User Controls -- Do they serve a special purpose?
As far as I can tell they are no different to forms - they have the same toolbox and features.
Are there certain times when they are appropriate to use over forms?
It would be interesting to understand what they are good for.
You use them to group a set of controls and behaviors together in a re-usable way. You can't show a control on the screen unless it's added to a form somewhere.
One good example is a textbox. It's very common to have a label next to your textboxes. You can build a user control to make this easier. Just drop a label and a textbox on the control, expose whatever your properties you want, setup the new control in your toolbox, and now you can just drop this control on your form instead of needing to arrange a label and a toolbox on the form separately.
You could kind of think of them as a panel which "remembers" what controls you put on it. And there's one more important piece. You can put code in these controls as well, and use that to also build special behaviors into your custom controls.
I have to disagree (slightly) with the selected answer. Reusability is only part of what a UserControl is for.
All Controls are reusable. Almost all controls are reusable on the same Form/Window/Panel/etc. For example, a TextBox is a control.
There are two ways to create your own reusable control:
Custom Control
Completely custom, and reusable.
Created entirely in code.
You get a bit more granular control over what your control is doing this way.
Lighter weight (usually), because there isn't anything added in for designability within Visual Studio.
In ASP.Net only: No "HTML" type file to use or edit.
User Control
Completely custom, and reusable.
Created partially in a designer in Visual Studio, and partially in code. (via code behind)
Much easier to deal with from a visual aspect.
A little heavier, as there is pre-existing code added in by the framework to support designing inside Visual Studio.
In ASP.Net only: You can change the appearance a bit simply by editing the .ascx file (basically HTML).
User Controls serve the purpose of reusing controls.
Imagine you need a search box in several pages of your application. You can create a search user control and drop it in every page where you want it visible.
So, it's nothing more than a container that aggregates reusable blocks for your pages.
Forms have a lot of extra furniture that you don't need if you simply want a collection of controls together - the minimize and maximize buttons for example. If you just simply grouped your controls in a Panel, you'd have all the event handlers on the same form as the panel - with a user control, the event handling code is in the user control class, not the form class.
You can reuse the same control on many forms. In fact all items you are using while creating windows forms are the controls. User controls are just extra controls extending controls library provided by .NET.
In ASP.NET, user controls enable you to split your page into reusable components. For example, you may want to have a search box which can be used in different places on your website, so you'd use a user control. They can also be used for partial page caching. You can cache portions of your page to improve performance.
Related
I am doing my first steps programming a little toolbox in C#.
I want to choose the program to run via a menustrip.
How can I switch all visible textboxes, buttons etc. on the same form? I don't want to open a new form. Do I have to show/hide every element "by hand" or is there a better solution?
I hope you get my problem.
Thanks in advance.
Yes totally understood.
You need a way to navigate between different fragments within your application.
Since these are your first steps and not a legacy app, why aren't you starting with WPF which is the successor of Winforms ? (newer better)
See how can you achieve such functionally in WPF
https://learn.microsoft.com/en-us/dotnet/desktop/wpf/app-development/navigation-overview?view=netframeworkdesktop-4.8
Although the terms are similar and also apply in winforms.
What you want to do is to create all the buttons etc as part of a UserControl. You can then add your custom UserControl to the form. This should allow you to switch the user control for some other control, or change the visibility for the whole user control.
This can also allow you to place multiple user controls side by side or in some other layout.
In my UWP app, my control options are User Control and Templated Control. My understanding of a User Control is KIND OF clear at this point.
I was told that a Custom Control's style/template is only instantiated in memory once, and that this only happens at the time the control is first used. That's what I want since I know the control I am creating will be used in a ListView.
In the book, XAML Unleashed, however, the author creates his Custom Control by starting with a User Control, and then simply changing it's base class. The thing is that the control he created calls InitializeComponent(). I hear that this type of class uses more memory because it is re-instatiated for each item in the ListView.
Also, I never thought that Custom Controls used the InitializeComponent() method. I thought there was simply a call to this.DefaultStyleKey = typeof(MyClass); in the constructor. What gives? I am confused on what is what...
And last, why is the style/template of the Templated Control placed in the global Generic.xaml file, instead of its own separate file (i.e., xaml file and a code-behind file pair)? If the control is supposed to be custom and "portable", then shouldn't it be totally separate from other code? I haven't found a single article explains any of these things in detail on any level.
This is something most people get wrong so I'll try to clarify a few things for you.
Memory
The whole memory thing, it's all in the Visual Tree. When you instantiate any control, whether templated or UserControl, you will use up memory with every instance because in both cases you are creating a full copy of the visual components in the template.
The templated control will create a copy from the ControlTemplate while the UserControl parses the XAML file when InitializeComponent() is called.
Memory usage will be the same if you create 100 templated controls or 100 user controls if their content is the same.
Usage
Templated controls are best for situations where you're creating a single component, like a Button, Slider, MyStarRatingInput, etc. and you're giving the users of your control the ability to swap out the template with their own. It takes a lot more effort to do this properly than UserControls because the logic has to be template agnostic and your templates have to react properly with visual state changes.
