Android Question Using drawline for trail effect

strat said:

I didn't write code now but you can use such method to plot it.

At every X moving, assign numbers to an array and draw dots and space into array coordinates

B4X:

dots_y[0]=Text_x.y-10dip
dots_y[1]=Text_x.y-20dip
dots_y[2]=Text_x.y-30dip
dots_y[3]=Text_x.y-40dip

Plot(Text_x.x,dots_y[0])
Plot(Text_x.x,dots_y[1])
Plot(Text_x.x,dots_y[2])
Space(Text_x.x,dots_y[3])



Sub plot(x,y as int)
...
..
Sub Space(x,y as int)
..
..

Text_x.x and Text_x.y Your Text's coordinates

Click to expand...

strat said:

I didn't write code now but you can use such method to plot it.

At every X moving, assign numbers to an array and draw dots and space into array coordinates

B4X:

dots_y[0]=Text_x.y-10dip
dots_y[1]=Text_x.y-20dip
dots_y[2]=Text_x.y-30dip
dots_y[3]=Text_x.y-40dip

Plot(Text_x.x,dots_y[0])
Plot(Text_x.x,dots_y[1])
Plot(Text_x.x,dots_y[2])
Space(Text_x.x,dots_y[3])



Sub plot(x,y as int)
...
..
Sub Space(x,y as int)
..
..

Text_x.x and Text_x.y Your Text's coordinates

Click to expand...

strat said:

Try this. Touch the screen and move. After movinx text X, puts after 3 big dots and a space.

B4X:

##Region  Project Attributes
    #ApplicationLabel: draw
    #VersionCode: 1
    #VersionName:
    'SupportedOrientations possible values: unspecified, landscape or portrait.
    #SupportedOrientations: unspecified
    #CanInstallToExternalStorage: False
#End Region

#Region  Activity Attributes
    #FullScreen: False
    #IncludeTitle: True
#End Region

Sub Process_Globals
    'These global variables will be declared once when the application starts.
    'These variables can be accessed from all modules.
 
End Sub

Sub Globals
    Private pnl As Panel
    Private lbl As Label
    Private old_x,old_y As Int
    Private first As Boolean
    Private coordx(5) As Int
    Private coordy(5) As Int
    Private c As Canvas
    Private uzunluk As Float
    Private xf,yf As Float
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")
    pnl.Initialize("pnl")
    lbl.Initialize("lbl")
    Activity.AddView(lbl,0,0,100%x,10%y)
    Activity.AddView(pnl,0,0,100%x,100%y)
    first=True
    c.Initialize(pnl)
    'pnl.Color=Colors.White
    lbl.Text="X"
End Sub



Sub Activity_Resume

End Sub

Sub Activity_Pause (UserClosed As Boolean)

End Sub

Sub pnl_Touch (Action As Int, X As Float, Y As Float)
    xf=X-old_x
    yf=Y-old_y
    uzunluk=Sqrt(xf*xf+yf*yf)
    If uzunluk>=50 Then
        lbl.Left=X
        lbl.Top=Y
        add_to_array(X,Y)
        draw_dots
        old_x=X
        old_y=Y
    End If
End Sub

Sub draw_dots
    'Dim c As Canvas
    c.Initialize(pnl)
    For i=1 To 3
        c.DrawCircle(coordx(i),coordy(i),5dip,Colors.White,True,1dip)
    Next
    c.DrawCircle(coordx(4),coordy(4),5dip,Colors.Black,True,1dip)
End Sub

Sub add_to_array(a_x As Int ,a_y As Int)
    If first Then
        For i=0 To 4
            coordx(i)=a_x
            coordy(i)=a_y
        Next
        first=False
    Else
        coordx(4)=coordx(3)
        coordx(3)=coordx(2)
        coordx(2)=coordx(1)
        coordx(1)=coordx(0)
        coordx(0)=a_x
        coordy(4)=coordy(3)
        coordy(3)=coordy(2)
        coordy(2)=coordy(1)
        coordy(1)=coordy(0)
        coordy(0)=a_y
    End If
End Sub

Click to expand...

tufanv said:

Thank you for your time ! it works perfect. Just a small note: When white dots disappear they stay as black dots on the screen( all the previous trails ) is it normal or is there way to completely remove them ?

Click to expand...

strat said:

I assume screen color is black. You can select the background color for last dot in order to complete disappear dots.
If panel has a picture, instead of putting last dot, original picture part should be paste at last coordinates. To do it, first, the part of picture should be copied to memory.

Click to expand...