请帮我看看，为什么总是提示错误呢

Question

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;namespace WindowsFormsApplication32
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            pictureBox1.MouseMove += new MouseEventHandler(pictureBox1_MouseMove);
        }
        public bool pick;
        public Bitmap mybitmap;
        
        private void Form1_Load(object sender, EventArgs e)
        {
            pick = true;
                   }        private void button1_Click(object sender, EventArgs e)
        {
            openbox.Filter = "*.bmp|*.bmp|*.jpg|*.jpeg";
            if (openbox.ShowDialog() == DialogResult.OK)
            {
                string mappath = openbox.FileName;
                pictureBox1.SizeMode = PictureBoxSizeMode.AutoSize;
                this.mybitmap = new Bitmap(mappath);
               
                pictureBox1.Image = (Image)mybitmap;
                this.ClientSize = new Size(pictureBox1.Width + 20, pictureBox1.Height + 20);
                pick = true;            }
        }
        private void pictureBox1_MouseMove(object sender, EventArgs e)
        {
            if (pick)
            {
                for (int i = 0; i < pictureBox1.Width; i++)
                {
                    for (int j = 0; j < pictureBox1.Height; j++)
                    {
                        Color pixelColor;
                        pixelColor = this.mybitmap.GetPixel(i, j);//总是提示pixelColor未将设置为实例
                        //pixelColor = Color.FromArgb(255,0,0);//这个语句对COLOR变量进行RGB值设置。
                        textBox1.Text = pixelColor.R.ToString();
                        textBox2.Text = pixelColor.G.ToString();
                        textBox3.Text = pixelColor.B.ToString();
                    }
                }            }
        }
    }
}

Answer 1

Color pixelColor;
改成 Color pixelColor =new Color;
就可实例化了啊

Answer 2

Color pixelColor;
改成 Color pixelColor =new Color（）;
就可实例化了啊

Answer 3

  public Form1()
        {
            InitializeComponent();
            pictureBox1.MouseMove += new MouseEventHandler(pictureBox1_MouseMove);
        }
当然哦，mybitmap 为null

Answer 4

在没有加载图片的时候（button1_Click没有执行），鼠标移动到图片框上，也会触发MouseMove。你需要一个判断。