WPF DataTemplate性能 [英] WPF DataTemplate performance

问题描述

这里的问题是，如果您为一个对象类型拥有一个DataTemplate，则每次存在该对象时，都会创建一个DataTemplate，听起来很正确.

Well the problem here is that if you have one DataTemplate for a type of object, each time the object is present, the DataTemplate will be created, that sounds about right.

我的问题是我们的DataTemplate太重了，使用该DataTemplate的应用可能有大约1000个对象.

My problem is that our DataTemplate is sort of heavy AND the app could have around 1000 objects using that DataTemplate.

我创建了一个简单的示例，其中创建了5个Person对象，并将它们绑定到ListView. Person对象的DataTemplate是带有标签的Grid和带有2个MenuItems的ContextMenu.为了简单起见，我只想专注于MenuItems.使用内存分析器，我可以看到总共有10个MenuItem对象(每人2个，5人* 2 MenuItem = 10 MenuItem)，我想知道是否有避免这种情况的方法.说，每个Person对象应该共享相同的MenuItem引用，以避免每次创建一个人时都重复DataTemplate.

I created a simplistic example where I created 5 Person objects and I bind them to a ListView. The DataTemplate for the Person object is a Grid with a Label and a ContextMenu with 2 MenuItems. For simplicity I just want to concentrate in the MenuItems. Using a memory profiler, I can see that there are a total of 10 MenuItem objects (2 per Person, 5 Person * 2 MenuItem = 10 MenuItem), and I want to know if there is a way to avoid this. Say, every Person object should share the same MenuItem reference, to avoid duplicating the DataTemplate each time a person is created.

这些是内存分析器中的结果.

These are the results in the memory profiler.

谢谢！

这是我的代码:

C#

using System.Collections.Generic;
using System.Windows;

namespace MenuItemsTest
{
    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();

            this.DataContext = new List<Person>()
            {
                new Person("Jim Morrison"),
                new Person("Jimmy Page"),
                new Person("Jimmy Hendrix"),
                new Person("Janis Joplin"),
                new Person("Peter Frampton")
            };
        }
    }

    public class Person
    {
        public string Name { get; set; }

        public Person(string name)
        {
            this.Name = name;
        }
    }
}

XAML:

<Window x:Class="MenuItemsTest.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:MenuItemsTest"
    Title="Window1" Height="300" Width="300">
    <Window.Resources>
        <DataTemplate DataType="{x:Type local:Person}">
            <Grid>
                <Grid.ContextMenu>
                    <ContextMenu>
                        <MenuItem Header="Select" />
                        <MenuItem Header="Deselect" />
                    </ContextMenu>
                </Grid.ContextMenu>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*" />
                </Grid.ColumnDefinitions>
                <Label Content="{Binding Name}" />
            </Grid>
        </DataTemplate>
    </Window.Resources>
    <Grid>
        <ListView ItemsSource="{Binding}" />
    </Grid>
</Window>

推荐答案

使用DataTemplates是可行的方法，但是如果只说20个在屏幕上可见，您不希望所有实例都被实例化:

DataTemplates are the way to go but you don't want all of them instansiated if only say 20 are visible on screen:

尝试虚拟化Stackpanel.如果不需要列表视图功能，请选择ListBox.控制更简单=>更好的性能.

Try virtualizing stackpanel. If you don't need the list view functionality opt for ListBox. Simpler control => better performance.

非常重要的一点是，不要让ListView维度不受限制(即，不要在其周围设置滚动查看器)，因为即使使用虚拟化堆栈面板，这也会实例化所有数据模板.

It's very important that you don't let ListView dimension get unbounded (ie don't set a scrollviewer around it) as that will instansiate all data templates even if you use virtualizing stackpanel.

  <ListView 
     ScrollViewer.HorizontalScrollBarVisibility="Disabled"
     ScrollViewer.VerticalScrollBarVisibility="Auto"
     VirtualizingStackPanel.IsVirtualizing="True"
     VirtualizingStackPanel.VirtualizationMode="Standard" 
     ItemsSource="{Binding}"
     />

这篇关于WPF DataTemplate性能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！