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 ?.
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.
Also a common practice is to use these methods (posted by Rohit Vats) as extension methods, like this:
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:
using Utils;
class MyCode
{
public static DataGridCellsPresenter GetPresenter(DataGridRow row)
{
return row.FindVisualChild<DataGridCellsPresenter>();
}
}
Related
This is my xaml code, a NavigationView contains a NavigationView.HeaderTemplate.
<NavigationView.HeaderTemplate>
<DataTemplate
x:Name="HeaderDataTemplate">
<TextBlock
Name="HeaderText"
Text="I am a TextBlock"
Margin="0,0,0,10"/>
</DataTemplate>
</NavigationView.HeaderTemplate>
I want to know how to get the Texkblock through c# code.
Here is my c# code bu it doesn't work.
private void nvSample_SelectionChanged(NavigationView sender, NavigationViewSelectionChangedEventArgs args)
{
var navView = sender as NavigationView;
NavigationViewItem item = args.SelectedItemContainer as NavigationViewItem;
if(item.Tag.ToString() == "SatrtPage")
{
DataTemplate dataTemplate = sender.HeaderTemplate;
DependencyObject dio = dataTemplate.LoadContent();
var rectangle= FindVisualChild<TextBlock>(dio);
if (rectangle != null)
{
rectangle.Text = "LLLLLLL";
}
contentFrame.Navigate(typeof(StartPage));
}
private childItem FindVisualChild<childItem>(DependencyObject obj)
where childItem : DependencyObject
{
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
{
DependencyObject child = VisualTreeHelper.GetChild(obj, i);
if (child != null && child is childItem)
{
return (childItem)child;
}
else
{
childItem childOfChild = FindVisualChild<childItem>(child);
if (childOfChild != null)
return childOfChild;
}
}
return null;
}
Try this:
private void nvSample_SelectionChanged(NavigationView sender, NavigationViewSelectionChangedEventArgs args)
{
var navView = sender as NavigationView;
if (FindVisualChild<SplitView>(navView) is SplitView splitView
&& splitView.Content is Panel panel
&& panel.Children.OfType<ContentControl>().FirstOrDefault() is ContentControl cc)
{
var textBlock = FindVisualChild<TextBlock>(cc);
if (textBlock != null)
textBlock.Text = "changed text...";
}
}
Visual tree code
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;
}
}
}
}
selectionChanged code
private void mylistBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
if (mylistBox.SelectedItem == null)
return;
foreach (Button tb in FindVisualChildren<Button>(mainListBox))
{
Debug.WriteLine(tb.Name);
}
}
output
Note it writes the name of the two button twice so it loops 4 times and it only has 2 buttons.
optionBtn
optionBtn2
optionBtn
optionBtn2
How many items are there in mainListBox at runtime? It must be 2 and that's why it print the buttons names twice (2 times for each item in the list box). There is nothing wrong with SelectionChanged or VisualTreeHelper
I would like to find all of the controls within a WPF control. I have had a look at a lot of samples and it seems that they all either require a Name to be passed as parameter or simply do not work.
I have existing code but it isn't working properly:
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;
}
}
}
}
For instance it will not get a DataGrid within a TabItem.
Any suggestions?
You can use these.
public static List<T> GetLogicalChildCollection<T>(this DependencyObject parent) where T : DependencyObject
{
List<T> logicalCollection = new List<T>();
GetLogicalChildCollection(parent, logicalCollection);
return logicalCollection;
}
private static void GetLogicalChildCollection<T>(DependencyObject parent, List<T> logicalCollection) where T : DependencyObject
{
IEnumerable children = LogicalTreeHelper.GetChildren(parent);
foreach (object child in children)
{
if (child is DependencyObject)
{
DependencyObject depChild = child as DependencyObject;
if (child is T)
{
logicalCollection.Add(child as T);
}
GetLogicalChildCollection(depChild, logicalCollection);
}
}
}
You can get child button controls in RootGrid f.e like that:
List<Button> button = RootGrid.GetLogicalChildCollection<Button>();
You can use this Example:
public Void HideAllControl()
{
/// casting the content into panel
Panel mainContainer = (Panel)this.Content;
/// GetAll UIElement
UIElementCollection element = mainContainer.Children;
/// casting the UIElementCollection into List
List < FrameworkElement> lstElement = element.Cast<FrameworkElement().ToList();
/// Geting all Control from list
var lstControl = lstElement.OfType<Control>();
foreach (Control contol in lstControl)
{
///Hide all Controls
contol.Visibility = System.Windows.Visibility.Hidden;
}
}
I have a StackPanel containing a number ofTextBox. Is there a way to get the Next / Previous visual elements ?
The functionality I want is fairly analogous to jQuery's .next() function that get the next object.
