一个非常容易回答的问题 [英] A very easy question to answer

问题描述

这可能是有史以来最愚蠢的问题之一。好的，我有一个表格：

This is probably one of the most stupid questions ever asked. Okay, so I have a form:

using System;
using System.Drawing;
using System.Windows.Forms;

namespace Whatever 
{
    public class Form1 : Form
    {
        public Form1
        {
            InitializeComponent();
            Graphics g = CreateGraphics();
            g.Clear(Color.Black);
            g.FillRectangle(Brushes.Tan, 0, 0, 20, 50);
        }
    }
}

无论我做什么都不会在屏幕上画出



正如我所说，这可能是一个愚蠢的问题，但是它会给你一些额外的分数。

No matter what I do nothing will be drawn on the screen

As I said this is probably a stupid question but hey it will give you some extra points.

推荐答案

覆盖OnPaint方法（受保护覆盖OnPaint（...）



然后将绘图代码放在那里，OnPaint方法有一个绘制事件参数，其中包含对图形对象的引用，所以你不需要单独创建它。

Override the OnPaint method (protected override OnPaint(... )

Then put your drawing code in there, the OnPaint method has a paint event args that includes a reference to the graphics object, so you don't need to create it separately.

public class Form1 : Form
{
    public Form1
    {
        InitializeComponent();
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        Graphics g = e.Graphics;
        g.Clear(Color.Black);
        g.FillRectangle(Brushes.Red, 0, 0, 20, 50);

    }
}

Form.OnPaint MSDN [ ^ ]



BTW，你用黑色清除图形然后画一个黑色矩形，所以你永远不会看到它。我将颜色更改为红色，您将看到背景现在为黑色，上面有一个红色矩形。

Form.OnPaint MSDN[^]

BTW, you are clearing the graphics with "Black" then painting a black rectangle, so you would never see it. I changed the color to red and you will see the background now black with a red rectangle on it.

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