[英]Image source changing in C# for windows phone 8.1 RT
I want to change image source in runtime using C#. 我想在运行时使用C#更改图像源。 I tried this.
我试过了
In the MainPage.xaml, 在MainPage.xaml中,
<Image x:Name="myImage" HorizontalAlignment="Left"
Height="125"
Margin="86,76,0,0"
VerticalAlignment="Top"
Width="220" />
<Button Content="Button"
HorizontalAlignment="Left"
Margin="134,230,0,0"
VerticalAlignment="Top"
Click="Button_Click"/>
and in the MainPage.xaml.cs 并在MainPage.xaml.cs中
private void Button_Click(object sender, RoutedEventArgs e)
{
myImage.Source = new BitmapImage(new Uri("/Assets/WorldCupFlags/Sri_Lanka.png", UriKind.Relative));
}
It shows no compile time error but when I run this and click the Button it shows an exception. 它没有显示编译时错误,但是当我运行它并单击Button时,它显示了异常。 It says "An exception of type 'System.ArgumentException' occurred in mscorlib.ni.dll but was not handled in user code."
它说:“ mscorlib.ni.dll中发生了'System.ArgumentException'类型的异常,但未在用户代码中处理。”
The hint is in the exception: 提示是例外:
The given System.Uri cannot be converted into a Windows.Foundation.Uri
给定的System.Uri无法转换为Windows.Foundation.Uri
You need to use an absolute URI for Universal XAML apps: 您需要为Universal XAML应用程序使用绝对URI:
myImage.Source = new BitmapImage(new Uri(
"ms-appx:///Assets/WorldCupFlags/Sri_Lanka.png", UriKind.Absolute));
Within an async code block, do this: 在异步代码块中,执行以下操作:
imgMyImageControl.Source = await GetBitmapAsFile("Folder\\ImageFileName.png");
The GetBimpageAsFile function: GetBimpageAsFile函数:
/// <summary>
/// Gets a bitmap image stored on the local file system
/// </summary>
/// <param name="strIFile">The input file path name</param>
/// <returns>The requested bitmap image, if successful; else, null</returns>
public static async Task<BitmapImage> GetBitmapAsFile(string strIFile)
{
try
{
StorageFile fOut = null;
BitmapImage biOut = null;
FileRandomAccessStream fasGet = null;
if (!strIFile.Equals(""))
{
fOut = await Windows.Storage.ApplicationData.Current.LocalFolder.GetFileAsync(strIFile);
if (fOut != null)
{
fasGet = (FileRandomAccessStream)await fOut.OpenAsync(FileAccessMode.Read);
if (fasGet != null)
{
biOut = new BitmapImage();
if (biOut != null)
{
await biOut.SetSourceAsync(fasGet);
return biOut;
}
else
YourApp.App.ShowMessage(true, "Error", "GetBitmapAsFile", "Bitmap [" + strIFile + "] is not set.");
}
else
YourApp.App.ShowMessage(true, "Error", "GetBitmapAsFile", "File stream [" + strIFile + "] is not set.");
}
}
else
YourApp.App.ShowMessage(true, "Error", "GetBitmapAsFile", "Input file path name is empty.");
}
catch (Exception ex)
{
YourApp.App.ShowMessage(true, "Error", "GetBitmapAsFile", "[" + strIFile + "] " + ex.Message);
}
return null;
}
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