C# Windows 窗体未加载

Question

我可能搞砸了一些东西，现在不知道如何修复它。

有以下代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Globalization;


namespace BeamDesiger
{
    public partial class SectionConstructor : Form
    {
        public static int sWidth = 0;
        public static int sHeight = 0;
        public static int symbolSize = 1;
        public static int fontSize = 2;
        public static int CsysArrowLength = 2;
        public int offset = 0;
        public int scaleFactor = 1;


        public SectionConstructor()
        {
            InitializeComponent();
        }

        private void SectionConstructor_Load(object sender, EventArgs e)
        {
            MessageBox.Show("picture box loaded: w: " + pictureBox1.Width.ToString());
            PictureSetup(pictureBox1);
            SetWhiteCanva(pictureBox1);
            DrawCSYS(pictureBox1, predefinedColors("black"));
            dataGridView1.Rows.Clear();
        }

        public void SetWhiteCanva(PictureBox pb)
        {
            Bitmap bmp = new Bitmap(pb.Image);
            for (int y = 0; y < bmp.Height; y++)
            {
                for (int x = 0; x < bmp.Width; x++)
                {
                    bmp.SetPixel(x, y, predefinedColors("white"));
                }
            }
            pb.Image = bmp;
        }
    }
}

问题是名为

SectionConstructor_Load

' 的方法不知何故没有被读取，所以我假设整个表单没有被编译器加载，amd 首先读取

SetWhiteCanva

并在第一行崩溃

Bitmap bmp = new Bitmap(pb.Image);

为什么我认为表单未加载：

SectionConstructor_Load

方法的第一行应该返回消息，但 id 没有：

MessageBox.Show("picture box loaded: w: " + pictureBox1.Width.ToString());

我检查了一下，pictureBox1 正在初始化

SectionConstructor.Designer.cs

:

            // 
            // pictureBox1
            // 
            this.pictureBox1.Location = new System.Drawing.Point(12, 19);
            this.pictureBox1.Name = "pictureBox1";
            this.pictureBox1.Size = new System.Drawing.Size(494, 351);
            this.pictureBox1.TabIndex = 6;
            this.pictureBox1.TabStop = false;

可能出了什么问题？ 以前有用过，不知道我搞砸了什么。上面的代码是不是少了什么？我是 C# 新手，所以这可能是一件微不足道的事情。

PS：我也删除了

pictureBox1

并再次添加以确保一切就位，但仍然有问题。

异常堆栈跟踪：

   at System.Drawing.Bitmap..ctor(Image original)
   at BeamDesiger.SectionConstructor.SetWhiteCanva(PictureBox pb) in C:\Users\tw\source\repos\Beam Designer\BeamDesiger\BeamDesiger\SectionConstructor.cs:line 43
   at BeamDesiger.SectionConstructor.dataGridViewValidator(DataGridView dgw) in C:\Users\tw\source\repos\Beam Designer\BeamDesiger\BeamDesiger\SectionConstructor.cs:line 219
   at BeamDesiger.SectionConstructor.dataGridView1_CellValueChanged(Object sender, DataGridViewCellEventArgs e) in C:\Users\tw\source\repos\Beam Designer\BeamDesiger\BeamDesiger\SectionConstructor.cs:line 438
   at System.Windows.Forms.DataGridView.OnCellValueChanged(DataGridViewCellEventArgs e)
   at System.Windows.Forms.DataGridView.OnCellValueChangedInternal(DataGridViewCellEventArgs e)
   at System.Windows.Forms.DataGridViewColumnHeaderCell.SetValue(Int32 rowIndex, Object value)
   at System.Windows.Forms.DataGridViewColumn.set_HeaderText(String value)
   at BeamDesiger.SectionConstructor.InitializeComponent() in C:\Users\tw\source\repos\Beam Designer\BeamDesiger\BeamDesiger\SectionConstructor.Designer.cs:line 203
   at BeamDesiger.SectionConstructor..ctor() in C:\Users\tw\source\repos\Beam Designer\BeamDesiger\BeamDesiger\SectionConstructor.cs:line 29
   at BeamDesiger.MainForm.button1_Click(Object sender, EventArgs e) in C:\Users\tw\source\repos\Beam Designer\BeamDesiger\BeamDesiger\MainForm.cs:line 2931
   at System.Windows.Forms.Control.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ButtonBase.WndProc(Message& m)
   at System.Windows.Forms.Button.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
   at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
   at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.Run(Form mainForm)
   at BeamDesiger.Program.Main() in C:\Users\tw\source\repos\Beam Designer\BeamDesiger\BeamDesiger\Program.cs:line 19

Answer 1

堆栈跟踪清楚地显示了 SetWhiteCanva 不是从 SectionConstructor_Load 调用的，而是从 dataGridViewValidator 调用的。如果您需要在 dataGridViewValidator 中触发 SetWhiteCanva，则很难绕过它。这里最好的解决方案是在 SetWhiteCanva 开始时检查 pictureBox1.Image 是否为 null：

        public void SetWhiteCanva(PictureBox pb) {
            if (pb.Image == null) return;
            for (int y = 0; y < pb.Image.Height; y++)
                for (int x = 0; x < pb.Image.Width; x++)
                    pb.Image.SetPixel(x, y, predefinedColors("white"));
        }