I have several controls in my WPF window. I have divided the window into 4 sections. If I click on the section in the upper left, I want to copy the contents of this section in another window popup.
What I want to copy is a grid that can contain a lot of different controls, ex: togglebutton, button, panel... derived from ItemsControl, Control... and with DependencyProperty, ObservableCollection etc..
I tried :
XamlWriter.Save(data);
XamlServices.Save(data);
but I always have these errors :
Cannot serialize a generic type 'System.Collections.ObjectModel.ObservableCollection`1 or
A BadImageFormatException has been thrown while parsing the signature. This is likely due to lack of a generic context. Ensure
genericTypeArguments and genericMethodArguments are provided and
contain enough context.
You should not clone XAML itself, this is brutal and wrong way.
Take a look at the possible MVVM solution below. Let's say single DataGird represents a single business Item, so you need following:
ItemsWindow.xaml - represents a ListView and single item of ListView is DataGrid representing an item details
ItemsViewModel - expose list of Item objects (ObservableCollection<Item> Items { get; set; })
Each item of the ItemsWindow.ListView is represented by a DataTemplate like ItemDataTemplate
ItemsViewModel exposed command ICommand CopyItem and in command handler actually copyiing only instance of the Item business entity and adding it to the Items list, WPF reflects this changes via bindings and UI will be updated by a new ListViewItem with a DataGrid representing a details of just copied Item
Useful links:
Model View ViewModel pattern
Commands
Data Templating Overview - short and clean overview of WPF data templates with examples
Related
I have a Window with a dynamic menu and a DataGrid that shows different records based on the which menu item has been clicked.
Each menu item returns an ObservableCollection of a custom class.
All the classes are diffent and not necessarily related to each other.
At the moment I created one ObservableCollection(Of Object) in my ViewModel, filling it with new results everytime a menu item is clicked.
The problem is that Object does not implement INotifyPropertyChanged, forcing me to manually assign the ItemsSource.
I'm sure there is a way to accomplish what I'm after, but I cannot think of it.
You have two options:
clear the ObservableCollection, then add the new items to it. This can be slow though as there are multiple notifications (events) fired when you do it, if it's any more than a few tens of items then you'll start to notice some UI slow downs while you do it
ensure that your viewmodel implements INotifyPropertyChanged and the property that contains the ObservableCollection fires a property change notification. Then simply assign a new ObservableCollection when you have a new list to show.
Because your collections contain different types of objects, I trust you've looked into Data Templating (another example) to structure your UI - that way you can have a custom layout that is dependent on the type of the list item.
Assume that I need to create a class called PictureWall, which will be used to show pictures.
Now I find that Panel and ItemsControl can both be used to hold Children elements. So should the class PictureWall derive from Panel? or should it derive from ItemsControl.
Note: This is not a real requirement, it's just a hypothetical question. The real question is: when should I create a subclass of Control (or ItemsControl) and when should I create a subclass of Panel?
Note 2: This imagined picture wall control is not to be used in one application only. It may be used by other developers. If it derives from Panel or ItemsControl, it'll expose the property named Children to other developers. So in this case, deriving from Control is a better idea, right?
Note 3: This imagined picture wall control has its own default way of loading certain pictures (for example, pulling pictures from a server) and it does not want this way to be messed around. If this is the case, then we should not inherit ItemsControl, right?
Panel is a container that is used to arrange its children. For example: Grid with a title and one button on the bottom and an image on center - Grid is very flexible to help you move stuff and arrange them when you change the size of window etc.
ItemsControl is a control that helps you with a collection of items. Let's take a concrete example: Listbox. You can very easly show a list of items, applay template to all of them, so on and so forth.
Control class is basically a UI element that can have its own template.
Note that, it is a way much better to define own UserControl, edit template or style of your PictureWall, insted of subclassing (there are many advantages, for example you can use Blend to redefine the style).
Edit:
# note2
If I were you I would make my own User Control to reuse existing controls to make what I want. If that won't be enough I would subclass Control.
[StyleTypedProperty(Property = "FooStyle", StyleTargetType = typeof(Control))]
public partial class MyDangControl: Control
{
...
# note3
This is a bad idea to combine all in one. You should split the logic that fetch the data form yout Picture Wall. For instance, user presses thumbnail to download the image and whole UI hangs. Horrible UX.
To be crystal clear, let me quote Pro WPF in C# 2010
Control
This is the most common starting
point when building a control
from scratch. It’s the base class for
all user-interactive widgets. The
Control class adds properties for
setting the background and foreground,
as well as the font and alignment of
content. The control class also places
itself into the tab order (through the
IsTabStop property) and introduces the
notion of double-clicking (through the
MouseDoubleClick and
PreviewMouseDoubleClick events). But
most important, the Control class
defines the Template property that
allows its appearance to be swapped
out with a customized element tree for
endless flexibility.
ContentControl
This is the base class for controls
that can display a single piece of
arbitrary content. That content can be
an element or a custom object that’s
used in conjunction with a template.
(The content is set through the
Content property, and an optional
template can be provided in the
ContentTemplate property.) Many
controls wrap a specific, limited type
of content (like a string of text in a
text box). Because these controls
don’t support all elements, they
shouldn’t be defined as content
controls.
ItemsControl
ItemsControl is the base class for
controls that wrap a list of items but
don’t support selection, while
Selector is the more specialized base
class for controls that do support
selection. These classes aren’t often
used to create custom controls,
because the data templating features
of the ListBox, ListView, and TreeView
provide a great deal of flexibility.
