wpf FindVisualChild 参考问题
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/25229503/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
FindVisualChild reference issue
提问by user3812509
I have found and modified following code in order to export my dataGrid to a pdf document using iTextSharp class.
我找到并修改了以下代码，以便使用 iTextSharp 类将我的 dataGrid 导出到 pdf 文档。
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:
问题出现在以下行中：
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 ?.
Visual Studio 返回以下错误“当前上下文中不存在名称‘FindVisualChild’”。我如何添加这个参数？。
回答by Rohit Vats
FindVisualChildmethod is not provided by WPF framework, you have to add them. May be you want this:
FindVisualChildWPF 框架不提供方法，您必须添加它们。可能你想要这个：
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.
在一些实用程序类中添加这些方法，以便它们可以重用。
回答by Shocked
Also a common practice is to use these methods (posted by Rohit Vats) as extension methods, like this:
另外一种常见的做法是使用这些方法（由 Rohit Vats 发布）作为扩展方法，如下所示：
static class Utils
{
public static IEnumerable<T> FindVisualChildren<T>(this DependencyObject depObj)
where T : DependencyObject
{
...
}
public static childItem FindVisualChild<childItem>(this DependencyObject obj)
where childItem : DependencyObject
{
...
}
}
And then in your code:
然后在你的代码中：
using Utils;
class MyCode
{
public static DataGridCellsPresenter GetPresenter(DataGridRow row)
{
return row.FindVisualChild<DataGridCellsPresenter>();
}
}
