I have multiple pictureboxes and I need to load random images into them during runtime. So I thought it would be nice to have a collection of all pictureboxes and then assign images to them using a simple loop. But how should I do it? Or maybe are there any other better solutions to such problem?
Using a bit of LINQ:
foreach(var pb in this.Controls.OfType<PictureBox>())
{
//do stuff
}
However, this will only take care of PictureBoxes in the main container.
You could use this method:
public static IEnumerable<T> GetControlsOfType<T>(Control root)
where T : Control
{
var t = root as T;
if (t != null)
yield return t;
var container = root as ContainerControl;
if (container != null)
foreach (Control c in container.Controls)
foreach (var i in GetControlsOfType<T>(c))
yield return i;
}
Then you could do something like this:
foreach (var pictureBox in GetControlsOfType<PictureBox>(theForm)) {
// ...
}
If you're at least on .NET 3.5 then you have LINQ, which means that since ControlCollection implements IEnumerable you can just do:
var pictureBoxes = Controls.OfType<PictureBox>();
I use this generic recursive method:
The assumption of this method is that if the control is T than the method does not look in its children. If you need also to look to its children you can easily change it accordingly.
public static IList<T> GetAllControlsRecusrvive<T>(Control control) where T :Control
{
var rtn = new List<T>();
foreach (Control item in control.Controls)
{
var ctr = item as T;
if (ctr!=null)
{
rtn.Add(ctr);
}
else
{
rtn.AddRange(GetAllControlsRecusrvive<T>(item));
}
}
return rtn;
}
A simple function, easy to understand, recursive, and it works calling it inside any form control:
private void findControlsOfType(Type type, Control.ControlCollection formControls, ref List<Control> controls)
{
foreach (Control control in formControls)
{
if (control.GetType() == type)
controls.Add(control);
if (control.Controls.Count > 0)
findControlsOfType(type, control.Controls, ref controls);
}
}
You can call it on multiple ways.
To get the Buttons:
List<Control> buttons = new List<Control>();
findControlsOfType(typeof(Button), this.Controls, ref buttons);
To get the Panels:
List<Control> panels = new List<Control>();
findControlsOfType(typeof(Panel), this.Controls, ref panels);
etc.
Here's another version since the existing provided ones weren't quite what I had in mind. This one works as an extension method, optionally, and it excludes checking the root/parent container's type. This method is basically a "Get all descendent controls of type T" method:
public static System.Collections.Generic.IEnumerable<T> ControlsOfType<T>(this System.Web.UI.Control control) where T: System.Web.UI.Control{
foreach(System.Web.UI.Control childControl in control.Controls){
if(childControl is T) yield return (T)childControl;
foreach(var furtherDescendantControl in childControl.ControlsOfType<T>()) yield return furtherDescendantControl;
}
}
public static List<T> FindControlByType<T>(Control mainControl,bool getAllChild = false) where T :Control
{
List<T> lt = new List<T>();
for (int i = 0; i < mainControl.Controls.Count; i++)
{
if (mainControl.Controls[i] is T) lt.Add((T)mainControl.Controls[i]);
if (getAllChild) lt.AddRange(FindControlByType<T>(mainControl.Controls[i], getAllChild));
}
return lt;
}
This to me is by far the easiest. In my application, I was trying to clear all the textboxes in a panel:
foreach (Control c in panel.Controls)
{
if (c.GetType().Name == "TextBox")
{
c.Text = "";
}
}
Takes Control as container into account:
private static IEnumerable<T> GetControlsOfType<T>(this Control root)
where T : Control
{
if (root is T t)
yield return t;
if (root is ContainerControl || root is Control)
{
var container = root as Control;
foreach (Control c in container.Controls)
foreach (var i in GetControlsOfType<T>(c))
yield return i;
}
}
I'm looking for a way to find all controls on Window by their type,
for example: find all TextBoxes, find all controls implementing specific interface etc.
This should do the trick:
public static IEnumerable<T> FindVisualChilds<T>(DependencyObject depObj) where T : DependencyObject
{
if (depObj == null) yield return (T)Enumerable.Empty<T>();
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++)
{
DependencyObject ithChild = VisualTreeHelper.GetChild(depObj, i);
if (ithChild == null) continue;
if (ithChild is T t) yield return t;
foreach (T childOfChild in FindVisualChilds<T>(ithChild)) yield return childOfChild;
}
}
then you enumerate over the controls like so
foreach (TextBlock tb in FindVisualChildren<TextBlock>(window))
{
// do something with tb here
}
This is the easiest way:
IEnumerable<myType> collection = control.Children.OfType<myType>();
where control is the root element of the window.
