float getOutputPixel(PositionType pos)
{
if (!IsValid(pos))
{
return(0);
}
return(m_output[pos.Y * m_imageWidth + pos.X]);
}
byte getPixel(PositionType pos)
{
if (!IsValid(pos))
{
return(0);
}
return(m_image[pos.Y * m_imageWidth + pos.X]);
}
void transformAt(PositionType pos, PositionType target, float distance)
{
target += pos;
if (IsValid(target) && getOutputPixel(target) + distance < getOutputPixel(pos))
{
target = getPosAt(target);
posAt(pos, target);
setOutputPixel(pos, (float)Math.Sqrt((pos.X - target.X) * (pos.X - target.X) + (pos.Y - target.Y) * (pos.Y - target.Y)));
}
}
PositionType posAt(PositionType pos, PositionType value)
{
posBuffer[pos.Y * m_imageWidth + pos.X] = value;
return(value);
}
PositionType getPosAt(PositionType pos)
{
return(posBuffer[pos.Y * m_imageWidth + pos.X]);
}
void setOutputPixel(PositionType pos, float value)
{
m_output[pos.Y * m_imageWidth + pos.X] = value;
}
private bool IsValid(PositionType pos)
{
return(pos.X >= 0 && pos.Y >= 0 && pos.X < m_imageWidth && pos.Y < m_imageHeight);
}
public float[] Transform(float backgroundVal, int [][] closestPoints = null)
{
for (int y = 0; y < m_imageHeight; ++y)
{
for (int x = 0; x < m_imageWidth; ++x)
{
PositionType pos = new PositionType(x, y);
byte center = getPixel(pos);
posAt(pos, pos);
setOutputPixel(pos,
(center != 0 && (getPixel(new PositionType(x - 1, y)) != center || getPixel(new PositionType(x + 1, y)) != center ||
getPixel(new PositionType(x, y - 1)) != center || getPixel(new PositionType(x, y + 1)) != center))
? 0
: backgroundVal
);
}
}
float[] distance = { (float)Math.Sqrt(2.0F), 1.0F, (float)Math.Sqrt(2.0F), 1.0F };
PositionType[] target =
{
new PositionType(-1, -1),
new PositionType(0, -1),
new PositionType(+1, -1),
new PositionType(-1, 0),
};
for (int y = 0; y < m_imageHeight; ++y)
{
for (int x = 0; x < m_imageWidth; ++x)
{
for (int i = 0; i < 4; ++i)
{
transformAt(new PositionType(x, y), target[i], distance[i]);
}
}
}
for (int y = 0; y < m_imageHeight; ++y)
{
for (int x = 0; x < m_imageWidth; ++x)
{
for (int i = 0; i < 4; ++i)
{
transformAt(new PositionType(m_imageWidth - x - 1, m_imageHeight - y - 1), -(target[3 - i]), distance[3 - i]);
}
}
}
for (int y = 0; y < m_imageHeight; ++y)
{
for (int x = 0; x < m_imageWidth; ++x)
{
PositionType pos = new PositionType(x, y);
if (getPixel(pos) != 0)
{
setOutputPixel(pos, -getOutputPixel(pos));
}
if (closestPoints != null)
{
var npos = getPosAt(pos);
closestPoints[pos.Y * m_imageWidth + pos.X] = new[] { npos.X, npos.Y };
}
}
}
return(m_output);
}
