Added stack type enums to love.graphics.push (resolves issue #906.) Current enums are "transform" and "all". "transform" is the default (for compatibility.) When love.graphics.push("all") is used, love.graphics.pop() will restore all love.graphics module state to what it was when push was called.

Updated the graphics code to use a custom matrix stack rather than OpenGL1's APIs.

src/modules/graphics/opengl/wrap_Canvas.cpp

@@ -19,6 +19,7 @@
  **/
 
 #include "wrap_Canvas.h"
+#include "Graphics.h"
 
 namespace love
 {
@@ -37,18 +38,26 @@ int w_Canvas_renderTo(lua_State *L)
 	Canvas *canvas = luax_checkcanvas(L, 1);
 	luaL_checktype(L, 2, LUA_TFUNCTION);
 
-	// Save the current Canvas so we can restore it when we're done.
-	Canvas *oldcanvas = Canvas::current;
+	Graphics *graphics = Module::getInstance<Graphics>(Module::M_GRAPHICS);
 
-	luax_catchexcept(L, [&](){ canvas->startGrab(); });
+	if (graphics)
+	{
+		// Save the current Canvas so we can restore it when we're done.
+		std::vector<Canvas *> oldcanvases = graphics->getCanvas();
 
-	lua_settop(L, 2); // make sure the function is on top of the stack
-	lua_call(L, 0, 0);
+		for (Canvas *c : oldcanvases)
+			c->retain();
 
-	if (oldcanvas != nullptr)
-		oldcanvas->startGrab(oldcanvas->getAttachedCanvases());
-	else
-		Canvas::bindDefaultCanvas();
+		luax_catchexcept(L, [&](){ graphics->setCanvas(canvas); });
+
+		lua_settop(L, 2); // make sure the function is on top of the stack
+		lua_call(L, 0, 0);
+
+		graphics->setCanvas(oldcanvases);
+
+		for (Canvas *c : oldcanvases)
+			c->release();
+	}
 
 	return 0;
 }