HSmartWindowControl 之 摄像头实时显示( 使用 WPF )

1、添加Halcon控件，创建WPF项目

在VS2013中创建一个WPF工程，然后添加halcon的控件和工具包，参见：

HSmartWindowControl之安装篇 (Visual Studio 2013 & Halcon 18）

在WPF工程中添加好HSmartWindowControlWPF控件后，将其拖入主窗体即可。

2、生成摄像头实时显示的halcon代码

使用Image Acquisition 连接笔记本自带的摄像头，然后生成实时显示的代码即可：

* Image Acquisition 01: Code generated by Image Acquisition 01
open_framegrabber ('DirectShow', 1, 1, 0, 0, 0, 0, 'default', 8, 'rgb', -1, 'false', 'default', '[0] Integrated Camera', 0, -1, AcqHandle)
grab_image_start (AcqHandle, -1)
while (true)
    grab_image_async (Image, AcqHandle, -1)
    * Image Acquisition 01: Do something
endwhile

3、导出C#代码

这里主要关注action函数：

// Main procedure 
  private void action()
  {
    // Local iconic variables 
    HObject ho_Image=null;
    // Local control variables 
    HTuple hv_AcqHandle = new HTuple();
    // Initialize local and output iconic variables 
    HOperatorSet.GenEmptyObj(out ho_Image);
    //Image Acquisition 01: Code generated by Image Acquisition 01
    //Image Acquisition 01: Attention: The initialization may fail in case parameters need to
    //Image Acquisition 01: be set in a specific order (e.g., image resolution vs. offset).
    hv_AcqHandle.Dispose();
    HOperatorSet.OpenFramegrabber("DirectShow", 1, 1, 0, 0, 0, 0, "default", 8, "rgb", 
        -1, "false", "default", "[0] Integrated Camera", 0, -1, out hv_AcqHandle);

    HOperatorSet.GrabImageStart(hv_AcqHandle, -1);
    while ((int)(1) != 0)
    {
      ho_Image.Dispose();
      HOperatorSet.GrabImageAsync(out ho_Image, hv_AcqHandle, -1);
      //Image Acquisition 01: Do something
    }
    ho_Image.Dispose();

    hv_AcqHandle.Dispose();

  }

这段代码只是实现了采集图像，没有在界面上显示。

4、向VS项目添加halcon导出的c#代码

向action()的代码中添加在窗口上显示图像的代码，即使用DispObj函数。然后把action添加到按钮响应中执行。

这样点击按钮之后就会进入死循环不停的GrabImage和DispObj，但是实际操作时界面会停止响应，而且图像并不会在窗口内刷新。

5、添加实时显示子线程

主线程中运行循环无法实时显示，必须创建子线程。

这里使用了工作者线程，点击按钮后，启动线程并执行一个循环显示采集的图像；再次点击按钮时，跳出循环结束worker线程。然后继续点击按钮又可以进入子线程开启实时显示，实现随意启停。

private void Button1_Click(object sender, RoutedEventArgs e)
        {
            if (isCameraOpened == false)
            {
                Button1.Content = "关闭实时显示";
                isCameraOpened = true;
                play_Thread = new Thread(action);
                play_Thread.Start();
            }
            else
            {
                Button1.Content = "开启实时显示";
                isCameraOpened = false;
            }            
        }

注意调用线程需添加引用：

using System.Threading;//多线程

需要注意的是，为了防止在实时显示过程中突然关闭窗体导致程序崩溃，在窗体的Un_load事件中加入强行停止子线程的代码。

private void Window_Unloaded(object sender, RoutedEventArgs e)
        {
            if(play_Thread.IsAlive)
            {
                play_Thread.Abort();
            }
        }

6、调整图像尺寸以适应halconwindow窗口

（1）使用HSmartWindowControlWPF控件时，无需再添加鼠标滚轮的响应函数便可使用鼠标滚轮控制图像缩放。

（2）显示单张图像时，可以直接向HSmartWindowControlWPF控件的HDisplayCurrentObject属性赋HObject类型的图像即可自动调整图像尺寸来适应窗口大小。

hSmartWindowControl1.HDisplayCurrentObject = new HImage("girl.png");

但是这个方式不能适用于动态捕获的图像，所以动态捕获的图像还需要手动判断来进行缩放。调整的方式比较简单，就是获取窗口尺寸和图像尺寸进行对比，根据图像过宽还是过高来缩放。

7、源代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using HalconDotNet;
using System.Threading;//多线程

namespace HalconWindowWPFDemo
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        #region 全局变量
        private static MainWindow mainWindow = new MainWindow();
        private static HWindow hwindow; //全局窗口变量
        Thread play_Thread; //实时显示线程
        private static bool isCameraOpened; //是否正在实时显示
        private static double halconWindowHeight; //halcon窗口高度
        private static double halconWindowWidth; ////halcon窗口宽度
        #endregion

