在分配位图时随机获取异常

Question

我有一个C#应用程序表单，它在关闭和打开另一个表单之前显示一个图像3秒。守则如下：

using System;
using System.Linq;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace SampleProgram
{
public partial class failureMessage : Form
{
    private Bitmap backgroundImage = null; // backgound image bitmap
    private System.Windows.Forms.Timer myTimer = new System.Windows.Forms.Timer();
    private const string imagePath = @"/NandFlash/MsgRefused.png";

    // Constructor
    public failureMessage()
    {
        InitializeComponent();

        this.Height = Screen.PrimaryScreen.Bounds.Height;
        this.Width = Screen.PrimaryScreen.Bounds.Width;

        try
        {
            backgroundImage = new Bitmap(imagePath);
        }
        catch (Exception ex)
        {
            throw ex;
        }

        myTimer.Tick += new EventHandler(TimerEventProcessor);

        // Sets the timer interval to 3 seconds.
        myTimer.Interval = 3000;
        myTimer.Enabled = true;
    }

    #region Timer event
    // This is the method to run when the timer is raised. 
    private void TimerEventProcessor(Object myObject, EventArgs myEventArgs)
    {
        myTimer.Enabled = false;
        myTimer.Dispose();
        backgroundImage.Dispose();
        backgroundImage = null;

        Form1 reopenMainpage = new Form1();

        reopenMainpage.Show();
        this.Close();
    }
    #endregion

    #region Paint the background
    protected override void OnPaintBackground(PaintEventArgs e)
    {
        e.Graphics.DrawImage(backgroundImage, 0, 0);
    }
    #endregion
}
}

然而，在随机情况下，我仍然得到以下例外情况：

System.Exception was unhandled
Message="Exception"
StackTrace:
Location: Microsoft.AGL.Common.MISC.HandleAr(PAL_ERROR ar)
Location: System.Drawing.Bitmap._InitFromMemoryStream(MemoryStream mstream)
Location: System.Drawing.Bitmap..ctor(String filename)
Location: SampleProgram.failureMessage..ctor()
Location: SampleProgram.Form1.ReceivedMsg(Object sender, FingerPrintSensorEventArgs e)
Location: SG7000.device.WndProcModification.onFGSensorTriggered(FingerPrintSensorEventArgs e)
Location: SG7000.device.WndProcModification.MyWndProc(IntPtr hWnd, UInt32 msg, IntPtr wParam, IntPtr lParam)
Location: Microsoft.AGL.Forms.EVL.EnterMainLoop(IntPtr hwnMain)
Location: System.Windows.Forms.Application.Run(Form fm)
Location: SampleProgram.Program.Main()

通过一些研究，我怀疑我可能没有在关闭表单之前释放位图对象或计时器对象，但是错误仍然是随机出现的。我的实现是出了什么问题，还是我忘了做什么？如有任何建议，敬请见谅。谢谢

Answer 1

堆栈跟踪显示，初始化位图时会出现异常。解决办法就是不要抛出异常。

    try
    {
        backgroundImage = new Bitmap(imagePath);
    }
    catch (Exception ex)
    {
        // Don't throw
    }

如果您经常加载位图，我会建议您将图片移到资源中，并从那里访问表单上的图片。

另外，将下面的行移动到Close事件处理程序。将处理程序附加到关闭事件。这将确保在窗体关闭时处理所有内容。

myTimer.Enabled = false;
myTimer.Dispose();
backgroundImage.Dispose();
backgroundImage = null;