Currently I’m playing around with ETO and started to implement a MVVM-Pattern.
In the end it should be used within the grasshopper-workflow to build custom UI-Interfaces on the fly.
I have no no problem to bind to “single-value” Property, but when it comes to collection I can not wrap my head around. I have not found any useful guidance in the www to do so.
Do I need to use a ObservableCollection? or any special class to deal with this?
I mean, Its not a big deal to populate a control from a collection with code directly (mod in loop) but ya… Isn’t there direct binding-mechanism like its used, lets say, XAML? Maybe in combination with a converter-object?
If anybody has an advice (OR a good reference/link to a working pattern) I would be very thankful to hear from u.
In the example below, I have a view model that has an ObservableCollection of ‘Properties’ and I bind the selected item to the view-model’s property ‘SelectedProperty’.
You need to set three things: the control’s data store and data context, and the SelectedValueBinding.
Is this helpful?
class PropertyListView : Panel
{
public PropertyListView(PropertyListViewModel vm)
{
Label properties = new Label {Text = "Properties", Font = new Font(FontFamilies.Sans, 16.0f)};
ListBox listbox = new ListBox
{
DataContext = vm,
DataStore = vm.Properties
};
listbox.SelectedValueBinding.BindDataContext((PropertyListViewModel avm) => avm.SelectedProperty);
Content = new TableLayout
{
Padding = new Padding(5),
Spacing = new Size(5,5),
Rows =
{
new TableRow(properties),
new TableRow(listbox)
}
};
}
I tried ur advice, and had kind of a success.
But, as I can see, ur example works for a ListBox (going to use it later ), but for now I’m just looking for a way to do the same with soemthing like a Stackpanel, but I do not find any equivalent class which has a Property named “DataStore” to follow ur pattern.
Do u have any advices in this direction?
Edit:
I’m also looking for a place to but my ‘IValueConverter’ to convert the given data, to a control.
But where?
StackPanel is not a control that has a list of values, but it is a container for other controls. Just like I used TableLayout in the example I give above, you could also use StackPanel.
As for converters, maybe the example from my code below can give you some insight in how to use/bind them.
PropertyViewModel pvm; // defined elsewhere
// text area control
TextArea ta = new TextArea
{
Height = 450,
Width = 250,
DataContext = vm,
AcceptsReturn = true,
AcceptsTab = false,
};
// bind the text to the view-model property StringRepresentation
ta.TextBinding.BindDataContext((PropertyViewModel pvm) => pvm.StringRepresentation);
// create a binding to the boolean property IsStringRepresentationValid
var validBinding = Binding.Property((PropertyViewModel pvm) => pvm.IsStringRepresentationValid);
// convert it to a color binding
var colorBinding = validBinding.Convert(tf => tf ? Colors.White : Colors.PaleVioletRed);
// use the color binding for setting the background.
// end result: the text area shows a white background if the entered string is valid
// and a red background if the entered string is not valid.
ta.Bind(area => area.BackgroundColor, vm, colorBinding);
I’m very thankful for ur support.
I allready know about this kind of bindings, and it works just fine in other cases. I use a different overload to setup my bindings, but I guess in the end it should become the same.
I tried to use this thingy with a StackLayout to bind a List of Controls to it. Do be more precise, I do not bind a List of Controls, I try to bind a List of Factories which is going to converted by building a Control (yellow) which is bind to an other Viewmodel setted up deeper in the build-tree.
At least it looks like Items (green) should be the right spot to bind [ *.Items.Add(…) ].
It does not work at all.
I tried some others which sound promising, but without any success.
Do u have some insights in this case, or any other idea how to go on?
EXCURSE:
I could go some other way (not use bindings at all with containers), but this comes with some sideeffects which I want to avoid. I want to be able to set the content of the layout after the creation (red group), without breaking the MVVM-pattern…
I’m looking for this, so Controls and Containers can follow the same rules during the use within Grasshopper… So there is no need to specialize major components at all…
), but for now I’m just looking for a way to do the same with soemthing like a Stackpanel, but I do not find any equivalent class which has a Property named “DataStore” to follow ur pattern.
