A recent Small Basic post about filling a region left by Turtle trails revived an old flood fill program I wrote a while ago.
This is the forum thread, turtle small basic.
And this is the program to flood fill regions.
'FloodFill example - for some theory see http://en.wikipedia.org/wiki/Flood_fill'Draw regions with left mouse button and fill with right mouse button gw = GraphicsWindow.Widthgh = GraphicsWindow.HeightGraphicsWindow.MouseMove = OnMouseMoveGraphicsWindow.MouseDown = OnMouseDownGraphicsWindow.MouseUp = OnMouseUp mouseMove = 0mouseDown = 0rightClick = 0 While ("True") If (mouseDown = 1 And mouseMove = 1) Then xM = GraphicsWindow.MouseX yM = GraphicsWindow.MouseY GraphicsWindow.DrawLine(xMLast,yMLast,xM,yM) xMLast = xM yMLast = yM mouseMove = 0 ElseIf (rightClick = 1) Then fillRegion() rightClick = 0 EndIf Program.Delay(20)EndWhile Sub fillRegion Stack.PushValue("X",xMLast) Stack.PushValue("Y",yMLast) colOld = GraphicsWindow.GetPixel(xMLast,yMLast) colFill = GraphicsWindow.PenColor While (Stack.GetCount("X") > 0) x = Stack.PopValue("X") y = Stack.PopValue("Y") If (GraphicsWindow.GetPixel(x,y) <> colFill) Then 'We could have multiple entries in the stack at x,y so only process those we haven't dealt with GraphicsWindow.SetPixel(x,y,colFill) If (x > 0) Then If (GraphicsWindow.GetPixel(x-1,y) = colOld) Then Stack.PushValue("X",x-1) Stack.PushValue("Y",y) EndIf EndIf If (x < gw-1) Then 'X pixels go from 0 to gw-1 If (GraphicsWindow.GetPixel(x+1,y) = colOld) Then Stack.PushValue("X",x+1) Stack.PushValue("Y",y) EndIf EndIf If (y > 0) Then If (GraphicsWindow.GetPixel(x,y-1) = colOld) Then Stack.PushValue("X",x) Stack.PushValue("Y",y-1) EndIf EndIf If (y < gh-1) Then ''Y pixels go from 0 to gh-1 If (GraphicsWindow.GetPixel(x,y+1) = colOld) Then Stack.PushValue("X",x) Stack.PushValue("Y",y+1) EndIf EndIf EndIf EndWhileEndSub Sub OnMouseMove mouseMove = 1EndSub Sub OnMouseDown GraphicsWindow.PenColor = GraphicsWindow.GetRandomColor() xMLast = GraphicsWindow.MouseX yMLast = GraphicsWindow.MouseY If (Mouse.IsLeftButtonDown) Then mouseDown = 1 ElseIf (Mouse.IsRightButtonDown) Then rightClick = 1 EndIfEndSub Sub OnMouseUp mouseDown = 0EndSub
While this program works fine, it is slow.
I added a new method to the LitDev extension to do a 'flood fill' quicker. Internally it uses exactly the same method, but doesn't have to load the drawing bitmap and other over-heads for each end every pixel check or change.
The new command is about 100 times faster and replaces fillRegion() with LDGraphicsWindow.FloodFill(GraphicsWindow.MouseX,GraphicsWindow.MouseY,GraphicsWindow.PenColor) in the code sample.