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

 

代码

         ///   <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

代码

        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：http://files.cnblogs.com/yizhuqing/AWFP.WFPictureBuilder.zip