Ctrl key press condition in WPF MouseLeftButtonDown event-handler

Question

How I can add an additional condition for a certain keyboard key, to a WPF MouseLeftButtonDown event-handler?

For example Ctrl + key

private void Grid_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{         
    ...
}

score 68 · Accepted Answer · edited Nov 05 '17 at 21:45

68

private void Grid_MouseLeftButtonDown(object sender, MouseButtonEventArgs e) {
    if(Keyboard.IsKeyDown(Key.LeftCtrl) || Keyboard.IsKeyDown(Key.RightCtrl)) {
        MessageBox.Show("Control key is down");
    } else {
        MessageBox.Show("Control key is up");
    }
}

edited Nov 05 '17 at 21:45

Ivar

6,138
12
49
61

answered Dec 07 '09 at 16:50

Stanislav Kniazev

5,386
3
35
44

score 42 · Answer 2 · answered May 11 '10 at 08:52

42

If you want to detect modifiers only, you can also use:

if (Keyboard.Modifiers == ModifierKeys.Control) {}
if (Keyboard.Modifiers == ModifierKeys.Shift) {}

etc. More here.

answered May 11 '10 at 08:52

742

3,009
3
23
18

This solution is simpler – Tyler Liu Jan 03 '15 at 02:13
9

Don't forget that `ModifierKeys` is a flag enum. So, properly checking for ctrl press is `if ((Keyboard.Modifiers & ModifierKeys.Control) == ModifierKeys.Control) {}` – mt_serg Oct 22 '15 at 14:21
1

@mt_serg you can make it even simpler by calling `if (Keyboard.Modifiers.HasFlag(ModifierKeys.Control)) { }` – BrainSlugs83 Jun 29 '20 at 22:14

score 14 · Answer 3 · answered Dec 10 '15 at 09:47

14

In .NET 4.0 you could use:

Keyboard.Modifiers.HasFlag(ModifierKeys.Control)

answered Dec 10 '15 at 09:47

Grzegorz Godlewski

141
1
2

Be careful though. You don't want `HasFlag()` on a hot path. On .NET Framework, it produces garbage on each run. See [this answer](https://stackoverflow.com/questions/11665279/why-enums-hasflag-method-need-boxing). – l33t May 03 '21 at 12:11
This code returns true if Ctrl+Shift (or Ctrl+Alt) is pressed. This may or may not be the intended result. If the intention is to handle the exact Ctrl+ combination, then the equals operator is the way to go. – Mustafa Özçetin Mar 10 '23 at 14:13

score 0 · Answer 4 · edited Aug 29 '22 at 14:51

As Grzegorz Godlewski said above, Keyboard.Modifiers.HasFlag(ModifierKey.Control) can be used.

Although @l33t points out it is not very performant, in the comment it appears there have been improvements in the performance of HasFlag in .NET 4.5/4.6. (see benchmarks results in What is it that makes Enum.HasFlag so slow? and the comments below, and also in this answer).

But still nothing as fast as doing a native check (i.e. flagsToCheck & flag != 0 ) judging by the conclusion here.

Ctrl key press condition in WPF MouseLeftButtonDown event-handler

4 Answers4