Microsoft Small Basic

Program Listing: MQB393-0

List Program

' Small Paint
' Copyright (c) 2014 Nonki Takahashi. The MIT License.
' Version 0.2
' added workaround for known issue 26992 in line 45
' Last update 2014-10-03
' Program ID MQB393-0
'
GraphicsWindow.Title = "Small Paint 0.2"
Form()
GraphicsWindow.MouseMove = OnMouseMove
GraphicsWindow.MouseDown = OnMouseDown
Sub Form
GraphicsWindow.BackgroundColor = "DimGray"
gw = 598
gh = 340
GraphicsWindow.Width = gw
GraphicsWindow.Height = gh
param = "x=20;y=20;r=60;light=True;"
DrawColorWheel()
GraphicsWindow.BrushColor = "Black"
canvasL = 2 * (param["x"] + param["r"])
canvasT = param["y"]
canvasW = 400
canvasH = 300
canvasR = canvasL + canvasW
canvasB = canvasT + canvasH
Erase()
Controls.AddButton("Erase", param["x"], canvasB - 32)
Controls.ButtonClicked = OnButtonClicked
GraphicsWindow.PenColor = "White"
EndSub
Sub OnButtonClicked
Erase()
EndSub
Sub Erase
GraphicsWindow.FillRectangle(canvasL, canvasT, canvasW, canvasH)
EndSub
Sub OnMouseDown
mx = GraphicsWindow.MouseX
my = GraphicsWindow.MouseY
If canvasL < mx And mx < canvasR And canvasT < my And my < canvasB Then
prevX = mx
prevY = my
ElseIf Math.Power(mx - cx, 2) + Math.Power(my - cy, 2) <= Math.Power(param["r"], 2) Then
GraphicsWindow.PenColor = GraphicsWindow.GetPixel(Math.Round(mx), Math.Round(my))
EndIf
EndSub
Sub OnMouseMove
mx = GraphicsWindow.MouseX
my = GraphicsWindow.MouseY
If canvasL < mx And mx < canvasR And canvasT < my And my < canvasB Then
x = mx
y = my
If (Mouse.IsLeftButtonDown) Then
GraphicsWindow.DrawLine(prevX, prevY, x, y)
EndIf
prevX = x
prevY = y
EndIf
EndSub
Sub DrawColorWheel
' param["x"] - left x co-ordinate
' param["y"] - top y co-ordinate
' param["r"] - radius
' param["light"] - "True" if light color
cx = param["x"] + param["r"]
cy = param["y"] + param["r"]
For py = param["y"] To param["y"] + 2 * param["r"]
absX = Math.Round(Math.SquareRoot(param["r"] * param["r"] - Math.Power(py - (param["y"] + param["r"]), 2)))
xs = cx - absX
xe = cx + absX
For px = xs To xe
GetColor()
GraphicsWindow.SetPixel(px, py, color)
EndFor
EndFor
EndSub
Sub GetColor
' param px, py - current point
' param cx, cy - center
' param["r"] - radius
' param["light"] - "True" if light color
x = px - cx
y = py - cy
Math_CartesianToPolar()
hue = 360 - a
saturation = 1
If param["light"] Then
lightness = 1 - 0.5 * r / param["r"]
Else
lightness = 0.5 * r / param["r"]
EndIf
Color_HSLtoRGB()
EndSub
Sub Math_CartesianToPolar
' Math | convert cartesian coodinate to polar coordinate
' param x, y - cartesian coordinate
' return r, a - polar coordinate
r = Math.SquareRoot(x * x + y * y)
If x = 0 And y > 0 Then
a = 90 ' [degree]
ElseIf x = 0 And y < 0 Then
a = -90
Else
a = Math.ArcTan(y / x) * 180 / Math.Pi
EndIf
If x < 0 Then
a = a + 180
ElseIf x > 0 And y < 0 Then
a = a + 360
EndIf
EndSub
Sub Color_HSLtoRGB
' Color | Convert HSL to RGB
' param hue - [0, 360) or UNDEFINED
' param lightness - [0, 1]
' param saturation - [0, 1]
' return color - "#rrggbb"
If lightness <= 0.5 Then
rN2 = lightness * (1 + saturation)
Else
rN2 = lightness + saturation - lightness * saturation
EndIf
rN1 = 2 * lightness - rN2
If saturation = 0 Then
iR = Math.Round(lightness * 255)
iG = Math.Round(lightness * 255)
iB = Math.Round(lightness * 255)
Else
rH = hue + 120
Color_Value()
iR = iValue
rH = hue
Color_Value()
iG = iValue
rH = hue - 120
Color_Value()
iB = iValue
EndIf
color = GraphicsWindow.GetColorFromRGB(iR, iG, iB)
EndSub
Sub Color_Value
' Color | Function value
' param rN1, rN2
' param rH - [-120, 480)
' return iValue - 0..255
If rH >= 360 Then
rH = rH - 360
EndIF
If rH < 0 Then
rH = rH + 360
EndIF
If rH < 60 Then
rV = rN1 + (rN2 - rN1) * rH / 60
ElseIf rH < 180 Then
rV = rN2
ElseIf rH < 240 Then
rV = rN1 + (rN2 - rN1) * (240 - rH) / 60
Else
rV = rN1
EndIf
iValue = Math.Round(rV * 255)
EndSub