Un applicazione che traccia una firma, raccoglie i punti principali della firma e disegna le curve di Bezier o C-Spline.
- Codice:
Sub Process_Globals
'These global variables will be declared once when the application starts.
'These variables can be accessed from all modules.
Type Type_Point(X As Float,Y As Float, p As Float, u As Float)
Dim Point() As Type_Point
Dim xi,yi As Int
Dim Fase As Int = 0
End Sub
Sub Globals
'These global variables will be redeclared each time the activity is created.
'These variables can only be accessed from this module.
Private PanelMain As Panel
End Sub
Sub Activity_Create(FirstTime As Boolean)
'Do not forget to load the layout file created with the visual designer. For example:
Activity.LoadLayout("Layout1")
End Sub
Sub Activity_Resume
End Sub
Sub Activity_Pause (UserClosed As Boolean)
End Sub
Sub ButtonClear_Click
Dim Point() As Type_Point
PanelMain.Color=Colors.White
PanelMain.RemoveAllViews
Fase=0
End Sub
Sub ButtonSpline_Click
DrawCspline
Fase=1
End Sub
Sub ButtonBezier_Click
DrawBezier
Fase=2
End Sub
#Region Sign
Sub PanelMain_Touch (Action As Int, X As Float, Y As Float)
Dim Range As Int = 25dip
If Fase=0 Then
Select Action
Case 0 ' Down
xi=X
yi=y
Dim Canv As Canvas
Canv.Initialize(PanelMain)
Canv.DrawCircle(X,Y,5dip,Colors.Black,True,1dip)
AddPoint(X,Y)
Case 1 ' Up
Case 2 ' Move
Dim L As Int = Sqrt(Power(X-xi,2)+Power(Y-yi,2))
Dim Canv As Canvas
Canv.Initialize(PanelMain)
Canv.DrawCircle(X,Y,5dip,Colors.Black,True,1dip)
If L>=Range Then
AddPoint(X,Y)
xi=X
yi=Y
End If
End Select
End If
End Sub
Sub AddPoint(X As Int, Y As Int)
Dim PointNew(Point.Length+1) As Type_Point
For i=0 To Point.Length-1
PointNew(i)=Point(i)
Next
Dim P As Type_Point
P.Initialize
P.X=x
P.Y=y
PointNew(Point.Length)=p
Point=PointNew
End Sub
#end region
#Region C-Spline
Sub DrawCspline
PanelMain.RemoveAllViews
For i=0 To Point.Length-1
Dim V As Panel
V.Initialize("ViewMove")
V.Tag=I
V.Color=Colors.Gray
PanelMain.AddView(V,Point(i).X-5dip,Point(i).Y-5dip,10dip,10dip)
Dim obj As Reflector
obj.Target=V
obj.SetOnTouchListener("ViewMove_Touch")
Next
DrawPointCSpline
End Sub
Private Sub DrawPointCSpline
Dim piece As Int
Dim xPos As Int
Dim yPos As Int
Dim Can As Canvas
Can.Initialize(PanelMain)
Can.DrawColor(Colors.White)
SetPandU
For piece = 0 To Point.Length - 2
For xPos = Point(piece).x To Point(piece + 1).x
yPos = getCurvePoint(piece, xPos)
Can.DrawCircle(xPos, yPos,1dip,Colors.Red,True,1dip)
Next
Next
End Sub
Sub getCurvePoint(i As Int, v As Float) As Float
Dim t As Float
'derived curve equation (which uses p's and u's for coefficients)
t = (v - Point(i).x) / Point(i).u
Return t * Point(i + 1).y + (1 - t) * Point(i).y + Point(i).u * Point(i).u * (f(t) * Point(i + 1).p + f(1 - t) * Point(i).p) / Point.Length
End Sub
Sub F(x As Float) As Float
Return x * x * x - x
End Sub
Private Sub SetPandU()
Dim i As Int
Dim d(Point.Length) As Float
Dim w(Point.Length) As Float
'Routine to compute the parameters of our cubic spline. Based on equations derived from some basic facts...
'Each segment must be a cubic polynomial. Curve segments must have equal first and second derivatives
'at knots they share. General algorithm taken from a book which has long since been lost.
'The math that derived this stuff is pretty messy... expressions are isolated and put into
'arrays. we're essentially trying to find the values of the second derivative of each polynomial
'at each knot within the curve. That's why theres only N-2 p's (where N is # points).
'later, we use the p's and u's to calculate curve points...