        #region 初始化
        public MainWindow()
        {
            InitializeComponent();           
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            hwindow = hSmartWindowControl1.HalconWindow;//初始化窗口变量          
            isCameraOpened = false;
            //获取halcon窗口大小
            halconWindowHeight = mainWindow.hSmartWindowControl1.WindowSize.Width;
            halconWindowWidth = mainWindow.hSmartWindowControl1.WindowSize.Height;      
        }
        #endregion

        #region 界面响应
        /// <summary>
        /// 开启和关闭实时显示按钮
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Button1_Click(object sender, RoutedEventArgs e)
        {
            if (isCameraOpened == false)
            {
                Button1.Content = "关闭实时显示";
                isCameraOpened = true;
                play_Thread = new Thread(action);
                play_Thread.Start();
            }
            else
            {
                Button1.Content = "开启实时显示";
                isCameraOpened = false;
            }
            
        }
        /// <summary>
        /// 显示一张图片
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Button2_Click(object sender, RoutedEventArgs e)
        {
            hSmartWindowControl1.HDisplayCurrentObject = new HImage("girl.png");
        }
        #endregion

        #region 实时显示用函数
        /// <summary>
        /// 摄像头实时显示
        /// </summary>
        private static void action()
        {
            // Local iconic variables 
            HObject ho_Image = null;
            // Local control variables 
            HTuple hv_AcqHandle = new HTuple();
            // Initialize local and output iconic variables 
            HOperatorSet.GenEmptyObj(out ho_Image);
            ho_Image.Dispose();
            hv_AcqHandle.Dispose();
            //Image Acquisition 01: Code generated by Image Acquisition 01          
            HOperatorSet.OpenFramegrabber("DirectShow", 1, 1, 0, 0, 0, 0, "default", 8, "rgb",
                -1, "false", "default", "[0] Integrated Camera", 0, -1, out hv_AcqHandle);
            HOperatorSet.GrabImageStart(hv_AcqHandle, -1);                 

            while (isCameraOpened)
            {            
                HOperatorSet.GrabImageAsync(out ho_Image, hv_AcqHandle, -1);
                if (!mainWindow.ShowHalconImage(ho_Image)) break;
            }
            ho_Image.Dispose();
            hv_AcqHandle.Dispose();
        }
        /// <summary>
        /// 显示图像
        /// </summary>
        /// <param name="image"></param>
        /// <returns></returns>
        private bool ShowHalconImage(HObject ho_Image)
        {           
            #region 缩放图像，适应窗口           
            //获取图像大小及纵横比
            HTuple hv_Width = new HTuple(), hv_Height = new HTuple();
            HOperatorSet.GetImageSize(ho_Image, out hv_Width, out hv_Height);
            int im_width = int.Parse(hv_Width.ToString());
            int im_height = int.Parse(hv_Height.ToString());
            double im_AspectRatio = (double)(im_width) / (double)(im_height);
            //获取窗口大小及纵横比        
            double w_AspectRatio = halconWindowWidth / halconWindowHeight;

            HOperatorSet.SetSystem("int_zooming", "false");//图像缩放之前最好将此参数设置为false.
            HTuple para = new HTuple("constant");
            HObject ho_zoomImage;
            HOperatorSet.GenEmptyObj(out ho_zoomImage);

            ho_zoomImage.Dispose();
            if (halconWindowWidth < im_width && im_AspectRatio > w_AspectRatio)
            {
                //超宽图像               
                HOperatorSet.ZoomImageSize(ho_Image, out ho_zoomImage, halconWindowWidth, halconWindowWidth / im_AspectRatio, "constant");             
            }
            else if (halconWindowHeight < im_height && im_AspectRatio < w_AspectRatio)
            {
                //超高图像                
                HOperatorSet.ZoomImageSize(ho_Image, out ho_zoomImage, halconWindowHeight * im_AspectRatio, halconWindowHeight, para);
            }
            #endregion

            #region 显示图像                   
            try
            {
                hwindow.SetPart(0, 0, -2, -2); 
                hwindow.DispObj(ho_zoomImage);
            }
            catch (Exception exp)
            {
                //MessageBox.Show(exp.ToString());
                return false;
            }
            #endregion
            return true;            
        }
        #endregion

        #region 析构函数
        /// <summary>
        /// 关闭窗体时推出子线程，防止崩溃
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Window_Unloaded(object sender, RoutedEventArgs e)
        {
            if(play_Thread.IsAlive)
            {
                play_Thread.Abort();
            }
        }
        #endregion
    }
}