You can try following method to enumerate the Visual Tree.
public static IEnumerable<T> FindVisualChildren<T>
(DependencyObject depObj, string childName) where T : DependencyObject
{
if (depObj != null)
{
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++)
{
DependencyObject child = VisualTreeHelper.GetChild(depObj, i);
var frameworkElement = child as FrameworkElement;
if (child != null && frameworkElement.Name == childName)
{
yield return (T)child;
}
foreach (T childOfChild in FindVisualChildren<T>(child, childName))
{
yield return childOfChild;
}
}
}
}
Assuming that you named your textBoxes "tbInsideStackPanel", use it like:
foreach (var textBox in FindVisualChildren<TextBox>(this.stackPanel1,
"tbInsideStackPanel").ToList())
{
textBox.Background = Brushes.Blue;
}
I have a WPF app that has a ListBox. The drag mechanism is already implemented, but when the list is too long and I want to move an item to a position not visible, I can't.
For example, the screen shows 10 items. And I have 20 items. If I want to drag the last item to the first position I must drag to the top and drop. Scroll up and drag again.
How can I make the ListBox auto scroll?
Got it. Used the event DragOver of the ListBox, used the function found here to get the scrollviewer of the listbox and after that its just a bit of juggling with the Position.
private void ItemsList_DragOver(object sender, System.Windows.DragEventArgs e)
{
ListBox li = sender as ListBox;
ScrollViewer sv = FindVisualChild<ScrollViewer>(ItemsList);
double tolerance = 10;
double verticalPos = e.GetPosition(li).Y;
double offset = 3;
if (verticalPos < tolerance) // Top of visible list?
{
sv.ScrollToVerticalOffset(sv.VerticalOffset - offset); //Scroll up.
}
else if (verticalPos > li.ActualHeight - tolerance) //Bottom of visible list?
{
sv.ScrollToVerticalOffset(sv.VerticalOffset + offset); //Scroll down.
}
}
public static childItem FindVisualChild<childItem>(DependencyObject obj) where childItem : DependencyObject
{
// Search immediate children first (breadth-first)
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
{
DependencyObject child = VisualTreeHelper.GetChild(obj, i);
if (child != null && child is childItem)
return (childItem)child;
else
{
childItem childOfChild = FindVisualChild<childItem>(child);
if (childOfChild != null)
return childOfChild;
}
}
return null;
}
Based on this I have created an Attached Behavior which can easily be used like this -
<ListView
xmlns:WpfExtensions="clr-namespace:WpfExtensions"
WpfExtensions:DragDropExtension.ScrollOnDragDrop="True"
Here is the code for attached behavior -
/// <summary>
/// Provides extended support for drag drop operation
/// </summary>
public static class DragDropExtension
{
public static readonly DependencyProperty ScrollOnDragDropProperty =
DependencyProperty.RegisterAttached("ScrollOnDragDrop",
typeof(bool),
typeof(DragDropExtension),
new PropertyMetadata(false, HandleScrollOnDragDropChanged));
public static bool GetScrollOnDragDrop(DependencyObject element)
{
if (element == null)
{
throw new ArgumentNullException("element");
}
return (bool)element.GetValue(ScrollOnDragDropProperty);
}
public static void SetScrollOnDragDrop(DependencyObject element, bool value)
{
if (element == null)
{
throw new ArgumentNullException("element");
}
element.SetValue(ScrollOnDragDropProperty, value);
}
private static void HandleScrollOnDragDropChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
FrameworkElement container = d as FrameworkElement;
if (d == null)
{
Debug.Fail("Invalid type!");
return;
}
Unsubscribe(container);
if (true.Equals(e.NewValue))
{
Subscribe(container);
}
}
private static void Subscribe(FrameworkElement container)
{
container.PreviewDragOver += OnContainerPreviewDragOver;
}
private static void OnContainerPreviewDragOver(object sender, DragEventArgs e)
{
FrameworkElement container = sender as FrameworkElement;
if (container == null)
{
return;
}
ScrollViewer scrollViewer = GetFirstVisualChild<ScrollViewer>(container);
if (scrollViewer == null)
{
return;
}
double tolerance = 60;
double verticalPos = e.GetPosition(container).Y;
double offset = 20;
if (verticalPos < tolerance) // Top of visible list?
{
scrollViewer.ScrollToVerticalOffset(scrollViewer.VerticalOffset - offset); //Scroll up.
}
else if (verticalPos > container.ActualHeight - tolerance) //Bottom of visible list?
{
scrollViewer.ScrollToVerticalOffset(scrollViewer.VerticalOffset + offset); //Scroll down.
}
}
private static void Unsubscribe(FrameworkElement container)
{
container.PreviewDragOver -= OnContainerPreviewDragOver;
}
private static T GetFirstVisualChild<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)
{
return (T)child;
}
T childItem = GetFirstVisualChild<T>(child);
if (childItem != null)
{
return childItem;
}
}
}
return null;
}
}