Develop Reference

WPF Button disables itself without binding or code making it so

I'll give some details below, but briefly I have a problem wherein a button in my WPF application will disable itself if I click somewhere else in the application. This button is linked to a Command but there is absolutely NOTHING bound to the IsEnabled property of the button and the Command CanExecute callback just sets e.CanExecute to true.
I saw this similar SO question (Weird problem where Button does not get re-enabled unless the mouse is clicked) but it was not helpful.
The application is simple and consists of a DockPanel divided into 4 parts. The left section contains a DataGrid and the right section contains a UserControl that also contains a couple DataGrids as well as the offending Button. It's so weird, but if I click on any row in the left DataGrid, the Button in the right section becomes disabled. The only way I can then re-enable it is to click on any row in either of the DataGrids in the right section!
Again, there IS absolutely nothing bound to the IsEnabled property of the button or any other code/markup implicitly in place that would allow this to happen.
Some relevant code snippets:
UserControl Command bindings:
<UserControl.CommandBindings>
<CommandBinding Command="cmd:DBScriptCommands.LoadScripts" CanExecute="cmdLoadScripts_CanExecute" Executed="cmdLoadScripts_Executed" />
<CommandBinding Command="cmd:DBScriptCommands.RunScripts" CanExecute="cmdRunScripts_CanExecute" Executed="cmdRunScripts_Executed" />
</UserControl.CommandBindings>
Button xaml:
<Button IsEnabled="True" x:Name="btnLoadScripts" Command="cmd:DBScriptCommands.LoadScripts">
<StackPanel HorizontalAlignment="Stretch">
<Image Source="/Images/folder-open.png" />
<TextBlock>Load Scripts</TextBlock>
</StackPanel>
</Button>
CanExecute for Command:
private void cmdLoadScripts_CanExecute(object sender, CanExecuteRoutedEventArgs e)
{
e.CanExecute = true;
}
This has me baffled and any ideas are appreciated. If more information is needed, please let me know.
Edit 1:
Seems like it is something to do with the Command (still not sure what) - if I remove the Command parameter from the Button, the problem goes away - not useful because I want the button to trigger the Command, but interesting. In the CanExecute(), if I set e.CanExecute to false, the button is always disabled which makes sense. When it is set to true (like it is now) then I have the problem I've describe where it seems like something is setting it to false by magic sometimes.
Thanks

How to set inktoolbar's pen color

As the code shown, I add a ballpointpen, and it support 30 colors, but not enough.
I got colorSelected(Color type) using some other ways, not discuss here.
Now I want to click ballpointPen, using my colorSelected to draw.
How? Thanks.
<Grid>
<InkToolbar TargetInkCanvas="{x:Bind inkCanvas}" InitialControls="AllExceptPens" VerticalAlignment="Top">
<InkToolbarBallpointPenButton x:Name="ballpointPen" Click="xxx_Click"/>
<InkToolbarCustomToolButton x:Name="toolButtonColorPicker" Click="ToolButton_ColorPicker">
<Image Height="20" Width="20" Source="ms-appx:///Assets/Palette.png"/>
<ToolTipService.ToolTip>
<ToolTip Content="ColorPicker"/>
</ToolTipService.ToolTip>
</InkToolbarCustomToolButton>
</InkToolbar>
<InkCanvas x:Name="inkCanvas" Margin="0,48,0,0"/>
</Grid>
The code below seems not working...
private void xxx_Click(object sender, RoutedEventArgs e)
{
if(bUserDefinedColor)
{
InkDrawingAttributes drawingAttributes = inkCanvas.InkPresenter.CopyDefaultDrawingAttributes();
drawingAttributes.Color = colorSelected;
inkCanvas.InkPresenter.UpdateDefaultDrawingAttributes(drawingAttributes);
}
}
by the way, I upload the test project to GitHub https://github.com/hupo376787/Test.git

Here is a better solution to your problem, without the need of calling UpdateDefaultDrawingAttributes directly.
What I would do is, whenever the user selects a new color from your ColorPicker and hits OK, add this color to the Palette of the InkToolbarBallpointPenButton, and then set the SelectedBrushIndex to the index of the newly created color.
In way you can completely remove your xxx_Click handler, and replace what's in LeftClick with the following
cpx.LeftClick += (ss, ee) =>
{
bUserDefinedColor = true;
colorSelected = cpx.pickerColor;
ballpointPen.Palette.Add(new SolidColorBrush(colorSelected));
ballpointPen.SelectedBrushIndex = ballpointPen.Palette.Count - 1;
};
This is it! You will see the selected color visual on the pen icon automatically reflects the new color, which gives a great user experience.
Here are two more things you might want to do to further enhance the UX.
Cache the added colors and manually add them back to the Palette at app startup so next time when the user opens the app, they are still available.
Instead of adding another icon to display the ColorPicker, try putting it inside the color popup of the InkToolbarBallpointPenButton so all color related things are in the same place. The control that sits inside this popup is called InkToolbarPenConfigurationControl. You should be able to locate its style (see path below) and add your ColorPicker to it.
C:\Program Files (x86)\Windows
Kits\10\DesignTime\CommonConfiguration\Neutral\UAP\10.0.xxxxx.0\Generic\generic.xaml
Hope this helps!

Why button changes color when I click or hover on it? Xaml windows 8

I have created a button using XAML and have defined some simple properties for it.
<Button Name="btnNext" Grid.Row="1" Content="PARA" Width="200" Grid.Column="1" Background="#FF2D2D2D" HorizontalAlignment="Right" FontSize="40" Height="380" BorderThickness="0" />
It happens that when I click on the button or put the mouse over, it changes color.
I have tried to escape this behaviour in the btnNext_Click method but it does not affect anything.
private void btnNext_Click(object sender, RoutedEventArgs e)
{
Button button = sender as Button;
if (button != null)
{
button.Background = new SolidColorBrush(hexToColorConvertor("#FF2D2D2D"));
START_POINT += (uint)NUMBER_OF_BUTTONS1;
ReadFile(START_POINT);
}
}
Does anyone have any idea how to resolve this?

In XAML, button have default style for different states like Normal, MouseOver, Pressed etc..
Whenever button moves from one state to another, it changes its look using default style obviously. You can find more information related to default style here
Now, If you want to override this default behavior, you can do it easily with Expression-blend. More of this can be found here and here
Hope this information will help you.. :)

When are tunneling and bubbling events useful in WPF?

I understand how bubbling and tunneling works. However, i'm confused about using them.
Here is why:
I want to handle a mouse click event. To bubble it, there is MouseDown and, to tunnel it, there is PreviewMouseDown. However, MouseDown doesn't necessarily mean the user clicked the control. May be the user pressed the button and moved away from it to cancel the click.
I wouldn't want to change anything if the button is not being clicked.
So my question is, how are the Bubbling/Tunneling strategies useful?

If the event is listed RoutedEventArgs, then it's routed event. Routed events support a RoutingStrategy of Bubble, Tunnel, or Direct. Let's take a look at the event handler of Button.Click:
private void Grid_Click(object sender, RoutedEventArgs e)
{
MessageBox.Show("Button Test clicked!");
}
There specified RoutedEventArgs, so it's routed event. Because the preview were not specified in the name, therefore this Bubble event. This can be demonstrated in the following way:
<Grid ButtonBase.Click="Grid_Click">
<Button Name="TestButton" Width="100" Height="30" Content="Test" />
</Grid>
When you click on the TestButton, the event is to rise above the Grid, and displays a message:
Button Test clicked!
Usefulness of Bubbling/Tunneling strategies
Tunneling
Many of the standard controls listen to events, such as KeyDown, MouseDown, etc. For example -DataGrid control. I want by pressing the enter key the function was called adding a record. But DataGrid already has KeyDown event, so the event is not raised. So you have to do your logic in the Tunnel event - PreviewKeyDown, it will work before the KeyDown event. The same applies to RichTextBoxControl.
Bubbling
Sometimes, you need a global handler for a specific event, so it worked for all controls in VisualTree. Naturally, the a direct event you can not do it. Hence on the stage comes Bubbling event.
Another reason is the ideology of the WPF. This Button can contain anything: Image, another Button, etc:
The user can click on the TextBlock/Image in the Button. How do we know that the click was in Button? That's right, with the help of Bubbling event.
For more information, please see:
Understanding Routed Events and Commands In WPF
Edit
I changed little bit a Click handler:
private void Grid_Click(object sender, RoutedEventArgs e)
{
String message = "#" + eventCounter.ToString() + ":\r\n" +
" Sender: " + sender.ToString() + ":\r\n" +
" Source: " + e.Source + ":\r\n" +
" Original Source: " + e.OriginalSource;
lstEvents.Items.Add(message);
}
Result of click on the Button:

