WPF常用知识点

1. Xaml中添加后台代码

2. Binding中的显示更新到源或UI

   BindingExpression binding = tb.GetBindingExpression(TextBox. TextProperty);
   binding.UpdateSource();//将UI上的值更新到后台数据
   binding.UpdateTarget();//将后台数据更新到UI
   

3. **获取某一依赖属性的binding**
     `var binding= BindingOperations.GetBinding(tb, TextBox.TextProperty);`
4. **StringFormat使用**

 < TextBlock Text="{ Binding Source={ x:Static system: DateTime.Now },StringFormat= Date:{0 :MMdd}} " VerticalAlignment= "Top" Width="120"/>

没有特殊文本时，需要添加额外的大括号：StringFormat= {}{0 : MMdd}

5. **字符渲染**     http://www.wpf-tutorial.com/control-concepts/text-rendering/
  WPF中有两个属性是用来控制字符渲染的，分别为TextOptions.TextFormattingMode和TextOptions.TextRenderingMode,分别定义字符串如何转换及在控件级别渲染，一般不需要定义，根据实际情况处理

6. **BitmapToBitmapSource**

public BitmapSource ToBmpSrc(Bitmap bitmap)
{
var ms = new MemoryStream();
bitmap.Save(ms, ImageFormat.Bmp);
ms.Position = 0;
ms.Seek(0, SeekOrigin.Begin);
var bi = new BitmapImage();
bi.CacheOption = BitmapCacheOption.OnLoad;
bi.BeginInit();
bi.StreamSource = ms;
bi.EndInit();
return bi;
}

7. **碰撞测试**
可用于获取特定位置所有的可视控件或特定组件

    void PreTest()        
    {
        Point pt = Mouse .GetPosition(this);
        VisualTreeHelper.HitTest(this , OnFilter, OnResult, new PointHitTestParameters (pt));
    }

    /// <summary>
    /// filter some uielement
    /// </summary>
    /// <param name="o"></param>
    /// <returns></returns>
    private HitTestFilterBehavior OnFilter(DependencyObject o)
    {
        if (o is Border)
            return HitTestFilterBehavior .ContinueSkipSelf;
        return HitTestFilterBehavior .Continue;
    }

    private HitTestResultBehavior OnResult(HitTestResult o)
    {
        Console.WriteLine(o.VisualHit.ToString());
        return HitTestResultBehavior .Continue;
    }

8. **获取具有焦点的控件**
     FocusManager .GetFocusedElement(this)
9. **获取鼠标下面的元素**
     Mouse.DirectlyOver as UIElement
10. **WPF中右键菜单及Tooltip由InputManager控制，与鼠标右键点击的事件没有特定的关联关系**