form1.vb

适合VB初学者看

Public Class Form1
    Inherits System.Windows.Forms.Form

#Region " Windows 窗体设计器生成的代码 "

    Public Sub New()
        MyBase.New()

        '该调用是 Windows 窗体设计器所必需的。
        InitializeComponent()

        '在 InitializeComponent() 调用之后添加任何初始化

    End Sub

    '窗体重写处置以清理组件列表。
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If Not (components Is Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub

    'Windows 窗体设计器所必需的
    Private components As System.ComponentModel.IContainer

    '注意：以下过程是 Windows 窗体设计器所必需的
    '可以使用 Windows 窗体设计器修改此过程。
    '不要使用代码编辑器修改它。
    Friend WithEvents label1 As System.Windows.Forms.Label
    Friend WithEvents trackBar1 As System.Windows.Forms.TrackBar
    Friend WithEvents pictureBox1 As System.Windows.Forms.PictureBox
    Friend WithEvents button1 As System.Windows.Forms.Button
    Friend WithEvents label2 As System.Windows.Forms.Label
    Friend WithEvents Button2 As System.Windows.Forms.Button
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Dim resources As System.Resources.ResourceManager = New System.Resources.ResourceManager(GetType(Form1))
        Me.label1 = New System.Windows.Forms.Label()
        Me.trackBar1 = New System.Windows.Forms.TrackBar()
        Me.pictureBox1 = New System.Windows.Forms.PictureBox()
        Me.button1 = New System.Windows.Forms.Button()
        Me.label2 = New System.Windows.Forms.Label()
        Me.Button2 = New System.Windows.Forms.Button()
        CType(Me.trackBar1, System.ComponentModel.ISupportInitialize).BeginInit()
        Me.SuspendLayout()
        '
        'label1
        '
        Me.label1.Location = New System.Drawing.Point(44, 266)
        Me.label1.Name = "label1"
        Me.label1.Size = New System.Drawing.Size(96, 24)
        Me.label1.TabIndex = 8
        Me.label1.Text = "<<--减少透明度"
        Me.label1.TextAlign = System.Drawing.ContentAlignment.MiddleCenter
        '
        'trackBar1
        '
        Me.trackBar1.LargeChange = 3
        Me.trackBar1.Location = New System.Drawing.Point(36, 226)
        Me.trackBar1.Maximum = 90
        Me.trackBar1.Name = "trackBar1"
        Me.trackBar1.Size = New System.Drawing.Size(368, 42)
        Me.trackBar1.TabIndex = 6
        Me.trackBar1.TickFrequency = 3
        Me.trackBar1.TickStyle = System.Windows.Forms.TickStyle.TopLeft
        '
        'pictureBox1
        '
        Me.pictureBox1.Image = CType(resources.GetObject("pictureBox1.Image"), System.Drawing.Bitmap)
        Me.pictureBox1.Location = New System.Drawing.Point(52, 18)
        Me.pictureBox1.Name = "pictureBox1"
        Me.pictureBox1.Size = New System.Drawing.Size(320, 200)
        Me.pictureBox1.SizeMode = System.Windows.Forms.PictureBoxSizeMode.StretchImage
        Me.pictureBox1.TabIndex = 4
        Me.pictureBox1.TabStop = False
        '
        'button1
        '
        Me.button1.DialogResult = System.Windows.Forms.DialogResult.Cancel
        Me.button1.Location = New System.Drawing.Point(248, 298)
        Me.button1.Name = "button1"
        Me.button1.Size = New System.Drawing.Size(88, 32)
        Me.button1.TabIndex = 5
        Me.button1.Text = "自动"
        '
        'label2
        '
        Me.label2.Location = New System.Drawing.Point(292, 266)
        Me.label2.Name = "label2"
        Me.label2.Size = New System.Drawing.Size(96, 24)
        Me.label2.TabIndex = 7
        Me.label2.Text = "增加透明度-->>"
        Me.label2.TextAlign = System.Drawing.ContentAlignment.MiddleCenter
        '
        'Button2
        '
        Me.Button2.DialogResult = System.Windows.Forms.DialogResult.Cancel
        Me.Button2.Location = New System.Drawing.Point(120, 296)
        Me.Button2.Name = "Button2"
        Me.Button2.Size = New System.Drawing.Size(88, 32)
        Me.Button2.TabIndex = 5
        Me.Button2.Text = "方形/环形"
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(6, 14)
        Me.ClientSize = New System.Drawing.Size(440, 349)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.label1, Me.trackBar1, Me.pictureBox1, Me.button1, Me.label2, Me.Button2})
        Me.Name = "Form1"
        Me.Text = "环形窗体示例"
        CType(Me.trackBar1, System.ComponentModel.ISupportInitialize).EndInit()
        Me.ResumeLayout(False)

    End Sub

#End Region
    '声明一个公共的布尔型变量
    Public hasNormalRegion As Boolean = True

    Private Sub trackBar1_ValueChanged(ByVal sender As Object, _
            ByVal e As System.EventArgs) Handles trackBar1.ValueChanged
        Dim i, j As Integer
        i = trackBar1.Value
        j = trackBar1.Maximum
        Me.Opacity = (j - i) / j
    End Sub

    Private Sub button1_Click(ByVal sender As System.Object, _
            ByVal e As System.EventArgs) Handles button1.Click
        '把滑块置到最左端
        trackBar1.Value = 0
        '在程序窗体的透明度渐变过程中，使滑杆和按钮不能用
        trackBar1.Enabled = False
        button1.Enabled = False
        Dim i As Double
        For i = 0.02 To 1 Step 0.02
            Me.Opacity = i
            System.Windows.Forms.Application.DoEvents()
            System.Threading.Thread.Sleep(5)
        Next
        Me.Opacity = 1
        button1.Enabled = True
        trackBar1.Enabled = True
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, _
            ByVal e As System.EventArgs) Handles Button2.Click
        If (hasNormalRegion) Then
            '构造一个GraphicsPath对象实例
            Dim p As New System.Drawing.Drawing2D.GraphicsPath()
            Dim bigDiameter As Integer = Me.ClientSize.Height
            '定义内椭圆的左上角从标
            Dim donutWidth As Integer = 100
            '在窗体上绘制一个大椭圆，左上角的坐标取为（0，0）
            '椭圆的边框高度和宽度设为同一个值，即成了圆。
            p.AddEllipse(0, 0, bigDiameter, bigDiameter)
            '再绘制一个小椭圆
            p.AddEllipse(donutWidth, donutWidth, _
                bigDiameter - (donutWidth * 2), bigDiameter - (donutWidth * 2))
            '设置窗口的可见区域
            Me.Region = New Region(p)
        Else
            Me.Region = Nothing
        End If
        hasNormalRegion = Not hasNormalRegion
    End Sub
End Class