Question

我试图仅为IP摄像机制作观众。没什么大不了的，但我遇到了一个问题，其中Image被打开并加载到picturebox1但它不会刷新，无论我是否将timer1中的计时器设置为500（ms）

代码：

    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        string url = "http://IPofIPCamera/now.jpg";
        WebClient webClient = new WebClient();
        CredentialCache myCache = new CredentialCache();
        myCache.Add(new Uri(url), "Basic",
            new NetworkCredential("SomeUser", "SomePass"));
        webClient.Credentials = myCache;
        MemoryStream imgStream = new MemoryStream(webClient.DownloadData(url));
        pictureBox1.Image = new System.Drawing.Bitmap(imgStream);
    }

    private void timer1_Tick(object sender, EventArgs e)
    {
        pictureBox1.Update();
    }
}

使用此代码PictureBox1是从网址加载的图片，但未刷新。我做错了什么？

Answer 1

所以，你对PictureBox.Update的工作原理有误解，这被描述为here：

使控件重绘其客户区域内的无效区域。

这意味着不会再次触发下载。

要解决您的问题，您应该提取一个下载和设置图像的方法，该方法将由计时器的勾号触发。

public void DownloadAndUpdatePicture()
{
  string url = "http://IPofIPCamera/now.jpg";
  WebClient webClient = new WebClient();
  CredentialCache myCache = new CredentialCache();
  myCache.Add(new Uri(url), "Basic", new NetworkCredential("SomeUser", "SomePass"));
  webClient.Credentials = myCache;
  MemoryStream imgStream = new MemoryStream(webClient.DownloadData(url));
  pictureBox1.Image = new System.Drawing.Bitmap(imgStream);
}

private void Form1_Load(object sender, EventArgs e)
{
  this.DownloadAndUpdatePicture();
}

private void timer1_Tick(object sender, EventArgs e)
{
  this.DownloadAndUpdatePicture();
}

从IP摄像头加载图像并在PictureBox1

1 个答案: