Develop Reference

c# WPF How to invoke or call button function using string variable, the string variable contains the button name?

string buttonName="";
private void _1btn_Click(object sender, RoutedEventArgs e){
var button = (Button) sender;
buttonName = button.Name;
ChangeButtonColour();
}
private void ChangeButtonColour() {
buttonName.Background = Brushes.Red;// doesn't Work!
}
I'm try to call the button function using the string variable buttonName(Which contains "_1btn") rather than calling _1btn which is the actually button Name.

//find the control by from form element tree
private void ChangeButtonColour(string _btname)
{
Button foundTextBox = FindChild<Button>(Application.Current.MainWindow, _btname);
}
public static T FindChild<T>(DependencyObject parent, string childName)where T : DependencyObject
{
// Confirm parent and childName are valid.
if (parent == null) return null;
T foundChild = null;
int childrenCount = VisualTreeHelper.GetChildrenCount(parent);
for (int i = 0; i < childrenCount; i++)
{
var child = VisualTreeHelper.GetChild(parent, i);
// If the child is not of the request child type child
T childType = child as T;
if (childType == null)
{
// recursively drill down the tree
foundChild = FindChild<T>(child, childName);
// If the child is found, break so we do not overwrite the found child.
if (foundChild != null) break;
}
else if (!string.IsNullOrEmpty(childName))
{
var frameworkElement = child as FrameworkElement;
// If the child's name is set for search
if (frameworkElement != null && frameworkElement.Name == childName)
{
// if the child's name is of the request name
foundChild = (T)child;
break;
}
}
else
{
// child element found.
foundChild = (T)child;
break;
}
}
return foundChild;
}

I have found the answer. You can't store the button properties in a string variable. So you have create a button object type variable then assign the button to the new button type variable and then you can call the button properties.
Button buttonName="";
private void _1btn_Click(object sender, RoutedEventArgs e){
buttonName = _1btn;
ChangeButtonColour();
}
private void ChangeButtonColour() {
buttonName.Background = Brushes.Red;// This works!
}

Finding ALL child controls WPF

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;
}
}

WPF + Controls.UserControl. How to find a control inside?

In my WPF project, I have a System.Windows.Controls.UserControl control. How to find a control inside that contol ?

use VisualTree, if I understood your question correctly.
refer to msdn : http://msdn.microsoft.com/en-us/library/dd409789.aspx

In that case you would probably want to walk the visual tree, like this extension method does:
internal static T FindVisualChild<T>(this DependencyObject parent) where T : DependencyObject
{
if (parent == null)
{
return null;
}
DependencyObject parentObject = parent;
int childCount = VisualTreeHelper.GetChildrenCount(parent);
for (int i = 0; i < childCount; i++)
{
DependencyObject childObject = VisualTreeHelper.GetChild(parentObject, i);
if (childObject == null)
{
continue;
}
var child = childObject as T;
return child ?? FindVisualChild<T>(childObject);
}
return null;
}
It requires that you know the type of the control you are looking for.

WPF: Get next /prev visual object

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;
}

How to find the ParentComboBox of a ComboBoxItem?

How can I get the ParentComboBox of an ComboBoxItem?
I would like to close an open ComboBox if the Insert-Key is pressed:
var focusedElement = Keyboard.FocusedElement;
if (focusedElement is ComboBox)
{
var comboBox = focusedElement as ComboBox;
comboBox.IsDropDownOpen = !comboBox.IsDropDownOpen;
}
else if (focusedElement is ComboBoxItem)
{
var comboBoxItem = focusedElement as ComboBoxItem;
var parent = comboBoxItem.Parent; //this is null
var parent = comboBoxItem.ParentComboBox; //ParentComboBox is private
parent.IsDropDownOpen = !parent.IsDropDownOpen;
}
It looks like there's no straight forward solution for this problem..

Basically, you want to retrieve an ancestor of a specific type. To do that, I often use the following method :
public static class DependencyObjectExtensions
{
public static T FindAncestor<T>(this DependencyObject obj) where T : DependencyObject
{
return obj.FindAncestor(typeof(T)) as T;
}
public static DependencyObject FindAncestor(this DependencyObject obj, Type ancestorType)
{
var tmp = VisualTreeHelper.GetParent(obj);
while (tmp != null && !ancestorType.IsAssignableFrom(tmp.GetType()))
{
tmp = VisualTreeHelper.GetParent(tmp);
}
return tmp;
}
}
You can use it as follows :
var parent = comboBoxItem.FindAncestor<ComboBox>();

As H.B. wrote you also can use
var parent = ItemsControl.ItemsControlFromItemContainer(comboBoxItem) as ComboBox;