From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 5 Nov 2016 15:07:59 +0000 (+0200)
Subject: Create a temporary context for calling wglGetProcAddress
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgui.git;a=commitdiff_plain;h=c703f5b01bf5d7eeb13091e64109b58f5d12f53c

Create a temporary context for calling wglGetProcAddress
---

diff --git a/source/graphics/wgl/glcontext.cpp b/source/graphics/wgl/glcontext.cpp
index 98aabb3..35ec8e9 100644
--- a/source/graphics/wgl/glcontext.cpp
+++ b/source/graphics/wgl/glcontext.cpp
@@ -45,7 +45,10 @@ void GLContext::platform_init(const GLOptions &opts)
 	priv = new Private;
 	if(opts.forward_compatible || opts.gl_version_major)
 	{
-		PFNWGLCREATECONTEXTATTRIBSARBPROC wglCreateContextAttribs = reinterpret_cast<PFNWGLCREATECONTEXTATTRIBSARBPROC>(wglGetProcAddress("wglCreateContextAttribs"));
+		ContextHandle fake_context = wglCreateContext(dc);
+		wglMakeCurrent(dc, fake_context);
+
+		PFNWGLCREATECONTEXTATTRIBSARBPROC wglCreateContextAttribs = reinterpret_cast<PFNWGLCREATECONTEXTATTRIBSARBPROC>(wglGetProcAddress("wglCreateContextAttribsARB"));
 		if(!wglCreateContextAttribs)
 			throw unsupported_gl_mode(opts);
 
@@ -68,6 +71,11 @@ void GLContext::platform_init(const GLOptions &opts)
 		ctx_attribs.push_back(0);
 
 		priv->context = wglCreateContextAttribs(dc, 0, &ctx_attribs[0]);
+		if(!priv->context)
+			throw unsupported_gl_mode(opts);
+
+		wglMakeCurrent(0, 0);
+		wglDeleteContext(fake_context);
 	}
 	else
 		priv->context = wglCreateContext(dc);