I wish to allow the user of my control to choose the licensing method for the control. The choice comes from an enumeration, so they must choose one of the methods I have laid out for them. This license needs to be chosen prior to the code executing at runtime. Therefore I wish for them to selected a value at design time. Furthermore I do not wish for this property to be writable at runtime, if that can be avoided. Is there a way to make a property only available at design time?
You can give a control design-time behavior by creating a separate designer class for the control. Since the control itself can only exist as an instance of your runtime, you can't really have a property directly on it which is set only at design-time (where would it get stored?). However, designer classes are only invoked and used by the designer, so you can encapsulate non-runtime behavior there.
Related
I am creating a custom control and I have created several dependency properties. I want to know how can I have my custom dependency properties show up on top with a star such as the picture below.
You cannot control this explicitly. The "IntelliCode" feature uses a form of machine learning to create models that are used by the editor to present this list and to decide which members show up at the top of the list with a star.
However, you can attempt to train a model specific to your code base. See IntelliCode team completions: AI-assisted IntelliSense based on your code for details about that. Note that since one of the primary factors is how often a particular property is in fact used by the code, you'll have to have some good examples of the properties you care about in the code base already, and they will need to be among the most commonly used members.
See Visual Studio IntelliCode FAQ for more details about how to use this feature.
MSDN: http://msdn.microsoft.com/en-us/library/system.windows.forms.control.tag.aspx
says it Gets or sets the object that contains data about the control.
How is this commonly used. Can it just contain a string related to the control ? Or does it commonly have an object the control uses ?
This is purely for your use. The control doesn't do anything with it other than store it for you.
People often put additional information about the control for reference later.
It isn't commonly used. The Tag property was inherited from the VB6 object model. Which didn't nearly have as much utilitarian power as the .NET framework or Winforms. So the Tag property was often used to hang context data off a control. That it is an Object didn't matter in Visual Basic.
In C# that's less than desirable. And much easier to separate the data from the view. And much easier to derive your own control from Checkbox and add your own methods and properties. But you can still use the Tag property if you want to.
I've recently been adding custom features to some of the various WinForms Controls by creating custom Component derived classes which just wrap the Control, hooking into the needed events to perform the extra functionality.
For instance, I wanted to add drag-and-drop functionality to a few different ListBox controls in my application, so I created a DragAndDropListBoxComponent which inherits from the Component class, then add this new component to the Forms I needed to add the functionality to, setting the DragAndDropListBoxComponent's ListBox property to the list box I wanted to add the functionality to.
I like this method of extending standard Control functionality because I can create more than one custom behavior type of Component for the same Control and mix them together for some interesting effects. This also favors the Composition over Inheritance principle.
It seems to have taken me awhile to come to the realization of using Component class list this. This is partly due to never seeing it used in such a way online - hence my question. Are custom Component classes commonly used in this way?
There are other options, which one you pick doesn't matter all that much as long as it achieves the desired result and you do not have the feeling your solution is working against you at every turn.
A possible alternative is using an Extender Provider. One advantage of the Extender Provider is that you seemingly add an "AllowDragAndDrop" property to each Control. (in your case the property would be added only to ListBox instances)
This new property is visible at Design Time so other consumers don't have to know the implementation nor location details of the DragAndDrop functionality, they only have to set a property in the PropertyGrid.
Another possible alternative is using the Decorator pattern. This is for example used in .NET streams: You have a stream and then you add additional behavior (buffering, (un)zipping, encryption, ...) by creating a new stream that takes the old one as a constructor parameter. In your case you would wrap a ListBox in a DragAndDropListBox. Be careful though, this approach might cause your more trouble than advantages in this particular case.
Yet another possible alternative is inheriting from the controls you want to extend and add a list of "CustomBehaviors" to the controls. CustomBehaviors would implement some interface which allows you to add new behavior to the control by adding a concrete instance of the interface to the collection.
From within a class library, I'd like to know if it is being accessed during design mode as opposed to normal runtime.
I tried using System.ComponentModel.LicenseManager.UsageMode but it seemed to have a value of Runtime even when I was editing a form.
UPDATE:
To clarify, I want to know if I am in design mode not from within a component, but rather from within a separate class that happens to be called by other items from within a form or control. I have a Utility class which is being called indirectly from a control and it is there that I need to know if I am in design mode or not.
I don't think Component.DesignMode will help in this case. What if the component or control is not loaded on the forms designer ? What you may try in this case is, create an enum that only sets the one value at normal startup which otherwise remains to another value by default. You can now check the value of the enum instance and decide if it's a design-time or runtime.
You can use Component.DesignMode to check this. However, be aware that this will always report false inside the constructor of the component, so it needs to be checked later. For details, see Debugging Design-Time Controls.
Edit in response to comments and edit:
Unfortunately, the LicenseMananger, as well as most other services which provide information about whether you're in Design Time (including Component.DesignMode and DesignerProperties.IsInDesignMode) as specifically geared at handling user interface elements. This makes sense, as they're intended to tell you when your item is being "designed" on a designer surface, which requires the component to be registered in the designer.
There is no single property that will cleanly tell you this from within an arbitrary class.
I could see two options, both of which are less than ideal:
Pass the required information into your class (ie: a Component or DependencyObject), so the methods above can be used to check for design-time access correctly. This is probably a more maintainable approach, and will likely work properly in more situations.
Resort to the "hack" of checking the current process name and looking for "devenv" - this is pretty awful, as it assumes Visual Studio only, relies on the executable name, etc... In general, I'll mention it because you'll find it with enough searching, but wouldn't recommend it, as it's very easy to circumvent and has many limitations and flaws.
Is it not possible to use Component.DesignMode property?
Here's some info on applying attributes in order to get design-time specific behavior: http://msdn.microsoft.com/en-us/library/37899azc.aspx
I have WinForm which is a tab based and including all Tabs it has around 60 UI Components. Depending upon value selected in some UI Components i am Auto filling rest of the UI components.For this i would like to write a helper class.But the problem is if i pass Winform object to that class i am not able to access values on that Form because all the member are declared private.
one possible solution is that I can write around 60 properties in the Winform but i think this is not the best way to do it. I would like to know what is the best way to handle problem like these ?
You could change the Modifiers for your UI components from private to internal. This would allow all classes within the same project to directly access the components.
However, I would argue that exposing the necessary components through properties is a better design than exposing them publically/internally. I acknowledge that it includes a fair amount of typing, but it's safer as you can expose them cleanly, in a manner specific to your use case.
That being said - there are a couple of things I would consider:
Can this be refactored into a smaller class, using fewer components by using UserControls? This might make it more managable, as well as promote reuse. 60 UI elements is a fair amount for a single screen.
Can you refactor this to pass the data, instead of trying to work with the controls directly? For example, you could auto-fill the data via a shared interface, and data bind the controls to the data, or something similar.
You can declare the members of a WinForm as public protected, protected internal, and internal. You can do this either in the properties window for a specific component (go to the Modifiers property) or you can change them in the Designer of the form (they are declared after the "Windows Form Designer generated code").
If you don't want to make the members public, nor make a property or method to get that information, then all you're left with is attempting to get the value via reflection, which is perhaps the worst option of all three.
Your best solution would be to make properties for each of those private members and expose them that way.
One way to approach this is to create a class that contains all of the data that you want to bind to (e.g. a class that implements INotifyPropertyChanged).
Then share this instance between the WinForm and the other class. Voila!