EDIT - As pointed out in the comments. This only goes one level deep. See the accepted answer for an option that goes deeper.
I adapted #Bryce Kahle's answer to follow #Mathias Lykkegaard Lorenzen's suggestion and use LogicalTreeHelper.
Seems to work okay. ;)
public static IEnumerable<T> FindLogicalChildren<T> ( DependencyObject depObj ) where T : DependencyObject
{
if( depObj != null )
{
foreach( object rawChild in LogicalTreeHelper.GetChildren( depObj ) )
{
if( rawChild is DependencyObject )
{
DependencyObject child = (DependencyObject)rawChild;
if( child is T )
{
yield return (T)child;
}
foreach( T childOfChild in FindLogicalChildren<T>( child ) )
{
yield return childOfChild;
}
}
}
}
}
(It still won't check tab controls or Grids inside GroupBoxes as mentioned by #Benjamin Berry & #David R respectively.)
(Also followed #noonand's suggestion & removed the redundant child != null)
Use the helper classes VisualTreeHelper or LogicalTreeHelper depending on which tree you're interested in. They both provide methods for getting the children of an element (although the syntax differs a little). I often use these classes for finding the first occurrence of a specific type, but you could easily modify it to find all objects of that type:
public static DependencyObject FindInVisualTreeDown(DependencyObject obj, Type type)
{
if (obj != null)
{
if (obj.GetType() == type)
{
return obj;
}
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
{
DependencyObject childReturn = FindInVisualTreeDown(VisualTreeHelper.GetChild(obj, i), type);
if (childReturn != null)
{
return childReturn;
}
}
}
return null;
}
I found that the line, VisualTreeHelper.GetChildrenCount(depObj);, used in several examples above does not return a non-zero count for GroupBoxes, in particular, where the GroupBox contains a Grid, and the Grid contains children elements. I believe this may be because the GroupBox is not allowed to contain more than one child, and this is stored in its Content property. There is no GroupBox.Children type of property. I am sure I did not do this very efficiently, but I modified the first "FindVisualChildren" example in this chain as follows:
public IEnumerable<T> FindVisualChildren<T>(DependencyObject depObj) where T : DependencyObject
{
if (depObj != null)
{
int depObjCount = VisualTreeHelper.GetChildrenCount(depObj);
for (int i = 0; i <depObjCount; i++)
{
DependencyObject child = VisualTreeHelper.GetChild(depObj, i);
if (child != null && child is T)
{
yield return (T)child;
}
if (child is GroupBox)
{
GroupBox gb = child as GroupBox;
Object gpchild = gb.Content;
if (gpchild is T)
{
yield return (T)child;
child = gpchild as T;
}
}
foreach (T childOfChild in FindVisualChildren<T>(child))
{
yield return childOfChild;
}
}
}
}
Here is yet another, compact version, with the generics syntax:
public static IEnumerable<T> FindLogicalChildren<T>(DependencyObject obj) where T : DependencyObject
{
if (obj != null) {
if (obj is T)
yield return obj as T;
foreach (DependencyObject child in LogicalTreeHelper.GetChildren(obj).OfType<DependencyObject>())
foreach (T c in FindLogicalChildren<T>(child))
yield return c;
}
}
To get a list of all childs of a specific type you can use:
private static IEnumerable<DependencyObject> FindInVisualTreeDown(DependencyObject obj, Type type)
{
if (obj != null)
{
if (obj.GetType() == type)
{
yield return obj;
}
for (var i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
{
foreach (var child in FindInVisualTreeDown(VisualTreeHelper.GetChild(obj, i), type))
{
if (child != null)
{
yield return child;
}
}
}
}
yield break;
}
Small change to the recursion to so you can for example find the child tab control of a tab control.
public static DependencyObject FindInVisualTreeDown(DependencyObject obj, Type type)
{
if (obj != null)
{
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
{
DependencyObject child = VisualTreeHelper.GetChild(obj, i);
if (child.GetType() == type)
{
return child;
}
DependencyObject childReturn = FindInVisualTreeDown(child, type);
if (childReturn != null)
{
return childReturn;
}
}
}
return null;
}
And this is how it works upwards
private T FindParent<T>(DependencyObject item, Type StopAt) where T : class
{
if (item is T)
{
return item as T;
}
else
{
DependencyObject _parent = VisualTreeHelper.GetParent(item);
if (_parent == null)
{
return default(T);
}
else
{
Type _type = _parent.GetType();
if (StopAt != null)
{
if ((_type.IsSubclassOf(StopAt) == true) || (_type == StopAt))
{
return null;
}
}
if ((_type.IsSubclassOf(typeof(T)) == true) || (_type == typeof(T)))
{
return _parent as T;
}
else
{
return FindParent<T>(_parent, StopAt);
}
}
}
}
Do note that using the VisualTreeHelper does only work on controls that derive from Visual or Visual3D. If you also need to inspect other elements (e.g. TextBlock, FlowDocument etc.), using VisualTreeHelper will throw an exception.
