[英]The most appropriate bitmap class for the model
I am writing a simple WPF application using MVVM.我正在使用 MVVM 编写一个简单的 WPF 应用程序。 What is the most convenient class to retrieve bitmaps from models and further data binding: Bitmap, BitmapImage, BitmapSource?从模型中检索位图和进一步数据绑定最方便的 class 是什么:Bitmap、BitmapImage、BitmapSource?
public class Student
{
public <type?> Photo
{
get;
}
}
Or maybe I can somehow convert Bitmap to BitmapSource using ViewModel?或者,也许我可以使用 ViewModel 以某种方式将 Bitmap 转换为 BitmapSource?
I always use BitmapImage
, it's quite specialized and offers nice properties and events that might be useful (eg IsDownloading
, DownloadProgress
& DownloadCompleted
).我总是使用BitmapImage
,它非常专业,并提供了可能有用的好属性和事件(例如IsDownloading
、 DownloadProgress
和DownloadCompleted
)。
I suppose the more flexible way is to return photo (or any other bitmap) as a stream.我想更灵活的方法是将照片(或任何其他位图)作为 stream 返回。 Furthermore, if the photo has been changed, the model should fire the photo changed event and the client should handle the photo changed event to retrieve a new one photo.此外,如果照片已更改,model 应触发照片更改事件,客户端应处理照片更改事件以检索新照片。
public class PhotoChangedEventArgs : EventArgs
{
}
public class Student
{
public Stream GetPhoto()
{
// Implementation.
}
public event EventHandler<PhotoChangedEventArgs> OnPhotoChanged;
}
public class StudentViewModel : ViewModelBase
{
// INPC has skipped for clarity.
public Student Model
{
get;
private set;
}
public BitmapSource Photo
{
get
{
BitmapImage image = new BitmapImage();
image.BeginInit();
image.StreamSource = Model.Photo;
image.EndInit();
image.Freeze();
return image;
}
}
public StudentViewModel(Student student)
{
Model = student;
// Set event handler for OnPhotoChanged event.
Model.OnPhotoChanged += HandlePhotoChange;
}
void HandlePhotoChange(object sender, PhotoChangedEventArgs e)
{
// Force data binding to refresh photo.
RaisePropertyChanged("Photo");
}
}
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