frmrgb.frm

Visual Basic 6 大学教程的代码

VERSION 5.00
Begin VB.Form frmRGB 
   BackColor       =   &H00FFFFFF&
   Caption         =   "Fig. 9.22: Demonstrating colors"
   ClientHeight    =   3195
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   4680
   LinkTopic       =   "Form1"
   ScaleHeight     =   3195
   ScaleWidth      =   4680
   StartUpPosition =   3  'Windows Default
   Begin VB.Timer tmrTimer 
      Interval        =   500
      Left            =   1800
      Top             =   1320
   End
End
Attribute VB_Name = "frmRGB"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
' Fig. 9.22
' Demonstrating function RGB
Option Explicit

Private Sub DrawShape()
   Dim x As Single, y As Single
   Dim totalRadians As Single, r As Single
   Dim a As Single, theta As Single
   Dim x1 As Single, y1 As Single
   
   Call Randomize
   Scale (3, -3)-(-3, 3)         ' Change scale
   totalRadians = 8 * Atn(1)     ' Circle in Radians
   
   ForeColor = RGB(Rnd() * 256, Rnd() * 256, Rnd() * 256)
   
   a = 3 * Rnd()  ' Offset used in equation
      
   For theta = 0.001 To totalRadians Step 0.01
      r = Sqr(a ^ 2 / theta)
      x = r * Cos(theta)     ' y coordinate
      y = r * Sin(theta)     ' x coordinate
      x1 = -r * Cos(theta)   ' y coordinate
      y1 = -r * Sin(theta)   ' x coordinate
      PSet (x, y)            ' Turn pixel on
      PSet (x1, y1)          ' Turn pixel on
   Next theta
   
End Sub

Private Sub tmrTimer_Timer()
   Call DrawShape   ' Call when time interval expires
End Sub