Here's an alternative that falls back to the logical tree if necessary:
http://www.hardcodet.net/2009/06/finding-elements-in-wpf-tree-both-ways
My version for C++/CLI
template < class T, class U >
bool Isinst(U u)
{
return dynamic_cast< T >(u) != nullptr;
}
template <typename T>
T FindVisualChildByType(Windows::UI::Xaml::DependencyObject^ element, Platform::String^ name)
{
if (Isinst<T>(element) && dynamic_cast<Windows::UI::Xaml::FrameworkElement^>(element)->Name == name)
{
return dynamic_cast<T>(element);
}
int childcount = Windows::UI::Xaml::Media::VisualTreeHelper::GetChildrenCount(element);
for (int i = 0; i < childcount; ++i)
{
auto childElement = FindVisualChildByType<T>(Windows::UI::Xaml::Media::VisualTreeHelper::GetChild(element, i), name);
if (childElement != nullptr)
{
return childElement;
}
}
return nullptr;
};
#Bryce, really nice answer.
VB.NET version:
Public Shared Iterator Function FindVisualChildren(Of T As DependencyObject)(depObj As DependencyObject) As IEnumerable(Of T)
If depObj IsNot Nothing Then
For i As Integer = 0 To VisualTreeHelper.GetChildrenCount(depObj) - 1
Dim child As DependencyObject = VisualTreeHelper.GetChild(depObj, i)
If child IsNot Nothing AndAlso TypeOf child Is T Then
Yield DirectCast(child, T)
End If
For Each childOfChild As T In FindVisualChildren(Of T)(child)
Yield childOfChild
Next
Next
End If
End Function
Usage (this disables all TextBoxes in a window):
For Each tb As TextBox In FindVisualChildren(Of TextBox)(Me)
tb.IsEnabled = False
Next
For this and more use cases you can add flowing extension method to your library:
public static List<DependencyObject> FindAllChildren(this DependencyObject dpo, Predicate<DependencyObject> predicate)
{
var results = new List<DependencyObject>();
if (predicate == null)
return results;
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(dpo); i++)
{
var child = VisualTreeHelper.GetChild(dpo, i);
if (predicate(child))
results.Add(child);
var subChildren = child.FindAllChildren(predicate);
results.AddRange(subChildren);
}
return results;
}
Example for your case:
var children = dpObject.FindAllChildren(child => child is TextBox);
I wanted to add a comment but I have less than 50 pts so I can only "Answer".
Be aware that if you use the "VisualTreeHelper" method to retrieve XAML "TextBlock" objects then it will also grab XAML "Button" objects. If you re-initialize the "TextBlock" object by writing to the Textblock.Text parameter then you will no longer be able to change the Button text using the Button.Content parameter. The Button will permanently show the text written to it from the Textblock.Text write action (from when it was retrieved --
foreach (TextBlock tb in FindVisualChildren<TextBlock>(window))
{
// do something with tb here
tb.Text = ""; //this will overwrite Button.Content and render the
//Button.Content{set} permanently disabled.
}
To work around this, you can try using a XAML "TextBox" and add methods (or Events) to mimic a XAMAL Button. XAML "TextBox" is not gathered by a search for "TextBlock".
For some reason, none of the answers posted here helped me to get all controls of given type contained in a given control in my MainWindow.
I needed to find all menu items in one menu to iterate them. They were not all direct descendants of the menu, so i managed to collect only the first lilne of them using any of the code above.
This extension method is my solution for the problem for anyone who will continue to read all the way down here.
public static void FindVisualChildren<T>(this ICollection<T> children, DependencyObject depObj) where T : DependencyObject
{
if (depObj != null)
{
var brethren = LogicalTreeHelper.GetChildren(depObj);
var brethrenOfType = LogicalTreeHelper.GetChildren(depObj).OfType<T>();
foreach (var childOfType in brethrenOfType)
{
children.Add(childOfType);
}
foreach (var rawChild in brethren)
{
if (rawChild is DependencyObject)
{
var child = rawChild as DependencyObject;
FindVisualChildren<T>(children, child);
}
}
}
}
Hope it helps.
