WPF: What is the best way to achieve continuous rendering? #16

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1. swharden commented on Jun 24, 2022

   

   swharden

   on Jun 24, 2022

   Last edited by swharden

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   Hi @trmcnealy,

   Thanks for this suggestion! I'm not very familiar with the pros and cons of using CompositionTarget.Rendering vs a timer for drawing graphics. A quick search advises timers are superior for limiting frame rate or implementing physics simulations where models should progress at a standard rate. This may favor the use of timers since many of the other projects on https://swharden.com/csdv/ (e.g., boids) would benefit from a constant speed.

   EDIT: A more extensive search reveals some people recommend the opposite!

   This discussion is worth including on the page though, so I'll create a new page comparing/contrasting these methods and link to it from all the relevant WPF pages.

   Note that the web page being referenced is

   • https://swharden.com/csdv/maui.graphics/quickstart-wpf/

   which references project code that lives here:

   Csharp-Data-Visualization/projects/maui-graphics/QuickstartWpf/MainWindow.xaml.cs

   Lines 9 to 43 in 0c7683d

   	public partial class MainWindow : Window
   	{
   	readonly DispatcherTimer Timer1 = new();
   	public MainWindow()
   	{
   	InitializeComponent();
   	Timer1.Interval = System.TimeSpan.FromMilliseconds(10);
   	Timer1.Tick += Timer1_Tick;
   	}
   	private void SKElement_PaintSurface(object sender, SkiaSharp.Views.Desktop.SKPaintSurfaceEventArgs e)
   	{
   	ICanvas canvas = new SkiaCanvas() { Canvas = e.Surface.Canvas };
   	canvas.FillColor = Colors.Navy;
   	canvas.FillRectangle(0, 0, (float)SkElement1.ActualWidth, (float)SkElement1.ActualHeight);
   	canvas.StrokeColor = Colors.White.WithAlpha(.5f);
   	canvas.StrokeSize = 2;
   	for (int i = 0; i < 100; i++)
   	{
   	float x = Random.Shared.Next((int)SkElement1.ActualWidth);
   	float y = Random.Shared.Next((int)SkElement1.ActualHeight);
   	float r = Random.Shared.Next(5, 50);
   	canvas.DrawCircle(x, y, r);
   	}
   	}
   	private void SKElement_SizeChanged(object sender, SizeChangedEventArgs e) => SkElement1.InvalidateVisual();
   	private void Button_Click(object sender, RoutedEventArgs e) => SkElement1.InvalidateVisual();
   	private void Timer1_Tick(object? sender, System.EventArgs e) => SkElement1.InvalidateVisual();
   	private void Checkbox1_Checked(object sender, RoutedEventArgs e) => Timer1.Start();
   	private void Checkbox1_Unchecked(object sender, RoutedEventArgs e) => Timer1.Stop();
   	}

   It sounds like CompositionTarget.Rendering is an event that fires at the rate of vsync (usually 60 Hz) and this topic is discussed on several pages:

   • https://docs.microsoft.com/en-us/dotnet/api/system.windows.media.compositiontarget.rendering?redirectedfrom=MSDN&view=windowsdesktop-6.0
   • https://docs.microsoft.com/en-us/dotnet/desktop/wpf/graphics-multimedia/how-to-render-on-a-per-frame-interval-using-compositiontarget?redirectedfrom=MSDN&view=netframeworkdesktop-4.8
   • https://docs.microsoft.com/en-us/dotnet/desktop/wpf/advanced/graphics-rendering-tiers?view=netframeworkdesktop-4.8
   • https://stackoverflow.com/questions/18353225/what-can-i-do-inside-compositiontarget-rendering
   • https://stackoverflow.com/questions/23854176/wpf-rendering-real-time-best-practice
   • https://stackoverflow.com/questions/58367035/compositiontarget-rendering-lag
   • https://evanl.wordpress.com/2009/12/06/efficient-optimal-per-frame-eventing-in-wpf/
   • https://stackoverflow.com/questions/16991949/how-to-make-a-render-loop-in-wpf
   • https://stackoverflow.com/questions/8713864/high-performance-graphics-using-the-wpf-visual-layer/
   • https://stackoverflow.com/questions/7733990/constant-framerate-in-wpf-for-game
   • https://stackoverflow.com/questions/5812384/why-is-frame-rate-in-wpf-irregular-and-not-limited-to-monitor-refresh
2. swharden

   changed the title [-][Suggestion] (projects\maui-graphics\QuickstartWpf)[/-] [+]WPF: What is the best way to achieve continuous rendering?[/+] on Jun 24, 2022