For i = 1 To Point.Length - 2
d(i) = 2 * (Point(i + 1).x - Point(i - 1).x)
Next
For i = 0 To Point.Length - 2
Point(i).u = Point(i + 1).x - Point(i).x
Next
For i = 1 To Point.Length - 2
w(i) = 6 * ((Point(i + 1).y - Point(i).y) / Point(i).u - (Point(i).y - Point(i - 1).y) / Point(i - 1).u)
Next
For i = 1 To Point.Length - 3
w(i + 1) = w(i + 1) - w(i) * Point(i).u / d(i)
d(i + 1) = d(i + 1) - Point(i).u * Point(i).u / d(i)
Next
Point(1).p = 0
For i = Point.Length - 2 To 1 Step -1
Point(i).p = (w(i) - Point(i).u * Point(i + 1).p) / d(i)
Next
Point(Point.Length-1).p = 0
End Sub
Sub ViewMove_Touch (viewtag As Object, action As Int, X As Float, Y As Float, motionevent As Object) As Boolean
Dim V As Panel = Sender
Dim Index As Int = V.Tag
Select action
Case 0
' Down
xi=X
yi=y
Case 1
' Up
Point(Index).X=V.Left
Point(Index).Y=V.Top
If Fase=1 Then
DrawCspline
else if Fase=2 Then
DrawBezier
End If
Case 2
' Move
X=Max(10,X)
Y=Max(10,Y)
V.Left=V.Left+X-xi
V.Top=v.Top+Y-yi
'Log($"Pto:${Index}=$1.0{x}-$1.0{y} ${Point(Index).x}-${Point(Index).y}"$)
End Select
Return True
End Sub
#end Region
#Region Bezier
Sub DrawBezier
PanelMain.RemoveAllViews
For i=0 To Point.Length-1
Dim V As Panel
V.Initialize("ViewMove")
V.Tag=I
V.Color=Colors.Gray
PanelMain.AddView(V,Point(i).X-5dip,Point(i).Y-5dip,10dip,10dip)
Dim obj As Reflector
obj.Target=V
obj.SetOnTouchListener("ViewMove_Touch")
Next
DrawPointBezier(Point)
End Sub
Private Sub DrawPointBezier(iPoint() As Type_Point)
Dim ax, bx, cx, ay, by, cy, xt, yt As Float 'ignore
Dim axN, bxN(), cxN(), ayN, byN(), cyN(), xtN, ytN As Float
Dim t As Float, I As Int 'ignore
Dim iTotPoints As Int
Dim X As Int
Dim Can As Canvas
Can.Initialize(PanelMain)
Can.DrawColor(Colors.White)
iTotPoints = iPoint.Length-1
Dim bxN(iTotPoints) As Float 'ignore
Dim cxN(iTotPoints) As Float
Dim byN(iTotPoints) As Float 'ignore
Dim cyN(iTotPoints) As Float
'Form2.Cls
'Form2.DrawWidth = 1
'Draws control lines
'Form2.ForeColor = vbBlue
For X = 0 To iTotPoints - 1
'Form2.Line (iPoint(X).X, iPoint(X).Y)-(iPoint(X + 1).X, iPoint(X + 1).Y)
Can.DrawLine(iPoint(X).X ,iPoint(X).Y,iPoint(X + 1).X, iPoint(X + 1).Y, Colors.Blue,1dip)
Next
'The following is the core of the program.
' All others are just for dragging.
cxN(0) = 0
For X = 1 To iTotPoints - 1
cxN(X) = iTotPoints * (iPoint(X).X - iPoint(X - 1).X) - cxN(X - 1)
Next
'Calcolo di ax
axN = iPoint(iTotPoints).X - iPoint(0).X
For X = 1 To iTotPoints - 1
axN = axN - cxN(X)
Next
cyN(0) = 0
For X = 1 To iTotPoints - 1
cyN(X) = iTotPoints * (iPoint(X).Y - iPoint(X - 1).Y) - cyN(X - 1)
Next
'Calcolo di ay
ayN = iPoint(iTotPoints).Y - iPoint(0).Y
For X = 1 To iTotPoints - 1
ayN = ayN - cyN(X)
Next
For t = 0 To 1 Step 0.0001
xtN = axN * Power(t , iTotPoints)
ytN = ayN * Power(t , iTotPoints)
For X = iTotPoints - 1 To 1 Step -1
xtN = xtN + cxN(X) * Power(t , X)
ytN = ytN + cyN(X) * Power(t , X)
Next
xtN = xtN + iPoint(0).X
ytN = ytN + iPoint(0).Y
Can.DrawCircle(xtN,ytN,1dip,Colors.Red,True,1dip)
Next
' For I = 0 To 3
' Can.DrawCircle(iPoint(I).X, iPoint(I).Y,3dip,Colors.Gray,True,1dip)
' Next
End Sub
#end region
