.0 || dimOR <= 8.0 || dimTX <= 8.0 || dimRX <= 8.0)
return DmtxFail;
/* Verify that the 4 corners define a reasonably fat quadrilateral */
ratio = dimOT / dimRX;
if(ratio <= 0.5 || ratio >= 2.0)
return DmtxFail;
ratio = dimOR / dimTX;
if(ratio <= 0.5 || ratio >= 2.0)
return DmtxFail;
/* Verify this is not a bowtie shape */
if(dmtxVector2Cross(&vOR, &vRX) <= 0.0 ||
dmtxVector2Cross(&vOT, &vTX) >= 0.0)
return DmtxFail;
if(RightAngleTrueness(p00, p10, p11, M_PI_2) <= dec->squareDevn)
return DmtxFail;
if(RightAngleTrueness(p10, p11, p01, M_PI_2) <= dec->squareDevn)
return DmtxFail;
/* Calculate values needed for transformations */
tx = -1 * p00.X;
ty = -1 * p00.Y;
dmtxMatrix3Translate(mtxy, tx, ty);
phi = atan2(vOT.X, vOT.Y);
dmtxMatrix3Rotate(mphi, phi);
dmtxMatrix3Multiply(m, mtxy, mphi);
dmtxMatrix3VMultiply(&vTmp, &p10, m);
shx = -vTmp.Y / vTmp.X;
dmtxMatrix3Shear(mshx, 0.0, shx);
dmtxMatrix3MultiplyBy(m, mshx);
scx = 1.0/vTmp.X;
dmtxMatrix3Scale(mscx, scx, 1.0);
dmtxMatrix3MultiplyBy(m, mscx);
dmtxMatrix3VMultiply(&vTmp, &p11, m);
scy = 1.0/vTmp.Y;
dmtxMatrix3Scale(mscy, 1.0, scy);
dmtxMatrix3MultiplyBy(m, mscy);
dmtxMatrix3VMultiply(&vTmp, &p11, m);
skx = vTmp.X;
dmtxMatrix3LineSkewSide(mskx, 1.0, skx, 1.0);
dmtxMatrix3MultiplyBy(m, mskx);
dmtxMatrix3VMultiply(&vTmp, &p01, m);
sky = vTmp.Y;
dmtxMatrix3LineSkewTop(msky, sky, 1.0, 1.0);
dmtxMatrix3Multiply(reg->raw2fit, m, msky);
/* Create inverse matrix by reverse (avoid straight matrix inversion) */
dmtxMatrix3LineSkewTopInv(msky, sky, 1.0, 1.0);
dmtxMatrix3LineSkewSideInv(mskx, 1.0, skx, 1.0);
dmtxMatrix3Multiply(m, msky, mskx);
dmtxMatrix3Scale(mscxy, 1.0/scx, 1.0/scy);
dmtxMatrix3MultiplyBy(m, mscxy);
dmtxMatrix3Shear(mshx, 0.0, -shx);
dmtxMatrix3MultiplyBy(m, mshx);
dmtxMatrix3Rotate(mphi, -phi);
dmtxMatrix3MultiplyBy(m, mphi);
dmtxMatrix3Translate(mtxy, -tx, -ty);
dmtxMatrix3Multiply(reg->fit2raw, m, mtxy);
return DmtxPass;
}
/**
*
*
*/
extern DmtxPassFail
dmtxRegionUpdateXfrms(DmtxDecode *dec, DmtxRegion *reg)
{
double radians;
DmtxRay2 rLeft, rBottom, rTop, rRight;
DmtxVector2 p00, p10, p11, p01;
assert(reg->leftKnown != 0 && reg->bottomKnown != 0);
/* Build ray representing left edge */
rLeft.p.X = (double)reg->leftLoc.X;
rLeft.p.Y = (double)reg->leftLoc.Y;
radians = reg->leftAngle * (M_PI/DMTX_HOUGH_RES);
rLeft.v.X = cos(radians);
rLeft.v.Y = sin(radians);
rLeft.tMin = 0.0;
rLeft.tMax = dmtxVector2Norm(&rLeft.v);
/* Build ray representing bottom edge */
rBottom.p.X = (double)reg->bottomLoc.X;
rBottom.p.Y = (double)reg->bottomLoc.Y;
radians = reg->bottomAngle * (M_PI/DMTX_HOUGH_RES);
rBottom.v.X = cos(radians);
rBottom.v.Y = sin(radians);
rBottom.tMin = 0.0;
rBottom.tMax = dmtxVector2Norm(&rBottom.v);
/* Build ray representing top edge */
