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Wpf converter multiple parameters

Wpf converter multiple parameters

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GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. If nothing happens, download GitHub Desktop and try again. If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again. MathConverter is available on NuGet. In WPF, bindings are absolutely incredible.

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They save a lot of time in GUI development. If you are unfamiliar with bindings, you can read Microsoft's documentation about them here.

MathConverter is the last converter you'll ever need. It can do anything you ask of it. What you want to do is bind to half of the height. But that's not possible. This is why Microsoft included Converters for bindings. In this case, we have to create our own custom Converter.

But this converter can only be used to create CornerRadius objects. To generalize it, the body of the Convert method would have to be changed to:.

Later, if you want to bind to two times a value, you have to add a new, similar class for DoubleValueConverter and add one to the resources before you can use it for a binding.

This is where MathConverter comes in handy. It is a single Converter class that does it all. Once you have MathConverter referenced, you need to add a MathConverter object to your resources. You can specify different radii by passing in multiple values for the parameter.

Those values can be separated by either commas or semicolons. But even this binding has a shortcoming.Could someone shed some light on how to do this, as i have no idea how create the converter, or reference it in the binding of the button click. I need the value converter to take the value of both edit text fields and then call my ICommand passing it the object it will return. Why do you think it would limit the core?

Bindable Converter Parameter

Aren't you going to display the values that you have in the two EditText instances on other platforms as well? In your View, you would bind those two properties to your EditText controls. Since they are bound, when the user types into the Edit Text boxes, the ViewModel will have those new values automatically. I need to execute an ICommand in my ViewModel passing it the value of both edit text regions. I found out from another question i asked that you can't pass more than one parameter to an ICommand.

So i was wondering how i could pass both edit text field values to this ICommand? Just use the values from the ViewModel? Sorry for the confusion this is the first time i've used this design pattern. Thats genius! Haven't even remotely thought of that, thats so much easier than what i was trying to accomplish, thank you!

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Best Answers. Cheesebaron DK mod. September Accepted Answer. September edited September Accepted Answer. Cheesebaron DK Insider, University mod. September I don't really understand what it is you want to achieve.

Care to give an example? Sign In or Register to comment. Facebook Twitter GitHub.In that post, I fired off a Message Box from the View Model, and commented that you shouldn't do this. However, I didn't expound on how to work around this. In this post, I am going to show how we can pass multiple values into the Command as the Command Parameter so we can interact with the user through the View with a much cleaner implementation. Instead of a message box, we are going to add a label to the form that will display the current price of the Product.

When we update the price, the label gets updated with the current price of the product displayed. Note the it isn't bound to anything in the product, it is purely a UI item. The XAML changes for the label are minor. We add an additional RowDefinition to the table, and in that row, add two label controls. One for the actual "Label" and the other to hold the price. The changes for the Button allow us to pass in the multiple parameters into the CommandParameter. To implement this, we need to execute the following steps:.

The Parameter class is very straightforward, having two properties. One is for the product that is the target of the invocation, and the other is for the UIElement that will receive the updated value for display to the user. I don't have any other uses currently, and some would argue YAGNI you ain't gonna need it here, but the code is still very clear, so I opted for the less specific implementation.

To implement IMultiValueConverter, create a new class. There are two methods in the interface, Convert and ConvertBack. For this use case we only need to implement Covert. The first parameter to the Convert method is an array of objects that are the binding values set in the XAML of the control on the Window.

There are several other parameters that we won't need to worry about here, but will be discussed in a later post.

A new ChangeNotificationParameter is created, and it's properties are set in the Convert method. I iterate through the list of objects, checking their type, and then correctly assign the properties of the parameter class.I have been working with WPF for about a year and some things annoying me very much. One of such things is converters. We can keep them in mind and use in different areas. However, often it happens that it is required to use a particular converter and you do not want to make the whole component of it because it takes much time, as well as clogs the global scope.

Thus, it is difficult to search the required information from all the garbage. Converters are used when working with bindings. They allow converting values using one-way or two-way binding modes.

The converters themselves will look like this. In this code, we have two converters in one class. However, we can use them separately:. The code is short, as the example is synthetic. However, it is difficult to understand what are these arrays, casting, targetType, and culture?

wpf converter multiple parameters

What does ConvertBack without implementation mean? Compare his implementation with the previous one. The less code is, the more clarity there is. The variant with a separate re-used converter may look similar:. Not bad at all, is it? So, how can we work with XAML if it understands only standard interfaces of converters? However, then there is no sense in declaring each readable converter by a wrapper.

One of the solutions is to make the wrapper unique, such as:. This all is a theory.

Simplifying Converters for WPF

How can we pass delegates to converters in practical terms and how can we take them with XAML? To do this, we can use the MarkupExtension mechanism. Just inherit the MarkupExtension class and override the ProvideValue method. Later in the XAML, you can write binding-similar expressions in figure brackets, but with their own working mechanisms.