I found it easier without Visual Tree Helpers:
foreach (UIElement element in MainWindow.Children) {
if (element is TextBox) {
if ((element as TextBox).Text != "")
{
//Do something
}
}
};
The accepted answer returns the discovered elements more or less unordered, by following the first child branch as deep as possible, while yielding the discovered elements along the way, before backtracking and repeating the steps for not yet parsed tree branches.
If you need the descendent elements in descending order, where the direct children will be yielded first, then their children and so on, the following algorithm will work:
public static IEnumerable<T> GetVisualDescendants<T>(DependencyObject parent, bool applyTemplates = false)
where T : DependencyObject
{
if (parent == null || !(child is Visual || child is Visual3D))
yield break;
var descendants = new Queue<DependencyObject>();
descendants.Enqueue(parent);
while (descendants.Count > 0)
{
var currentDescendant = descendants.Dequeue();
if (applyTemplates)
(currentDescendant as FrameworkElement)?.ApplyTemplate();
for (var i = 0; i < VisualTreeHelper.GetChildrenCount(currentDescendant); i++)
{
var child = VisualTreeHelper.GetChild(currentDescendant, i);
if (child is Visual || child is Visual3D)
descendants.Enqueue(child);
if (child is T foundObject)
yield return foundObject;
}
}
}
The resulting elements will be ordered from nearest to farthest.
This will be useful e.g. if you are looking for the nearest child element of some type and condition:
var foundElement = GetDescendants<StackPanel>(someElement)
.FirstOrDefault(o => o.SomeProperty == SomeState);
UnifomGrid has loaded Data, I want to Hide the first row?
How can I implement that?
I've never worked with the UniformGrid so there might be a better solution for this but as far as I can tell the UniformGrid doesn't hold much information except how many rows and columns it currently have so therefore this is the only solution that I can think of.
private List<UIElement> GetElementsAtRow(int rowNumber)
{
List<UIElement> elementsAtRow = new List<UIElement>();
for (int i = 0; i < uniformGrid.Columns; i++)
{
if (i < uniformGrid.Children.Count)
{
elementsAtRow.Add(uniformGrid.Children[i] as UIElement);
}
}
return elementsAtRow;
}
private void HideFirstRow()
{
List<UIElement> elementsAtRow = GetElementsAtRow(0);
foreach (UIElement element in elementsAtRow)
{
// Or Hidden if you want row to remain but with no Visible children.
element.Visibility = Visibility.Collapsed;
}
}
private void ShowFirstRow()
{
List<UIElement> elementsAtRow = GetElementsAtRow(0);
foreach (UIElement element in elementsAtRow)
{
element.Visibility = Visibility.Visible;
}
}
My code is as follows:
void mainDataContextObj_CutSelectedColumnEvent(string columnId)
{
IList<DataGridColumn> columns = dg.Columns;
for(int i=2; i<dg.Columns.Count; i++)
{
DataGridColumnHeader headerObj = dg.Columns[i].Header as DataGridColumnHeader;
//This always returns headerObj as null!!!
}
}
I need DataGridColumnHeader from the column. Where am I going wrong?
The Header object of the DataGridColumn is actually the visible header of that column, whatever you set it to be. DataGridColumn is not part of the Visual Tree so there is not direct way to access the DataGridColumnHeader for it (we can't even be sure it exists yet). But you can do something like this to try and access it
DataGridColumnHeader headerObj = GetColumnHeaderFromColumn(column);
private DataGridColumnHeader GetColumnHeaderFromColumn(DataGridColumn column)
{
// dataGrid is the name of your DataGrid. In this case Name="dataGrid"
List<DataGridColumnHeader> columnHeaders = GetVisualChildCollection<DataGridColumnHeader>(dataGrid);
foreach (DataGridColumnHeader columnHeader in columnHeaders)
{
if (columnHeader.Column == column)
{
return columnHeader;
}
}
return null;
}
public List<T> GetVisualChildCollection<T>(object parent) where T : Visual
{
List<T> visualCollection = new List<T>();
GetVisualChildCollection(parent as DependencyObject, visualCollection);
return visualCollection;
}
private void GetVisualChildCollection<T>(DependencyObject parent, List<T> visualCollection) where T : Visual
{
int count = VisualTreeHelper.GetChildrenCount(parent);
for (int i = 0; i < count; i++)
{
DependencyObject child = VisualTreeHelper.GetChild(parent, i);
if (child is T)
{
visualCollection.Add(child as T);
}
else if (child != null)
{
GetVisualChildCollection(child, visualCollection);
}
}
}
While Fredrik's answer provides a refactored approach with additional method that could potentially be reused in other parts of the code, I preferred to consolidate his methods in to one single method. There may also be some small performance gain because it can end the search as soon as it finds the header and it does not need to continue to search through all the children in the visual tree (this is most likely negligible for most cases).