if(reg->topKnown != 0) {
rTop.p.X = (double)reg->topLoc.X;
rTop.p.Y = (double)reg->topLoc.Y;
radians = reg->topAngle * (M_PI/DMTX_HOUGH_RES);
rTop.v.X = cos(radians);
rTop.v.Y = sin(radians);
rTop.tMin = 0.0;
rTop.tMax = dmtxVector2Norm(&rTop.v);
}
else {
rTop.p.X = (double)reg->locT.X;
rTop.p.Y = (double)reg->locT.Y;
radians = reg->bottomAngle * (M_PI/DMTX_HOUGH_RES);
rTop.v.X = cos(radians);
rTop.v.Y = sin(radians);
rTop.tMin = 0.0;
rTop.tMax = rBottom.tMax;
}
/* Build ray representing right edge */
if(reg->rightKnown != 0) {
rRight.p.X = (double)reg->rightLoc.X;
rRight.p.Y = (double)reg->rightLoc.Y;
radians = reg->rightAngle * (M_PI/DMTX_HOUGH_RES);
rRight.v.X = cos(radians);
rRight.v.Y = sin(radians);
rRight.tMin = 0.0;
rRight.tMax = dmtxVector2Norm(&rRight.v);
}
else {
rRight.p.X = (double)reg->locR.X;
rRight.p.Y = (double)reg->locR.Y;
radians = reg->leftAngle * (M_PI/DMTX_HOUGH_RES);
rRight.v.X = cos(radians);
rRight.v.Y = sin(radians);
rRight.tMin = 0.0;
rRight.tMax = rLeft.tMax;
}
/* Calculate 4 corners, real or imagined */
if(dmtxRay2Intersect(&p00, &rLeft, &rBottom) == DmtxFail)
return DmtxFail;
if(dmtxRay2Intersect(&p10, &rBottom, &rRight) == DmtxFail)
return DmtxFail;
if(dmtxRay2Intersect(&p11, &rRight, &rTop) == DmtxFail)
return DmtxFail;
if(dmtxRay2Intersect(&p01, &rTop, &rLeft) == DmtxFail)
return DmtxFail;
if(dmtxRegionUpdateCorners(dec, reg, p00, p10, p11, p01) != DmtxPass)
return DmtxFail;
return DmtxPass;
}
/**
*
*
*/
static double
RightAngleTrueness(DmtxVector2 c0, DmtxVector2 c1, DmtxVector2 c2, double angle)
{
DmtxVector2 vA, vB;
DmtxMatrix3 m;
dmtxVector2Norm(dmtxVector2Sub(&vA, &c0, &c1));
dmtxVector2Norm(dmtxVector2Sub(&vB, &c2, &c1));
dmtxMatrix3Rotate(m, angle);
dmtxMatrix3VMultiplyBy(&vB, m);
return dmtxVector2Dot(&vA, &vB);
}
/**
* \brief Read color of Data Matrix module location
* \param dec
* \param reg
* \param symbolRow
* \param symbolCol
* \param sizeIdx
* \return Averaged module color
*/
static int
ReadModuleColor(DmtxDecode *dec, DmtxRegion *reg, int symbolRow, int symbolCol,
int sizeIdx, int colorPlane)
{
int i;
int symbolRows, symbolCols;
int color, colorTmp;
double sampleX[] = { 0.5, 0.4, 0.5, 0.6, 0.5 };
double sampleY[] = { 0.5, 0.5, 0.4, 0.5, 0.6 };
DmtxVector2 p;
symbolRows = dmtxGetSymbolAttribute(DmtxSymAttribSymbolRows, sizeIdx);
symbolCols = dmtxGetSymbolAttribute(DmtxSymAttribSymbolCols, sizeIdx);
color = 0;
for(i = 0; i < 5; i++) {
p.X = (1.0/symbolCols) * (symbolCol + sampleX[i]);
p.Y = (1.0/symbolRows) * (symbolRow + sampleY[i]);
dmtxMatrix3VMultiplyBy(&p, reg->fit2raw);
//fprintf(stdout, "%dx%d\n", (int)(p.X + 0.5), (int)(p.Y + 0.5));
dmtxDecodeGetPixelValue(dec, (int)(p.X + 0.5), (int)(p.Y + 0.5),
colorPlane, &colorTmp);
