深入C#（二）--Converter

Converter的使用

Converter<TInput, TOutput> Delegate

概述：Represents a method that converts an object from one type to another type.     

作用於泛型集合的類型轉換，主要是用於ConverAll函數

Demo:

using System;
using System.Drawing;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        List<PointF> lpf = new List<PointF>();

        lpf.Add(new PointF(27.8F, 32.62F));
        lpf.Add(new PointF(99.3F, 147.273F));
        lpf.Add(new PointF(7.5F, 1412.2F));

        Console.WriteLine();
        foreach( PointF p in lpf )
        {
            Console.WriteLine(p);
        }

        List<Point> lp = lpf.ConvertAll( 
            new Converter<PointF, Point>(PointFToPoint));

        Console.WriteLine();
        foreach( Point p in lp )
        {
            Console.WriteLine(p);
        }
    }

    public static Point PointFToPoint(PointF pf)
    {
        return new Point(((int) pf.X), ((int) pf.Y));
    }
}

/* This code example produces the following output:

{X=27.8, Y=32.62}
{X=99.3, Y=147.273}
{X=7.5, Y=1412.2}

{X=27,Y=32}
{X=99,Y=147}
{X=7,Y=1412}
 */

IValueConverter Interface

概述：Exposes methods that allow modifying the data as it passes through the binding engine.

     在Windows Phone開發時候，有些數據需要綁定，但是綁定時候格式或者類型需要改變。

可以用一個Converter實現IValueConvert接口，然後實現Convert方法和ConvertBack方法（主要是Convert就行）

MSDN:

http://msdn.microsoft.com/en-us/library/system.windows.data.ivalueconverter%28v=vs.95%29.aspx

Windows Phone Toolkit DateTime Converters:

http://www.windowsphonegeek.com/articles/Windows-Phone-Toolkit-DateTime-Converters

Useful Value Converters

http://compiledexperience.com/blog/posts/useful-calue-converters