API-PolylineTo绘制曲线_c api 函数画个曲线-优快云博客

本文提供了一个使用Visual Basic编程语言绘制动态变化的螺旋线图案的示例代码。通过调整变量X的值，图案会随时间变化而产生动态效果。此示例涉及了API函数PolylineTo和MoveToEx的使用，展示了如何在窗体上绘制从中心向外扩展的复杂螺旋线。

Option Explicit
Dim X As Double
Private Type POINTAPI
          X   As Long
          y   As Long
End Type
Private Declare Function PolylineTo Lib "gdi32" (ByVal hdc As Long, ByVal lppt As POINTAPI, ByVal cCount As Long) As Long
Private Declare Function MoveToEx Lib "gdi32" (ByVal hdc As Long, ByVal X As Long, ByVal y As Long, ByVal lpPoint As Any) As Long
Private Sub Form_Load()
    Timer1.Interval = 100
    Me.ScaleMode = vbPixels
    X = 0.1
    AutoRedraw = True
End Sub
Private Sub draw()
    Dim Pt(1 To 1000)         As POINTAPI, A       As Double, R       As Double
    Dim N As Long, Xm As Long, Ym As Long
    Xm = Me.ScaleWidth / 2
    Ym = Me.ScaleHeight / 2
    For N = 1 To 1000
        A = N * X
        R = R + A * 0.01
        Pt(N).X = Xm + Cos(A) * R
        Pt(N).y = Ym - Sin(A) * R
    Next N
    MoveToEx Me.hdc, Me.ScaleWidth / 2, Me.ScaleHeight / 2, ByVal 0&
    PolylineTo Me.hdc, Pt(1), 100
End Sub
Private Sub Form_Paint()
    draw
End Sub
Private Sub Timer1_Timer()
    X = X + 0.01
    Me.Caption = X
    Me.Cls
    Form_Paint
End Sub