label and textblock stringformat

mzy666888 commented 4 years ago

.NET Core Version:.net core 3.1
Windows version: 1909 Does the bug reproduce also in WPF for .NET Framework 4.8?: unknown
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Problem description: in .net core wpf ,I use Label and TextBlock like:
```
<Label
    HorizontalAlignment="Center"
   VerticalAlignment="Center"
    Content="{Binding Three, StringFormat={}{0:F1}}"
   FontSize="36"
   Foreground="White">
</Label>
```



 **Actual behavior:** <!-- callstack for crashes / exceptions -->
if Three and Four value :3
Lable output:  3
TextBlock output: 3.0

why appear this case?

 **Expected behavior:**

 **Minimal repro:**

lindexi commented 4 years ago

@mzy666888 Here is my demo and I find not only the Lable but also the Button has the same behavior.

    <StackPanel>
        <Button Width="100" Height="100" Content="{Binding Three, StringFormat={}{0:F2}}" />
        <Label HorizontalAlignment="Center"
            VerticalAlignment="Center"
            FontSize="36" Content="{Binding Three, StringFormat={}{0:F1}}" />

        <Label HorizontalAlignment="Center"
            VerticalAlignment="Center"
            FontSize="36">
            <Label.Content>
                <TextBlock Text="{Binding Three, StringFormat={}{0:F1}}" />
            </Label.Content>
        </Label>

        <TextBlock
            HorizontalAlignment="Center"
            VerticalAlignment="Center"
            FontSize="36"
            Text="{Binding Four, StringFormat={}{0:F1}}" />
    </StackPanel>

    public MainWindow()
    {
        InitializeComponent();

        Three = 3.0;
        Four = 3.0;

        DataContext = this;
    }

    public static readonly DependencyProperty FourProperty = DependencyProperty.Register(
        "Four", typeof(double), typeof(MainWindow), new PropertyMetadata(default(double)));

    public double Four
    {
        get { return (double) GetValue(FourProperty); }
        set { SetValue(FourProperty, value); }
    }

    public static readonly DependencyProperty ThreeProperty = DependencyProperty.Register(
        "Three", typeof(double), typeof(MainWindow), new PropertyMetadata(default(double)));

    public double Three
    {
        get { return (double) GetValue(ThreeProperty); }
        set { SetValue(ThreeProperty, value); }
    }

lindexi commented 4 years ago

And I add the Trace to Label Content and find the code.

System.Windows.Data Warning: 56 : Created BindingExpression (hash=28278595) for Binding (hash=63993496)
System.Windows.Data Warning: 58 :   Path: 'Three'
System.Windows.Data Warning: 60 : BindingExpression (hash=28278595): Default mode resolved to OneWay
System.Windows.Data Warning: 61 : BindingExpression (hash=28278595): Default update trigger resolved to PropertyChanged
System.Windows.Data Warning: 62 : BindingExpression (hash=28278595): Attach to System.Windows.Controls.Label.Content (hash=36936550)
System.Windows.Data Warning: 67 : BindingExpression (hash=28278595): Resolving source 
System.Windows.Data Warning: 70 : BindingExpression (hash=28278595): Found data context element: Label (hash=36936550) (OK)
System.Windows.Data Warning: 71 : BindingExpression (hash=28278595): DataContext is null
System.Windows.Data Warning: 65 : BindingExpression (hash=28278595): Resolve source deferred
System.Windows.Data Warning: 67 : BindingExpression (hash=28278595): Resolving source 
System.Windows.Data Warning: 70 : BindingExpression (hash=28278595): Found data context element: Label (hash=36936550) (OK)
System.Windows.Data Warning: 78 : BindingExpression (hash=28278595): Activate with root item MainWindow (hash=62468121)
System.Windows.Data Warning: 107 : BindingExpression (hash=28278595):   At level 0 using cached accessor for MainWindow.Three: DependencyProperty(Three)
System.Windows.Data Warning: 104 : BindingExpression (hash=28278595): Replace item at level 0 with MainWindow (hash=62468121), using accessor DependencyProperty(Three)
System.Windows.Data Warning: 101 : BindingExpression (hash=28278595): GetValue at level 0 from MainWindow (hash=62468121) using DependencyProperty(Three): '3'
System.Windows.Data Warning: 80 : BindingExpression (hash=28278595): TransferValue - got raw value '3'
System.Windows.Data Warning: 89 : BindingExpression (hash=28278595): TransferValue - using final value '3'

And then I add the trace to TextBlock and find the code

System.Windows.Data Warning: 56 : Created BindingExpression (hash=11958757) for Binding (hash=12674872)
System.Windows.Data Warning: 58 :   Path: 'Three'
System.Windows.Data Warning: 60 : BindingExpression (hash=11958757): Default mode resolved to OneWay
System.Windows.Data Warning: 61 : BindingExpression (hash=11958757): Default update trigger resolved to PropertyChanged
System.Windows.Data Warning: 62 : BindingExpression (hash=11958757): Attach to System.Windows.Controls.TextBlock.Text (hash=8864859)
System.Windows.Data Warning: 67 : BindingExpression (hash=11958757): Resolving source 
System.Windows.Data Warning: 70 : BindingExpression (hash=11958757): Found data context element: TextBlock (hash=8864859) (OK)
System.Windows.Data Warning: 71 : BindingExpression (hash=11958757): DataContext is null
System.Windows.Data Warning: 65 : BindingExpression (hash=11958757): Resolve source deferred
System.Windows.Data Warning: 67 : BindingExpression (hash=11958757): Resolving source 
System.Windows.Data Warning: 70 : BindingExpression (hash=11958757): Found data context element: TextBlock (hash=8864859) (OK)
System.Windows.Data Warning: 78 : BindingExpression (hash=11958757): Activate with root item MainWindow (hash=62468121)
System.Windows.Data Warning: 107 : BindingExpression (hash=11958757):   At level 0 using cached accessor for MainWindow.Three: DependencyProperty(Three)
System.Windows.Data Warning: 104 : BindingExpression (hash=11958757): Replace item at level 0 with MainWindow (hash=62468121), using accessor DependencyProperty(Three)
System.Windows.Data Warning: 101 : BindingExpression (hash=11958757): GetValue at level 0 from MainWindow (hash=62468121) using DependencyProperty(Three): '23'
System.Windows.Data Warning: 80 : BindingExpression (hash=11958757): TransferValue - got raw value '23'
System.Windows.Data Warning: 84 : BindingExpression (hash=11958757): TransferValue - implicit converter produced '23.0'
System.Windows.Data Warning: 89 : BindingExpression (hash=11958757): TransferValue - using final value '23.0'

I find the TextBlock will use System.Windows.Data Warning: 84 : BindingExpression (hash=11958757): TransferValue - implicit converter produced '23.0' to convert '23' to '23.0' and I think it is why the Label Content show without the format code.

lindexi commented 4 years ago

And then I run with .NET Framework 4.7 and find the same behavior

miloush commented 4 years ago

Duplicate of #681 (This is by design, as Content is of type object and does not need a converter.)

dotnet / wpf

label and textblock stringformat #2699