正在将BlockUIContainer打印到XpsDocument/FixedDocument

问题

如何打印具有BlockUIContainer的FlowDocument
如何强制对FlowDocument进行度量/更新/排列

背景

我有一个生成的FlowDocument，其中包含一些Rectangle元素的文本段落，这些元素填充了资源字典中的DrawingBrushes，而BlockUIContainer则包含自定义控件。

当在任何FlowDocument*控件中查看时，文档都会正确呈现HOWEVER当文档转换为FixedDocument/XpsDocument时，Rectangle或BlockUIContainer元素都不会呈现。

我几乎可以肯定，这是因为控件没有被测量/排列，但在转换为XpsDocument之前，我不知道如何强制执行。

我已经递归地遍历了LogicalTree，并完成了以下操作，
```
UIElement element = (UIElement)d;
element.Measure(new Size(Double.PositiveInfinity, Double.PositiveInfinity));
element.Arrange(new Rect(element.DesiredSize));
element.UpdateLayout();
```
其中CCD_ 9是CCD_。我可以看到，当调试器中出现断点时，这会设置ActualWidth和ActualHeight属性。
我已尝试强制Dispatcher按照Will的建议进行渲染♦.

用于打印XpsDocument的代码

public class XpsDocumentConverter
{
    public static XpsDocumentReference CreateXpsDocument(FlowDocument document)
    {
        // Need to clone the document so that the paginator can work
        FlowDocument clonedDocument = DocumentHelper.Clone<FlowDocument>(document);
        Uri uri = new Uri(String.Format("pack://temp_{0}.xps/", Guid.NewGuid().ToString("N")));
        MemoryStream ms = new MemoryStream();
        Package pkg = Package.Open(ms, FileMode.Create, FileAccess.ReadWrite);
        PackageStore.AddPackage(uri, pkg);
        XpsDocument xpsDocument = new XpsDocument(pkg, CompressionOption.Normal, uri.AbsoluteUri);
        XpsSerializationManager rsm = new XpsSerializationManager(new XpsPackagingPolicy(xpsDocument), false);
        DocumentPaginator paginator = new FixedDocumentPaginator(clonedDocument, A4PageDefinition.Default);
        rsm.SaveAsXaml(paginator);
        return new XpsDocumentReference(ms, xpsDocument);
    }
}

正如你所看到的，我还使用了一个名为"FixedDocumentPaginator"的自定义DocumentPaginator；然而，我不会发布该代码，因为我怀疑问题是否存在，因为当它开始在GetPage(int pageNumber)中对文档进行分页时，所有内容都已转换为Visual，布局为时已晚。

编辑

嗯。当我键入此内容时，我突然想到克隆的文档可能没有完成Measure/Arrange/UpdateLayout。

问题：如何强制对FlowDocument进行度量/更新/排列？

我可以使用的一个可能的破解方法是在一个FlowDocumentViewer中显示克隆的文档（可能是在屏幕外）。

另一个可能的解决方案，我刚刚了解并没有尝试过，将是调用：ContextLayoutManager.From(Dispatcher.CurrentDispatcher).UpdateLayout();

ContextLayoutManager为您遍历逻辑树并更新布局。

用于克隆文档的代码

public static FlowDocument Clone(FlowDocument originalDocument)
{
    FlowDocument clonedDocument = new FlowDocument();
    TextRange sourceDocument = new TextRange(originalDocument.ContentStart, originalDocument.ContentEnd);
    TextRange clonedDocumentRange = new TextRange(clonedDocument.ContentStart, clonedDocument.ContentEnd);
    try
    {
        using (MemoryStream ms = new MemoryStream())
        {
            sourceDocument.Save(ms, DataFormats.XamlPackage);
            clonedDocumentRange.Load(ms, DataFormats.XamlPackage);
        }
        clonedDocument.ColumnWidth = originalDocument.ColumnWidth;
        clonedDocument.PageWidth = originalDocument.PageWidth;
        clonedDocument.PageHeight = originalDocument.PageHeight;
        clonedDocument.PagePadding = originalDocument.PagePadding;
        clonedDocument.LineStackingStrategy = clonedDocument.LineStackingStrategy;
        return clonedDocument;
    }
    catch (Exception)
    {               
    }
    return null;
}

将其发布为其他使用FlowDocument/FixedDocument/XpsDocument存在类似呈现问题的人的未来参考。

需要注意的几点：

使用上述方法时，不会克隆BlockUIContainers。直到我使用一些辅助方法将逻辑树打印出调试窗口（这些方法发布在下面，非常有用），这一点才立即显现出来
您需要在查看器中显示文档，并在屏幕上简要显示它。下面是我为自己编写的帮助方法