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The simplest solution to pass a reference to conversion methods using markup extensions is to use their string names. MethodName type. You can distinguish them by a dot of the latter one. We have already analyzed how it is possible to identify methods. So, how can we get them in the markup extension as delegates to pass to the converter? The overridden method must return what is eventually assigned to the property. The value of this property in XAML markup defines this markup extension.

There is no sense in creating different converters. Instead, we can create one class and implement both interfaces for the converter to be suitable for one-value and multi-value binding. To pass a string to the markup extension that specifies the function name from the code-behind or static library to be called by the converter, you must define the public string property in the MarkupExtension instance:. However, we can simplify it as well.

Just leave it as conv:GenericConv. You can then define the constructor in the extension so that you do not explicitly specify the property name with the function name:.I came across the MultiBinding markup extension and IMultiValueConveter today when looking for a solution to a problem. Not sure how I missed it previously. The problem basically went like this, I have a TabControl that is hosting content with a Title property and an IsChanged property. Now anyone who learnt WPF from a book or tutorial probably had a section all about this pair and how useful they are.

Those of us who learn as we go however might have missed this one like I did. A MultiBinding works just a regular Binding except it must have a Converter specified and can have multiple pieces of data bound to it, so when any of these change it fires a re-evaluation of the lot.

There are two cases where this is helpful, and I will explain both. The first is probably the intended use, which is where you want to combine two data elements into a single value and update that value when either changes. For our example we are using a basic dataclass with two properties, a WPF form with a textbox to enter both of these values and a textblock to display the combination, and an implementation of IMultiValueConverter that does the combining.

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I have cut a few lines of code out for readability, but the whole lot is in the download linked at the bottom of this post. The XAML looks basically like this, again I have cut out non-essential code so grab the download if you need it. Nice and simple, does just what you would expect.

wpf converter multiple parameters

But what I found more useful was to include the object itself as the first Bindingand then use the extra bindings simply for their triggers. What this lets you do is call methods on the object to aid in the production of your new value. This could save some duplicating of code if you already have a method that does the transformation for example builds a name or address string from its components while still having the update triggered when any component changes.

So there you have it. FirstNamedata. Surnamedata.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Next, I created data template that is going to present objects of type Person. Here's XAML code:.

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Of course the??? Genderagainst the given Person. GenderType value provided in the parameter and return true if the values match. I don't know how to make the converter parameter pass Person.

FemalePerson. Male and nullfor the first, second and third radio button, respectively. OR, you could just pass a string and use Enum. Parse to convert that string to the enum type in the converter:. Since you're creating your own converter why don't you just send a nullable bool as the converter parameter?

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If you don't want to do that you will have to reference your namespace in the beginning like this:. Learn more. How to pass specific value to the converter parameter? Ask Question. Asked 9 years ago. Active 1 year, 7 months ago. Viewed 94k times. Boris Boris 8, 29 29 gold badges 92 92 silver badges bronze badges. Active Oldest Votes. Parse typeof GenderTypeparameter.

wpf converter multiple parameters

ToString. Pavlo Glazkov Pavlo Glazkov Jose Jose 9, 18 18 gold badges 60 60 silver badges 84 84 bronze badges. I would not cast an enum to a trenary for several reasons - it obscures the intended meaning of the enum, it makes the code less readable i. Sign up or log in Sign up using Google. Sign up using Facebook.A Multivalue Converter is required when your target is bound to multiple sources and if the source and targets have different data formats or need some conversion.

Data namespace that will check all the text of the textboxes to determine whether it is filled or not, if it is filled then it will return true otherwise return false and that will enable or disable the button control.

In the preceding code, the convert function checks all the bound data, if any of them are null or empty then it will return false to disable the button control otherwise it will return true to enable the button control. In this example if the text of the two texboxs is found to be empty then the convert function will return false otherwise true. I have another example for the convert back function.

Let's say you have three textboxes, the first TextBox is for taking the first name of a person, the second is for taking the last name and the third one is for displaying the text of the preceding two textboxs jointly with a space between them and vice-versa.

wpf converter multiple parameters

In this case the convert back function of IMultiValueConverter interface must be usde. In the following code example of the fullnameconverter class I have used both the convert and convert back functions to do it. The convert function in the preceding code concatenates the two data items coming from the two sources with a space between them and returns the concatenated data to the target.

The convert back function splits the concatenated string with a space to an array of strings and returns the items of the array to the corresponding source.

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In the preceding scenario the convert back function takes the text of both the first name TextBox and the last name TextBox and concatenates the text with a space between the two texts and returns that to the third TextBox. Again, when you fill in the data in the third TextBox, the convert back function takes the text and splits it into an array string using a space and returns that to the source textboxes first name TextBox and last name TextBox.

To use a converter you need to implement the interface of the converter class in the XAML page of WPF, you need to declare the resource. After declaring the resource it is necessary to use it with binding. See the following XAML code example.

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Visual Basic - Passing Multiple Parameters

Kailash Chandra Behera Updated date, May 16 MultiValue Converters A Multivalue Converter is required when your target is bound to multiple sources and if the source and targets have different data formats or need some conversion. Next Recommended Article. Getting Started With.

NET 5.