WPF Discussion Boards

Re: KeepTextBoxDisplaySynchronizedWithTextProperty

28-Jul-16 7:18

I just found this in our app's CTOR:

System.Windows.FrameworkCompatibilityPreferences.KeepTextBoxDisplaySynchronizedWithTextProperty = false;

MSDN Says [^]

Gets or sets a value that indicates whether a data-bound TextBox should display a string that is identical to the value of the source its Text property

As is typical with MSDN, this explanation says nothing of value.

Why wouldn't a textbox display what's in its Text property by default?

Anyone ever used this? Can you shed some light on what this really means?

If it's not broken, fix it until it is

Matt T Heffron28-Jul-16 7:33

Matt T Heffron

28-Jul-16 7:33

I've never used it but it looks like it is referring not to the Text property of the TextBox, but to the source that is data bound to the Text property.
From looking at the code it appears it has to do with an edge case where the TextBox is pushing a change back to the binding source but may not notice if the binding source has modified that string.

// when Text is data-bound, _newTextValue is converted from a
// deferred reference to a string.  The binding writes the string
// back to the source, then computes a new value for Text (which
// may be different, either because the source normalizes the value
// or because of conversion and formatting).  Usually this raises
// a change notification for Text, which brings the Text property and
// the text container into [....].  But this doesn't happen in one
// case:  when the normalized value is the same as the original
// value for Text.  The property engine thinks that Text hasn't
// changed, and doesn't raise the notification.  It's true that
// Text hasn't changed, but we still need to update the text container,
// which now displays the wrong value.
// We detect that case by checking whether _newTextValue (the
// text container value) agrees with Text.

"Fairy tales do not tell children the dragons exist. Children already know that dragons exist. Fairy tales tell children the dragons can be killed."
- G.K. Chesterton

Re: KeepTextBoxDisplaySynchronizedWithTextProperty

Kevin Marois28-Jul-16 7:39

Creating a line break to keep visible tabitems from wrapping when other tabitems become visible.

28-Jul-16 7:39

Just found this[^]

Seems like a good explanation, although this property seems to be because of a bug.

If it's not broken, fix it until it is

Stephen Holdorf28-Jul-16 3:16

Re: Creating a line break to keep visible tabitems from wrapping when other tabitems become visible.

28-Jul-16 3:16

I have tried a lot of things without luck. What I'm trying to do is create a XAML TabControl that keeps all of the first five visible TabItems on the first row when the last two hidden TabItems become visible. What I want is for the two last TabItems to wrap when they become visible but keep the first five on the first row. I have tried to use a TextBlock with a LineBreak but when the last two TabItems become visible the fifth TabItem wraps with the new visible last two TabItems. Any help would be great.

Stephen Holdorf28-Jul-16 14:41

28-Jul-16 14:41

The answer to my problem had to do with setting the widths of the collapsed tabs once they were changed to visible. What I did was give the newly visible tabs the correct width and they pushed the other tabs to the first row.

DP not Working

Kevin Marois27-Jul-16 8:01

27-Jul-16 8:01

This is a very simple example, and I can't get it to work

My UserControl

<Grid>
    <Border>
        <TextBlock Text="{Binding DayNameCaption}"
                    Background="Green"
                    Foreground="White"
                    Height="25"
                    Width="75"/>
    </Border>
</Grid>

Code Behind

public partial class MonthViewDayColumnHeader : UserControl
{
    #region DP DayName
    public static readonly DependencyProperty DayNameCaptionProperty =
        DependencyProperty.Register("DayNameCaption",
            typeof(string),
            typeof(MonthViewDayColumnHeader),
            new PropertyMetadata("Today", 
            new PropertyChangedCallback(OnDayNameCaptionChanged), 
            new CoerceValueCallback(CoerceDayNameCaption)));

    public string DayNameCaption
    {
        get { return (string)GetValue(DayNameCaptionProperty); }
        set { SetValue(DayNameCaptionProperty, value); }
    }

    private static void OnDayNameCaptionChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        MonthViewDayColumnHeader control = (MonthViewDayColumnHeader)d;
        var dayNameCaption = control.DayNameCaption;  // dayNameCaption is null
    }

    private static object CoerceDayNameCaption(DependencyObject d, object value)
    {
        MonthViewDayColumnHeader control = (MonthViewDayColumnHeader)d;
        var dayNameCaption = control.DayNameCaption;   // dayNameCaption is 'Today', the default value
        return null;
    }
    #endregion

    #region CTOR
    public MonthViewDayColumnHeader()
    {
        InitializeComponent();

        this.DataContext = this;
    }
    #endregion
}

Usage:

<Grid>
    <schedule:MonthViewDayColumnHeader DayNameCaption="Monday" 
                                        Height="50"
                                        Width="120"/>
</Grid>

The text "Monday" doesn't show up.