ForceRenderFlowDocument

private static string ForceRenderFlowDocumentXaml = 
@"<Window xmlns=""http://schemas.microsoft.com/netfx/2007/xaml/presentation""
          xmlns:x=""http://schemas.microsoft.com/winfx/2006/xaml"">
       <FlowDocumentScrollViewer Name=""viewer""/>
  </Window>";
public static void ForceRenderFlowDocument(FlowDocument document)
{
    using (var reader = new XmlTextReader(new StringReader(ForceRenderFlowDocumentXaml)))
    {
        Window window = XamlReader.Load(reader) as Window;
        FlowDocumentScrollViewer viewer = LogicalTreeHelper.FindLogicalNode(window, "viewer") as FlowDocumentScrollViewer;
        viewer.Document = document;
        // Show the window way off-screen
        window.WindowStartupLocation = WindowStartupLocation.Manual;
        window.Top = Int32.MaxValue;
        window.Left = Int32.MaxValue;
        window.ShowInTaskbar = false;
        window.Show();
        // Ensure that dispatcher has done the layout and render passes
        Dispatcher.CurrentDispatcher.Invoke(DispatcherPriority.Loaded, new Action(() => {}));
        viewer.Document = null;
        window.Close();
    }
}

编辑：我刚刚将window.ShowInTaskbar = false添加到该方法中，就好像你很快就能看到任务栏中出现的窗口一样。

用户永远不会"看到"窗口，因为它位于屏幕外的Int32.MaxValue位置——这在早期的多媒体创作中很常见（例如Macromedia/Adobe Director）。

对于搜索并找到此问题的人，我可以告诉您，没有其他方法可以强制呈现文档。

可视化和逻辑树帮助程序

public static string WriteVisualTree(DependencyObject parent)
{
    if (parent == null)
        return "No Visual Tree Available. DependencyObject is null.";
    using (var stringWriter = new StringWriter())
    using (var indentedTextWriter = new IndentedTextWriter(stringWriter, "  "))
    {               
        WriteVisualTreeRecursive(indentedTextWriter, parent, 0);
        return stringWriter.ToString();
    }
}
private static void WriteVisualTreeRecursive(IndentedTextWriter writer, DependencyObject parent, int indentLevel)
{
    if (parent == null)
        return;
    int childCount = VisualTreeHelper.GetChildrenCount(parent);
    string typeName = parent.GetType().Name;
    string objName = parent.GetValue(FrameworkElement.NameProperty) as string;
    writer.Indent = indentLevel;
    writer.WriteLine(String.Format("[{0:000}] {1} ({2}) {3}", indentLevel, 
                                                              String.IsNullOrEmpty(objName) ? typeName : objName, 
                                                              typeName, childCount)
                    );
    for (int childIndex = 0; childIndex < childCount; ++childIndex)
        WriteVisualTreeRecursive(writer, VisualTreeHelper.GetChild(parent, childIndex), indentLevel + 1);
}
public static string WriteLogicalTree(DependencyObject parent)
{
    if (parent == null)
        return "No Logical Tree Available. DependencyObject is null.";
    using (var stringWriter = new StringWriter())
    using (var indentedTextWriter = new IndentedTextWriter(stringWriter, "  "))
    {
        WriteLogicalTreeRecursive(indentedTextWriter, parent, 0);
        return stringWriter.ToString();
    }
}
private static void WriteLogicalTreeRecursive(IndentedTextWriter writer, DependencyObject parent, int indentLevel)
{
    if (parent == null)
        return;
    var children = LogicalTreeHelper.GetChildren(parent).OfType<DependencyObject>();
    int childCount = children.Count();
    string typeName = parent.GetType().Name;
    string objName = parent.GetValue(FrameworkElement.NameProperty) as string;
    double actualWidth = (parent.GetValue(FrameworkElement.ActualWidthProperty) as double?).GetValueOrDefault();
    double actualHeight = (parent.GetValue(FrameworkElement.ActualHeightProperty) as double?).GetValueOrDefault();
    writer.Indent = indentLevel;
    writer.WriteLine(String.Format("[{0:000}] {1} ({2}) {3}", indentLevel,
                                                              String.IsNullOrEmpty(objName) ? typeName : objName,
                                                              typeName, 
                                                              childCount)
                    );
    foreach (object child in LogicalTreeHelper.GetChildren(parent))
    {
        if (child is DependencyObject)
            WriteLogicalTreeRecursive(writer, (DependencyObject)child, indentLevel + 1);
    }
}

用法

#if DEBUG
    Debug.WriteLine("--- Start -------");
    Debug.WriteLine(VisualAndLogicalTreeHelper.WriteLogicalTree(document));
    Debug.WriteLine("--- End -------");
#endif

我在这里找到了这个解决方案，它帮助我打印FlowDocment，而不必在屏幕外渲染它。。。所以我希望它能帮助你！！

String copyString = XamlWriter.Save(flowDocViewer.Document);
FlowDocument copy = XamlReader.Parse(copyString) as FlowDocument;

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