Animate Expander in WPF

Question

How to animate the expanded and collapsed actions of a Wpf expander control?

Answer 1

I created a style based on msdn Style and the point in this answer:

 


    #FFE8EDF9
    #FFC5CBF9
    #FF7381F9

    #FFE8EDF9
    #FFC5CBF9
    #FF888888

    #FFC5CBF9
    #FFDDDDDD

    White
    #FF7381F9
    #FF211AA9

    #FF3843C4
    #FF211AA9


    #FF444444
    sc#1, 0.004391443, 0.002428215, 0.242281124

    
    #FFCCCCCC
    #FF888888
    #FF444444

    #FF888888
    #FF444444

    #FFAAAAAA
    #FF888888

    Black

    
    #FFC5CBF9
    Black
    #FFC5CBF9

    #FF3843C4

    
        
        
        
    

    
        
            
                
                
                
                
            
        
    

    
        
            
                
                    
                    
                
            
            
                
                    
                        
                            
                            
                        
                    
                

            
            
                
                    
                    
                        
                            
                                
                            
                        
                    
                    
                        
                            
                                
                            
                        
                    
                    
                        
                            
                                
                            
                            
                                
                            
                        
                    
                
                
                    
                        
                            
                                
                            
                            
                                
                            
                        
                    
                    
                    
                
            
            
                
                    
                        
                    
                
                
                    
                        
                    
                
            
        
    

    

  
    
        
            
            
            
        
    

    
        
            
            
            
        
    
    
        
            
            
            
        
    

Which requires this converter:

public class MultiplyConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        return new GridLength((double)values[0] * (double)values[1], GridUnitType.Pixel);
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

The main point is to set DoubleAnimation on ContentRow.Height in the template. However, you need to use a MultiBinding to bind the To property of this animation.