WTF IS WRONG HERE!!!!

If it's not broken, fix it until it is

Gerry Schmitz27-Jul-16 15:44

Gerry Schmitz

27-Jul-16 15:44

Over-engineering.

Kevin Marois27-Jul-16 16:38

27-Jul-16 16:38

Thanks for your thoughtful response. That fixed it.

If it's not broken, fix it until it is

PureNsanity28-Jul-16 12:50

PureNsanity

28-Jul-16 12:50

The reason why it's not working is the MonthViewDayColumnHeader class doesn't support INotifyPropertyChanged. It's being initialized, then updated with Monday after. If you take the existing and default it to 'Sunday' you should be able to see the default value.

On that note, I know it's an example but you should probably start off with MVVM in your learning process. Have the underlying layers implement the INotifyPropertyChanged and set the context to an appropriate view model.

Kevin Marois28-Jul-16 13:29

28-Jul-16 13:29

Actually, it wasn't working because I'm a dumba$$...

private static object CoerceDayNameCaption(DependencyObject d, object value)
    {
        MonthViewDayColumnHeader control = (MonthViewDayColumnHeader)d;
        var dayNameCaption = control.DayNameCaption;value
        return null;   //<=== ALWAYS RETURNS NULL
    }

changed it to

private static object CoerceDayNameCaption(DependencyObject d, object value)
    {
        MonthViewDayColumnHeader control = (MonthViewDayColumnHeader)d;
        var dayNameCaption = control.DayNameCaption;value
        return dayNameCaption ;   //<=== NOW IT WORKS
    }

If it's not broken, fix it until it is

PureNsanity28-Jul-16 13:51

PureNsanity

28-Jul-16 13:51

Yes and no. You shouldn't be using a callback in this case. The callback is circumventing the whole point of the binding. Taking my advice would fix it the appropriate way.

Kevin Marois28-Jul-16 14:14

28-Jul-16 14:14

Well, actually, I put in the callback for testing and ended up breaking my code Poke tongue | ;-P

If it's not broken, fix it until it is

Richard Deeming29-Jul-16 2:11

Richard Deeming

29-Jul-16 2:11

I assume the rogue ;value is just a typo in your message?

var dayNameCaption = control.DayNameCaption;value // <-- This won't compile.

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Richard Deeming29-Jul-16 2:12

Richard Deeming

29-Jul-16 2:12

You don't need to implement INotifyPropertyChanged when you're using dependency properties.
DependencyProperties or INotifyPropertyChanged ?[^]

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

PureNsanity29-Jul-16 3:47

PureNsanity

29-Jul-16 3:47

Yes, you're correct. For some reason I was thinking the underlying source still need to be explicitly hooked, but it does not.

Scrolling data table area on a XAML page

Meshack Musundi2-Aug-16 22:33

Meshack Musundi

2-Aug-16 22:33

It should be,

XML

<TextBlock Text="{Binding DayNameCaption, RelativeSource={RelativeSource FindAncestor, AncestorType={UserControl}}}"... />

You don't need the callback.

"As beings of finite lifespan, our contributions to the sum of human knowledge is one of the greatest endeavors we can undertake and one of the defining characteristics of humanity itself"

Stephen Holdorf26-Jul-16 13:41

Re: Scrolling data table area on a XAML page

26-Jul-16 13:41

I have been trying for several days to come up with a solution for the my application page. My page contains an upper section with a menu, page header, and two columns for a human head silhouette image and empty white section. That section works fine. What I have been trying to add to my page are two DataGrids side by side so it will create a single table of a total of four columns. Now on each DataGrid the first column is a Description and the second column is the Value it displayed for the Description. What I am trying to do is have a table on the page that appears to make up a single table with 17 rows of Description/values. I don't want either DataGrid to have a scroll bar and each not to be able to scroll. In some of the DataGrid cell a want a background color of blue. Now on the page this table is in a DockPanel with a height of 368 units. What I want is the DockPanel to have a scroll bar so both DataGrids can be scrolled up and down as a single table. First, I have found the it is almost impossible to change the background of a DataGrid Column's Cell. Next my DockPanel scroll bar does not appear and each of the DataGrids are still able to scroll. Below is both the XAML and the code behind. I am only showing 8 rows for testing. If anyone can help that would be great.

