Diagram Serialization and Export

    Xml deserialization speed?

    Using LoadFromString?

    Using LoadFromXml?

    Convert FlowChart To Image?

    Convert shape to an image?

    Exporting a diagram to emf file?

    Saving a Selection?

    Drawing database ER diagrams with FlowChart.NET?

    Generating FlowChart Diagram from SQL-Data?

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Q:    Has the XML deserialization speed been improved in the Diagram.LoadFromXml in v5?

A:    Version 5 uses the DOM API and version 4 used linear serialization, so the XML serialization is a bit slower in V5, but you will notice it only with a big number of items (in the thousands). In addition, version 5 serializes saved a single copy of shared node images, so XML serialization in the new version is much faster when using images. We have done some tests with 400 nodes and 400 links:

• V4.3, without images: the file loads for a second
• V5.0, without images: the file loads for a second
• V4.3, with 10 images: the file loads for 12 seconds
• V5.0, with 10 images: the file loads for 2 seconds

Each image from the last tests was assigned to 40 nodes. In this case, the speed in version 5 is better because the bytes of shared images are encoded and saved just once; whereas version 4 saves a separate copy for each node, and subsequently decodes 400 image copies when loading.

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Q:    Can Diagram.LoadFromXml read XML strings created using previous version's XmlWriter class?

A:    The old XML format is still supported for reading; actually you must use the LoadFromString method to load an XML string.

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Q:    In v5, is there a performance difference between the LoadFromXml overload which takes a document vs. the one which takes a string?

A:    The latter calls the former after creating an XmlDocument object from the string content.

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Q:    Is it possible to convert a Diagram to a bitmap file.

A:    Call the Diagram.CreateImage method and then the Image.Save method.

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Q:    I am trying to create a custom drag&drop icon to show up when dragging the shape around on the screen. Is there a way to convert a flowChart shape into an image on the fly?

A:    Create a graphics object using Graphics.FromImage. In order to draw a shape on the Graphics instance, create a temporary node, set its shape, and then call the ShapeNode.Draw method. A similar method is shown in the Flowcharter sample project where the icons in a list box represent Flowchart.NET shapes.

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Q:    How can I export a diagram to emf file?

A:    Use the following code.

using (FileStream stream = new FileStream(
        @"C:\temp.wmf", FileMode.Create))
{
      Graphics g = CreateGraphics();
      IntPtr hDC = g.GetHdc();
      Metafile metafile = new Metafile(stream, hDC);
      g.ReleaseHdc(hDC);
      g.Dispose();       IGraphics gMeta = new GdiGraphics(
	    Graphics.FromImage(metafile));
	  
      diagram.Draw(gMeta, new RenderOptions(), 
	    diagram.Bounds, false);
	  
      gMeta.Dispose();
	  
      metafile.Dispose();
}

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Q:    Can I save to a file a selection of items.

A:    Use the CopySelection and PasteSelection methods to copy the selected items to a second Diagram instance, and call the Diagram.SaveToFile method to save them to a file.

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Q:    Can FlowChart.NET read my database schema and generate an ER diagram for it?

A:    No. You should read the schema by ADO.NET and generate a diagram programmatically with the CreateTableNode and CreateDiagramLink methods.

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Q:     I have an SQL-Table with some entries containing state and connection information in several columns. I already imported the nodes. Now I would like to organize the connections. Have you some hints which way I should choose to reach that?

A:    To create the connections, assign the node ID from the database to the ShapeNode.Tag property while creating the nodes. Run a second loop over the link records, and for each related node ID you have for a node, call CreateDiagramLink(node, Diagram.FindNode (relatedID)). If you already use the Tags to store other information, save the relations in a Hashtable. To arrange the diagram, use some of the layout algorithm classes, for example LayeredLayout.

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