Why is 'StringFormat' malfunctioning?

About Data Type

If you are binding a string value to text property of TextBlock or TextBox, then append StringFormat, it will work.
For example:
Otherwise, let's say if there's a object value is bound to text, it won't work at all. In this situation, you need a Converter to solve.

Decimal Type

If you are binding a string value to text property and the StringFormat is like: {}{0:N0}(formatted number), it won't work either. This also won't work in c# code like string.Format("{0:n0}", value)(if value is astring)

Why does my UI text blurry after apply DropShadowEffect?

Solution 1: Separate Control which applied DropShadowEffect from your text Control.
Solution 2: Add RenderingBias="Quality" attribute to DropShadowEffect. See ref
Solution 3: DropShadowEffect may cause performance issue, try SystemDropShadowChrome instead:
- Add reference to project: PresentationFramework.Aero
- Add using: xmlns:dropShadow="clr-namespace:Microsoft.Windows.Themes;assembly=PresentationFramework.Aero"

How to debug codes in design mode?

Here are the steps to debug a control at design time:

Start a second instance of Visual Studio
Attach to the first instance(vs designer is called XDesProc.exe) from the Debug menu
In the second instance, open the source code of your control
Set breakpoints at appropriate locations
In the first VS instance, reload the designer

Note that this technique isn't limited to controls; you can also use it to debug VS extensions, or anything that executes within Visual Studio.

see ref

How to binding control events to commands

How to use async command execute

private async void MyCommandExecute()
{
    IsBusy = true;
    var models = await Task.Run(() =>
    {
        return GetDataFromServer();
    });
    IsBusy = false;
}

or in a better way, encapsulate DoWork method in ViewModelBase:

ViewModelBase.cs
rprc IsBusy;
public async void DoProgressAsync(Func workFunc, Action callbackAction)
{
    IsBusy = true;
    var result = await Task.Run(workFunc);
    callbackAction(result);
    IsBusy = false;
}

Events for Switch TextBlock to TextBox when mousedown

Here is fields and properties in the custom control we need: _isMouseDown; IsEditMode(dependency property)

public override void OnApplyTemplate()
{
    _textblock.PreviewMouseLeftButtonDown += delegate { _isMouseDown = true; };
    _textblockv.PreviewMouseLeftButtonUp += delegate {
        if(_isMouseDown) {
          IsEditMode = true;
          Keyboard.Focus(_textBox);
          _isMouseDown = false;
        }
    };
    _label.GotKeyboardFocus += delegate{
       //same as left button up
    };
    _textBox.LostKeyboardFocus += delegate {
        IsEditMode = false;
    };
}

Simple Loading Ellipse

Solid color style ProgressBar

for Indeterminate

for Determinate

Usage

**for 30 seconds pending progress

A little trick using rectangle by scale animation rather than ProgressBar with Timer:

AddSorted to List/Collection

/// 
/// Adds a new item with sorted by comparer in the collection.
/// 
public static void AddSorted(this IList list, T item, IComparer comparer = null)
{
    var comparerPara = comparer;

    if (comparerPara == null)
        comparerPara = Comparer.Default;

    int i = 0;
    while (i < list.Count && comparerPara.Compare(list[i], item) < 0)
    {
        i++;
    }

    //you may want to invoke this on UI thread if context is at background.
    list.Insert(i, item);
}

Then any model which has IComparable implemented will take effect in this extension method.

WPF Notes