Page XAML

HTML

  <ScrollViewer Height="368" Width="900" VerticalScrollBarVisibility="Auto">
     <DockPanel Background="White" Height="368" VerticalAlignment="Top">
         <DataGrid Name="main1" ScrollViewer.CanContentScroll="False" AutoGenerateColumns="False" BorderBrush="White" DockPanel.Dock="Left" HorizontalAlignment="Left" Width="495" >
             <DataGrid.Columns>
                 <DataGridTextColumn FontSize="14" FontWeight="Bold" Header="Test Description" Binding="{Binding Description }" />
                 <DataGridTextColumn FontSize="14" FontWeight="Bold"  Binding="{Binding Value}" />
             </DataGrid.Columns>
        </DataGrid>
         <DataGrid Name="main1" ScrollViewer.CanContentScroll="False" AutoGenerateColumns="False" BorderBrush="White" DockPanel.Dock="Left" HorizontalAlignment="Left" Width="495" >
             <DataGrid.Columns>
                 <DataGridTextColumn FontSize="14" FontWeight="Bold" Header="Test Description" Binding="{Binding Description }" />
                 <DataGridTextColumn FontSize="14" FontWeight="Bold"  Binding="{Binding Value}" />
             </DataGrid.Columns>
        </DataGrid>
    </DockPanel>
</ScrollViewer>

Code behind:

List<InformationValues> InformationValuess = new List<InformationValues>();
List<InformationValues> InformationValuess2 = new List<InformationValues>();
List<InformationValues> InformationValuess3 = new List<InformationValues>();
List<InformationValues> InformationValuess4 = new List<InformationValues>();

InformationValuess.Add(new InformationValues() { Description = "Test Description1", Value = "Test Value1" });
InformationValuess.Add(new InformationValues() { Description = "Test Description2", Value = "Test Value2" });
InformationValuess.Add(new InformationValues() { Description = "Test Description3", Value = "Test Value3" });
InformationValuess.Add(new InformationValues() { Description = "Test Description4", Value = "Test Value4" });

InformationValuess2.Add(new InformationValues() { Description = "Test Description1", Value = "Test Value1" });
InformationValuess2.Add(new InformationValues() { Description = "Test Description2", Value = "Test Value2" });
InformationValuess2.Add(new InformationValues() { Description = "Test Description3", Value = "Test Value3" });
InformationValuess2.Add(new InformationValues() { Description = "Test Description4", Value = "Test Value4" });

InformationValuess3.Add(new InformationValues() { Description = "Test Description1", Value = "Test Value1" });
InformationValuess3.Add(new InformationValues() { Description = "Test Description2", Value = "Test Value2" });
InformationValuess3.Add(new InformationValues() { Description = "Test Description3", Value = "Test Value3" });
InformationValuess3.Add(new InformationValues() { Description = "Test Description4", Value = "Test Value4" });

InformationValuess4.Add(new InformationValues() { Description = "Test Description1", Value = "Test Value1" });
InformationValuess4.Add(new InformationValues() { Description = "Test Description2", Value = "Test Value2" });
InformationValuess4.Add(new InformationValues() { Description = "Test Description3", Value = "Test Value3" });
InformationValuess4.Add(new InformationValues() { Description = "Test Description4", Value = "Test Value4" });



main1.ItemsSource = InformationValuess;
main2.ItemsSource = InformationValuess2;

Mycroft Holmes26-Jul-16 14:32

Mycroft Holmes

26-Jul-16 14:32

Change your datasource to a single collection and use a datagrid.
Create a model to meet your view requirements either in the VM or code behind. It should probably have 4 properties for display and 2 object properties to have the underlying data object if you need to do any additional processing when the user interacts with the selected value.

Bind the single collection to a datagrid and forget your scrollviewer.

See if the datagrid supports a CellStyleSelector (I use Telerik tools and they have this concept). I'm pretty sure there are some implementations for the standard tooling out there.

Never underestimate the power of human stupidity
RAH

Re: Scrolling data table area on a XAML page

Stephen Holdorf27-Jul-16 0:31