I am creating an interface for an XNA game and can't seem to figure something out. I'm new to programming, and feel like I have to be missing something obvious.
I'm creating a grid of levels, much like something you'd see in Angry Birds.
The number of levels will be variable, so I don't want to statically program them.
All of the buttons I use for level icons are created dynamically at runtime, based on a list of level objects. As I create the buttons I set up all of the click events to point to one method that is supposed to determine which button they clicked on, and load that specific level.
My problem is I can't seem to figure out a reliable way to actually tell which button they clicked on and associated that with one of my level objects in the list. I feel like I must be missing something extremely obvious.
Things I've tried so far:
As I generate the buttons dynamically I add them as children to a grid. So I tried using the index number of the sender as the index number in my list of levels (because they should both have the same number of elements).
For example:
App.CurrentLevel = PuzzleLevelsGrid.Children.IndexOf(sender as Button);
This worked great the first time I navigate to the level picking screen, but whenever I come back to it the children of my grid gets reset to a count of 0 for some reason, so it breaks down.
I've set break points and I can't explain how it gets set to 0. I load the children in my onNavigatedTo(), and sometime between the end of that and me pressing a button to load a level it gets wiped.
The other thing I tried was setting up a button object inside my actual level object, then when dynamically creating the level buttons I actually make changes to the button property in the appropriate level.
Then when I need to find out which button was the sender I just loop through all levels and match the sender to the button property. This method actually worked pretty well... until I started trying to load my levels using a background worker thread. The worker thread can't deal with the Button because it's a UI thread thing, and crashes.
Like I said, I'm a new programmer, so I welcome any and all feedback.
Thanks in advance.
The button, like almost every UI control, has a "Tag" property. This property has been designed for you, and only for you, so that you can put any value you like to identify the control.
For instance, you can put your level object in the Tag property of the button, then just read this value back in the click event.
Related
What is a quick way to reset all the Controls inside a panel to their initial states (Compile-time state)? I have TextBoxes, RadioButtons, ComboBoxes, and CheckBoxes to reset. I'd like them to reset to the values when the program first ran. I'd like a solution that does not involve looping or recursion mainly because I don't want to reimplement the same thing over again when I start witha new project. I'm simply finding a set of methods to call that will do the job. Are there any?
Your controls have no compile time state, because state is a runtime concept.
I think you mean you want controls re-initialized to the state as shown on your property sheets. This state is applied by the generated code located in InitializeComponent, so to re-apply that state, you could just call it again.
The only problem is InitializeComponent also wires up events, and you probably don't want to do that twice. You could possibly work around this by deregistering all of your events before calling it, or by deduplicating the invocation list afterward (see this answer).
I don't recommend any of this. The best approach would be to write your own method that sets the properties the way you want them, one by one. Sometimes ya gotta write code.
I'd like to control which button is focused in my view. User must be able to perform a job without need to use mouse. And job is going through all elements. Depending on element, some buttons will appears, some disappears.
I could do it with dependency properties. To example, if there are buttons Previous and Next, then I can provide IsPreviousFocused and IsNextFocused to set focus to them after certain event. Events can be: showing window for the first time (something should have focus already), reaching 1 element (hiding Previous button, setting IsNextFocused), reaching last element (opposite), etc.
This looks reasonable more or less.
But, if I have, to example, 10 buttons (different operations), then all of them will have to have dependency property!
So I was thinking about much easier approach: when I hide button, there will be no focus
if(FocusManager.FocusedElement == null) { ... }
If I can detect, when there are no focus, then I can try to set it to one of the buttons somehow. This way, I don't really need any complicated focus management
Question is: how to deal with FocusManager.FocusedElement in MVVM scenario? How to detect when there is no focus (when window is shown first time, when certain button is clicked and become invisible, etc)?
P.S.: I actually hate ms for making another technology without thinking fully into it; focus is very basic feature (and everybody care about it in their software), but there is no direct support for it (in xaml); looks like "oh, its too complicated, lets skip it" solution.
You could control your focus from your ViewModel by using the approach shown here:
Set focus on textbox in WPF from view model (C#)
I think the title for this question is probably wrong, but I'm not sure quite how to phrase it. I have a C# 4.0 (VS2010) WPF application.
This application consists of a single window with a header including the basics (logos, captions, etc) and a set of navigation buttons (back, retry, next, etc). The rest of the window is comprised of a listbox that is populated with one or more usercontrols based on what mode the app is currently in.
The way the code is currently written when the mode changes the listbox is cleared, all new user controls are added, and the buttons are set to their required state. This is fine for the initial state of each window mode but I'm having trouble deciding a good approach to update the navigation buttons as the contents of the controls change.
For example one screen is a configuration screen and there are three user controls contained within the listbox. These controls are custom classes that inherit from UserControl. Additionally they implement an interface that defines a method 'bool Validate' which determines if the control has been completely filled out.
This same scenario could apply to lots of other situations but this is a generic use case that is pretty straightforward to understand. When the screen initially loads the 'Next' button, whose visibility is controled by the parent window, is visible but disabled as the child controls can't possibly yet be valid. At some point as the user fills out arbitrary data within one or more controls each one would return true if its Validate method was called.
At the point where all controls are valid, the next button would then become enabled. Fairly straightforward design.
The problem is each control doesn't know what screen it is on, and this is by design. I don't want the controls having to be aware of each other and updating a button status in the parent window. I also don't want the parent window to run a polling thread to call Validate every second because in some cases the validation could be complex.