Panel
This is the base class for controls
with layout logic. A layout control
can hold multiple children and
arranges them according to specific
layout semantics. Often, panels
include attached properties that can
be set on the children to configure
how the children are arranged.
They both can be used to display elements, but really an ItemsControl offers much more functionality. In addition, an ItemsControl doesn't really display it's elements, it leverages a Panel to do that.
An ItemsControl can display a list of items, which may or may not be UIElements/Visuals. The items can be templated using a configurable DataTemplate, which ultimately determines how the item is displayed. In addition, then items can be bound to an observable collection so it will automatically update.
Neither of these features are supported by a Panel. DataTemplates can be used, but you have to manually create an associated ContentControl/ContentPresenter and add it to your panel.
Ultimately, their functions are different. A Panel is used to display UIElements/Visuals. An ItemsControl is used to display any type of data and apply templates as needed.
I searched this site and i found 2 Links
how to load wpf usercontrol in MVVM pattern
MVVM-Light: Load UserControl into Window
but still i cant find the answer to my problem and this link
MVVM-Light Locator Pattern and Reusable UserControl
i Didn't Understood.... so here is i am stating my problem which might help others struggling like me ......
I have a MainWindow which has 2 parts one has a TreeView(a
UserControl) and the other Displays different user controls(named DisplayPanel).... just like windows Explorer.
The Display Panel on the Right side will display different user controls on Clicking nodes of tree view.
and my TreeView is Itself a user Control.
How can i make this composite UI Work using MVVM. Also I am planning to use MVVM light Toolkit. Does this have something that can help...
An Example will be great
Thanks... :)
Edit
My TreeView in a UserControl I made a dependency property in the UserControl which catches the selected Item fo the tree view so that i can use this dependency property to populate the required view in the "MainView" ContentControl binding....as you advised me in the comments. Everything is till now
Problem is that i want to display data contained in the the selected item and i cannot set the DataContext of the UserControls(which will be displayed in right hand side) to the selected item as then i will not be able to use my view model for the respective usercontrol for commands and other operations
I tried to solve this too.... i used the Mediator (Messenger) in my TreeViewUserControl view model to send a Message to the Usercontrol's(the one that i need to display) view model . Message will be passed whenever the item is selected in the tree view. and message contains the selected node. I forgot to mention i set the datacontext of the UserControl to its view model so that i could display data
But using this approach the problem is that when the I click a type of node for the first time the data is not populated but if the same type of node is clicked again its populated. What’s happening is that UserControls object is availabe when the the tree item is clicked for the first time and Mediator sends the message. So Mediator is not able to pass the message to the userControl view model.....
I totally do not have ne idea to solve this further.... is my way if displaying user control right or I should do something that else....totally confused.....
You could try defining a DataTemplate for each type in the TreeView's ItemsSource and instead of having a specific UserControl on the right side, just bind to the TreeView's SelectedItem. Alternatively, you could use a DataTemplateSelector.
Edited for OP's Edit
Did you do this?
MainWindow has TreeView whose ItemsSource=Binding MainVM.Items.
MainWindow has ContentControl whose Content=Binding TreeView.SelectedItem.
Somewhere in project, have ResourceDictionary where each possible type in MainVM.Items has a DataTemplate defined?
Which ViewModel (MainVM or ItemVM) are you trying to use and why can't you use it?
I create a new UserControl for reuse. The UserControl contains a toolbar with several Buttons.
When I use the UserControl, I hope I can add additional Buttons on it but can not modified the orginal ones.
This is easily implemented in WinForm by inheritance. But in WPF, I have no idea how to do it.
There is a few ways to do what you need.
For example, your UserControl could expose ICollection TabButtons property, which is ItemsSource for toolbar. In this case, your toolbar should contain some ItemsControl to host buttons and should be binded to aforementioned TabButtons property.
And TabButton struct should describe all needed information (for example, properties Header, Icon, ToolTip and Command).
Or you could provide appropriate methods: AddToolbarButton(), RemoveToolbarButton(). This methods change TabButtons collection (but the collection itself cann't be accessed from outer realm).
Why there is no HeaderedContentControl ItemsSource property?
How then can I databind to a list of objects to be represented by HeaderedContentControl?
Thanks
John
Because ItemsSource is all about multiple pieces of content, and HeaderedContentControl has one piece of content. Put another way, HeaderedContentControl's job is to present a single object, so it doesn't need a property whose job is to feed it multiple pieces of content.
Use HeaderedItemsControl instead, or (depending on your requirements) an ItemsControl where the DataTemplate is a HeaderedContentControl. (Though in the latter case you might as well just use a Panel and multiple elements within the panel -- the HCC isn't really buying you anything.) HIC's job is to present multiple items under a single header, and it's pretty flexible. For example, the framework uses HIC as the base class for both TreeViewItem (whose "header" is the item at hand, and whose "items" are the children of that item) and MenuItem (whose "header" is the menu item, and whose "items" are any sub-menu-items, for example in a drop-down or pop-out menu).
There's no ItemsSource property, since it can have only a single child (or two children if you count Header in), just like the class it inherits from - ContentControl. Use Content property instead.
You can find more about it on MSDN.
If you want to display list of objects within HeaderedContentControl, then just add ListBox as its Content and fill ListBox with objects.
Maybe you need a HeaderedItemsControl.
You can find a sample here.
You should be able to bind the collection to the Content property.
HeaderedContentControl by name itself is a collection of ContentControl each with Header.