From 931ba89aad873df74b6bcb63010b6e20c62c4f13 Mon Sep 17 00:00:00 2001
From: Doug Binks <doug@enkisoftware.com>
Date: Tue, 14 Jul 2020 11:41:42 +0100
Subject: [PATCH] User context null platform and OSMESA implementation.

---
 src/glx_context.c    |  1 -
 src/null_platform.h  |  1 +
 src/null_window.c    |  9 ++++++
 src/osmesa_context.c | 77 ++++++++++++++++++++++++++++++++++++++------
 4 files changed, 78 insertions(+), 10 deletions(-)

diff --git a/src/glx_context.c b/src/glx_context.c
index e58584ee..19ccf7f9 100644
--- a/src/glx_context.c
+++ b/src/glx_context.c
@@ -726,7 +726,6 @@ _GLFWusercontext* _glfwCreateUserContextGLX(_GLFWwindow* window)
     context->makeCurrent = _glfwMakeUserContextCurrentGLX;
     context->destroy = _glfwDestroyUserContextGLX;
 
-
     return context;
 }
 
diff --git a/src/null_platform.h b/src/null_platform.h
index 49436dcc..d476f2fa 100644
--- a/src/null_platform.h
+++ b/src/null_platform.h
@@ -34,6 +34,7 @@
 #define _GLFW_PLATFORM_CONTEXT_STATE         struct { int dummyContext; }
 #define _GLFW_PLATFORM_CURSOR_STATE          struct { int dummyCursor; }
 #define _GLFW_PLATFORM_LIBRARY_CONTEXT_STATE struct { int dummyLibraryContext; }
+#define _GLFW_PLATFORM_USER_CONTEXT_STATE    struct { int dummyUserContext; }
 
 #include "posix_time.h"
 #include "posix_thread.h"
diff --git a/src/null_window.c b/src/null_window.c
index ba85571b..1f760e84 100644
--- a/src/null_window.c
+++ b/src/null_window.c
@@ -649,3 +649,12 @@ VkResult _glfwPlatformCreateWindowSurface(VkInstance instance,
     return VK_ERROR_EXTENSION_NOT_PRESENT;
 }
 
+_GLFWusercontext* _glfwPlatformCreateUserContext(_GLFWwindow* window)
+{
+    if (window->context.osmesa.handle)
+    {
+        return _glfwCreateUserContextOSMesa(window);
+    }
+
+    return GLFW_FALSE;
+}
diff --git a/src/osmesa_context.c b/src/osmesa_context.c
index 07baabed..69ae4e2e 100644
--- a/src/osmesa_context.c
+++ b/src/osmesa_context.c
@@ -195,9 +195,9 @@ void _glfwTerminateOSMesa(void)
     attribs[index++] = v; \
 }
 
-GLFWbool _glfwCreateContextOSMesa(_GLFWwindow* window,
-                                  const _GLFWctxconfig* ctxconfig,
-                                  const _GLFWfbconfig* fbconfig)
+GLFWbool _glfwCreateContextForConfigOSMesa(const _GLFWctxconfig* ctxconfig,
+                                           const _GLFWfbconfig* fbconfig,
+                                           OSMesaContext* context )
 {
     OSMesaContext share = NULL;
     const int accumBits = fbconfig->accumRedBits +
@@ -248,7 +248,7 @@ GLFWbool _glfwCreateContextOSMesa(_GLFWwindow* window,
 
         setAttrib(0, 0);
 
-        window->context.osmesa.handle =
+        *context =
             OSMesaCreateContextAttribs(attribs, share);
     }
     else
@@ -260,7 +260,7 @@ GLFWbool _glfwCreateContextOSMesa(_GLFWwindow* window,
             return GLFW_FALSE;
         }
 
-        window->context.osmesa.handle =
+        *context =
             OSMesaCreateContextExt(OSMESA_RGBA,
                                    fbconfig->depthBits,
                                    fbconfig->stencilBits,
@@ -268,13 +268,27 @@ GLFWbool _glfwCreateContextOSMesa(_GLFWwindow* window,
                                    share);
     }
 
-    if (window->context.osmesa.handle == NULL)
+    if (*context == NULL)
     {
         _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                         "OSMesa: Failed to create context");
         return GLFW_FALSE;
     }
 
+    return GLFW_TRUE;
+}
+
+#undef setAttrib
+
+GLFWbool _glfwCreateContextOSMesa(_GLFWwindow* window,
+                                  const _GLFWctxconfig* ctxconfig,
+                                  const _GLFWfbconfig* fbconfig)
+{
+    if(!_glfwCreateContextForConfigOSMesa(ctxconfig,fbconfig,&window->context.osmesa.handle))
+    {
+        return GLFW_FALSE;
+    }
+
     window->context.makeCurrent = makeContextCurrentOSMesa;
     window->context.swapBuffers = swapBuffersOSMesa;
     window->context.swapInterval = swapIntervalOSMesa;
@@ -285,12 +299,57 @@ GLFWbool _glfwCreateContextOSMesa(_GLFWwindow* window,
     return GLFW_TRUE;
 }
 
-#undef setAttrib
+static void _glfwMakeUserContextCurrentOSMesa(_GLFWusercontext* context)
+{
+    if(context)
+    {
+        if (!OSMesaMakeCurrent(context->osmesa.handle,
+                               context->window->context.osmesa.buffer,
+                               GL_UNSIGNED_BYTE,
+                               context->window->context.osmesa.width, context->window->context.osmesa.height))
+        {
+            _glfwInputError(GLFW_PLATFORM_ERROR,
+                            "OSMesa: Failed to make context current");
+            return;
+        }
+    }
+}
+
+static void _glfwDestroyUserContextOSMesa(_GLFWusercontext* context)
+{
+    if (context->osmesa.handle)
+    {
+        OSMesaDestroyContext(context->osmesa.handle);
+    }
+    free(context);
+}
 
 _GLFWusercontext* _glfwCreateUserContextOSMesa(_GLFWwindow* window)
 {
-    // TODO
-    return NULL;
+    _GLFWusercontext* context;
+    _GLFWctxconfig ctxconfig;
+    _GLFWfbconfig fbconfig;
+
+    context = calloc(1, sizeof(_GLFWusercontext));
+    context->window = window;
+
+    ctxconfig = _glfw.hints.context;
+    ctxconfig.share = window;
+
+    fbconfig = _glfw.hints.framebuffer;
+
+    if(!_glfwCreateContextForConfigOSMesa(&ctxconfig,&fbconfig,&context->osmesa.handle))
+    {
+        _glfwInputError(GLFW_PLATFORM_ERROR,
+                                "OSMesa: Failed to create user OpenGL context");
+        free(context);
+        return NULL;
+    }
+
+    context->makeCurrent = _glfwMakeUserContextCurrentOSMesa;
+    context->destroy = _glfwDestroyUserContextOSMesa;
+
+    return context;
 }
 
 //////////////////////////////////////////////////////////////////////////