From 876336f455907bb2dff191d4fd38322a7f3f2a81 Mon Sep 17 00:00:00 2001
From: Ted John <ted@brambles.org>
Date: Mon, 6 Jun 2016 19:13:50 +0100
Subject: [PATCH] fallback to software mode if engine fails to initialise

---
 src/config.h               |  1 +
 src/drawing/NewDrawing.cpp | 66 ++++++++++++++++++++++++++++++--------
 2 files changed, 53 insertions(+), 14 deletions(-)

diff --git a/src/config.h b/src/config.h
index 6055702d59..ba5a033006 100644
--- a/src/config.h
+++ b/src/config.h
@@ -132,6 +132,7 @@ enum {
 };
 
 enum {
+	DRAWING_ENGINE_NONE = -1,
 	DRAWING_ENGINE_SOFTWARE,
 	DRAWING_ENGINE_SOFTWARE_WITH_HARDWARE_DISPLAY,
 	DRAWING_ENGINE_OPENGL,
diff --git a/src/drawing/NewDrawing.cpp b/src/drawing/NewDrawing.cpp
index e213207245..c2e2ea20df 100644
--- a/src/drawing/NewDrawing.cpp
+++ b/src/drawing/NewDrawing.cpp
@@ -14,6 +14,7 @@
  *****************************************************************************/
 #pragma endregion
 
+#include "../core/Exception.hpp"
 #include "IDrawingContext.h"
 #include "IDrawingEngine.h"
 
@@ -24,21 +25,27 @@ extern "C"
     #include "../platform/platform.h"
 }
 
-static IDrawingEngine * _drawingEngine = nullptr;
+static sint32           _drawingEngineType  = DRAWING_ENGINE_SOFTWARE;
+static IDrawingEngine * _drawingEngine      = nullptr;
 
-extern "C" rct_string_id DrawingEngineStringIds[] =
+extern "C"
 {
-    STR_DRAWING_ENGINE_SOFTWARE,
-    STR_DRAWING_ENGINE_SOFTWARE_WITH_HARDWARE_DISPLAY,
-    STR_DRAWING_ENGINE_OPENGL,
-};
+    rct_string_id DrawingEngineStringIds[] =
+    {
+        STR_DRAWING_ENGINE_SOFTWARE,
+        STR_DRAWING_ENGINE_SOFTWARE_WITH_HARDWARE_DISPLAY,
+        STR_DRAWING_ENGINE_OPENGL,
+    };
+}
 
 extern "C"
 {
     void drawing_engine_init()
     {
         assert(_drawingEngine == nullptr);
-        switch (gConfigGeneral.drawing_engine) {
+
+        _drawingEngineType = gConfigGeneral.drawing_engine;
+        switch (_drawingEngineType) {
         case DRAWING_ENGINE_SOFTWARE:
             _drawingEngine = DrawingEngineFactory::CreateSoftware();
             break;
@@ -52,16 +59,47 @@ extern "C"
 
         if (_drawingEngine == nullptr)
         {
-            log_error("Unable to create drawing engine. Falling back to software.");
+            if (_drawingEngineType == DRAWING_ENGINE_SOFTWARE)
+            {
+                _drawingEngineType = DRAWING_ENGINE_NONE;
+                log_fatal("Unable to create a drawing engine.");
+                exit(-1);
+            }
+            else
+            {
+                log_error("Unable to create drawing engine. Falling back to software.");
 
-            // Fallback to software
-            gConfigGeneral.drawing_engine = DRAWING_ENGINE_SOFTWARE;
-            config_save_default();
-
-            _drawingEngine = DrawingEngineFactory::CreateSoftware();
+                // Fallback to software
+                gConfigGeneral.drawing_engine = DRAWING_ENGINE_SOFTWARE;
+                config_save_default();
+                drawing_engine_init();
+            }
         }
+        else
+        {
+            try
+            {
+                _drawingEngine->Initialise(gWindow);
+            }
+            catch (Exception ex)
+            {
+                if (_drawingEngineType == DRAWING_ENGINE_SOFTWARE)
+                {
+                    _drawingEngineType = DRAWING_ENGINE_NONE;
+                    log_fatal("Unable to initialise a drawing engine.");
+                    exit(-1);
+                }
+                else
+                {
+                    log_error("Unable to initialise drawing engine. Falling back to software.");
 
-        _drawingEngine->Initialise(gWindow);
+                    // Fallback to software
+                    gConfigGeneral.drawing_engine = DRAWING_ENGINE_SOFTWARE;
+                    config_save_default();
+                    drawing_engine_init();
+                }
+            }
+        }
     }
 
     void drawing_engine_resize()