WF4小试牛刀之生成流程图

为何需要流程图？

用户可以清晰的看到流程参与对象、流程节点状态及其整个流程结构；

因为WF4设计器本身没有天然提供这一功能，所以还需自己动手DIY；生成窗体图片因为需要用到底层GUI功能，所以是单独建立一个WPF工程，然后通过暴露服务的方式，实现同步调用，并返回数据；

功能实现及其步骤：

1.加载流程

        /// <summary>
        /// 加载流程设计器
        /// </summary>
        /// <param name="instance"></param>
        private void LoadWorkflowDesigner(System.Activities.Activity instance)
        {
            (new DesignerMetadata()).Register();
            _workflowDesigner = new WorkflowDesigner();
            if (instance is System.Activities.DynamicActivity)
            {
                instance = System.Activities.WorkflowInspectionServices.GetActivities(instance).First();
            }
            _workflowDesigner.Load(instance);

            this.rehostGrid.Children.Clear();
            this.rehostGrid.Children.Add(_workflowDesigner.View);

            _workflowDesigner.View.LayoutUpdated += new EventHandler(View_LayoutUpdated);
        }

2.利用控件截图功能，实现对设计器控件截图；

        /// <summary>
        /// 创建屏幕截图
        /// </summary>
        /// <returns></returns>
        BitmapFrame CreateScreenShot()
        {
            const double DPI = 96.0;
            // 获取设计器下的主窗体设计器，this._workflowDesigner.View是指整个容器，容器包含的第一个子窗体才是主窗体设计器
            DesignerView designerView = (DesignerView)VisualTreeHelper.GetChild(this._workflowDesigner.View, 0);
            Visual visual = designerView.RootDesigner;
            Rect size = VisualTreeHelper.GetDescendantBounds(visual);
            int imageWidth = (int)size.Width;　　
            int imageHeight = (int)size.Height;
            RenderTargetBitmap renderBitmap = new RenderTargetBitmap(imageWidth, imageHeight, DPI, DPI, PixelFormats.Pbgra32);
            renderBitmap.Render(visual);
            return BitmapFrame.Create(renderBitmap);
        }

        /// <summary>

3.两种生成图的方式；a.生成图然后返回图片路径 b.直接返回生成后的二进制数据

        /// <summary>
        /// 获取二进制图片数据
        /// </summary>
        /// <returns></returns>
        public byte[] GetPictureBytes()
        { 
            Dispatcher.Invoke((Action)(() =>
            {
                try
                {
                    MemoryStream ms = new MemoryStream();
                    JpegBitmapEncoder encoder = new JpegBitmapEncoder();
                    encoder.Frames.Add(BitmapFrame.Create(this.CreateScreenShot()));
                    encoder.Save(ms);
                    ms.Close();
                    ImageBytes = ms.ToArray();
                }catch(Exception ex)
                { MessageBox.Show(ex.Message); }
                // 关闭窗口
                this.Close();
                // 优先级必须为System.Windows.Threading.DispatcherPriority.Background，否则流程图会生成不全；
            }), System.Windows.Threading.DispatcherPriority.Background);
            return ImageBytes;
        }

        /// <summary>
        /// 创建本地图片
        /// </summary>
        /// <param name="fileName">生成图片文件名称</param>
        /// <returns>是否生成成功</returns>
        public bool CreateLocalPircture(string fileName)
        {
            bool b = false;

            Dispatcher.Invoke((Action)(() =>
            {
                try
                {
                    string fileDirectory = fileName.Substring(0, (fileName.LastIndexOf('\\') + 1));

                    // 如果目录不存在，则创建
                    if (!Directory.Exists(fileDirectory))
                    {
                        Directory.CreateDirectory(fileDirectory);
                    }

                    using (FileStream fs = new FileStream(fileName, FileMode.Create))
                    {
                        BitmapEncoder encoder = new JpegBitmapEncoder();
                        encoder.Frames.Add(BitmapFrame.Create(this.CreateScreenShot()));
                        encoder.Save(fs);
                        fs.Close();
                    }
                    b = true;
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message);
                }
                // 关闭窗口
                this.Close();

                // 优先级必须为System.Windows.Threading.DispatcherPriority.Background，否则流程图会生成不全；
                }), System.Windows.Threading.DispatcherPriority.Background);
            return b;
        }

3.WCF调用生成流程窗体

    [ServiceContract]
    public interface IWFPictureFactory
    {
        /// <summary>
        /// 根据申请ID获取二进制图片数据
        /// </summary>
        /// <param name="aiid">申请ID</param>
        /// <returns></returns>
        [OperationContract]
        byte[] GetPictureBytes(int aiid);

        /// <summary>
        /// 根据申请ID和图片文件名称生成本地图片
        /// </summary>
        /// <param name="aiid">申请ID</param>
        /// <param name="filename">文件名称</param>
        /// <returns></returns>
        [OperationContract]
        bool CreateLocalPircture(int aiid, string filename);
    }

    public class WFPictureFactory : IWFPictureFactory
    {
        /// <summary>
        /// 根据申请ID获取二进制图片数据
        /// </summary>
        /// <param name="aiid">申请ID</param>
        /// <returns></returns>
        public byte[] GetPictureBytes(int aiid)
        {
            MainWindow window = new MainWindow();
            window.AIID = aiid;
            window.Show();
            var bytes= window.GetPictureBytes();
            return bytes;
        }

        /// <summary>
        /// 根据申请ID和图片文件名称生成本地图片
        /// </summary>
        /// <param name="aiid">申请ID</param>
        /// <param name="filename">文件名称</param>
        /// <returns></returns>
        public bool CreateLocalPircture(int aiid,string filename)
        {
            MainWindow window = new MainWindow();
            window.AIID = aiid;
            window.Show();
            var b = window.CreateLocalPircture(filename);
            return b;
        }

 4.启动/关闭服务

        ServiceHost myServiceHost = null;
        void StartService(Type type)
        {
            try
            {
                //Instantiate new ServiceHost with the singleton instance being passed in
                myServiceHost = new ServiceHost(type);
                myServiceHost.Open();
                lblMsg.Content = "服务已启动！";

            }
            catch(Exception ex) {
                lblMsg.Content = "启动失败！";
                System.Windows.MessageBox.Show(ex.Message);
            }
        }

        void StopService()
        { 
            if(myServiceHost!=null){
                try
                {
                    myServiceHost.Close();
                    lblMsg.Content = "服务已关闭！";

                }
                catch (Exception ex)
                {
                    lblMsg.Content = "关闭服务失败！";
                    System.Windows.MessageBox.Show(ex.Message);
                }
            }
        }

 未完待续ing！下一步攻克流程节点状态显示的问题！ 

Demo下载：https://files.cnblogs.com/yizhuqing/AWFP.WFPictureBuilder.zip