I assume the default for UpdateSourceTrigger is LostFocus, and it is set that way for performance reasons. Every time you call the setter, the setter raises the OnPropertyChanged event, WPF listens to that event and calls the getter.
The WPF textbox has a default UpdateSourceTrigger of LostFocus, which means that it only updates it's bound value when the user focuses on another control. By changing the trigger to update when the property changes, it updates it's bound value every time the user enters/deletes/changes a letter. Here is the MSDN page that discusses this How to: Control when the TextBox Text Updates the Source[^] .
Hope this helps
When I was a coder, we worked on algorithms. Today, we memorize APIs for countless libraries — those libraries have the algorithms - Eric Allman
Every time I look at learning about DP's, I walk away confused.
Anyone know of any decent entry level tutorials?
What's confusing about them?
By now, I assume you are familiar with data binding? Well, as you know... in order for the WPF UI subsystem to know when to update a UI element, it needs to know when the data value has changed. It needs to be able to know that on ANY object, so there needs to be a standard mechanism.
In fact, there are two standard mechanisms.
1) INotifyPropertyChanged / INotifyCollectionChanged - this is how you implement your view models & business objects... typically you'll have your ViewModelBase / ObservableObject base classes and derive everything from them
2) Dependency Properties - Generally, you shouldn't really need to use them in user applications since mechanism #1 is favored for that and DPs are a relative PITA to implement (vs mech #1). They are just objects that are stored by the framework instead of in your object and automatically implement change notification. I generally like to use them in custom controls only.
The benefit of DPs is that you don't need to liter your code with OnPropertyChanged("Foo"); type code.
The downside of DPs is that you have to 1) register them (around 2 to 10 lines of code depending on what options you use) 2) implement getter & setter (just call GetValue / SetValue).
There is a Visual Studio macro that spits out the code, so no biggie.
If you want to hook into the change notification, you need to register a STATIC callback, redirect into your VM, etc.
Just a royal PITA.
Basically, you should only use DP's in controls.
EDIT: there are some features that require use of DPs such as animations.
Hello guys anyone has the code of how to move an image from one place to another using the mouse in silverlight ? I still want the image that has been moved to another beneath it so that it can also be moved up or reach a certain number.
I have huge amount of data (months to years...every 10 seconds) from different data sources.... ( As shown in three blocks in the link)
I want to visualize the the data from three different data sources on a common timeline.
I should then be able to drag the timebars to select a particular window of data. If all the data is present between the timebars it should turn gray.
The requirements are kind of similar to meeting scheduler. I have a SNAPSHOT of the Lotus Notes Meeting scheduler. It is kind of cool as it shows resource availability (also resources are grouped) on a common timeline.
1. In the above link it has divided Resources into groups(Invitees, Scheduled Rooms, Resources) 2. It has a time scale in hours. 3. Each Row in the group... say...Robert has his availability listed in time. Similarly the availability of Room1, User1, Projector is also listed. 4. Now I know when are all the resources available. So, I drag the vertical green bar to the space where all the resources are available. 5. I can schedule the meeting. 6. I can also adjust the start time and end time by dragging the ends of the green bar left or right.
I hope you got my question.
I am looking for a WPF or Windows Forms project. I could not find any similar project online. I would appreciate any help. Thank you.