From efa36d16004db93b89735e25e1e0bed7094ffc49 Mon Sep 17 00:00:00 2001
From: Arawn Davies <arawn.davies780@gmail.com>
Date: Sat, 24 Feb 2018 22:10:18 +0000
Subject: [PATCH] Re-write of GetFullScreenCanvas

---
 .../Graphics/FullScreenCanvas.cs              | 100 +++++++++++-------
 1 file changed, 60 insertions(+), 40 deletions(-)

diff --git a/source/Cosmos.System2/Graphics/FullScreenCanvas.cs b/source/Cosmos.System2/Graphics/FullScreenCanvas.cs
index 40e6e2940..0b36e1926 100644
--- a/source/Cosmos.System2/Graphics/FullScreenCanvas.cs
+++ b/source/Cosmos.System2/Graphics/FullScreenCanvas.cs
@@ -12,55 +12,75 @@ namespace Cosmos.System.Graphics
             //VGADriver,
             VBEDriver
         }
-        
+
         private static PCIDevice SVGAIIDevice = PCI.GetDevice(VendorID.VMWare, DeviceID.SVGAIIAdapter);
-        
+
         private static bool SVGAIIExists = SVGAIIDevice.DeviceExists;
-        
+
         private static VideoDriver videoDevice;
-        
+
         // Created null - NullReferenceException when calling GetFullScreenCanvas() with 0 overloads
         private static Canvas MyVideoDriver = null;
 
-        public static Canvas GetFullScreenCanvas(Mode mode)
-        {
-            Global.mDebugger.SendInternal("GetFullScreenCanvas() with mode " + mode);
-
-            /* Use SVGAII When Exists in PCI */
-            if(SVGAIIExists)
-                videoDevice = VideoDriver.VMWareSVGAIIDriver;
-		
-	    // If there's no instance of a video driver created (which there isn't), create it:
-            if (MyVideoDriver == null)
-            {
-    		    // If running on VMWare and using SVGAII, then use that driver:
-        		if (videoDevice == VideoDriver.VMWareSVGAIIDriver)
-                {
-                    // Creates the instance
-                    return MyVideoDriver = new SVGAIIScreen(mode);
-                }
-		        // If not running on VMWare, then use the VESA BIOS Extensions:
-		        else if (videoDevice == VideoDriver.VBEDriver)
-                {
-			        // Creates the instance
-			        return MyVideoDriver = new VBEScreen(mode);
-	            }
-            }
-
-            /* We have already got a VideoDriver instance, simply change its mode */
-            MyVideoDriver.Mode = mode;
-            return MyVideoDriver;
-        }
-
         public static Canvas GetFullScreenCanvas()
         {
-            Global.mDebugger.SendInternal($"GetFullScreenCanvas() with default mode");
+            // If MyVideoDriver is null (hasn't checked if VMWare SVGA exists),
+            // Do necessary check and set to default gfx mode
+            if (MyVideoDriver == null)
+            {
+                return GetFullScreenCanvas(MyVideoDriver.DefaultGraphicMode);
+            }
+            // If it's not null, simply change graphics mode */
+            else
+            {
+                MyVideoDriver.Mode = MyVideoDriver.DefaultGraphicMode;
+                return MyVideoDriver;
+            }
+            // Old check left for reference
+            /*
+                if (videoDevice == VideoDriver.VMWareSVGAIIDriver)
+                {
 
-            /*            
-            WARNING: MyVideoDriver is initiated as null - needs changing!
-             We have already got a VideoDriver instance
-                - reset its mode to DefaultGraphicMode */
-            return GetFullScreenCanvas(MyVideoDriver.DefaultGraphicMode);
+                }
+                else
+                {
+
+                }
+            */
+        }
+        public static Canvas GetFullScreenCanvas(Mode mode)
+        {
+            Global.mDebugger.SendInternal($"GetFullScreenCanvas() with default mode");
+            // If MyVideoDriver is null (hasn't checked if VMWare SVGA exists),
+            // Do necessary check and set gfx mode as specified (mode)
+            if (MyVideoDriver == null)
+            {
+                if (SVGAIIExists)
+                {
+                    // Set videoDevice to SVGA, initialize MyVideoDriver as an SVGA display using specified mode
+                    // MyVideoDriver.Mode = mode; isn't exactly needed, just done in case it doesn't set.
+                    // returns MyVideoDriver as the Canvas
+                    videoDevice = VideoDriver.VMWareSVGAIIDriver;
+                    MyVideoDriver = new SVGAIIScreen(mode);
+                    MyVideoDriver.Mode = mode;
+                    return MyVideoDriver;
+                }
+                else
+                {
+                    // Does the same as above, this time using VESA BIOS Extensions (supported by loads of graphics cards)
+                    videoDevice = VideoDriver.VBEDriver;
+                    MyVideoDriver = new VBEScreen(mode);
+                    MyVideoDriver.Mode = mode;
+                    return MyVideoDriver;
+                }
+            }
+            else
+            {
+                // If MyVideoDriver has been initialized before (Graphics mode has previously been set)
+                // Change the graphics mode to the mode specified
+                MyVideoDriver.Mode = mode;
+                return MyVideoDriver;
+            }
         }
     }
 }