hi, let say you would like to fill an ellipse with a color. the color should be related to the x position of the mouse. like if x is 0 the color should be black... but what would happen if your canvas size is bigger then 255 ?? you will probably get an error. so what you need to do is get a number with the same ratio as the coordinate u want to use but that will fit your needs. EXAMPLE: Canvas = 0 to 640 (width/x axis) Color = 0 to 255 now according to my x position in that canvas i would like to get a number between 0 and 255 so we could use this function: Code: Sub mapping(var As Float, min_real As Float, max_real As Float, min_scaled As Float, max_scaled As Float) As Float Return (var * ((max_scaled-min_scaled) / (max_real-min_real))) + min_scaledEnd Sub we put the X position and the space from minimum to maximum of that x position (= canvas size) and the limits from the new minimum and maximum range we would like to get. like: Code: #Region Project Attributes #MainFormWidth: 600 #MainFormHeight: 400#End RegionSub Process_Globals Private fx As JFX Private MainForm As Form Dim c As CanvasEnd SubSub AppStart (Form1 As Form, Args() As String) MainForm = Form1 MainForm.SetFormStyle("UNIFIED") MainForm.Show c.Initialize("c") MainForm.RootPane.AddNode(c,0,0,MainForm.RootPane.Width,MainForm.RootPane.Height)End SubSub mapping(var As Float, min_real As Float, max_real As Float, min_scaled As Float, max_scaled As Float) As Float Return (var * ((max_scaled-min_scaled) / (max_real-min_real))) + min_scaledEnd Sub Sub MainForm_MouseMoved (EventData As MouseEvent) c.ClearRect(0,0,c.Width,c.Height) c.DrawCircle(c.Width/2,c.Height/2,mapping(EventData.X,0,c.Width,50,100),fx.Colors.RGB(255,mapping(EventData.X,0,c.Width,0,255),0),True,1)End Sub what we do here is we draw an ellipse that's size is between 50 and 100 and fill it with a color between 0 and 255. even if we use our x coordinate we can still get the number we need with the same ratio. this is very useful if you need to get a number in a specific range but would like to use a bigger range as the reference (like mouse coordinates, slider (0-100), progressbar (0-100),...) i dont know if such function already exists in b4x, i just saw it in another coding language and came with that function in b4j. regards, ilan

why don't you just use percentage math? Code: col=(mouseX/100%x)*256size=50+(mouseX/100%x)*50 Edit: my size method seems to be the same as your function, I justed swapped adder & multipliers.

I did, I first replied with the color line as I thought it was the same for the size. I ran the jar and noticed the circle didn't size to 0 that's why I added the size line after that.