KeyDown Event is triggered twice

Question

I have a style which includes two TextBoxes in order to create a PlaceHolder / Watermark, so far is working fine.
The only exception is that the events are triggered twice, the first one comes from the CustomTextBox I have in the Style, and the second one from the CustomTextBox I have in XAML.

Is there any way to prevent this behaviour? I have already tried to set IsEnable="False" and ReadOnly="True" but doesn't seems to work.

Here the style I use to simulate the Watermark:

<Style x:Key="CustomTextBoxStyle"
       TargetType="{x:Type utils:CustomTextBox}">
    <Setter Property="FontFamily"
            Value="/UserInterface;component/Resources/Fonts/#Avenir LT Std 35 Light" />
    <Setter Property="FontSize"
            Value="16" />
    <Setter Property="Foreground"
            Value="#FF414042" />
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type utils:CustomTextBox}">
                <Border Name="Border"
                        BorderBrush="#FF348781"
                        BorderThickness="0,0,0,4"
                        CornerRadius="2">
                    <ScrollViewer x:Name="PART_ContentHost"
                                  Margin="0" />
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup x:Name="CommonStates">
                            <VisualState x:Name="Normal" />
                            <VisualState x:Name="Disabled" />
                            <VisualState x:Name="ReadOnly" />
                            <VisualState x:Name="MouseOver" />
                        </VisualStateGroup>
                    </VisualStateManager.VisualStateGroups>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

<Style TargetType="{x:Type utils:CustomTextBox}"
       BasedOn="{StaticResource CustomTextBoxStyle}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type utils:CustomTextBox}">
                <Grid>
                    <utils:CustomTextBox
                        Text="{TemplateBinding Text}"
                        x:Name="textSource"
                        Background="Transparent"
                        Panel.ZIndex="2"
                        Style="{StaticResource CustomTextBoxStyle}"
                        KeyboardViewModel="{TemplateBinding KeyboardViewModel}"/>
                    <utils:CustomTextBox Text="{TemplateBinding HintText}"
                                         Background="{TemplateBinding Background}"
                                         Panel.ZIndex="1"
                                         IsEnabled="False">
                        <utils:CustomTextBox.Style>
                            <Style TargetType="{x:Type utils:CustomTextBox}"
                                   BasedOn="{StaticResource CustomTextBoxStyle}">
                                <Setter Property="Foreground"
                                        Value="Transparent" />
                                <Style.Triggers>
                                    <DataTrigger Binding="{Binding Path=Text, Source={x:Reference textSource}}"
                                                 Value="">
                                        <Setter Property="Foreground"
                                                Value="Gray" />
                                        <Setter Property="HorizontalContentAlignment"
                                                Value="Left" />
                                        <Setter Property="VerticalContentAlignment"
                                                Value="Center" />
                                    </DataTrigger>
                                </Style.Triggers>
                            </Style>
                        </utils:CustomTextBox.Style>
                    </utils:CustomTextBox>
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

Any help would be appreciated. Thanks in advance.

EDIT 1: Code on the CustomTextBox Class for the Event handling

protected override void OnKeyDown(KeyEventArgs e)
{
    //Filtering "solution"
    if (e.Source is CustomTextBox sourceTextBox && sourceTextBox.Name.Equals("textSource"))
     {
         return;
     }

    base.OnKeyDown(e);

    if (e.Key == Key.Enter && EnterKeyCommand != null)
    {
        if (EnterKeyCommand.CanExecute(null))
        {
            EnterKeyCommand.Execute(null);
        }
    }
}

EDIT 2: Use of the CustomTextBox on my UserControl:

<Utils:CustomTextBox Grid.Row="0"
                             Margin="0,10"
                             KeyboardViewModel="{Binding Path=MainWindowViewModel.KeyboardViewModel}" 
                             HintText="Patient"
                             x:Name="Patient"/>

