图像被保存，但不会加载 [英] Image gets saved, but won't load
本文介绍了图像被保存，但不会加载的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我可以选择在我的应用程序中添加新客户。客户存储在DB中，其ID，名称和徽标。 Logo只是图像文件的字符串（如logo.png）
I have the option to add a new Customer in my application. The Customer is stored in the DB with its ID, Name, and Logo. Logo is just the string of the image file (like logo.png)
添加徽标似乎很好。当我选择一个图像时，它会显示在CustomerAddView中。
The adding of the logo seems fine. When I select an Image, it shows in the CustomerAddView.
添加Customer后，CustomerAddView窗口关闭。客户在数据库中创建，数据库中的徽标值很好。
刷新主窗口中的客户列表（CustomerListView）。另一个客户的徽标工作正常。但新客户的徽标（随AddView窗口添加）抛出此警告：
After adding the Customer, the CustomerAddView window closes. The Customer is created in the DB, the Logo value in the DB is fine.
The list of Customers in the main window is refreshed (CustomerListView). The other Customer's Logo's are working fine. But the new Customer's Logos (added with the AddView window) throw this warning:
System.Windows.Data Warning: 6 : 'DynamicValueConverter' converter failed to convert value '../../Media/Images/Logos/testlogo.png' (type 'String'); fallback value will be used, if available. BindingExpression:Path=Logo; DataItem='Customer_5A59789E69DE0B010CE32D4E23A696EDB09551158A85050E8CA80E51475D369B' (HashCode=45868004); target element is 'Image' (Name=''); target property is 'Source' (type 'ImageSource') IOException:'System.IO.IOException: Kan bron media/images/logos/testlogo.png niet vinden.
bij MS.Internal.AppModel.ResourcePart.GetStreamCore(FileMode mode, FileAccess access)
bij System.IO.Packaging.PackagePart.GetStream(FileMode mode, FileAccess access)
bij System.IO.Packaging.PackWebResponse.CachedResponse.GetResponseStream()
bij System.IO.Packaging.PackWebResponse.GetResponseStream()
bij System.IO.Packaging.PackWebResponse.get_ContentType()
bij System.Windows.Media.Imaging.BitmapDecoder.SetupDecoderFromUriOrStream(Uri uri, Stream stream, BitmapCacheOption cacheOption, Guid& clsId, Boolean& isOriginalWritable, Stream& uriStream, UnmanagedMemoryStream& unmanagedMemoryStream, SafeFileHandle& safeFilehandle)
bij System.Windows.Media.Imaging.BitmapDecoder.CreateFromUriOrStream(Uri baseUri, Uri uri, Stream stream, BitmapCreateOptions createOptions, BitmapCacheOption cacheOption, RequestCachePolicy uriCachePolicy, Boolean insertInDecoderCache)
bij System.Windows.Media.Imaging.BitmapFrame.CreateFromUriOrStream(Uri baseUri, Uri uri, Stream stream, BitmapCreateOptions createOptions, BitmapCacheOption cacheOption, RequestCachePolicy uriCachePolicy)
bij System.Windows.Media.ImageSourceConverter.ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, Object value)
bij MS.Internal.Data.DefaultValueConverter.ConvertHelper(Object o, Type destinationType, DependencyObject targetElement, CultureInfo culture, Boolean isForward)
bij MS.Internal.Data.TargetDefaultValueConverter.Convert(Object o, Type type, Object parameter, CultureInfo culture)
bij MS.Internal.Data.DynamicValueConverter.Convert(Object value, Type targetType, Object parameter, CultureInfo culture)
bij System.Windows.Data.BindingExpression.ConvertHelper(IValueConverter converter, Object value, Type targetType, Object parameter, CultureInfo culture)'
System.Windows.Data Error: 11 : Fallback value 'Default' (type 'String') cannot be converted for use in 'Source' (type 'ImageSource'). BindingExpression:Path=Logo; DataItem='Customer_5A59789E69DE0B010CE32D4E23A696EDB09551158A85050E8CA80E51475D369B' (HashCode=45868004); target element is 'Image' (Name=''); target property is 'Source' (type 'ImageSource') NullReferenceException:'System.NullReferenceException: De objectverwijzing is niet op een exemplaar van een object ingesteld.
