vb.net - 为什么 Paint 不绘制此图像？

Question

我正在重写我的控件中的 OnPaint 方法，该方法是直接从我自己的ICan3D.Graphics类生成的图像中绘制的。当我保存图像时（如您所见，该行已被注释掉）图像是正确的。但是，当表单加载时，它不会将图像作为背景显示。

Imports System

Namespace ICan3D

    Public Class RenderSurface
        Inherits Control

        Dim nImg As Graphics

        Protected Overrides Sub OnPaint(e As System.Windows.Forms.PaintEventArgs)
            Dim img As Bitmap = nImg.Visual
            'img.Save("C:\image.png")
            Dim nGraphDis As System.Drawing.Graphics = System.Drawing.Graphics.FromImage(img)
            Dim nPaintEventArgs As New PaintEventArgs(nGraphDis, New Rectangle(0, 0, Width, Height))
            MyBase.OnPaint(nPaintEventArgs)
        End Sub

        Private Sub RenderSurface_Resize(sender As Object, e As System.EventArgs) Handles Me.Resize
            nImg = New Graphics(Width, Height)
        End Sub

    End Class

End Namespace

我正在使用 VB.net，所以所有 .net 答案都是可以接受的 :)

Answer 1

Protected Overrides Sub OnPaint(e As PaintEventArgs)
    MyBase.OnPaint(e)
    e.Graphics.DrawImageUnscaled(nImg.Visual, 0, 0, Width, Height)
End Sub