FindVisualChild参考问题

问题描述

我已经找到并修改了以下代码，以便将我的dataGrid导出到使用iTextSharp类的pdf文档。

  private void ExportToPdf（DataGrid grid）
 {
 PdfPTable table = new PdfPTable（grid.Columns。计数）; 
 using（Document doc = new Document（iTextSharp.text.PageSize.A4））
 {
 using（PdfWriter writer = PdfWriter.GetInstance（doc，new System.IO.FileStream（Test .pdf，FileMode.Create）））
 {
 doc.Open（）; （int j = 0; j< grid.Columns.Count; j ++）
 {
 table.AddCell（new Phrase（grid.Columns [j] .Header.ToString（） ））; 
} 
 table.HeaderRows = 1; 
 IEnumerable itemsSource = grid.ItemsSource as IEnumerable; 
 if（itemsSource！= null）
 {
 foreach（itemSource中的var item）
 {
 DataGridRow row = grid.ItemContainerGenerator.ContainerFromItem（item）as DataGridRow; 
 if（row！= null）
 {
 DataGridCellsPresenter presenter = FindVisualChild< DataGridCellsPresenter>（row）; （int i = 0; i< grid.Columns.Count; ++ i）
 
 DataGridCell cell =（DataGridCell）presenter.ItemContainerGenerator.ContainerFromIndex（i）; 
 TextBlock txt = cell.Content为TextBlock; 
 if（txt！= null）
 {
 table.AddCell（new Phrase（txt.Text））; 
} 
} 
} 
} 
 doc.Add（table）; 
 doc.Close（）; 
} 
} 
} 
} 
  

问题发生在以下行中：

  DataGridCellsPresenter Presenter = FindVisualChild< DataGridCellsPresenter>（row）; 
  

Visual Studio返回以下错误名称FindVisualChild在当前上下文中不存在。如何添加此参数？

解决方案

FindVisualChild 通过WPF框架，你必须添加它们。可能你想要这样：

  public static IEnumerable< T> FindVisualChildren< T>（DependencyObject depObj）
其中T：DependencyObject 
 {
 if（depObj！= null）
 {
 for（int i = 0; i< ; VisualTreeHelper.GetChildrenCount（depObj）; i ++）
 {
 DependencyObject child = VisualTreeHelper.GetChild（depObj，i）; 
 if（child！= null&&& child是T）
 {
 yield return（T）child; 
} 
 
 foreach（FindVisualChildren< T>（child）中的T childOfChild）
 {
 yield return childOfChild; 
} 
} 
} 
} 
 
 public static childItem FindVisualChild< childItem>（DependencyObject obj）
其中childItem：DependencyObject 
 {
 foreach（FindVisualChildren< childItem>（obj）中的childItem子项）
 {
 return child; 
} 
 
返回null; 
} 
  

在一些实用程序类中添加这些方法，以便它们可以重用。 >

I have found and modified following code in order to export my dataGrid to a pdf document using iTextSharp class.

private void ExportToPdf(DataGrid grid)
    {
        PdfPTable table = new PdfPTable(grid.Columns.Count);
        using (Document doc = new Document(iTextSharp.text.PageSize.A4))
        {
            using (PdfWriter writer = PdfWriter.GetInstance(doc, new System.IO.FileStream("Test.pdf", FileMode.Create)))
            {
                doc.Open();
                for (int j = 0; j < grid.Columns.Count; j++)
                {
                    table.AddCell(new Phrase(grid.Columns[j].Header.ToString()));
                }
                table.HeaderRows = 1;
                IEnumerable itemsSource = grid.ItemsSource as IEnumerable;
                if (itemsSource != null)
                {
                    foreach (var item in itemsSource)
                    {
                        DataGridRow row = grid.ItemContainerGenerator.ContainerFromItem(item) as DataGridRow;
                        if (row != null)
                        {
                            DataGridCellsPresenter presenter = FindVisualChild<DataGridCellsPresenter>(row);
                            for (int i = 0; i < grid.Columns.Count; ++i)
                            {
                                DataGridCell cell = (DataGridCell)presenter.ItemContainerGenerator.ContainerFromIndex(i);
                                TextBlock txt = cell.Content as TextBlock;
                                if (txt != null)
                                {
                                    table.AddCell(new Phrase(txt.Text));
                                }
                            }
                        }
                    }
                    doc.Add(table);
                    doc.Close();
                }
            }
        }
    } 

The problem occurs in the following line:

DataGridCellsPresenter presenter = FindVisualChild<DataGridCellsPresenter>(row);

Visual Studio returns following error 'The name 'FindVisualChild' does not exist in the current context'. How do I add this parameter ?.

解决方案

FindVisualChild method is not provided by WPF framework, you have to add them. May be you want this:

public static IEnumerable<T> FindVisualChildren<T>(DependencyObject depObj)
       where T : DependencyObject
{
    if (depObj != null)
    {
        for (int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++)
        {
            DependencyObject child = VisualTreeHelper.GetChild(depObj, i);
            if (child != null && child is T)
            {
                yield return (T)child;
            }

            foreach (T childOfChild in FindVisualChildren<T>(child))
            {
                yield return childOfChild;
            }
        }
    }
}

public static childItem FindVisualChild<childItem>(DependencyObject obj)
    where childItem : DependencyObject
{
    foreach (childItem child in FindVisualChildren<childItem>(obj))
    {
        return child;
    }

    return null;
}

Add these methods in some utility class so they can be reuse.

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