bij System.Windows.Media.ImageSourceConverter.ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, Object value)
bij System.Windows.Data.BindingExpressionBase.ConvertValue(Object value, DependencyProperty dp, Exception& e)'
我想知道为什么我的徽标图片在文件资源管理器中，在指定文件夹，但不会显示在客户列表中。
我想知道为什么图像在通过Visual Studio的解决方案资源管理器添加时可以正常工作，但是当我添加时不起作用它们（到同一个文件夹）通过CustomerAddView（模型）。
以下是添加新客户的文件：
CustomerAddView：
Here's the files for adding a new Customer: CustomerAddView:
<Grid Margin="5">
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="auto" />
<ColumnDefinition Width="auto" />
<ColumnDefinition Width="100" />
<ColumnDefinition Width="100" />
</Grid.ColumnDefinitions>
<TextBlock Name="TBCustomerTitle" FontWeight="Bold">Customer name:</TextBlock>
<TextBlock Grid.Column="1" FontWeight="Bold" Margin="5,0">*</TextBlock>
<TextBox Name="TBCustomerData" Grid.Column="2" Grid.ColumnSpan="2"
Text="{Binding NewCustomer.Name, UpdateSourceTrigger=PropertyChanged}"></TextBox>
<TextBlock Grid.Row="1" FontWeight="Bold">Customer logo:</TextBlock>
<Image Grid.Row="1" Grid.Column="2" MaxHeight="100" MaxWidth="100"
Source="{Binding NewCustomerLogo, UpdateSourceTrigger=PropertyChanged}" />
<Button Grid.Row="1" Grid.Column="3" Content="Choose logo"
Command="{Binding SelectLogoCommand}"/>
<TextBlock Margin="0,10" Grid.Row="2" Grid.ColumnSpan="4">Fields marked with * are required fields.</TextBlock>
<Button Grid.Row="3" Grid.ColumnSpan="4" Margin="0,50,0,0"
Command="{Binding AddConfirmCommand}">Add this customer</Button>
</Grid>
CustomerAddViewModel：
CustomerAddViewModel:
class CustomerAddViewModel : INotifyPropertyChanged
{
private RelayCommand addConfirmCommand;
private RelayCommand selectLogoCommand;
Image customerLogo;
string logoDirectory = "../../Media/Images/Logos/";
DBCustomer dbCustomer = new DBCustomer();
#region Add Customer
public ICommand AddConfirmCommand
{
get { return addConfirmCommand ?? (addConfirmCommand = new RelayCommand(() => AddConfirmCustomer())); }
}
private void AddConfirmCustomer()
{
if(newCustomer.Logo != null)
{
customerLogo.Save(logoDirectory + newCustomer.Logo);
}
else
{
newCustomer.Logo = "Default.png";
}
if (!dbCustomer.Create(newCustomer))
{
return;
}
App.Messenger.NotifyColleagues("AddCustomerDone");
}
#endregion
#region Add logo
public ICommand SelectLogoCommand
{
get { return selectLogoCommand ?? (selectLogoCommand = new RelayCommand(() => SelectLogo())); }
}
private void SelectLogo()
{
OpenFileDialog chooseFile = new OpenFileDialog();
chooseFile.Title = "Select a logo";
chooseFile.Filter = "All supported graphics|*.jpg;*.jpeg;*.png|" +
"JPEG (*.jpg;*.jpeg)|*.jpg;*.jpeg|" +
"Portable Network Graphic (*.png)|*.png";
if(chooseFile.ShowDialog() == DialogResult.OK)
{
Stream reader = File.OpenRead(chooseFile.FileName);
customerLogo = System.Drawing.Image.FromStream((Stream)reader);
MemoryStream finalStream = new MemoryStream();
customerLogo.Save(finalStream, ImageFormat.Png);
// translate to image source
PngBitmapDecoder decoder = new PngBitmapDecoder(finalStream, BitmapCreateOptions.PreservePixelFormat,
BitmapCacheOption.Default);
NewCustomerLogo = decoder.Frames[0];
newCustomer.Logo = newCustomer.Name + ".png";
}
}
private ImageSource newCustomerLogo;
public ImageSource NewCustomerLogo
{
get
{
return newCustomerLogo;
}
set
{
newCustomerLogo = value;
OnPropertyChanged(new PropertyChangedEventArgs("NewCustomerLogo"));
}
}
#endregion
private Customer newCustomer = new Customer();
public Customer NewCustomer
{
get { return newCustomer; }
set { newCustomer = value; OnPropertyChanged(new PropertyChangedEventArgs("NewCustomer")); }
}
#region PropertyChanged
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(PropertyChangedEventArgs e)
{
if (PropertyChanged != null)
PropertyChanged(this, e);
}
#endregion
}
CustomerListView
CustomerListView
<ListBox.ItemTemplate>
<!-- This DataTemplate is used for every Customer object in the ListBox.-->
<DataTemplate>
<Border BorderThickness="2" BorderBrush="Black"
Padding="10" Margin="10"
Name="CustomerBorder">
<Grid Name="ItemGrid">
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="100" />
<ColumnDefinition Width="100" />
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<!-- Logo picture -->
<Image Grid.Row="0" Grid.Column="0" Grid.RowSpan="3" HorizontalAlignment="Center"
Source="{helpers:ConcatString FrontString=../../Media/Images/Logos/, BindTo={Binding Path=Logo, FallbackValue=Default}}"
Height="{Binding ActualHeight, ElementName=ItemGrid}"/>
<!-- Customer name Row-->
<TextBlock Grid.Row="0" Grid.Column="1" Margin="10,0,8,0" FontWeight="Bold"
Name="CustomerTitle">
Customer:
</TextBlock>
<TextBlock Grid.Row="0" Grid.Column="2"
Name="CustomerDataType"
Text="{Binding Path=Name}">
</TextBlock>
<!-- Environment name Row-->
<TextBlock Grid.Row="1" Grid.Column="1" Margin="10,0,8,0" FontWeight="Bold" />
<TextBlock Grid.Row="2" Grid.Column="1" Margin="10,0,8,0" FontWeight="Bold" />
</Grid>
</Border>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
编辑：
此屏幕截图可能会删除一些点亮我的困惑。
我通过CustomerAddView（Model）添加了testlogo.png，另外3个是在VS Solution Explorer中添加的。
如您所见：
This screenshot might shed some light on my confusion.
I added the testlogo.png via the CustomerAddView(Model), the other 3 were added right in VS Solution Explorer.
As you can see:
- 徽标都在同一目录中。
- VS解决方案资源管理器中仅显示通过VS解决方案资源管理器添加的徽标。新的不会。
- 新徽标未显示在CustomerListView中。其他人呢。
编辑2：
保存图片可能是个更好的主意到数据库而不是将文件名保存为数据库中的字符串？
EDIT 2:
Is it maybe a better idea to save the image to the database instead of saving the file name as a string in the database?
推荐答案
MSDN 说：
要访问存储在应用程序包中的文件，但是从代码
中没有推断的root权限，请指定ms-appx：
方案。
To access files stored inside the application package, but from code where there is no inferred root authority, specify the ms-appx: scheme.
var uri = new System.Uri("ms-appx:///images/logo.png");
这篇关于图像被保存，但不会加载的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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