Am new to Xamarin-forms and c# and I want to convert this function to its best alternative in Xamarin-forms to complete my code please help me and am still learning.
This the function override from winforms form class but winforms form is not supported in Xamarin-forms so I want its best alternative or hack arroud it:
protected override void WndProc(ref Message m)
{
}
Please kindly help me out.
Related
I have app with lot of windows and Im just curious is there (in WPF) something like global.asax which was in ASP.NET? I just want to clean some data after somebody shutdown application with alt-f4 for example.
Thanks for answers!
The rough equivalent of Global.asax in WPF is app.xaml/app.xaml.cs. You can override methods there to handle startup and shutdown.
For example, in your app.xaml.cs, you can add this:
protected override void OnExit(ExitEventArgs e)
{
base.OnExit(e);
// custom exit code here
}
Basically, I have a custom control FooControl.
public class FooControl : ItemsControl
{
//Code
}
I need to add some event handling, but rather than using a RoutedEvent I'd much more prefer to use Commanding instead. I'm not really sure how to go about doing this though. If I want it so that when Bar1Property (DependencyProperty) changes it raises the Execute associated execute property. I looked at the ButtonBase code through .NET Reflector and wow, that looks overly complicated. Is adding a command this complex?? Obviously I'd also have to make it so that my control enables/disables certain parts of itself depending on if the CanExecuteChanged is altered or not. But I guess that's another portion.
Here is my OnBar1Changed function so far...
private static void OnBar1Changed(DependencyObject obj, DependencyPropertyChangedEventArgs e)
{
FooControl element = (FooControl)obj;
//What to do here?
}
It sounds like by the way you are asking your question, you want to support commanding in your custom control (like for example Button supports). To do this you I recommend looking at how ICommandSource is implemented. Microsoft gives a great walk through on how you can implement it yourself:
http://msdn.microsoft.com/en-us/library/ms748978.aspx
At the simplest level, all you really need is something like:
FooControl element = obj as FooControl;
if (element == null) return;
if (element.MyCommand != null && element.CanExecute(this.CommandParameter)
{
element.MyCommand.Execute(this.CommandParameter);
}
You'd have to create Dependency Properties for both the Command and the CommandParameter, as well.
Hope that helps,
I'm fairly new to Silverlight but experienced in web development, and I'm finding myself highly annoyed with Silverlight's default combobox. It seems to be lacking any concept of use for regular data entry. Primarily I'm wishing it would function like an HTML select box, where you can hit the drop down, then type a letter and it takes you down to the first item with that letter. Is there an easy way I'm missing to make it function like this, or a third party control that can do this?
Thanks!
You could write an attached behavior to provide this functionality. The problem is that the items in a ComboBox in Silverlight aren't always strings. They may be entire controls that the user has templated as the ItemTemplate. If you know yours are going to be string you can implement a Behavior<ComboBox> to attach to the KeyDown event and select the correct one.
public class HTMLSelectBehavior : Behavior<ComboBox>
{
protected override void OnAttached()
{
AssociatedObject.KeyDown += OnKeyDown;
}
private void OnKeyDown(object sender, KeyEventArgs e)
{
SelectedItem = AssociatedObject.ItemsSource
.FirstOrDefault(i => i.ToString().BeginsWith((char)e.Key));
}
}
This is off the top of my head so it may not be exactly right and definitely lacks many safety checks, but it should give you an idea.
I am able to load an rtf document in a RichTextBox, but the links that the document contains to some websites are not working.
Anyone have any idea why? Some solution to make the links work?
Best regards,
Paulo Azevedo
WPF by default doesn't understand where you want the links to be displayed, so what's happening is that the Hyperlink class is firing an event, RequestNavigate, and expecting you, the application designer, to cause the actual navigation to occur.
I assume you just want to launch the system configured web browser, so here's all you need to do:
Hook the Hyperlink::RequestNavigate routed event
Call Process.Start with the URL you receive to have the OS launch the browser.
