WPF Binding

Introduction

Data binding is the mechanism to flow the Data from source to target and vice versa. This mechanism provide a way to update the user interface when there is change in data in ViewModel side.

A 'Binding' can only be set on a DependencyProperty of a DependencyObject

Data binding can be Unidirectional or Bidirectional.

Binding work along with Notification mechanism on both side.

.Net Property: in this side, use INotifyPropertyChanged interface to raise the PropertyChanged event.

Dependency Property:  In this side, PropertyChanged callback of the property metadata is in Action.

Binding Mode

Binding mode describes the direction of the data flow in a binding.

Default

The default value varies for each dependency property. In general, user-editable control properties, such as those of text boxes and check boxes, default to two-way bindings, whereas most other properties default to one-way bindings

OneTime :Update the binding target when the application start or when the data context change.

OneWay :Update the biding target from source not vice versa.

OneWayToSource : Update the source from binding target not vice versa.

TwoWay : This binding to ensure data synchronization between source and target, when any change in source reflect in target and any change in target reflect in source.

In XAML {Binding} mark up extension is use for Data Binding.

<Grid>

<Label Content=”Binding [.Net Property of ViewModel]” />

e.g.  FirstName is the property in the View Model and want to bind with Lable

<Label Content=”Binding FirstName” /> 

</Grid>

Markup Extension

https://msdn.microsoft.com/en-us/library/ms747254(v=vs.100).aspx

Common markup extension specific to WPF only.

1. StaticResource
2. DynamicResource
3. Binding
4. RelativeSource
5. TempletBinding
6. ColorConvertedBitmap
7. ComponentResourceKey
8. ThemeDictionary

Some Terminology

Source: View Model Property (.Net property)

Target: UI (XAML) DP property

...In progress