I have a control which contains my custom dependencyproperty like this:
public static readonly DependencyProperty MouseEnterColorProperty =
DependencyProperty.Register("MouseEnterColor", typeof (Color), typeof (SCADAPolyline), new PropertyMetadata(default(Color)));
public Color MouseEnterColor
{
get { return (Color) GetValue(MouseEnterColorProperty); }
set { SetValue(MouseEnterColorProperty, value); }
}
Its weird problem.I am using reflection to get my property for setting new value.But cant get my property.I tried every possibility from type.GetFields()
FieldInfo fieldInfo = type.GetField(name, BindingFlags.FlattenHierarchy | BindingFlags.Public | BindingFlags.Static);
or
fieldInfo = type.GetFields(BindingFlags.Static | BindingFlags.Public)
.Where(p => p.FieldType.Equals(typeof(DependencyProperty)) && p.Name==name).FirstOrDefault();
sounds like my property is missing.I cant access and this problem makes me so angry.
How can i solve this problem any ideas? I am using silverlight 5.0
A Dependency Property is not a Field. It is not a part of the class definition in the usual sense.
Behind the scenes it is stored in a collection of Dependency Properties.
Try this example from here as a guide on how to access them:
public static class DependencyObjectHelper
{
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;
}
Related
I have a UserControl that has an ObservableCollection dependency property with a property changed callback. The callback rebuilds the nodes in a TreeView control. This all works fine but I would like to be able to have design data. Unfortunately, neither the constructor, the callback nor a default value function call is called by the designer unless I embed my control in another. Is there a way loading default data in this scenario?
Below is the code behind for my control
public partial class ScheduleResourcesSummaryTreeView : UserControl
{
public ObservableCollection<PerformanceProjection> SelectedPerformances
{
get { return (ObservableCollection<PerformanceProjection>)GetValue(SelectedPerformancesProperty); }
set { SetValue(SelectedPerformancesProperty, value); }
}
// Using a DependencyProperty as the backing store for MyProperty. This enables animation, styling, binding, etc...
public static readonly DependencyProperty SelectedPerformancesProperty =
DependencyProperty.Register("SelectedPerformances",
typeof(ObservableCollection<PerformanceProjection>),
typeof(ScheduleResourcesSummaryTreeView),
new FrameworkPropertyMetadata(
new ObservableCollection<PerformanceProjection>(),
FrameworkPropertyMetadataOptions.AffectsRender, SelectedPerformancesChanged)
);
private static void SelectedPerformancesChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
if (!(d is ScheduleResourcesSummaryTreeView resourcesTree)) return;
resourcesTree.ResourcesTree.Items.Clear();
var sessions = e.NewValue as ObservableCollection<PerformanceProjection> ?? new ObservableCollection<PerformanceProjection>();
if (sessions.Count == 0) return;
var projections = sessions.SelectMany(x => x.ResourceBookingProjections);
TreeNode<ResourceBookingProjection> resourceBookingTreeRoot = new RvtSummaryTree(new ObservableCollection<ResourceBookingProjection>(projections), "");
foreach (var treeNode in resourceBookingTreeRoot.Children)
{
resourcesTree.ResourcesTree.Items.Add((TreeNode<ResourceBookingProjection>)treeNode);
}
}
private static ObservableCollection<PerformanceProjection> DefaultCollection()
{
var prop = DesignerProperties.IsInDesignModeProperty;
var designMode = (bool) DependencyPropertyDescriptor
.FromProperty(prop, typeof(FrameworkElement))
.Metadata.DefaultValue;
if (!designMode)
return new ObservableCollection<PerformanceProjection>();
var designdata = new PerformanceProjectionsViewModelDesignData();
return designdata.SelectedPerformances;
}
public ScheduleResourcesSummaryTreeView()
{
InitializeComponent();
}
}
I would like to know what is the Type that is bound to the DependencyProperty of my control. Is there a way to know that?