That might look a little something like this:
public class MyWindow : Window
{
public MyWindow()
{
this.InitializeComponent();
this.myRichTextBox.AddHandler(Hyperlink.RequestNavigate, MyWidow.HandleRequestNavigate);
}
private static void HandleRequestNavigate(object sender, RequestNavigateEventArgs args)
{
Process.Start(args.Uri.ToString());
}
}
Let's take a very simple example:
In my window1.xaml, i have a label
control named 'lblProduct'.
In my window1.xaml.cs, i have a
public method called
CalculateProduct(Int Var1, Int
Var2). CalculateProduct will, as
you may have guessed, calculate the
product of the variables passed in.
I'd like to simply bind the results of 'CalculateProduct' to my label. My actual use case is a little more complicated than this. However, if I could get this up and running not only would I be quite happy, I'd be able to figure out the rest.
I've seen interesting examples using the ObjectDataProvider to bind to a static method of a new class. While this is well and good, I don't feel the need to create a new class when I've already instantiated the one for my window. In addition, there may be other global variables that I'd like to take advantage of in my Window1 class.
Thanks for your time and help,
Abel.
It's quick and dirty but I'd probably just have CalculateProduct set a property with its result and databind to the property.
Yes, there is a way. It's not pretty. You have to add an xmlns:Commands attribute to your window1.xaml tag. I ended up bastardizing some code I found in this Code Project article.
Is the product that you want to display in the label something that's generated on load, or from another control event?
I'm not sure this will help you, but I ran into something similar where I was trying to generate XAML dynamically with XSLT. My solution worked, kind of...well, not really for what I was trying to do. But maybe it will help you.
As I said, you have to declare the xmlns in your page tag, like so:
<Page x:Class="WpfBrowserApplication1.Page1"
blah blah blah
xmlns:Commands="clr-namespace:WpfBrowserApplication1">
Then, define a static class in your application with the same namespace, pretty much the same as the example in the Code Project article, with handlers for a RoutedUICommand:
namespace WpfBrowserApplication1
{
public static class CommandHandlers
{
private static System.Windows.Input.RoutedUICommand _submitCommand;
static CommandHandlers()
{
_submitCommand = new System.Windows.Input.RoutedUICommand("Submit", "SubmitCommand", typeof(CommandHandlers));
}
public static void BindCommandsToPage(System.Windows.Controls.Page caller)
{
caller.CommandBindings.Add(new System.Windows.Input.CommandBinding(SubmitCommand, SubmitContact_Executed, SubmitContact_CanExecute));
}
public static System.Windows.Input.RoutedUICommand SubmitCommand
{
get { return _submitCommand; }
}
public static void SubmitContact_Executed(object sender, System.Windows.Input.ExecutedRoutedEventArgs e)
{
...do stuff...
}
public static void SubmitContact_CanExecute(object sender, System.Windows.Input.CanExecuteRoutedEventArgs e)
{
if (e.Source is System.Windows.Controls.Button)
e.CanExecute = true;
else
e.CanExecute = false;
}
}
}
The nasty part is that, so far as I've found, the only way to map things back to Page1.xaml is to cast the sender object and dig through the UI elements of the Page, similar to how you would dig through the DOM on a web page. I had some success with this, but certainly don't pretend to be an expert.
The last thing you have to do is wire up your control in the Page1.xaml.cs. In the XAML, you do it like so:
<Button Name="btnSubmit" Command="Commands:CommandHandlers.SubmitCommand" etc... />
In the code-behind, like so:
private void Page_Loaded(object sender, RoutedEventArgs e)
{
CommandHandlers.BindCommandsToPage(this);
}
I hope that helps, and good luck.
Why you not just set the label value in your CalculateProduct method before you return from the method. Basically way do you need data binding here? It is one way anyhow, since you are binding to a label.
ObjectDataProvider has an ObjectInstance property that you can assign your Window instance to.
aogan: The idea here is to leverage the flexibility of WPF databinding. I could set the entire UI in the code behind, but MS has developed this binding system and i wanted to easily take advantage of it. Also, this was a simple example for a more complicated problem.
To everyone else involved, i've gone with PITAdev's solution. Thanks for the help.