Hi though you can get some good articles regading this on net but still I will try to answer this.
Suppose you give a button a very plain appearance consisting of a single Rectangle, and provide a simple piece of text as the content Even with such basic visuals, there are still two elements present: the text and the rectangle.The button should respond to a mouse click whether the mouse is over the text or the rectangle. In the standard .NET event handling model, this would mean registering a MouseLeftButtonUp event handler for both elements.
This problem would get much worse when taking advantage of WPF’s content
model. A Button is not restricted to having plain text as a caption—it can contain any
object as content. The xaml below is not especially ambitious, but even
this has six visible elements: the yellow outlined circle, the two dots for the eyes, the
curve for the mouth, the text, and the button background itself. Attaching event
handlers for every single element would be tedious and inefficient. To work MouseDown We would have to add 8 MouseDownEvents to this bit of code.
<Button PreviewMouseDown="PreviewMouseDownButton" MouseDown="MouseDownButton">
<Grid PreviewMouseDown="PreviewMouseDownGrid" MouseDown="MouseDownGrid">
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<Canvas PreviewMouseDown="PreviewMouseDownCanvas" MouseDown="MouseDownCanvas" Width="20" Height="18" VerticalAlignment="Center">
<Ellipse PreviewMouseDown="PreviewMouseDownEllipse" MouseDown="MouseDownEllipse" x:Name="myEllipse" Canvas.Left="1" Canvas.Top="1" Width="16" Height="16" Fill="Yellow" Stroke="Black" />
<Ellipse Canvas.Left="4.5" Canvas.Top="5" Width="2.5" MouseDown="MouseDownEllipse" Height="3" Fill="Black" />
<Ellipse Canvas.Left="11" Canvas.Top="5" Width="2.5" MouseDown="MouseDownEllipse" Height="3" Fill="Black" />
<Path Data="M 5,10 A 3,3 0 0 0 13,10" Stroke="Black" MouseDown="Path_MouseDown_1"/>
</Canvas>
<TextBlock Grid.Column="1" MouseDown="TextBlock_MouseDown_1">Click!</TextBlock>
</Grid>
</Button>
WPF uses RoutedEvents Bubble/Tunnel /Normal, which are rather more thorough than normal events. Instead
of just calling handlers attached to the element that raised the event, WPF walks the
tree of user interface elements, calling all handlers for the routed event attached to
any node from the originating element right up to the root of the user interface tree.

As you said you know the concept of bubbling/tunneling so not going into that. But this is what these events are intended for i.e they let you know if the Mouse button was Down or Up on the control or its children.Events are working fine.For your scenario you should use the Click event of your button which tell if the mouse was down and up on the button itself.
Thanks

Event trigger not working on RichEditBox XAML-C# windows 8

I am using RichEditBox with XAML and C#
I have following 3 events in XAML and corresponding handlers in C#(back code)
DoubleTapped="RichEditBox_DoubleTapped" RightTapped="RichEditBox_RightTapped" PointerReleased="RichEditBox_PointerReleased"
But after putting debug points, I found, none of them is getting triggered.
DoubleTapped event gets triggered if I double tap not on the word but on empty space within the RichEditBox. Once this event is handled, double tap starts working even on words.
I need to handle any of the above events on words. But none of them is responding as expected.
How can I achieve it?

okies. Got other 2 events working as:
SelectionChanged="RichEditBox_SelectionChanged" Holding="RichEditBox_Holding"
Above events mentioned in the question might be a bug, not sure though.

this is a user control and I've got this code XAML:
<RichEditBox x:Name="TextElementControl" Background="{Binding Background, ElementName=userControlModified}" ManipulationMode="None" ScrollViewer.HorizontalScrollMode="Disabled"
AcceptsReturn="True" TextWrapping="Wrap"
SizeChanged="TextElementControlSizeChanged"
IsDoubleTapEnabled="False" DoubleTapped="TextElementControl_DoubleTapped" BorderThickness="0" BorderBrush="{x:Null}" Padding="10,10,10,10"/>
in the code behind :
private void TextElementControl_DoubleTapped(object sender, DoubleTappedRoutedEventArgs e)
{
//log message, breakpoint is hitting this during double click.
}
on some portion of the code we've set
void ControlLoaded(object sender, RoutedEventArgs e)
{
TextElementControl.IsReadOnly = false;
}
it works and I hope it helps you.