背景
帧率是啥意思：Frame Person Seconds 每秒帧数。用白话讲就是--单位时间内画面刷新了多少次。
Avalonia打开开发者调试工具(快捷键F12)，顶部菜单选择 overlays 勾选 FPS可以看到帧率：
怎么在WPF中显示帧率呢？
参考两篇文章：
如何：使用 CompositionTarget 以每帧间隔呈现
[WPF] 使用Silk.NET绘制D3D9或OpenGL内容并完美解决空域问题
实现
CompositionTarget这个静态类，提供了一个事件：Rendering，每当WPF要绘制一帧前都会引发一下这个事件。
那么计算公式如下：
实现代码如下：
using System.Windows;
using System.Windows.Input;
using System.Windows.Media;namespace WpfApp1
{/// <summary>/// Interaction logic for MainWindow.xaml/// </summary>public partial class MainWindow : Window{public MainWindow(){InitializeComponent();CompositionTarget.Rendering += CompositionTarget_Rendering;this.MouseMove += MainWindow_MouseMove;}private TimeSpan _lastRenderTime;private List<int> _fpsSample = new List<int>();private void CompositionTarget_Rendering(object sender, EventArgs e){RenderingEventArgs args = (RenderingEventArgs)e;if (_lastRenderTime != args.RenderingTime){_fpsSample.Add(Convert.ToInt32(1000.0d / (args.RenderingTime.TotalMilliseconds - _lastRenderTime.TotalMilliseconds)));if (_fpsSample.Count == 30){var fps = Convert.ToInt32(_fpsSample.Average());framwPerSecondsLabel.Content = $"FPS: {fps}";_fpsSample.Clear();}_lastRenderTime = args.RenderingTime;}}private void MainWindow_MouseMove(object sender, MouseEventArgs e){var point=e.GetPosition(this);this.Background= new SolidColorBrush(Color.FromArgb(255, (byte)point.X, (byte)point.Y, 100));}}
}
界面代码
<Windowx:Class="WpfApp1.MainWindow"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"xmlns:d="http://schemas.microsoft.com/expression/blend/2008"xmlns:local="clr-namespace:WpfApp1"xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"Title="MainWindow"Width="800"Height="450"mc:Ignorable="d"><StackPanel x:Name="panelCtrl"><Labelx:Name="framwPerSecondsLabel"Height="32"HorizontalContentAlignment="Center"VerticalContentAlignment="Center"FontSize="18"Foreground="Red" /></StackPanel>
</Window>运行效果
WPF和Aalonia上限貌似都是：一秒60帧(FPS:60)