I have a DependencyProperty like this:
public static readonly DependencyProperty MyValueProperty =
DependencyProperty.Register("MyValue", typeof(double?), typeof(MyControl),
new FrameworkPropertyMetadata
{
BindsTwoWayByDefault = true,
DefaultUpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged,
PropertyChangedCallback = OnMyValueChanged
});
public double? MyValue
{
get { return (double?)GetValue(MyValueProperty); }
set { SetValue(MyValueProperty, value); }
}
This is a property of my control, and people can use it like:
<myNamespace:MyControl MyValue="{Binding THEIRProperty}"/>
THEIRProperty can be anything, I would like to know the actual type of THEIRProperty inside my control, is this possible?
I tried checking on the BindingOperations, but I couldn't find anything. I would like to know, for example if they are binding a double or a double?.
There is no publicly exposed property on BindingExpression which can get you source type but it is stored in private field i.e. _sourceType which you can get via reflection:
private static void OnMyValueChanged(DependencyObject d,
DependencyPropertyChangedEventArgs args)
{
var bindingExpression = BindingOperations.GetBindingExpression(d,
MyControl.MyValueProperty);
Type sourceType = (Type)bindingExpression.GetType()
.GetField("_sourceType", BindingFlags.NonPublic |
BindingFlags.Instance).GetValue(bindingExpression);
bool isNullableDouble = sourceType == typeof(double?);
bool isDouble = sourceType == typeof(double);
}
Also it is stored in private getter property ConverterSourceType which can also be used to get the source type:
Type sourceType = (Type)bindingExpression.GetType()
.GetProperty("ConverterSourceType", BindingFlags.Instance |
BindingFlags.NonPublic).GetGetMethod(true)
.Invoke(bindingExpression, null);
I have a simple search text box. This text box acts as a filter. I've now copied/pasted the code for the 5th time and enough is enough. Time for a custom control.
left and right brackets have been replaced with ()
My custom control will be simple. My problem is I want to have a dependencyProperty on this control that is of type List(T).
I created a test project to proof it out and make sure it works. It works well. Ignore List.
Below is the entire class. The problem is that the only thing holding me up is replacing List (Person) with List(T). Something like List where: T is Object
typeof(List(T) where: T is Object) <= Obviously I can't do that but gives an idea what I'm trying to accomplish.
public class SearchTextBox : TextBox
{
public static readonly DependencyProperty SourceProperty =
DependencyProperty.Register("FilterSource", typeof(List<Person>), typeof(SearchTextBox), new UIPropertyMetadata(null)); //I WANT THIS TO BE LIST<T>
public List<Person> FilterSource
{
get
{
return (List<Person>)GetValue(SourceProperty);
}
set
{
SetValue(SourceProperty, value);
}
}
public static readonly DependencyProperty FilterPropertyNameProperty =
DependencyProperty.Register("FilterPropertyName", typeof(String), typeof(SearchTextBox), new UIPropertyMetadata());
public String FilterPropertyName
{
get
{
return (String)GetValue(FilterPropertyNameProperty);
}
set
{
SetValue(FilterPropertyNameProperty, value);
}
}
public SearchTextBox()
{
this.KeyUp += new System.Windows.Input.KeyEventHandler(SearchBox_KeyUp);
}
void SearchBox_KeyUp(object sender, System.Windows.Input.KeyEventArgs e)
{
ICollectionView view = CollectionViewSource.GetDefaultView(FilterSource);
view.Filter = null;
view.Filter = new Predicate<object>(FilterTheSource);
}
bool FilterTheSource(object obj)
{
if (obj == null) return false;
Type t = obj.GetType();
PropertyInfo pi = t.GetProperty(FilterPropertyName);
//object o = obj.GetType().GetProperty(FilterPropertyName);
String propertyValue = obj.GetType().GetProperty(FilterPropertyName).GetValue(obj, null).ToString().ToLower();
if (propertyValue.Contains(this.Text.ToLower()))
{
return true;
}
return false;
}
}
No; that's not possible.
Instead, just use the non-generic typeof(IList).
