实例115百叶窗效果

Graphics.DrawImage 方法

https://docs.microsoft.com/zh-cn/dotnet/api/system.drawing.graphics.drawimage?view=dotnet-plat-ext-3.1#System_Drawing_Graphics_DrawImage_System_Drawing_Image_System_Drawing_PointF___

DrawImage(Image, Point)	在指定的位置使用原始物理大小绘制指定的 Image。
DrawImage(Image, Rectangle, Rectangle, GraphicsUnit)	在指定位置并且按指定大小绘制指定的 Image 的指定部分。   第一个参数是要绘制的图像； 第二个参数是要绘制图像的指定目标区域： 第三个参数要绘制的源图像的指定部分： 第四个参数为图像最单位。

 

Public Class Form1
    Dim pic As Image
    Dim myGraph As Graphics

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        myGraph = PictureBox1.CreateGraphics
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        dlgOpen.Filter = "图片文件|*.bmp;jpg|所有文件|*.*"
        If dlgOpen.ShowDialog = DialogResult.OK Then
            pic = Image.FromFile(dlgOpen.FileName)
            myGraph.DrawImage(pic, New Point(0, 0))
        End If
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Timer1.Start()

    End Sub


    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        Me.Close()
    End Sub

    Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        PictureBox1.Image = Nothing
        Dim picLine As Integer = 0
        Dim h As Integer = 10
        Dim desRect As New Rectangle
        Dim srcRect As New Rectangle
        Dim i As Long
        Dim lnNum As Integer
        For lnNum = 0 To 38 Step 2
            With srcRect
                .X = 0
                .Y = lnNum * h
                .Width = pic.Width
                .Height = h
            End With

            With desRect
                .X = 0
                .Y = lnNum * Me.PictureBox1.Height / 40
                .Width = PictureBox1.Width
                .Height = PictureBox1.Height / 40
            End With

            myGraph.DrawImage(pic, desRect, srcRect, GraphicsUnit.Pixel)

            '延时
            For i = 0 To 10000000
            Next
        Next

        For lnNum = 1 To 39 Step 2
            With srcRect
                .X = 0
                .Y = lnNum * h
                .Width = pic.Width
                .Height = h
            End With

            With desRect
                .X = 0
                .Y = lnNum * Me.PictureBox1.Height / 40
                .Width = PictureBox1.Width
                .Height = PictureBox1.Height / 40
            End With

            myGraph.DrawImage(pic, desRect, srcRect, GraphicsUnit.Pixel)

            '延时
            For i = 0 To 10000000
            Next
        Next
    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
        Timer1.Stop()
    End Sub
End Class