private PointData getBorderData(byte[] bytes)
{
PointData isborderpoint = new PointData(size.Height * size.Width);
bool prevtrans = false;
bool currenttrans = false;
for (int y = 0; y < size.Height; y++)
{
prevtrans = false;
for (int x = 0; x <= size.Width; x++)
{
if (x == size.Width)
{
if (!prevtrans)
{
isborderpoint.SetPoint(y * size.Width + x - 1, true);
}
continue;
}
currenttrans = bytes[y * stride + x * 4 + 3] == 0;
if (x == 0 && !currenttrans)
{
isborderpoint.SetPoint(y * size.Width + x, true);
}
if (prevtrans && !currenttrans)
{
isborderpoint.SetPoint(y * size.Width + x - 1, true);
}
if (!prevtrans && currenttrans && x != 0)
{
isborderpoint.SetPoint(y * size.Width + x, true);
}
prevtrans = currenttrans;
}
}
for (int x = 0; x < size.Width; x++)
{
prevtrans = false;
for (int y = 0; y <= size.Height; y++)
{
if (y == size.Height)
{
if (!prevtrans)
{
isborderpoint.SetPoint((y - 1) * size.Width + x, true);
}
continue;
}
currenttrans = bytes[y * stride + x * 4 + 3] == 0;
if (y == 0 && !currenttrans)
{
isborderpoint.SetPoint(y * size.Width + x, true);
}
if (prevtrans && !currenttrans)
{
isborderpoint.SetPoint((y - 1) * size.Width + x, true);
}
if (!prevtrans && currenttrans && y != 0)
{
isborderpoint.SetPoint(y * size.Width + x, true);
}
prevtrans = currenttrans;
}
}
return(isborderpoint);
}
public List <Point[]> Find(Bitmap bmp, bool outside = true)
{
this.outside = outside;
List <Point> border = new List <Point>();
BitmapData bmpdata = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
stride = bmpdata.Stride;
bytes = new byte[bmp.Width * bmp.Height * 4];
size = bmp.Size;
Marshal.Copy(bmpdata.Scan0, bytes, 0, bytes.Length);
// Get all Borderpoint
borderdata = getBorderData(bytes);
bmp.UnlockBits(bmpdata);
List <List <Point> > regions = new List <List <Point> >();
//Loop until no more borderpoints are available
while (borderdata.PointCount > 0)
{
List <Point> region = new List <Point>();
//if valid is false the region doesn't close
bool valid = true;
//Find the first borderpoint from where whe start crawling
Point startpos = getFirstPoint(borderdata);
//we need this to know if and how often we already visted the point.
//we somtime have to visit a point a second time because we have to go backward until a unvisted point is found again
//for example if we go int a narrow 1px hole
visited = new int[bmp.Size.Width * bmp.Size.Height];
region.Add(startpos);
//Find the next possible point
Point current = getNextPoint(startpos);
if (current != zeropoint)
{
visited[current.Y * bmp.Width + current.X]++;
region.Add(current);
}
//May occure with just one transparent pixel without neighbors
if (current == zeropoint)
{
valid = false;
}
//Loop until the area closed or colsing the area wasn't poosible
while (!current.Equals(startpos) && valid)
{
var pos = current;
//Check if the area was aready visited
if (visited[current.Y * bmp.Width + current.X] < 2)
{
current = getNextPoint(pos);
visited[pos.Y * bmp.Width + pos.X]++;
//If no possible point was found, search in reversed direction
if (current == zeropoint)
{
current = getNextPointBackwards(pos);
}
}
else
{ //If point was already visited, search in reversed direction
current = getNextPointBackwards(pos);
}
//No possible point was found. Closing isn't possible
if (current == zeropoint)
{
valid = false;
break;
}
visited[current.Y * bmp.Width + current.X]++;
region.Add(current);
}
//Remove point from source borderdata
foreach (var p in region)
{
borderdata.SetPoint(p.Y * bmp.Width + p.X, false);
}
//Add region if closing was possible
if (valid)
{
regions.Add(region);
}
}
//Checks if Region goes the same way back and trims it in this case
foreach (var region in regions)
{
int duplicatedpos = -1;
bool[] duplicatecheck = new bool[size.Width * size.Height];
int length = region.Count;
for (int i = 0; i < length; i++)
{
var p = region[i];
if (duplicatecheck[p.Y * size.Width + p.X])
{
duplicatedpos = i - 1;
break;
}
duplicatecheck[p.Y * size.Width + p.X] = true;
}
if (duplicatedpos == -1)
{
continue;
}
if (duplicatedpos != ((region.Count - 1) / 2))
{
continue;
}
bool reversed = true;
for (int i = 0; i < duplicatedpos; i++)
{
if (region[duplicatedpos - i - 1] != region[duplicatedpos + i + 1])
{
reversed = false;
break;
}
}
if (!reversed)
{
continue;
}
region.RemoveRange(duplicatedpos + 1, region.Count - duplicatedpos - 1);
}
List <List <Point> > tempregions = new List <List <Point> >(regions);
regions.Clear();
bool connected = true;
//Connects region if possible
while (connected)
{
connected = false;
foreach (var region in tempregions)
{
int connectionpos = -1;
int connectionregion = -1;
Point pointstart = region.First();
Point pointend = region.Last();
for (int ir = 0; ir < regions.Count; ir++)
{
var otherregion = regions[ir];
if (region == otherregion)
{
continue;
}
for (int ip = 0; ip < otherregion.Count; ip++)
{
var p = otherregion[ip];
if ((isConnected(pointstart, p) && isConnected(pointend, p)) ||
(isConnected(pointstart, p) && isConnected(pointstart, p)))
{
connectionregion = ir;
connectionpos = ip;
}
if ((isConnected(pointend, p) && isConnected(pointend, p)))
{
region.Reverse();
connectionregion = ir;
connectionpos = ip;
}
}
}
if (connectionpos == -1)
{
regions.Add(region);
}
else
{
regions[connectionregion].InsertRange(connectionpos, region);
}
}
tempregions = new List <List <Point> >(regions);
regions.Clear();
}
List <Point[]> returnregions = new List <Point[]>();
foreach (var region in tempregions)
{
returnregions.Add(region.ToArray());
}
return(returnregions);
}