如何在.NET中实时捕获numericUpDown ctrl的值更改？

Question

I have implement the ValueChanged event, but I found it will be triggered only after change the focus from numericUpDown to other control or by clicking the up/down arrow.

Inputting the value in the control will not trigger ValueChanged event.

What I did now is adding an KeyDown event and judge if the input value is numeric (can not include SHIFT/CTRL/ALT key); but there is another case need to be involved: the user can paste value into the numericUpDown ctrl

What I need is :

1. When I was typing numeric value (only numeric) in the numericUpDown ctrl, it will known the content has been changed;
2. When pasted a numeric value into the ctrl, it also kowns the content changed

Answer 1

I answered your related other question about numeric updown control:

how to hold the invalid value for NumericUpDown after it loses focus?

You can use the same technique I described there to handle the TextChanged event of the embedded textbox.

Best regards...

Answer 2

I would suggest subclassing the NumericUpDown and overriding the OnTextBoxTextChanged method to raise the ValueChanged event.

You would also need to consider what represents a change, you may get unexpected results if you raise the Valuechanged when the user has typed a single digit and then a second digit. Or a non-numeric character.

Answer 3

CodeProject to the rescue:

A Derived NumericUpDown that Provides Handlers for NumericUpDown's Up and Down Button

Extended NumericUpDown control

And as a bonus, here's a wrapping NumericUpDown:

class WrappingNumericUpDown : NumericUpDown
{
    public override void DownButton()
    {
        if (this.Value == this.Minimum)
            this.Value = this.Maximum;
        else
            base.DownButton();
    }

    public override void UpButton()
    {
        if (this.Value == this.Maximum)
            this.Value = this.Minimum;
        else
            base.UpButton();
    }
}