发表新帖
发表新帖

How to paginate an ObservableCollection?

前端 未结
关注
1 1724
-上瘾入骨i
-上瘾入骨i 2021-01-03 06:26

I have a ListBox with way too many items in it and the UI is getting slower and slower (virtualization is on, etc). So I was thinking about displaying only the first 20 item

1条回答
  • 不知归路
    不知归路 (楼主)
    2021-01-03 07:01

    This facility is not directly available in the base ObservableCollecton class. You can extend the ObservableCollection and create a custom Collection which does this. You need to hide the original Collection inside this new class and based on a FromIndex and ToIndex give dynamically add the range of items to the class. Override InsertItem and RemoveItem. I am giving a not-tested version bellow. But please take this as just pseudo code.

     //This class represents a single Page collection, but have the entire items available in the originalCollection
public class PaginatedObservableCollection : ObservableCollection
{
    private ObservableCollection originalCollection;

    public int CurrentPage { get; set; }
    public int CountPerPage { get; set; }

    protected override void InsertItem(int index, object item)
    {
        //Check if the Index is with in the current Page then add to the collection as bellow. And add to the originalCollection also
        base.InsertItem(index, item);
    }

    protected override void RemoveItem(int index)
    {
        //Check if the Index is with in the current Page range then remove from the collection as bellow. And remove from the originalCollection also
        base.RemoveItem(index);
    }
}



    UPDATE: I have a blog post about this topic on here - http://jobijoy.blogspot.com/2008/12/paginated-observablecollection.html and the source code is uploaded to Codeplex.
    
    
    
             
    
                                                        
    
            
            
    
              
                
                0
              
                   
                
               讨论(0)
              
                                                  
              
              
    
                          
             
       
          
              
    
                                    
    
                         
          
                              			
        
        
        
    
          
    
            
            
    
              
              
    
            
    


                                 
              
    
            
    
                          
    

        
         
    
                
                
    
                  
                
    
                
    
                   看不清?
                
    
              
    
                                  
    
                    
   
                 
             
              
    提交回复
    
            
    
          
    
        
    
      
       
      
    
    
    
          
 
     
 
    
        
    热议问题