public override BitMatrix sampleGrid(BitMatrix image, int dimension, PerspectiveTransform transform)
{
BitMatrix bits = new BitMatrix(dimension);
float[] points = new float[dimension << 1];
for (int y = 0; y < dimension; y++)
{
int max = points.Length;
//UPGRADE_WARNING: Data types in Visual C# might be different. Verify the accuracy of narrowing conversions. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1042'"
float iValue = (float) y + 0.5f;
for (int x = 0; x < max; x += 2)
{
//UPGRADE_WARNING: Data types in Visual C# might be different. Verify the accuracy of narrowing conversions. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1042'"
points[x] = (float) (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)
{
//UPGRADE_WARNING: Data types in Visual C# might be different. Verify the accuracy of narrowing conversions. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1042'"
if (image.get_Renamed((int) points[x], (int) points[x + 1]))
{
// Black(-ish) pixel
bits.set_Renamed(x >> 1, y);
}
}
}
catch (System.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;
}
// Applies a single threshold to an 8x8 block of pixels.
private static void threshold8x8Block(sbyte[] luminances, int xoffset, int yoffset, int threshold, int stride, BitMatrix matrix)
{
for (int y = 0; y < 8; y++)
{
int offset = (yoffset + y) * stride + xoffset;
for (int x = 0; x < 8; x++)
{
int pixel = luminances[offset + x] & 0xff;
if (pixel < threshold)
{
matrix.set_Renamed(xoffset + x, yoffset + y);
}
}
}
}