我试图在F＃中实现自定义Windows.Forms控件，但似乎根本没有调用“ OnPaint”方法（它不会显示，并且调试消息也不会打印到控制台）。我究竟做错了什么？
open System
open System.Drawing
open System.Windows.Forms
let form = new Form(Visible=true, Text="Drawing App", WindowState=FormWindowState.Maximized)
type Canvas() =
class
inherit Control()
override c.OnPaint(e:PaintEventArgs) =
System.Diagnostics.Debug.WriteLine("OnPaint")
base.OnPaint(e)
let g = e.Graphics
g.DrawLine(Pens.Blue, 0, 0, c.Width, c.Height)
end
System.Diagnostics.Debug.WriteLine("hello")
let canvas = new Canvas()
canvas.Visible <- true
form.Controls.Add(canvas)
[<STAThread>]
Application.Run(form)
如果我将“ let canvas ...”块替换为下面的块，则会在窗口中显示一个标签：
let label = new Label(Text="sample label")
form.Controls.Add(label)
受到@FoggyFinder的答案的启发，这就是我现在要讨论的内容：
open System
open System.Drawing
open System.Windows.Forms
let form = new Form(Visible=true, Text="Drawing App", WindowState=FormWindowState.Maximized)
type Canvas() =
inherit Control()
override c.OnPaint(e:PaintEventArgs) =
//System.Diagnostics.Debug.WriteLine("OnPaint")
base.OnPaint(e)
let g = e.Graphics
g.DrawLine(Pens.Blue, 0, 0, c.Width, c.Height)
override c.OnResize(e:EventArgs) =
c.Refresh()
let canvas = new Canvas(Dock = DockStyle.Fill)
form.Controls.Add(canvas)
[<STAThread>]
Application.Run(form)
似乎为我工作，并且在我眼中看起来更合适。我现在会将其标记为公认的解决方案，但是我仍然对可能的改进或其他主张感兴趣。
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我来说两句