我如何在richTextBox1上绘制字符串

本文关键字：绘制 字符串 richTextBox1 | 更新日期: 2023-09-27 18:10:12

我在设计器中创建了一个新的UserControl，我添加了一个richTextBox。然后我在UserControl构造函数中做了:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace ScrollLabelTest
{
    public partial class ScrollText : UserControl
    {
        Font drawFonts1 = new Font("Arial", 20, FontStyle.Bold, GraphicsUnit.Pixel);
        Point pt = new Point(50, 50);
        public ScrollText()
        {
            InitializeComponent();
            System.Drawing.Font f = new System.Drawing.Font("hi",5);
            Graphics e = richTextBox1.CreateGraphics();
            e.DrawString("hello",drawFonts1,new SolidBrush(Color.Red),pt);
            this.Invalidate();
        }
    }
}

然后我把新的UserControl拖到form1设计器中，但它是空的。

我如何在richTextBox1上绘制字符串

一种方法是扩展RichTextBox控件并在OnPaint方法中实现您的自定义绘图。但是通常RichTextBox控件不会调用OnPaint方法，所以你必须通过钩接WndProc方法来手动调用该方法。

的例子:

class ExtendedRTB : System.Windows.Forms.RichTextBox
{
    // this piece of code was taken from pgfearo's answer
    // ------------------------------------------
    // https://stackoverflow.com/questions/5041348/richtextbox-and-userpaint
    private const int WM_PAINT = 15;
    protected override void WndProc(ref System.Windows.Forms.Message m)
    {
        base.WndProc(ref m);
        if (m.Msg == WM_PAINT)
        {
            // raise the paint event
            using (Graphics graphic = base.CreateGraphics())
                OnPaint(new PaintEventArgs(graphic,
                 base.ClientRectangle));
        }
    }
    // --------------------------------------------------------
    protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
    {
        base.OnPaint(e);
        e.Graphics.DrawString("hello", this.Font, Brushes.Black, 0, 0);
    }
}

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