private void InitializeDisplay()

in source/SkiaSharp.Views/SkiaSharp.Views.WinUI/GlesInterop/GlesContext.cs [155:244]
55 lines of code
8 McCabe index (conditional complexity)

		private void InitializeDisplay()
		{
			if (eglDisplay != Egl.EGL_NO_DISPLAY)
				return;

			int[] defaultDisplayAttributes = new[]
			{
				// These are the default display attributes, used to request ANGLE's D3D11 renderer.
				// eglInitialize will only succeed with these attributes if the hardware supports D3D11 Feature Level 10_0+.
				Egl.EGL_PLATFORM_ANGLE_TYPE_ANGLE, Egl.EGL_PLATFORM_ANGLE_TYPE_D3D11_ANGLE,

				// EGL_ANGLE_DISPLAY_ALLOW_RENDER_TO_BACK_BUFFER is an optimization that can have large performance benefits on mobile devices.
				// Its syntax is subject to change, though. Please update your Visual Studio templates if you experience compilation issues with it.
				Egl.EGL_EXPERIMENTAL_PRESENT_PATH_ANGLE, Egl.EGL_EXPERIMENTAL_PRESENT_PATH_FAST_ANGLE, 

				// EGL_PLATFORM_ANGLE_ENABLE_AUTOMATIC_TRIM_ANGLE is an option that enables ANGLE to automatically call 
				// the IDXGIDevice3::Trim method on behalf of the application when it gets suspended. 
				// Calling IDXGIDevice3::Trim when an application is suspended is a Windows Store application certification requirement.
				Egl.EGL_PLATFORM_ANGLE_ENABLE_AUTOMATIC_TRIM_ANGLE, Egl.EGL_TRUE,
				Egl.EGL_NONE,
			};

			int[] fl9_3DisplayAttributes = new[]
			{
				// These can be used to request ANGLE's D3D11 renderer, with D3D11 Feature Level 9_3.
				// These attributes are used if the call to eglInitialize fails with the default display attributes.
				Egl.EGL_PLATFORM_ANGLE_TYPE_ANGLE, Egl.EGL_PLATFORM_ANGLE_TYPE_D3D11_ANGLE,
				Egl.EGL_PLATFORM_ANGLE_MAX_VERSION_MAJOR_ANGLE, 9,
				Egl.EGL_PLATFORM_ANGLE_MAX_VERSION_MINOR_ANGLE, 3,
				Egl.EGL_EXPERIMENTAL_PRESENT_PATH_ANGLE, Egl.EGL_EXPERIMENTAL_PRESENT_PATH_FAST_ANGLE,
				Egl.EGL_PLATFORM_ANGLE_ENABLE_AUTOMATIC_TRIM_ANGLE, Egl.EGL_TRUE,
				Egl.EGL_NONE,
			};

			int[] warpDisplayAttributes = new[]
			{
				// These attributes can be used to request D3D11 WARP.
				// They are used if eglInitialize fails with both the default display attributes and the 9_3 display attributes.
				Egl.EGL_PLATFORM_ANGLE_TYPE_ANGLE, Egl.EGL_PLATFORM_ANGLE_TYPE_D3D11_ANGLE,
				Egl.EGL_PLATFORM_ANGLE_DEVICE_TYPE_ANGLE, Egl.EGL_PLATFORM_ANGLE_DEVICE_TYPE_D3D_WARP_ANGLE,
				Egl.EGL_EXPERIMENTAL_PRESENT_PATH_ANGLE, Egl.EGL_EXPERIMENTAL_PRESENT_PATH_FAST_ANGLE,
				Egl.EGL_PLATFORM_ANGLE_ENABLE_AUTOMATIC_TRIM_ANGLE, Egl.EGL_TRUE,
				Egl.EGL_NONE,
			};

			EGLConfig config = IntPtr.Zero;

			//
			// To initialize the display, we make three sets of calls to eglGetPlatformDisplayEXT and eglInitialize, with varying 
			// parameters passed to eglGetPlatformDisplayEXT:
			// 1) The first calls uses "defaultDisplayAttributes" as a parameter. This corresponds to D3D11 Feature Level 10_0+.
			// 2) If eglInitialize fails for step 1 (e.g. because 10_0+ isn't supported by the default GPU), then we try again 
			//    using "fl9_3DisplayAttributes". This corresponds to D3D11 Feature Level 9_3.
			// 3) If eglInitialize fails for step 2 (e.g. because 9_3+ isn't supported by the default GPU), then we try again 
			//    using "warpDisplayAttributes".  This corresponds to D3D11 Feature Level 11_0 on WARP, a D3D11 software rasterizer.
			//

			// This tries to initialize EGL to D3D11 Feature Level 10_0+. See above comment for details.
			eglDisplay = Egl.eglGetPlatformDisplayEXT(Egl.EGL_PLATFORM_ANGLE_ANGLE, Egl.EGL_DEFAULT_DISPLAY, defaultDisplayAttributes);
			if (eglDisplay == Egl.EGL_NO_DISPLAY)
			{
				throw new Exception("Failed to get EGL display");
			}

			if (Egl.eglInitialize(eglDisplay, out int major, out int minor) == Egl.EGL_FALSE)
			{
				// This tries to initialize EGL to D3D11 Feature Level 9_3, if 10_0+ is unavailable (e.g. on some mobile devices).
				eglDisplay = Egl.eglGetPlatformDisplayEXT(Egl.EGL_PLATFORM_ANGLE_ANGLE, Egl.EGL_DEFAULT_DISPLAY, fl9_3DisplayAttributes);
				if (eglDisplay == Egl.EGL_NO_DISPLAY)
				{
					throw new Exception("Failed to get EGL display");
				}

				if (Egl.eglInitialize(eglDisplay, out major, out minor) == Egl.EGL_FALSE)
				{
					// This initializes EGL to D3D11 Feature Level 11_0 on WARP, if 9_3+ is unavailable on the default GPU.
					eglDisplay = Egl.eglGetPlatformDisplayEXT(Egl.EGL_PLATFORM_ANGLE_ANGLE, Egl.EGL_DEFAULT_DISPLAY, warpDisplayAttributes);
					if (eglDisplay == Egl.EGL_NO_DISPLAY)
					{
						throw new Exception("Failed to get EGL display");
					}

					if (Egl.eglInitialize(eglDisplay, out major, out minor) == Egl.EGL_FALSE)
					{
						// If all of the calls to eglInitialize returned EGL_FALSE then an error has occurred.
						throw new Exception("Failed to initialize EGL");
					}
				}
			}
		}