color += colorTmp;
}
//fprintf(stdout, "\n");
return color/5;
}
/**
* \brief Determine barcode size, expressed in modules
* \param image
* \param reg
* \return DmtxPass | DmtxFail
*/
static DmtxPassFail
MatrixRegionFindSize(DmtxDecode *dec, DmtxRegion *reg)
{
int row, col;
int sizeIdxBeg, sizeIdxEnd;
int sizeIdx, bestSizeIdx;
int symbolRows, symbolCols;
int jumpCount, errors;
int color;
int colorOnAvg, bestColorOnAvg;
int colorOffAvg, bestColorOffAvg;
int contrast, bestContrast;
// DmtxImage *img;
// img = dec->image;
bestSizeIdx = DmtxUndefined;
bestContrast = 0;
bestColorOnAvg = bestColorOffAvg = 0;
if(dec->sizeIdxExpected == DmtxSymbolShapeAuto) {
sizeIdxBeg = 0;
sizeIdxEnd = DmtxSymbolSquareCount + DmtxSymbolRectCount;
}
else if(dec->sizeIdxExpected == DmtxSymbolSquareAuto) {
sizeIdxBeg = 0;
sizeIdxEnd = DmtxSymbolSquareCount;
}
else if(dec->sizeIdxExpected == DmtxSymbolRectAuto) {
sizeIdxBeg = DmtxSymbolSquareCount;
sizeIdxEnd = DmtxSymbolSquareCount + DmtxSymbolRectCount;
}
else {
sizeIdxBeg = dec->sizeIdxExpected;
sizeIdxEnd = dec->sizeIdxExpected + 1;
}
/* Test each barcode size to find best contrast in calibration modules */
for(sizeIdx = sizeIdxBeg; sizeIdx < sizeIdxEnd; sizeIdx++) {
symbolRows = dmtxGetSymbolAttribute(DmtxSymAttribSymbolRows, sizeIdx);
symbolCols = dmtxGetSymbolAttribute(DmtxSymAttribSymbolCols, sizeIdx);
colorOnAvg = colorOffAvg = 0;
/* Sum module colors along horizontal calibration bar */
row = symbolRows - 1;
for(col = 0; col < symbolCols; col++) {
color = ReadModuleColor(dec, reg, row, col, sizeIdx, reg->flowBegin.plane);
if((col & 0x01) != 0x00)
colorOffAvg += color;
else
colorOnAvg += color;
}
/* Sum module colors along vertical calibration bar */
col = symbolCols - 1;
for(row = 0; row < symbolRows; row++) {
color = ReadModuleColor(dec, reg, row, col, sizeIdx, reg->flowBegin.plane);
if((row & 0x01) != 0x00)
colorOffAvg += color;
else
colorOnAvg += color;
}
colorOnAvg = (colorOnAvg * 2)/(symbolRows + symbolCols);
colorOffAvg = (colorOffAvg * 2)/(symbolRows + symbolCols);
contrast = abs(colorOnAvg - colorOffAvg);
if(contrast < 20)
continue;
if(contrast > bestContrast) {
bestContrast = contrast;
bestSizeIdx = sizeIdx;
bestColorOnAvg = colorOnAvg;
bestColorOffAvg = colorOffAvg;
}
}
/* If no sizes produced acceptable contrast then call it quits */
if(bestSizeIdx == DmtxUndefined || bestContrast < 20)
return DmtxFail;
reg->sizeIdx = bestSizeIdx;
reg->onColor = bestColorOnAvg;
reg->offColor = bestColorOffAvg;
reg->symbolRows = dmtxGetSymbolAttribute(DmtxSymAttribSymbolRows, reg->sizeIdx);
reg->symbolCols = dmtxGetSymbolAttribute(DmtxSymAttribSymbolCols, reg->sizeIdx);
reg->mappingRows = dmtxGetSymbolAttribute(DmtxSymAttribMappingMatrixRows, reg->sizeIdx);
