五彩繽紛的清屏效果

在一些軟件演示中，屏幕內容間的切換往往以一些有趣的清屏圖案來相互切換。有的像演出舞臺上的開幕、閉幕方式，有的像百葉窗效果，也有一些圓形、菱形等形態各異的清屏效果。本例將介紹在VB中如何實現這些清屏效果。

'設置清屏色
Dim bcolor
Private Sub Clscolor()
    Randomize
    bcolor = RGB(Int(Rnd * 256), Int(Rnd * 256), Int(Rnd * 256))
End Sub
    '從左右兩邊到中間清屏
    Private Sub ClrScrl()
        Dim i As Integer
        Clscolor
        For i = 0 To ScaleWidth / 2
            Line (i, 0)-(i, ScaleHeight), bcolor
            Line (ScaleWidth - i, 0)-(ScaleWidth - i, ScaleHeight), bcolor
        Next i
    End Sub
    '從中間到左右兩邊清屏
    Private Sub ClrScr2()
        Dim i As Integer
        Clscolor
        For i = ScaleWidth / 2 To 0 Step -1
            Line (i, 0)-(i, ScaleHeight - 1), bcolor
            Line (ScaleWidth - i, 0)-(ScaleWidth - i, ScaleHeight), bcolor
        Next i
    End Sub
    '從上(頂)下(低)到中間清屏
    Private Sub ClrScr3()
        Dim i As Integer
        Clscolor
        For i = 0 To ScaleHeight / 2
            Line (0, i)-(ScaleWidth, i), bcolor
            Line (0, ScaleHeight - i)-(ScaleWidth, ScaleHeight - i), bcolor
        Next i
    End Sub
    '從中間到上(頂)下(底)清屏
    Private Sub ClrScr4()
        Dim i As Integer
        Clscolor
        For i = ScaleHeight / 2 To 0 Step -1
            Line (0, i)-(ScaleWidth, i), bcolor
            Line (0, ScaleHeight - i)-(ScaleWidth, ScaleHeight - i), bcolor
        Next i
    End Sub
    '菱形清屏，從四角向中心
    Private Sub ClrScr5()
        Dim i, j As Integer
        Clscolor
        For i = 0 To ScaleWidth Step 200
            For j = 0 To ScaleHeight Step 200 * ScaleHeight / ScaleWidth
                Line (i, 0)-(0, j), bcolor
                Line (ScaleWidth - i, ScaleHeight)-(ScaleWidth, ScaleHeight - j), bcolor
                Line (0, ScaleHeight - j)-(i, ScaleHeight), bcolor
                Line (ScaleWidth - i, 0)-(ScaleWidth, ScaleHeight - j), bcolor
            Next j
        Next i
    End Sub
    '圓形清屏，由大至小從外圍向中心
    Private Sub ClrScr6()
        Dim i As Integer
        Clscolor
        For i = ScaleWidth To 0 Step -3
        Circle (ScaleWidth / 2, ScaleHeight / 2), i / 2, bcolor
        Next i
    End Sub
    '圓形清屏，由小至大從中心向外圍
    Private Sub ClrScr7()
        Dim i As Integer
        Clscolor
        For i = 0 To ScaleHeight Step 3
        Circle (ScaleWidth / 2, ScaleHeight / 2), i / 2, bcolor
        Next i
    End Sub

Private Sub Command1_Click()
    ClrScr7
    ClrScr6
    ClrScr5
    ClrScr4
    ClrScr3
    ClrScr2
    ClrScrl
End Sub

  
Private Sub Form_Load()

End Sub