C# – Paste Event in a WPF TextBox

ceventstextboxwpf

I have created a custom control inheriting TextBox. This custom control is a numeric TextBox, only supporting numbers.

I am using OnPreviewTextInput to check each new character being typed to see if the character is a valid input. This works great. However, if I paste the text into the TextBox, OnPreviewTextInput is not fired.

What is the best way to capture pasted text in a TextBox?

Also, I have a problem when the back space is pressed, I can't figure out what event this will fire. OnPreviewTextInput is not fired!

Any ideas how to capture pasted text and back space events in WPF TextBox?

Best Answer

Here's some code I had lying around in case I ever needed it. Might help you.

public Window1()
{
    InitializeComponent();

    // "tb" is a TextBox
    DataObject.AddPastingHandler(tb, OnPaste);
}

private void OnPaste(object sender, DataObjectPastingEventArgs e)
{
    var isText = e.SourceDataObject.GetDataPresent(DataFormats.UnicodeText, true);
    if (!isText) return;

    var text = e.SourceDataObject.GetData(DataFormats.UnicodeText) as string;
    ...
}

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As of jQuery 1.7 you should use jQuery.fn.on with the selector parameter filled:

$(staticAncestors).on(eventName, dynamicChild, function() {});

Explanation:

This is called event delegation and works as followed. The event is attached to a static parent (staticAncestors) of the element that should be handled. This jQuery handler is triggered every time the event triggers on this element or one of the descendant elements. The handler then checks if the element that triggered the event matches your selector (dynamicChild). When there is a match then your custom handler function is executed.

Prior to this, the recommended approach was to use live():

$(selector).live( eventName, function(){} );

However, live() was deprecated in 1.7 in favour of on(), and completely removed in 1.9. The live() signature:

$(selector).live( eventName, function(){} );

... can be replaced with the following on() signature:

$(document).on( eventName, selector, function(){} );

For example, if your page was dynamically creating elements with the class name dosomething you would bind the event to a parent which already exists (this is the nub of the problem here, you need something that exists to bind to, don't bind to the dynamic content), this can be (and the easiest option) is document. Though bear in mind document may not be the most efficient option.

$(document).on('mouseover mouseout', '.dosomething', function(){
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Any parent that exists at the time the event is bound is fine. For example

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would apply to

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If you just need to inspect what's happening on a page, you might try the Visual Event bookmarklet.

Update: Visual Event 2 available.

Best Answer

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