protected virtual void OnPaint()

in source/SkiaSharp.Views/SkiaSharp.Views.WPF/SKGLElement.cs [117:181]
45 lines of code
9 McCabe index (conditional complexity)

		protected virtual void OnPaint(TimeSpan e)
		{
			if (disposed)
			{
				return;
			}
			if (designMode)
			{
				return;
			}

			// create the contexts if not done already
			if (grContext == null)
			{
				var glInterface = GRGlInterface.Create();
				grContext = GRContext.CreateGl(glInterface);
			}

			// get the new surface size
			var newSize = GetSize();

			GL.ClearColor(Color4.Transparent);
			GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit | ClearBufferMask.StencilBufferBit);

			// manage the drawing surface
			if (renderTarget == null || lastSize != newSize || !renderTarget.IsValid)
			{

				// create or update the dimensions
				lastSize = newSize;

				GL.GetInteger(GetPName.FramebufferBinding, out var framebuffer);
				GL.GetInteger(GetPName.StencilBits, out var stencil);
				GL.GetInteger(GetPName.Samples, out var samples);
				var maxSamples = grContext.GetMaxSurfaceSampleCount(colorType);
				if (samples > maxSamples)
					samples = maxSamples;
				glInfo = new GRGlFramebufferInfo((uint)framebuffer, colorType.ToGlSizedFormat());

				// destroy the old surface
				surface?.Dispose();
				surface = null;
				canvas = null;

				// re-create the render target
				renderTarget?.Dispose();
				renderTarget = new GRBackendRenderTarget(newSize.Width, newSize.Height, samples, stencil, glInfo);
			}

			// create the surface
			if (surface == null)
			{
				surface = SKSurface.Create(grContext, renderTarget, surfaceOrigin, colorType);
				canvas = surface.Canvas;
			}

			using (new SKAutoCanvasRestore(canvas, true))
			{
				// start drawing
				OnPaintSurface(new SKPaintGLSurfaceEventArgs(surface, renderTarget, surfaceOrigin, colorType));
			}

			// update the control
			canvas.Flush();
		}