public override void Apply(byte **p, int length, int width, int height)
{
byte *ptr = *p;
int bpp = length / width / height;
int stride = length / height;
var tmpOnes = new List <int>();
for (int i = stride + bpp; i < stride * height - stride - bpp; i += bpp)
{
if (ptr[i] == One)
{
tmpOnes.Add(i);
}
}
int[] ones = tmpOnes.ToArray();
bool hasDeleted = true;
while (hasDeleted)
{
hasDeleted = false;
foreach (int i in ones)
{
if (ptr[i + 3] == Zero || ptr[i + stride] == Zero ||
ptr[i - 3] == Zero || ptr[i - stride] == Zero)
{
ptr[i] = ptr[i + 1] = ptr[i + 2] = Two;
}
}
foreach (int i in ones)
{
if (ptr[i] != Two && (
ptr[i + stride + 3] == Zero || ptr[i + stride - 3] == Zero ||
ptr[i - stride + 3] == Zero || ptr[i - stride - 3] == Zero))
{
ptr[i] = ptr[i + 1] = ptr[i + 2] = Three;
}
}
foreach (int i in ones)
{
if (Fours.Contains(ComputeSum(i)))
{
ptr[i] = ptr[i + 1] = ptr[i + 2] = Four;
}
}
foreach (int i in ones)
{
if (ptr[i] == Four && Deletion.Contains(ComputeSum(i)))
{
ptr[i] = ptr[i + 1] = ptr[i + 2] = Zero;
}
}
foreach (int i in ones)
{
if (ptr[i] == Two && Deletion.Contains(ComputeSum(i)))
{
ptr[i] = ptr[i + 1] = ptr[i + 2] = Zero;
hasDeleted = true;
}
}
foreach (int i in ones)
{
if (ptr[i] == Three && Deletion.Contains(ComputeSum(i)))
{
ptr[i] = ptr[i + 1] = ptr[i + 2] = Zero;
hasDeleted = true;
}
}
var tmp = new List <int>(ones.Length >> 1);
for (int i = 0; i < ones.Length; i++)
{
if (ptr[ones[i]] != Zero)
{
tmp.Add(ones[i]);
}
}
ones = tmp.ToArray();
}
int ComputeSum(int sumOffset)
{
int sum = 0;
if (ptr[sumOffset + bpp] != Zero)
{
sum += Matrix[5];
}
if (ptr[sumOffset - bpp] != Zero)
{
sum += Matrix[3];
}
sumOffset += stride;
if (ptr[sumOffset + bpp] != Zero)
{
sum += Matrix[2];
}
if (ptr[sumOffset] != Zero)
{
sum += Matrix[1];
}
if (ptr[sumOffset - bpp] != Zero)
{
sum += Matrix[0];
}
sumOffset -= stride + stride;
if (ptr[sumOffset + bpp] != Zero)
{
sum += Matrix[8];
}
if (ptr[sumOffset] != Zero)
{
sum += Matrix[7];
}
if (ptr[sumOffset - bpp] != Zero)
{
sum += Matrix[6];
}
return(sum);
}
}
public static unsafe Bitmap GetSkeletonization(this Bitmap sourceBitmap)
{
BitmapData data = sourceBitmap.LockBits(
new System.Drawing.Rectangle(System.Drawing.Point.Empty, sourceBitmap.Size),
ImageLockMode.ReadWrite,
System.Drawing.Imaging.PixelFormat.Format24bppRgb
);
byte[] p = new byte[data.Stride * data.Height];
Marshal.Copy(data.Scan0, p, 0, p.Length);
sourceBitmap.UnlockBits(data);
int length = data.Stride * sourceBitmap.Height;
int bpp = length / sourceBitmap.Width / sourceBitmap.Height;
var tmpOnes = new List <int>();
for (int i = data.Stride + bpp; i < data.Stride * sourceBitmap.Height - data.Stride - bpp; i += bpp)
{
if (p[i] == One)
{
tmpOnes.Add(i);
}
}
int[] ones = tmpOnes.ToArray();
bool hasDeleted = true;
while (hasDeleted)
{
hasDeleted = false;
foreach (int i in ones)
{
if (p[i + 3] == Zero || p[i + data.Stride] == Zero ||
p[i - 3] == Zero || p[i - data.Stride] == Zero)
{
p[i] = p[i + 1] = p[i + 2] = Two;
}
}
foreach (int i in ones)
{
if (p[i] != Two && (
p[i + data.Stride + 3] == Zero || p[i + data.Stride - 3] == Zero ||
p[i - data.Stride + 3] == Zero || p[i - data.Stride - 3] == Zero))
{
p[i] = p[i + 1] = p[i + 2] = Three;
}
}
foreach (int i in ones)
{
if (Fours.Contains(ComputeSum(i)))
{
p[i] = p[i + 1] = p[i + 2] = Four;
}
}
foreach (int i in ones)
{
if (p[i] == Four && Deletion.Contains(ComputeSum(i)))
{
p[i] = p[i + 1] = p[i + 2] = Zero;
}
}
foreach (int i in ones)
{
if (p[i] == Two && Deletion.Contains(ComputeSum(i)))
{
p[i] = p[i + 1] = p[i + 2] = Zero;
hasDeleted = true;
}
}
foreach (int i in ones)
{
if (p[i] == Three && Deletion.Contains(ComputeSum(i)))
{
p[i] = p[i + 1] = p[i + 2] = Zero;
hasDeleted = true;
}
}
var tmp = new List <int>(ones.Length >> 1);
for (int i = 0; i < ones.Length; i++)
{
if (p[ones[i]] != Zero)
{
tmp.Add(ones[i]);
}
}
ones = tmp.ToArray();
}
int ComputeSum(int sumOffset)
{
int sum = 0;
if (p[sumOffset + bpp] != Zero)
{
sum += Matrix[5];
}
if (p[sumOffset - bpp] != Zero)
{
sum += Matrix[3];
}
sumOffset += data.Stride;
if (p[sumOffset + bpp] != Zero)
{
sum += Matrix[2];
}
if (p[sumOffset] != Zero)
{
sum += Matrix[1];
}
if (p[sumOffset - bpp] != Zero)
{
sum += Matrix[0];
}
sumOffset -= data.Stride + data.Stride;
if (p[sumOffset + bpp] != Zero)
{
sum += Matrix[8];
}
if (p[sumOffset] != Zero)
{
sum += Matrix[7];
}
if (p[sumOffset - bpp] != Zero)
{
sum += Matrix[6];
}
return(sum);
}
Bitmap resultBitmap = new Bitmap(sourceBitmap.Width, sourceBitmap.Height);
BitmapData resultData = resultBitmap.LockBits(new Rectangle(0, 0, resultBitmap.Width, resultBitmap.Height),
ImageLockMode.WriteOnly,
PixelFormat.Format24bppRgb);
Marshal.Copy(p, 0, resultData.Scan0, p.Length);
resultBitmap.UnlockBits(resultData);
return(resultBitmap);
}