Are you handling events in the codebehind of your custom control? — , Feb 21 '18 at 12:24
Thanks @AmolBavannavar, just test it out, still not working. — Nekeniehl, Feb 21 '18 at 12:28
If you're handling view logic, you should do it in your codebehind file, not your ViewModel. Try using e.Handled = true after doing your logic but it will prevent event bubbling. — , Feb 21 '18 at 12:29
That make the trick @IamDOM. If there is no other side effect than the event bubling its okey, as I do not have to bubble it. — Nekeniehl, Feb 21 '18 at 12:31
Sure, go ahead and if you can explain side effects would be amazing — Nekeniehl, Feb 21 '18 at 12:34
Use x:Name on HintTest CustomTextBox, and check the source in CustomTextBox.KeyDown/KeyUp or whichever event.. If it's coming from HintTest, handle that particular event using e.Handled = True... — Amol Bavannavar, Feb 21 '18 at 12:36
Works the same, but the events still triggering twice, one from the "testSource" and another one from the CustomTextBox in XAML =( — Nekeniehl, Feb 21 '18 at 13:03
I think we all learned a lesson about trying to answer low quality answers. It's just waste of time because the only one who can understand his mess is OP. This question is unlikely to help anyone. — , Feb 21 '18 at 14:24
You can ask about that mess you are saying, I think we are all here to learn, specially me. I have provided all the necessary code and explain everything, so I dont see your point. — Nekeniehl, Feb 21 '18 at 14:28
If you're willing to learn, start here: https://stackoverflow.com/help/mcve. I didn't downvote your question but I used to be upset when people downvoted mine but the truth is they were low quality. The number of not proper answers you got just proves my point. If you want feedback, I'm giving you one. — , Feb 21 '18 at 14:31
Now I see your point, but not agree with it, I have provided the necessary code to create a minimal example (actually I cannot post more regarding the "too much code" error), I have point it out where the error might be and I have edited and answer any question regarding the matter. But I appreciate your feedback and I will try to do it better next time. — Nekeniehl, Feb 21 '18 at 14:37

score 0 · Answer 1 · answered Feb 21 '18 at 13:42

0

Based on your comment, first it comes from the "test source" and then goes to CustomTextBox means that the KeyDown event is received on first user control and then passed to the second user control.

Can you make sure that you put e.Handled = true in the "test source" to notify that it is handled on the first user control?

answered Feb 21 '18 at 13:42

kurakura88

2,185
2
12
18

Sure, it was one of the suggestion, I can check `e.Source!="testSource"` but it doesn't seems to be the proper way, basically, I would like to understand why the event is triggering from the CustomTextBox inside the Style. – Nekeniehl Feb 21 '18 at 13:55

score -1 · Answer 2 · edited Feb 21 '18 at 16:33

-1

"Fixed" filtering the e.Source as sugesstion from @Amol Bavannavar on the comments:

protected override void OnKeyDown(KeyEventArgs e)
{
    if (e.Source is CustomTextBox sourceTextBox && sourceTextBox.Name.Equals("textSource"))
    {
        return;
    }

    base.OnKeyDown(e);

    if (e.Key == Key.Enter && EnterKeyCommand != null)
    {
        if (EnterKeyCommand.CanExecute(null))
        {
            EnterKeyCommand.Execute(null);
        }
    }
}

edited Feb 21 '18 at 16:33

Stephen Kennedy

20,585
22
95
108

answered Feb 21 '18 at 14:13

Nekeniehl

1,633
18
35

Does this satisfactorily answer your own question? If yes, you can accept it. – Stephen Kennedy Feb 21 '18 at 16:38
I cannot accept my own answer, I have to wait 2 days. – Nekeniehl Feb 21 '18 at 16:41
@Nekeniehl Ah thanks for reminding me of that rule. I don't ask many questions and had forgotten about that. – Stephen Kennedy Feb 21 '18 at 16:51

KeyDown Event is triggered twice

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