C# 使用aforge.net调用本地摄像头画面和抓拍图片

在日常开发过程中，c#调用本地摄像头由很多种方式可以实现，今天我们就来讲一下如何通过Aforge图像处理库来调用本地摄像头并实现抓拍功能。
首先，我们新建一个空白的Winform程序，在Nuget包管理器中搜索Aforge，会出现很多结果，其中安装AForge.Video.DirectShow和AForge.Controls两个库即可。
c#安装Aforge
AForge.Video.DirectShow和AForge.Controls两个库安装好以后，我们先生成一下项目，目的是确保Aforge自定义控件能够正确地添加到VS控件工具箱中，如下图所示
c#Aforge自定义控件
最后我们开始实现代码逻辑，先全局定义FilterInfoCollection、VideoCaptureDevice、VideoCapabilities三个变量，然后具体代码流程如下。

在窗体加载Load事件时，扫描摄像头信息并显示在下拉列表中。
切换摄像头列表时根据选中的摄像头信息获取支持的分辨率列表
点击连接按钮开始连接指定摄像头，并把摄像头画面显示在控件中
点击抓拍按钮获取摄像头画面当前帧保存到程序根目录
点击断开连接按钮断开与摄像头的连接

至此整个代码逻辑梳理完毕，下面附上Aforge调用摄像头示例代码。

using AForge.Video.DirectShow;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace AforgeExp
{
    public partial class FrmMain : Form
    {
        public FrmMain()
        {
            InitializeComponent();
        }

        private FilterInfoCollection videoDevices;
        private VideoCaptureDevice videoDevice;
        private VideoCapabilities[] videoCapabilities;

        private void FrmMain_Load(object sender, EventArgs e)
        {
            //获取内置、外接摄像头，非网络摄像头
            videoDevices = new FilterInfoCollection(FilterCategory.VideoInputDevice);
            if (videoDevices.Count != 0)
            {
                foreach (FilterInfo device in videoDevices)
                {
                    cbo_camera.Items.Add(device.Name);
                }
            }
            else
            {
                cbo_camera.Items.Add("没有找到摄像头");
            }

            cbo_camera.SelectedIndex = 0;
        }

        private void cbo_camera_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (videoDevices.Count != 0)
            {
                //获取每个摄像头支持的分辨率
                videoDevice = new VideoCaptureDevice(videoDevices[cbo_camera.SelectedIndex].MonikerString);
                GetDeviceResolution(videoDevice);
            }
        }

        /// <summary>
        /// 获取每个摄像头支持的分辨率
        /// </summary>
        /// <param name="videoCaptureDevice"></param>
        private void GetDeviceResolution(VideoCaptureDevice videoCaptureDevice)
        {
            cbo_rate.Items.Clear();
            videoCapabilities = videoCaptureDevice.VideoCapabilities;
            foreach (VideoCapabilities capabilty in videoCapabilities)
            {
                cbo_rate.Items.Add($"{capabilty.FrameSize.Width} x {capabilty.FrameSize.Height}");
            }
            cbo_rate.SelectedIndex = 0;
        }

        private void btn_conn_Click(object sender, EventArgs e)
        {
            if (videoDevice != null)
            {
                if ((videoCapabilities != null) && (videoCapabilities.Length != 0))
                {
                    videoDevice.VideoResolution = videoCapabilities[cbo_rate.SelectedIndex];

                    myvideo.VideoSource = videoDevice;
                    myvideo.Start();

                    btn_conn.Enabled = false;
                    btn_stop.Enabled = true;
                    btn_cap.Enabled = true;
                }
            }
        }

        private void btn_stop_Click(object sender, EventArgs e)
        {
            if (myvideo.VideoSource != null)
            {
                myvideo.SignalToStop();
                myvideo.WaitForStop();
                myvideo.VideoSource = null;

                btn_conn.Enabled = true;
                btn_stop.Enabled = false;
                btn_cap.Enabled = false;
            }
        }

        private void btn_cap_Click(object sender, EventArgs e)
        {
            if (myvideo.VideoSource != null)
            {
                Bitmap img = myvideo.GetCurrentVideoFrame();
                img.Save("001.jpg");
                MessageBox.Show("抓拍成功，文件在程序根目录下。");
            }
        }

        /// <summary>
        /// 窗体关闭程序退出时断开摄像头连接
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void FrmMain_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (myvideo.VideoSource != null)
            {
                myvideo.SignalToStop();
                myvideo.WaitForStop();
                myvideo.VideoSource = null;

                btn_conn.Enabled = true;
                btn_stop.Enabled = false;
                btn_cap.Enabled = false;
            }
        }
    }
}