At runtime I am creating a WPF control. It can be any WPF Control.
I want to find out whether this WPF Control, IS A CONTAINER CONTROL.
i.e. can this control can embed/contain another control.
Does there exist any Attribute through which the above can be achieved?
e.g. a label, panel, groupBox can contain other control like button, but textBOX cant.
In WPF there are a few base classes that controls extend from.
ContentControl: Most controls extend from this because most controls can store some type of single content within them.
ItemsControl: These are types of collection controls, which contain a collection of content within them.
Panel: These are special controls for layouts. They implement the ArrangeOverride and MeasureOverride methods to measure/arrange the children controls within them. Most of them also expose attached properties for best use.
That being said, you would typically want to use the is operator to check if your control inherits from what you intend it to. You can be specific or general, but typically you want to be as general as possible. I'm not sure what you meant by "container", which is why I listed the three (3) typical base controls that could contain other controls. For example:
if (myControl is ContentControl)
{
// Do something here.
}
All the controls mentioned here and here apart from TabControl inherit from Panel
So you can do something like:
if (myControl is Panel || myControl is TabControl)
{
// Then it's a container
}
Related
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 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).
I just want to wrap a standard control with some more additional properties (look stay the same, I don't want to do theming in first stage).
Can I just inherit from this standard control instead of UserControl or Control ? In fact I read it is obligatoryb to use Custom Control Project Template and not UserControl ontrol Project Template. Why ?
Update: I try with a Custom Control Project and inherit from the standard slider but I have nothing show up visually ! Now what should I do to have the same visual slider as the standard one ?
I know the difference between a user control and a custom control but in practice how do you do when you just want ONE single standard control ? How will a slider for example resize AUTOMATICALLY if I encapsulate it inside a User Control instead of a Custom Control ?
A custom control is a single control and can derive from another control, this would support styling. A UserControl is a composite control out of many different controls, and as a whole, doesn't support styling (the parts do however).
If you want to add features of any kind to an existing control, derive from it. If you want to pack several controls together to make it easier to handle them (you could still add DP's to it), use a UserControl.
A custom control alone won't do anything related to resizing etc, that is dependent on the settings you supply to it from the outside (ie. HorizontalAlignment, VerticalAlignment and others) when you used it in a container. The custom control should inherit the default template from the base class unless you override it.
Can someone elaborate the difference between ControlTemplate and DataTemplate in wpf?
What should one use in case of custom controls? Like for example a StackPanel which possibly has an image and a TextBox?
It seems confusing in some cases where you define a custom control using the 'Content' property.
It would be great if an example of how each can be used in different scenarios can be provided.
A ControlTemplate is used to change the look of an existing control. So if you don't want your buttons to look rectangular, you can define a control Template which makes them look oval or any irregular shape. It's a way to customize 'look-less' stock WPF controls ; an alternative to writing your own user-controls. More details
A DataTemplate is used to specify how an instance of a specific class (usually a Data Transfer object - an object with properties) is to be rendered visually. e.g. define a DataTemplate to visualize a Customer instance in a listbox displaying all customers. More details
I want that some of the controls in my window will be surrounded by a border and a label above them that will contains a title, which tells something about a control (e.g. a list of persons, surrounded by a border, and above the list there is a label with the text "My Persons"). Since I want apply this on many controls, I don't want to write a specific xaml for each one of them. Should I create a user control, or is there a way to use styles/templates for that?
Visual Example:
http://dl.getdropbox.com/u/829214/example.GIF
I would look into adorners and the adorner layer.
Another way to accomplish this would be to create a custom/user control that derives from contentcontrol. Use a contentcontrol to vary the content and design the control to look however you want.