reg->mappingCols = dmtxGetSymbolAttribute(DmtxSymAttribMappingMatrixCols, reg->sizeIdx);
/* Tally jumps on horizontal calibration bar to verify sizeIdx */
jumpCount = CountJumpTally(dec, reg, 0, reg->symbolRows - 1, DmtxDirRight);
errors = abs(1 + jumpCount - reg->symbolCols);
if(jumpCount < 0 || errors > 2)
return DmtxFail;
/* Tally jumps on vertical calibration bar to verify sizeIdx */
jumpCount = CountJumpTally(dec, reg, reg->symbolCols - 1, 0, DmtxDirUp);
errors = abs(1 + jumpCount - reg->symbolRows);
if(jumpCount < 0 || errors > 2)
return DmtxFail;
/* Tally jumps on horizontal finder bar to verify sizeIdx */
errors = CountJumpTally(dec, reg, 0, 0, DmtxDirRight);
if(jumpCount < 0 || errors > 2)
return DmtxFail;
/* Tally jumps on vertical finder bar to verify sizeIdx */
errors = CountJumpTally(dec, reg, 0, 0, DmtxDirUp);
if(errors < 0 || errors > 2)
return DmtxFail;
/* Tally jumps on surrounding whitespace, else fail */
errors = CountJumpTally(dec, reg, 0, -1, DmtxDirRight);
if(errors < 0 || errors > 2)
return DmtxFail;
errors = CountJumpTally(dec, reg, -1, 0, DmtxDirUp);
if(errors < 0 || errors > 2)
return DmtxFail;
errors = CountJumpTally(dec, reg, 0, reg->symbolRows, DmtxDirRight);
if(errors < 0 || errors > 2)
return DmtxFail;
errors = CountJumpTally(dec, reg, reg->symbolCols, 0, DmtxDirUp);
if(errors < 0 || errors > 2)
return DmtxFail;
return DmtxPass;
}
/**
* \brief Count the number of number of transitions between light and dark
* \param img
* \param reg
* \param xStart
* \param yStart
* \param dir
* \return Jump count
*/
static int
CountJumpTally(DmtxDecode *dec, DmtxRegion *reg, int xStart, int yStart, DmtxDirection dir)
{
int x, xInc = 0;
int y, yInc = 0;
int state = DmtxModuleOn;
int jumpCount = 0;
int jumpThreshold;
int tModule, tPrev;
int darkOnLight;
int color;
assert(xStart == 0 || yStart == 0);
assert(dir == DmtxDirRight || dir == DmtxDirUp);
if(dir == DmtxDirRight)
xInc = 1;
else
yInc = 1;
if(xStart == -1 || xStart == reg->symbolCols ||
yStart == -1 || yStart == reg->symbolRows)
state = DmtxModuleOff;
darkOnLight = (int)(reg->offColor > reg->onColor);
jumpThreshold = abs((int)(0.4 * (reg->onColor - reg->offColor) + 0.5));
color = ReadModuleColor(dec, reg, yStart, xStart, reg->sizeIdx, reg->flowBegin.plane);
tModule = (darkOnLight) ? reg->offColor - color : color - reg->offColor;
for(x = xStart + xInc, y = yStart + yInc;
(dir == DmtxDirRight && x < reg->symbolCols) ||
(dir == DmtxDirUp && y < reg->symbolRows);
x += xInc, y += yInc) {
tPrev = tModule;
color = ReadModuleColor(dec, reg, y, x, reg->sizeIdx, reg->flowBegin.plane);
tModule = (darkOnLight) ? reg->offColor - color : color - reg->offColor;
if(state == DmtxModuleOff) {
if(tModule > tPrev + jumpThreshold) {
