使用Line绘制图形，和图形重绘（源码）

2：

窗体大小，自动适应

源码，很短。大家可以去研究：
Const pi = 3.14159
Dim a, b
Private Sub form_click()
Cls
Form1.ScaleMode = 3
Form1.Scale (-20, 20)-(20, -20)
Form1.DrawWidth = 1
Line (-20, 0)-(20, 0), vbRed
Line (18.5, 0.5)-(20, 0), vbRed
Line -(18.5, -0.5), vbRed
Print "X"
Line (0, -20)-(0, 20), vbRed
Line (0.5, 18.5)-(0, 20), vbRed
Line -(-0.5, 18.5), vbRed
Print "Y"
CurrentX = 1: CurrentY = -1: Print "0"
For b = 0 To 19 Step 1 / 2
For a = 0 To 2 * pi Step pi / 1000
PSet (b * Cos(a) ^ 3, b * Sin(a) ^ 1), vbBlue
Next a
Next
End Sub

直接复制源码运行就行。

我添加一下注释吧：
Const pi = 3.14159
Dim a, b
Private Sub form_click()
Cls '清空窗体
Form1.ScaleMode = 3
Form1.Scale (-20, 20)-(20, -20) '设置坐标系
Form1.DrawWidth = 1 '设置绘制宽度
Line (-20, 0)-(20, 0), vbRed '绘制X轴
Line (18.5, 0.5)-(20, 0), vbRed
Line -(18.5, -0.5), vbRed '绘制X轴箭头
Print "X" '显示X
Line (0, -20)-(0, 20), vbRed '绘制Y轴
Line (0.5, 18.5)-(0, 20), vbRed
Line -(-0.5, 18.5), vbRed '绘制Y轴箭头
Print "Y" '显示Y
CurrentX = 1: CurrentY = -1: Print "0" '显示远点
For b = 0 To 19 Step 1 / 2 '绘制曲线
For a = 0 To 2 * pi Step pi / 1000
PSet (b * Cos(a) ^ 3, b * Sin(a) ^ 1), vbBlue
Next a
Next
End Sub

在来一个用pset画曲线的
效果图：





源码，加注释了：
Private Sub form_click()
Dim x, y, i As Single '定义坐标值变量x和y以及循环参数i
Scale (-16, 16)-(16, -16) '自定义坐标系
Line (0, 15)-(0, -15) '绘制垂直直线
Line (15, 0)-(-15, 0) '绘制水平直线
For i = -14.5 To 14.5 Step 0.01
x = i '正弦曲线参数
y = 10 * Cos(i) '正弦曲线参数
PSet (x, y), vbGreen '绘制正弦曲线
Next i
End Sub
Private Sub form_dblclick() '窗体双击事件
Cls '清除屏幕内容
End Sub