如何从按钮单击事件调用绘制事件? [英] How to call paint event from a button click event?

问题描述

我有一个带有事件paint"的图片框，我还在那里获得了用于绘制图形的代码.

I have a pictureBox with the event "paint" and I also got code in there to draw graphics.

例如:

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

    private void pictureBox1_Paint(object sender, PaintEventArgs e)
    {
        Graphics graphics = e.Graphics;
        graphics.DrawEllipse(Pens.Blue, 10, 10, 100, 100);
    }

    private void button1_Click(object sender, EventArgs e)
    {
        pictureBox1.Invalidate();
    }
}

}

我的问题是.如何从 button_click 事件触发这些事件?我在网上搜索了很多，发现了很多 awnsers，如.invalidate()"或.Refresh()"和.Update".但是我的作业告诉我需要使用 .Refresh() 方法来完成，并且绘画需要在一个 pictureBox 中.

My question is. How to fire these events of from a button_click event? I searched alot on the web and found alot of awnsers like ".invalidate()" or ".Refresh()" and ".Update". But my assignment tells me that I need to do it with the .Refresh() method and the painting needs to be in a pictureBox.

我从 .Refresh() 方法中注意到的.是它擦除了图片框(绘制图片框是如何在初始化时创建的).所以在按钮中触发 .Refresh 方法对我不起作用.

What I notice from .Refresh() method. Is that it erases the pictureBox(draws the pictureBox how it was created on initialize). So firing off .Refresh method in a button did not work for me.

关于如何从按钮触发绘画事件的任何其他建议?

Any other suggestions how to fire off a paint event from a button?

推荐答案

这应该可以解决问题:

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

        pictureBox1.Image = new Bitmap(pictureBox1.Width, pictureBox1.Height);
    }

    private void button1_Click(object sender, EventArgs e)
    {
        using (var g = Graphics.FromImage(pictureBox1.Image))
        {
            g.DrawEllipse(Pens.Blue, 10, 10, 100, 100);
            pictureBox1.Refresh();
        }
    }
}

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