jumpCount++;
state = DmtxModuleOn;
}
}
else {
if(tModule < tPrev - jumpThreshold) {
jumpCount++;
state = DmtxModuleOff;
}
}
}
return jumpCount;
}
/**
*
*
*/
static DmtxPointFlow
GetPointFlow(DmtxDecode *dec, int colorPlane, DmtxPixelLoc loc, int arrive)
{
static const int coefficient[] = { 0, 1, 2, 1, 0, -1, -2, -1 };
int err;
int patternIdx, coefficientIdx;
int compass, compassMax;
int mag[4] = { 0 };
int xAdjust, yAdjust;
int color, colorPattern[8];
DmtxPointFlow flow;
for(patternIdx = 0; patternIdx < 8; patternIdx++) {
xAdjust = loc.X + dmtxPatternX[patternIdx];
yAdjust = loc.Y + dmtxPatternY[patternIdx];
err = dmtxDecodeGetPixelValue(dec, xAdjust, yAdjust, colorPlane,
&colorPattern[patternIdx]);
if(err == DmtxFail)
return dmtxBlankEdge;
}
/* Calculate this pixel's flow intensity for each direction (-45, 0, 45, 90) */
compassMax = 0;
for(compass = 0; compass < 4; compass++) {
/* Add portion from each position in the convolution matrix pattern */
for(patternIdx = 0; patternIdx < 8; patternIdx++) {
coefficientIdx = (patternIdx - compass + 8) % 8;
if(coefficient[coefficientIdx] == 0)
continue;
color = colorPattern[patternIdx];
switch(coefficient[coefficientIdx]) {
case 2:
mag[compass] += color;
/* Fall through */
case 1:
mag[compass] += color;
break;
case -2:
mag[compass] -= color;
/* Fall through */
case -1:
mag[compass] -= color;
break;
}
}
/* Identify strongest compass flow */
if(compass != 0 && abs(mag[compass]) > abs(mag[compassMax]))
compassMax = compass;
}
/* Convert signed compass direction into unique flow directions (0-7) */
flow.plane = colorPlane;
flow.arrive = arrive;
flow.depart = (mag[compassMax] > 0) ? compassMax + 4 : compassMax;
flow.mag = abs(mag[compassMax]);
flow.loc = loc;
return flow;
}
/**
*
*
*/
static DmtxPointFlow
FindStrongestNeighbor(DmtxDecode *dec, DmtxPointFlow center, int sign)
{
int i;
int strongIdx;
int attempt, attemptDiff;
int occupied;
unsigned char *cache;
DmtxPixelLoc loc;
DmtxPointFlow flow[8];
attempt = (sign < 0) ? center.depart : (center.depart+4)%8;
occupied = 0;
strongIdx = DmtxUndefined;
for(i = 0; i < 8; i++) {
loc.X = center.loc.X + dmtxPatternX[i];
loc.Y = center.loc.Y + dmtxPatternY[i];
cache = dmtxDecodeGetCache(dec, loc.X, loc.Y);
if(cache == NULL)
continue;
if((int)(*cache & 0x80) != 0x00) {
if(++occupied > 2)
return dmtxBlankEdge;
else
continue;
}
attemptDiff = abs(attempt - i);
if(attemptDiff > 4)
attemptDiff = 8 - attemptDiff;
if(attemptDiff > 1)
continue;
flow[i] = GetPointFlow(dec, center.plane, loc, i);
if(strongIdx == DmtxUndefined || flow[i].mag > flow[strongIdx].mag ||
(flow[i].mag == flow[strongIdx].mag && ((i & 0x01) != 0))) {
strongIdx = i;
}
}
return (strongIdx == DmtxUndefined) ? dmtxBlankEdge : flow[strongIdx];
}
/**
*