public override BitMatrix sampleGrid(BitMatrix image, int dimension, PerspectiveTransform transform)
{
var bits = new BitMatrix(dimension);
var points = new float[dimension << 1];
for (int y = 0; y < dimension; y++)
{
int max = points.Length;
float iValue = y + 0.5f;
for (int x = 0; x < max; x += 2)
{
points[x] = (x >> 1) + 0.5f;
points[x + 1] = iValue;
}
transform.transformPoints(points);
// Quick check to see if points transformed to something inside the image;
// sufficient to check the endpoints
checkAndNudgePoints(image, points);
try
{
for (int x = 0; x < max; x += 2)
{
if (image.get_Renamed((int) points[x], (int) points[x + 1]))
{
// Black(-ish) pixel
bits.set_Renamed(x >> 1, y);
}
}
}
catch (IndexOutOfRangeException)
{
// This feels wrong, but, sometimes if the finder patterns are misidentified, the resulting
// transform gets "twisted" such that it maps a straight line of points to a set of points
// whose endpoints are in bounds, but others are not. There is probably some mathematical
// way to detect this about the transformation that I don't know yet.
// This results in an ugly runtime exception despite our clever checks above -- can't have
// that. We could check each point's coordinates but that feels duplicative. We settle for
// catching and wrapping ArrayIndexOutOfBoundsException.
throw ReaderException.Instance;
}
}
return bits;
}
private static BitMatrix sampleGrid(BitMatrix image, PerspectiveTransform transform, int dimension)
{
GridSampler sampler = GridSampler.Instance;
return sampler.sampleGrid(image, dimension, transform);
}