private DataGridColumnHeader GetHeader(DataGridColumn column, DependencyObject reference)
{
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(reference); i++)
{
DependencyObject child = VisualTreeHelper.GetChild(reference, i);
DataGridColumnHeader colHeader = child as DataGridColumnHeader;
if ((colHeader != null) && (colHeader.Column == column))
{
return colHeader;
}
colHeader = GetHeader(column, child);
if (colHeader != null)
{
return colHeader;
}
}
return null;
}
And it is used like so:
DataGridColumnHeader colHeader = GetHeader(column, myDataGrid);
if (colHeader == null) { /* Not found */ }
I have a WPF form which has many controls on it. Many (but not all) of these controls are databound to an underlying object. At certain times, such as when the Save button is pressed, I need to check all the validation rules of my controls. Is there a way to do this programatically, WITHOUT hard-coding a list of the controls to be validated? I want this to continue to work after another developer adds another control and another binding, without having to update some list of bindings to be refreshed.
In a nutshell, is there any way to retrieve the collection of all data bindings from a WPF window?
Try out my sample below. I haven't fully tested this so it may have issues. Also, performance may be questionable. Maybe others can help out to make it faster. But anyway, it seems to do the trick.
Note: A limitation to this, however, is that it may not pick up the bindings defined within Styles or DataTemplates. I'm not sure though. Needs more testing.
Anyway, the solution has three parts basically:
Use VisualTreeHelper to walk the entire visual tree.
For each item in the visual tree, get all dependency properties. Reference.
Use BindingOperations.GetBindingBase to get the binding for each property.
GetBindingsRecursive function:
void GetBindingsRecursive(DependencyObject dObj, List<BindingBase> bindingList)
{
bindingList.AddRange(DependencyObjectHelper.GetBindingObjects(dObj));
int childrenCount = VisualTreeHelper.GetChildrenCount(dObj);
if (childrenCount > 0)
{
for (int i = 0; i < childrenCount; i++)
{
DependencyObject child = VisualTreeHelper.GetChild(dObj, i);
GetBindingsRecursive(child, bindingList);
}
}
}
DependencyObjectHelper class:
public static class DependencyObjectHelper
{
public static List<BindingBase> GetBindingObjects(Object element)
{
List<BindingBase> bindings = new List<BindingBase>();
List<DependencyProperty> dpList = new List<DependencyProperty>();
dpList.AddRange(GetDependencyProperties(element));
dpList.AddRange(GetAttachedProperties(element));
foreach (DependencyProperty dp in dpList)
{
BindingBase b = BindingOperations.GetBindingBase(element as DependencyObject, dp);
if (b != null)
{
bindings.Add(b);
}
}
return bindings;
}
public static List<DependencyProperty> GetDependencyProperties(Object element)
{
List<DependencyProperty> properties = new List<DependencyProperty>();
MarkupObject markupObject = MarkupWriter.GetMarkupObjectFor(element);
if (markupObject != null)
{
foreach (MarkupProperty mp in markupObject.Properties)
{
if (mp.DependencyProperty != null)
{
properties.Add(mp.DependencyProperty);
}
}
}
return properties;
}
public static List<DependencyProperty> GetAttachedProperties(Object element)
{
List<DependencyProperty> attachedProperties = new List<DependencyProperty>();
MarkupObject markupObject = MarkupWriter.GetMarkupObjectFor(element);
if (markupObject != null)
{
foreach (MarkupProperty mp in markupObject.Properties)
{
if (mp.IsAttached)
{
attachedProperties.Add(mp.DependencyProperty);
}
}
}
return attachedProperties;
}
}
Sample usage:
List<BindingBase> bindingList = new List<BindingBase>();
GetBindingsRecursive(this, bindingList);
foreach (BindingBase b in bindingList)
{
Console.WriteLine(b.ToString());
}
There is a better solution in .NET 4.5 and above:
foreach (BindingExpressionBase be in BindingOperations.GetSourceUpdatingBindings(element))
{
be.UpdateSource();
}