如何存储从网络接收的图像，并在Windows Phone 7的应用程序中显示它 [英] how to store an image received from the web and display it in the windows phone 7 application

问题描述

我建设我的第一个应用程序在Windows Phone 7的应用程序。我有一个来自于网络，并单击图像当我导航到另一个页面的图像。
我的XAML代码是：

I am building my first app in windows phone 7 application. I have an image which comes from the web and when the image is clicked i am navigated to another page. My xaml code is:

 <Button Click="Image_Click" Name="image1" Margin="-33,-16,-26,-13">
            <Button.Background>
                <ImageBrush Stretch="Fill"  ImageSource = "http://political-leader.vzons.com/ArvindKejriwal/images/icons/landing.png"/>
            </Button.Background>
        </Button>

我的.cs代码是

My .cs code is

private void Image_Click(object sender, RoutedEventArgs e)
    {
        NavigationService.Navigate(new Uri("/AAP.xaml", UriKind.Relative));
    }

现在的问题是，我要存储图像，以便它可以即使观看而脱机。谁能帮我我应该做的修改，以达到这一目的。

Now the issue is that i want to store the image so that it can be even viewed while offline. Can anyone help me what modification should i do to for this purpose.

推荐答案

这是如何做到这一点的工作示例。其逻辑如下：

This is a working example on how to do that. The logic is as follow :

1. 在页面的构造函数，调用的LoadImage 方法。


2. 的方法（如果可用）将设置的ImageBrush的ImageSource的图像独立存储。


3. 如果图像不存在于独立存储，的LoadImage 方法从网络下载的图像，并调用事件处理程序时，下载完成。


4. 事件处理程序（ DownloadCompleted 方法），保存图片到独立存储和再次调用的LoadImage。参照点2为下发生什么。



1. In the page's constructor, call LoadImage method.
2. The method will set imageBrush's ImageSource to image in Isolated storage if available.
3. If the image not exists in Isolated storage, LoadImage method will download the image from web and call an event handler when download completed.
4. The event handler (DownloadCompleted method) will then, save the image to Isolated Storage and call LoadImage again. Refer to point 2 for what happen next.

您想在以后改进它来实现MVVM，并使用数据绑定。

You may want to improve it later to implement MVVM and using DataBinding.

参考文献：的 nickharris.net ，的 geekchamp.com

string imageName = "myImage.jpg";
string imageUrl = "http://political-leader.vzons.com/ArvindKejriwal/images/icons/landing.png";

public MainPage()
{
    InitializeComponent();
    LoadImage();
}

private void LoadImage()
{
    BitmapImage bi = new BitmapImage();
    using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
    {
        //load image from Isolated Storage if it already exist
        if (myIsolatedStorage.FileExists(imageName))
        {
            using (IsolatedStorageFileStream fileStream = myIsolatedStorage.OpenFile(imageName, FileMode.Open, FileAccess.Read))
            {
                bi.SetSource(fileStream);
                imageBrushName.ImageSource = bi;
            }
        }
        //else download image to Isolated Storage
        else
        {
            WebClient wc = new WebClient();
            wc.OpenReadCompleted += new OpenReadCompletedEventHandler(DownloadCompleted);
            wc.OpenReadAsync(new Uri(imageUrl, UriKind.Absolute), wc);
        }
    }
}

private void DownloadCompleted(object sender, OpenReadCompletedEventArgs e)
{
    if (e.Error == null && !e.Cancelled)
    {
        try
        {
            using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
            {
                IsolatedStorageFileStream fileStream = myIsolatedStorage.CreateFile(imageName);

                BitmapImage bitmap = new BitmapImage();
                bitmap.SetSource(e.Result);
                WriteableBitmap wb = new WriteableBitmap(bitmap);

                // Encode WriteableBitmap object to a JPEG stream.
                Extensions.SaveJpeg(wb, fileStream, wb.PixelWidth, wb.PixelHeight, 0, 85);
                fileStream.Close();
            }
            //after image saved to Iso storage, call LoadImage method again
            //so the method will set imageBrush's ImageSource to image in Iso storage
            LoadImage();
        }
        catch (Exception ex)
        {
            //Exception handle appropriately for your app  
        }
    }
    else
    {
        //Either cancelled or error handle appropriately for your app  
    }
}

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