I need to add a UIElement to two different canvases, but one UIElement can only be a child of ONE canvas, so I have to create a ShallowCopy (DeepCopy not needed) of the UIElement.
I want to use MemberwiseClone, but it's protected, I cannot use it.
I also want to define an extension method UIElement.ShallowCopy, but it sill still call MemberwiseClone, which is protected again.
EDIT:
Tried all the following, but all of them failed in Silverlight environment:
// System.Runtime.Serialization.InvalidDataContractException was unhandled by user code
// Message=Type 'System.Windows.UIElement' cannot be serialized. Consider marking it with the DataContractAttribute attribute, and marking all of its members you want serialized with the DataMemberAttribute attribute. Alternatively, you can ensure that the type is public and has a parameterless constructor - all public members of the type will then be serialized, and no attributes will be required.
public static T CloneEx<T>(this T obj) where T : class
{
T clone;
DataContractSerializer dcs = new DataContractSerializer(typeof(T));
using (MemoryStream ms = new MemoryStream())
{
dcs.WriteObject(ms, obj);
ms.Position = 0;
clone = (T)dcs.ReadObject(ms);
}
return clone;
}
// This one also throws Access/Invoke exceptions
private readonly static object _lock = new object();
public static T MemberwiseCloneEx<T>(this T obj) where T : class
{
if (obj == null)
return null;
try
{
Monitor.Enter(_lock);
T clone = (T)Activator.CreateInstance(obj.GetType());
PropertyInfo[] fields = obj.GetType().GetProperties(BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
foreach (PropertyInfo field in fields)
{
object val = field.GetValue(obj, null);
field.SetValue(clone, val, null);
}
return clone;
}
finally
{
Monitor.Exit(_lock);
}
}
// System.MethodAccessException was unhandled by user code
// Message=Attempt by method 'ToonController.ControllerUtils.MemberwiseCloneEx<System.__Canon>(System.__Canon)' to access method 'System.Object.MemberwiseClone()' failed.
public static T MemberwiseCloneEx<T>(this T obj) where T : class
{
if (obj == null)
return null;
MethodInfo mi = obj.GetType().GetMethod("MemberwiseClone", BindingFlags.Instance | BindingFlags.NonPublic);
if (mi == null)
return null;
return (T)mi.Invoke(obj, null);
}
if you have something that you want to use in multiple ui elements, 'sync them up' then you should create a ViewModel or something similar. This viewmodel would be set to the datacontext of any element you want to use it. Then your shallow reference is simple and you can just create two independent UI elements binding to the same data.
I have a class called MyComponent and it has a DependencyProperty caled BackgroundProperty.
public class MyComponent
{
public MyBackground Background
{
get { return (MyBackground)GetValue(BackgroundProperty); }
set { SetValue(BackgroundProperty, value); }
}
public static readonly DependencyProperty BackgroundProperty =
DependencyProperty.Register("Background", typeof(MyBackground),
typeof(MyComponent), new FrameworkPropertyMetadata(default(MyBackground), new PropertyChangedCallback(OnPropertyChanged)));
}
MyBackground is a class that derives from DependencyObject and it has some DependencyProperties.
public class MyBackground : DependencyObject
{
public Color BaseColor
{
set { SetValue(BaseColorProperty, value); }
get { return (Color)GetValue(BaseColorProperty); }
}
public static readonly DependencyProperty BaseColorProperty =
DependencyProperty.Register("BaseColor", typeof(Color),
typeof(MyBackground ), new UIPropertyMetadata(Colors.White));
[...]
}
Now, what I want is when a property from MyBackground is changed, MyComponent to be notified that MyBackground has changed and the PropertyChangedCallback named OnPropertyChanged to be called.
Bear with me for a second because it appears that you are trying to go against the grain of WPF. Since it seems you are writing code related to display logic, the typical method for getting related DependencyObjects to interact with one another is through bindings.
If, for example, MyComponent is a control of some sort and it uses the Background property in its ControlTemplate, you would use a TemplateBinding that references the Background property and any important sub-properties.
