double ExportFileAbstractBase::linearlyInterpolateYRadiusFromTwoPoints (double xThetaValue,
const DocumentModelCoords &modelCoords,
const QPointF &posGraphBefore,
const QPointF &posGraph) const
{
// X coordinate scaling is linear or log
double s;
if (modelCoords.coordScaleXTheta() == COORD_SCALE_LINEAR) {
s = (xThetaValue - posGraphBefore.x()) / (posGraph.x() - posGraphBefore.x());
} else {
s = (qLn (xThetaValue) - qLn (posGraphBefore.x())) / (qLn (posGraph.x()) - qLn (posGraphBefore.x()));
}
// Y coordinate scaling is linear or log
double yRadius;
if (modelCoords.coordScaleYRadius() == COORD_SCALE_LINEAR) {
yRadius = (1.0 - s) * posGraphBefore.y() + s * posGraph.y();
} else {
yRadius = qExp ((1.0 - s) * qLn (posGraphBefore.y()) + s * qLn (posGraph.y()));
}
return yRadius;
}
void Checker::createSide (int pointRadius,
const QList<Point> &points,
const DocumentModelCoords &modelCoords,
double xFrom,
double yFrom,
double xTo,
double yTo,
const Transformation &transformation,
SideSegments &sideSegments)
{
LOG4CPP_INFO_S ((*mainCat)) << "Checker::createSide"
<< " pointRadius=" << pointRadius
<< " xFrom=" << xFrom
<< " yFrom=" << yFrom
<< " xTo=" << xTo
<< " yTo=" << yTo
<< " transformation=" << transformation;
// Originally a complicated algorithm tried to intercept a straight line from (xFrom,yFrom) to (xTo,yTo). That did not work well since:
// 1) Calculations for mostly orthogonal cartesian coordinates worked less well with non-orthogonal polar coordinates
// 2) Ambiguity in polar coordinates between the shorter and longer paths between (theta0,radius) and (theta1,radius)
//
// Current algorithm breaks up the interval between (xMin,yMin) and (xMax,yMax) into many smaller pieces and stitches the
// desired pieces together. For straight lines in linear graphs this algorithm is very much overkill, but there is no significant
// penalty and this approach works in every situation
// Should give single-pixel resolution on most images, and 'good enough' resolution on extremely large images
const int NUM_STEPS = 1000;
bool stateSegmentIsActive = false;
QPointF posStartScreen (0, 0);
// Loop through steps. Final step i=NUM_STEPS does final processing if a segment is active
for (int i = 0; i <= NUM_STEPS; i++) {
double s = (double) i / (double) NUM_STEPS;
// Interpolate coordinates assuming normal linear scaling
double xGraph = (1.0 - s) * xFrom + s * xTo;
double yGraph = (1.0 - s) * yFrom + s * yTo;
// Replace interpolated coordinates using log scaling if appropriate, preserving the same ranges
if (modelCoords.coordScaleXTheta() == COORD_SCALE_LOG) {
xGraph = qExp ((1.0 - s) * qLn (xFrom) + s * qLn (xTo));
}
if (modelCoords.coordScaleYRadius() == COORD_SCALE_LOG) {
yGraph = qExp ((1.0 - s) * qLn (yFrom) + s * qLn (yTo));
}
QPointF pointScreen;
transformation.transformRawGraphToScreen (QPointF (xGraph, yGraph),
pointScreen);
double distanceToNearestPoint = minScreenDistanceFromPoints (pointScreen,
points);
if ((distanceToNearestPoint < pointRadius) ||
(i == NUM_STEPS)) {
// Too close to point, so point is not included in side. Or this is the final iteration of the loop
if (stateSegmentIsActive) {
// State transition
finishActiveSegment (modelCoords,
posStartScreen,
pointScreen,
yFrom,
yTo,
transformation,
sideSegments);
stateSegmentIsActive = false;
}
} else {
// Outside point, so include point in side
if (!stateSegmentIsActive) {
// State transition
stateSegmentIsActive = true;
posStartScreen = pointScreen;
}
}
}
}