自定义控件，绑定依赖属性
有时候需要绑定一个自定义的依赖属性，比如你有个Image控件，如果在默认的属性Source赋值设置某个url如：http://f.hiphotos.baidu.com/image/h%3D360/sign=f7030d1d1a178a82d13c79a6c602737f/6c224f4a20a446237cd252b39c22720e0df3d7c3.jpg
的时候不见得能显示这个图片，因为百度有防盗链措施，其实就是判断了请求的来源是否为百度自己的网站服务器，解决方法就是http请求的header 里的"Referer"设置为"http://www.baidu.com"
//也可这样去请求
// HttpWebRequest re = (HttpWebRequest)WebRequest.Create("http://f.hiphotos.baidu.com/image/h%3D360/sign=f7030d1d1a178a82d13c79a6c602737f/6c224f4a20a446237cd252b39c22720e0df3d7c3.jpg");
// re.Headers["Referer"]= "http://www.baidu.com";
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Media.Imaging;
using Windows.Storage.Streams;
using System.Runtime.InteropServices.WindowsRuntime;
namespace wgscd_test
{
public class ImageEx:UserControl
{
public ImageEx()
{
img = new Image();
Content = img;
}
Image img;
BitmapImage bmp;
//注册依赖属性
public static DependencyProperty UrlProperty = DependencyProperty.Register("Url",
typeof(string),
typeof(ImageEx),
new PropertyMetadata("默认属性值", OnUrlPropertyChanged));
//依赖属性对应的控件属性
public string Url
{
get { return (string)GetValue(UrlProperty); }
set { SetValue(UrlProperty, value); }
}
//依赖属性回掉函数（static）
private static void OnUrlPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
//这里MySilverButton是控件类名
var mySilverButton = d as ImageEx;
if (mySilverButton != null)
{
mySilverButton.PropertyChangedMethodFun(e);
}
}
bool loaded = false;
//属性变化回掉（通过静态函数调用，也可以在静态函数里写）
private async void PropertyChangedMethodFun(DependencyPropertyChangedEventArgs e)
{
// var bgTextBlock = GetTemplateChild("ButtonCaption") as TextBlock;
// if (bgTextBlock != null) bgTextBlock.Text = e.NewValue as string;
if (e.NewValue != e.OldValue && ""+e.NewValue!="") {
if (loaded) return;
loaded = true;
// await System.Threading.Tasks.Task.Delay(5000);
try {
HttpClient client = new HttpClient();
var bytes = await client.GetByteArrayAsync("" + e.NewValue);
IBuffer buffer = WindowsRuntimeBufferExtensions.AsBuffer(bytes, 0, bytes.Length);
//Ibuffer转IrandomAccessStream
InMemoryRandomAccessStream inStream = new InMemoryRandomAccessStream();
DataWriter datawriter = new DataWriter(inStream.GetOutputStreamAt(0));
datawriter.WriteBuffer(buffer, 0, buffer.Length);
await datawriter.StoreAsync();
// bmp = new BitmapImage(new Uri(""+e.NewValue ,UriKind.Absolute ));
// img.Source = bmp;
bmp = new BitmapImage();
bmp.SetSourceAsync(inStream);
img.Source = bmp;
}
catch { }
}
}
}}
这个自定义控件就可在设置 URL的时候自动去请求这个图片了！
例子里的HTTP请求可以改为你实际情况适合的方式 如 webclient ，HttpWebRequest 这种方式！
调用直接设置Url就是
如： 《UI:ImageEx Url ="{Binding url}" Width="222" Height="380"
注意 Url ="{Binding url} 就是绑定的图片地址数据
ObservableCollection ObservableObj = new ObservableCollection<object>();
ObservableObj.Add(new { url = "http://img1.mm131.com/pic/1918/1.jpg", Name = "帅1", Sex = "男", Age = 20 });
ObservableObj.Add(new { url = "http://img1.mm131.com/pic/1918/2.jpg", Name = "帅2", Sex = "女", Age = 60 });
ObservableObj.Add(new { url = "http://img1.mm131.com/pic/1918/3.jpg", Name = "帅3", Sex = "女", Age = 50 });
ObservableObj.Add(new { url = "http://img1.mm131.com/pic/1918/4.jpg", Name = "帅4", Sex = "女", Age = 40 });
ObservableObj.Add(new { url = "http://img1.mm131.com/pic/1918/5.jpg", Name = "帅5", Sex = "男", Age = 20 });
list2.ItemsSource = ObservableObj;