c# - 如何使用 PictureBox 打开/关闭相机

Question

IDE:Visual Studio 2010 Express
库:Emgu CV 2.2 级别:初学者

我在单击 PictureBox 时打开了相机，反之亦然，但它给出了错误:

Object reference not set to an instance of an object

这里是事件处理器:

private void pictureBoxCapture_Click(object sender, EventArgs e)
{
    try
    {
        if (Clicked == true) //i dont know how to make it right
        {
            Application.Idle -= ProcessFrame;
        }
        else
        {
            Application.Idle += ProcessFrame;
        }
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

电话来自:

private void ProcessFrame(object sender, EventArgs e)
{
    //Cap = new Emgu.CV.Capture();
    ImageFrame = Cap.QueryFrame();
    pictureBoxCapture.Image = ImageFrame.ToBitmap();
}

如何设置 if else 参数，有什么建议吗？

Answer 1

创建一个类级别的 bool 变量，然后在 PictureBox 的点击事件中切换它。

public partial class Form1 : Form
{
    bool Clicked; //Create this Class level variable to be used in your handler
    public Form1()
    {
        InitializeComponent();
    }

    private void pictureBoxCapture_Click(object sender, EventArgs e)
    {
        Clicked =! Clicked; //Toggle your Boolean here
        try
        {
            if (Clicked)
            {
                Application.Idle -= ProcessFrame;
                FaceDetect();
            }
            else
            {
                Application.Idle += ProcessFrame;
            }
        }
        catch (Exception ex)
        {

            MessageBox.Show(ex.Message);
        }
    }
}