I'm thinking that the change event of each control within the UserControl (text boxes, radio buttons, etc) would all call a trigger a private validate event and this would set some public property on the interface or class.
f I can do that is there a way for the parent window to respond in an event-driven manner to the change of that property? I'm not looking to do this in WPF, doing this in C# code is preferable as I don't want to get into the complexity of WPF quite yet. I'm just not sure, other than constant polling, how to tell when every control's 'IsValid' property will have synchronized all to 'true', if that is even a good approach.
EDIT:
Okay, here is another way to ask the question. I have a List of something (in this case a list of an interface) and want to be able to respond to a public property change on each item in the list so I can take an action when all items are (bool in this case) true. The above explains the use case, but this is a more generic version of the question.
EDIT:
#Vincent "you might do it in an even simpler way with a custom "ValidatedChanged()" event that you can hook in the same way."
It turns out that this is really what I was looking for. The property notification approach seems to be more for ease of use with data-bound controls. I read a lot of posts on this site about how to implement that but it really wasn't what I wanted. I just wanted my objects to notify that an event occured, which happened to be a property change, but that is beside the point. I found documentation on implementing an event in an interface and I have it working now. Thanks for pointing me in the right direction and helping me realize what is really is that I needed.
So you have a ListBox which contains all your controls, and when all controls are validated, the Next button should be enabled ?
If so, when one of your control validates, you might search all sons of the ListBox to check them for validation, using VisualTreeHelper.GetChildren to get them all.
If you don't want / can't have a handle on the ListView, you might find it by searching up the visual tree starting from the control that just validated.
Each 'Validated' event of each control would be handled by a 'CheckIfAllValidated' event handler, and when all are validated, you could raise a 'AllValidated' events that would be handled by the button (and maybe some other controls as well) to enable it.
Edit : I understood that you did not want each component to know about their children, but notice that even the quite common PropertyChanged event has a 'sender' fields that tells who did raise the event. So any listener of a PropertyChanged on, say, the 'validated' property, can go up the visual tree, stop when it encounters a ListView, then search downstairs if all control that have a validated property do have this property set to true...
Edit 2 :
To be more clear about how to do it, either in your window new or on the window loaded event
or maybe on the ContentRendered Event, depending on how your controls are loaded, you
might use once that code to hook a handler to all your controls :
For Each ThisControl In MainListView.
Dim ThisControlType = ThisControl.GetType
Dim ThisControlPropertyChangedEvent = ThisControlType.GetEvent("PropertyChanged")
' you might wanna check here if event is not null / nothing
ThisControlPropertyChangedEvent.AddEventHandler(ThisControl, New PropertyChangedEventHandler(AddressOf APropChanged))
Next
and you write the APropChanged somehow like that :
Public Sub APropChanged(ByVal sender As Object, ByVal e As PropertyChangedEventArgs)
If e.PropertyName = "Validated" Then
Dim ValidatedForAll = True
For Each ThisControl In MainListView.Items
Dim ThisControlType = ThisControl.GetType
Dim ThisControlValidatedProperty = ThisControlType.GetProperty("Validated")
'you might wanna check for non null here
If Not ThisControlValidatedProperty.GetValue(ThisControl, Nothing) Then
ValidatedForAll = False
Exit For
End If
Next
If ValidatedForAll Then
MessageBox.Show("Yeeppee") ' you might send an event instead.
End If
End If
End Sub
Edit 3 : you might do it in an even simpler way with a custom "ValidatedChanged()" event that you can hook in the same way.
This seems very simple, but I can find nothing on a web concerning the behaviour I want to add to my custom control.
My custom control is a textBox with a list of choices. When the text entered by the user is not part of the list, a popup will appear with the list allowing the user to select a correct choice.
Sometimes, there may be a default button on the container in wich the custom control has been added. If so, when the enter key has been pressed, if the text is wrong, The popup must been displayed. If there is no default button, on enter, nothing must happen even if the text is wrong.
To be able to create this behaviour, I must be able to detect the presence of a defaultbutton in the container, and it must be done inside the c# code of the cutom control.
I hope the description is clear enough.
Thanks in advance
Have you thought about implementing an MVVM approach and the Command pattern? So long as your view model knows what the choices are, you can bind the default button to a command. So long as the commands CanExecute handler returns false, i.e., an appropriate choice has not been entered/selected, the button will be disabled and won't respond to the user pressing enter.
Since I was unable to know what other controls I had from the custom control I chose to go like this:
I made a recursive function to find the first parent using FrameworkElement.Parent
Having the parent, I could take a look at every controls it contains.
As soon as I saw a button, I had to verify if IsDefault.
For this one, I used the VisualTreeHelper GetChildrenCount(DependencyObject obj_Parent) and GetChild(DependencyObject obj_Parent, int childIndex). Recursivity once again...
It works very well even though it means more code to execute.
I know this may seem like an odd question, but I am after the information queried in the title.
So far I have tried LayoutRoot.Loaded, but found that LayoutRoot.LayoutUpdated happens even later.
My motivation for this knowledge is the ability to have one component interact with another in code, but for this to happen I must be guaranteed they both exist.
Any ideas?
Clarification of what I'm attempting to do:
I have a collapsing gridsplitter control. From here
When the main page loads I make it collapse; which shrinks the object preceding it to width 0. If that object isn't 'loaded' yet then it doesn't collapse and the gridsplitter is in an odd state where it thinks it has collapsed the item but needs two clicks to effectively do that.
LayoutUpdated is the last event raised in the control object initialization timeline. However keep in mind that LayoutUpdated will be raised multiple time subsequently as required. Maybe you can share a little more detail on what you are trying to do.