Since 1) you probably already know that and 2) you either aren't using templates or don't have them available, you can set up a binding in code in order to react to changes in to the Background property. If you provide more detail about what your OnPropertyChanged method does I can provide some sample code.
One way to do what you describe would be to derive from Freezable instead of DependencyObject. When a property of a Freezable changes the PropertyChangedCallback for any DO referencing that Freezable will be invoked so the callback for the Background property of your MyComponent. In that case the e.OldValue and e.NewValue will be the same reference. Internally WPF has some flag on the event args that indicates that it is a subobject change.
This is what the framework does for things like brushes so that an element can be invalidated if say the Color property of a SolidColorBrush is changed. If an object will never be changed (or you want to make it thread safe) then one can freezing the object (i.e. making it immutable).
BTW I would probably avoid using Background as the name of the property. Most developers will assume that is of type Brush as that is what the framework uses for that named property on several of its elements (e.g. control, border).
Sounds like you want to use a DependencyPropertyDescriptor and AddValueChanged.
Here's an article on it: http://www.codeproject.com/Articles/34741/Change-Notification-for-Dependency-Properties.aspx
..and possibly a better implementation: http://agsmith.wordpress.com/2008/04/07/propertydescriptor-addvaluechanged-alternative/
Here's a small static class of extension methods I wrote for WPF -- it allows you to register an EventHandler or an Action callback for the changing of any DependencyProperty on any DependencyObject. No changes to the dependency object are necessary.
It also prevents recursion (i.e. if you change that same property during the callback, etc..)
It takes advantage of the DependencyPropertyDescriptor that #ScottBilas linked to.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Windows;
namespace BrainSlugs83.Writes.Too.Much.Code
{
public static class WpfExtensions
{
public static void OnPropertyChanged<T>(this T obj, DependencyProperty prop, Action<T> callback) where T : DependencyObject
{
if (callback != null)
{
obj.OnPropertyChanged(prop, new EventHandler((o, e) =>
{
callback((T)o);
}));
}
}
public static void OnPropertyChanged<T>(this T obj, DependencyProperty prop, EventHandler handler) where T : DependencyObject
{
var descriptor = DependencyPropertyDescriptor.FromProperty(prop, typeof(T));
descriptor.AddValueChanged(obj, new EventHandler((o, e) =>
{
if (handler != null)
{
if (o == null) { handler(o, e); }
else
{
lock (PreventRecursions)
{
if (IsRecursing(obj, prop)) { return; }
SetIsRecursing(obj, prop, true);
}
try
{
handler(o, e);
}
finally
{
SetIsRecursing(obj, prop, false);
}
}
}
}));
}
#region OnPropertyChanged Recursion Prevention
private static readonly Dictionary<object, List<DependencyProperty>> PreventRecursions = new Dictionary<object, List<DependencyProperty>>();
private static bool IsRecursing(object obj, DependencyProperty prop)
{
lock (PreventRecursions)
{
List<DependencyProperty> propList = null;
if (PreventRecursions.ContainsKey(obj))
{
propList = PreventRecursions[obj];
}
return propList == null ? false : propList.Contains(prop);
}
}
private static void SetIsRecursing(object obj, DependencyProperty prop, bool value)
{
lock (PreventRecursions)
{
List<DependencyProperty> propList = null;
if (PreventRecursions.ContainsKey(obj))
{
propList = PreventRecursions[obj];
}
if (propList == null)
{
if (!value) { return; }
propList = PreventRecursions[obj] = new List<DependencyProperty>();
}
if (value)
{
if (!propList.Contains(prop))
{
propList.Add(prop);
}
}
else
{
while (propList.Contains(prop))
{
propList.Remove(prop);
}
if (!propList.Any())
{
propList = PreventRecursions[obj] = null;
}
}
}
}
#endregion
public static bool IsInDesignMode(this DependencyObject obj)
{
try
{
return DesignerProperties.GetIsInDesignMode(obj);
}
catch { /* do nothing */ }
return false;
}
}
}