A UserControl is best for layout or views, like forms, popups, screens, pages, etc. You will not give someone the freedom to tamper with the content of your view. You may expose a few public/dependency properties if some views are reusable in a small way, but generally they are set in stone.
Generic.xaml
I honestly don't have an answer for this. Microsoft should've allowed multiple resource dictionaries to enable cleaner partitioning of control templates. Generic.xaml is a reserved filename that referencing projects will look for as the root source of the base styles of your controls. You could reference other XAML files from Generic.xaml, but that's annoying and it bloats the root of your resource dictionary. For now, you're stuck with this method.
Recommendation
If you're sharing a control library, you would want to use templated controls as much as possible. If you're building controls, views, pages, etc for your current project and they're not meant for reuse, then use UserControls.
You can still create a UserControl in your control library if you plan on owning the template and forcing all users to accept your design.
I also recommend templated controls for items that you plan on instantiating a hundred times in a single view, like a ListView. You will see noticeable speed improvement if your template is preloaded into memory instead of parsing a XAML file on every instance.
I am attempting to create a WinForms application which allows the user to display and edit data stored in a MSSQL database. The data being altered is hierarchical, and within a single level of the hierarchy the properties which may be altered are identical; in other words the controls for a single level of the hierarchy are the same, but they may differ from other levels.
I am trying to create the application in such a way that there is only a single form with controls that update based on the hierarchical level of the item being viewed by the user. I realize this is possible by putting all the controls for all levels on a single form and updating their 'Visible' property, but that method makes design of the form difficult due to clutter... Have any of you found a more elegant/less ugly solution?
If you want to do this in WinForms, you can take advantage of the fact that visibility and enabled-ness are both "heritable" traits in the Windows model.
In other words, if you group all of your controls within a parent container (such a Panel or UserControl), then disable that container control and make it invisible, all of its child controls will also become likewise disabled and invisible.
I recommend creating UserControls for each level of the hierarchy. The line of thinking is pretty much the same as if you used separate Forms, except that they're not actually separate Forms. Multiple UserControl objects can be displayed on a single form, so you can have as many as you need. This keeps all related controls together, which makes management much easier. You can also interact individually with these UserControls in the WinForms designer, just like they were separate Forms, solving the "clutter" problem.
To toggle between "active" hierarchies, loop through all of your UserControl objects. Make the currently "active" one enabled and visible (all of its children will automatically become likewise). Make the rest of them disabled and hidden (and all of their children will automatically become likewise).
I won't argue with HighCore here, though. If you don't already know WinForms, you could just as easily spend your time learning WPF. If you decide to do so and want to know how to accomplish this same task in that UI framework, please be sure to ask a new question.
I have a winforms tab control which has several tab pages. Within each tab page controls (textboxes, radio buttons, etc...) are group into groupboxes. These group boxes are arranged from top to bottom but in some occassions some groupboxes needs to be visible and other ones to be hidden. Also control within each group box sometimes (depending on the scenario) needs to be visible and sometimes hidden. So I would like to know if someone knows a good approach to do this, maybe some kind of pattern if any. Also it would be good to implement a generic solution to do this. Could any expert in GUI guide me in the right direction to do this?
Using C# and dot NET Framework 4.0, WinForms. This is a desktop application, not Web-based.
You can define the scenarios in a class then add another class that will manage the layout by reading the scenario and laying the elements based on the scenario. I have not provided details because it varies on how specific you want to be and what behavior you want to achieve. It is better to put the Widgets inside a User Control and let that user control communicate with the layout manager.You can use the Mediator pattern or variation of it to coordinate between the widgets. Hope this helps.
I usually try to group related controls into UserControls (even if this means doubling up on some controls) and adding them to or removing them from the form as needed. An example of this could be payment methods - when the user selects a specific payment method (Credit Card, Cash, Cheque, etc) a UserControl with the correct elements is displayed within a panel on the form.
A good pattern to use when managing this sort of set up is Model-View-Presenter, in the example, all the UserControls would probably implement an IPaymentMethod view interface and provide a way to update the corresponding models.
I have to design a control_panel form. This will have many tabs. How should I design this? Should I make different new forms for each tab or is there a concept of Masterpage in C# WinForms?
Please give me your opinions. Thanks.
It's easy enough to whip up something like this in WinForms, using a TabControl, filled with several different TabPages, and a corresponding ImageList to hold the icons for each tab:
Then you can just place the controls you want on each TabPage as you normally would. The designer has excellent built-in support for the TabControl, allowing you to simply click on the tab you want to switch to it as you could if your application was running. Here's a tutorial on implementing tabs in C#.
If you need more extensibility and encapsulation than provided by adding individual controls to each TabPage, you can create a custom UserControl corresponding to each of your tabs, and then place an instance of that UserControl into the TabPage. I don't really know much about MasterPages, but creating a base UserControl that all of your other UserControls inherit off (and then add their unique elements) of seems like it would provide similar functionality.
You have tab control in windows form.
you can go through MSDN article for creating tabs.