Rename Framebuffer to Canvas (issue #263). Move error reporting code.

Error reporting now resides in Graphics::newCanvas() instead of the
previous location wrap_newFramebuffer(). Changed error text for
"Error in implementation" to point to a possible fix.

src/modules/graphics/opengl/wrap_Canvas.cpp

@@ -0,0 +1,161 @@
+#include "Graphics.h"
+#include "wrap_Canvas.h"
+
+namespace love
+{
+namespace graphics
+{
+namespace opengl
+{
+	Canvas * luax_checkcanvas(lua_State * L, int idx)
+	{
+		return luax_checktype<Canvas>(L, idx, "Canvas", GRAPHICS_CANVAS_T);
+	}
+
+	int w_Canvas_renderTo(lua_State * L)
+	{
+		// As startGrab() clears the framebuffer, better not allow
+		// grabbing inside another grabbing
+		if (Canvas::current != NULL) {
+			Canvas::bindDefaultCanvas();
+			return luaL_error(L, "Current render target not the default canvas!");
+		}
+
+		Canvas * canvas = luax_checkcanvas(L, 1);
+		if (!lua_isfunction(L, 2))
+			return luaL_error(L, "Need a function to render to canvas.");
+
+		canvas->startGrab();
+		lua_settop(L, 2); // make sure the function is on top of the stack
+		lua_call(L, 0, 0);
+		canvas->stopGrab();
+
+		return 0;
+	}
+
+	int w_Canvas_getImageData(lua_State * L)
+	{
+		Canvas * canvas = luax_checkcanvas(L, 1);
+		love::image::Image * image = luax_getmodule<love::image::Image>(L, "image", MODULE_IMAGE_T);
+		love::image::ImageData * img = canvas->getImageData( image );
+		luax_newtype(L, "ImageData", IMAGE_IMAGE_DATA_T, (void *)img);
+		return 1;
+	}
+
+	int w_Canvas_setFilter(lua_State * L)
+	{
+		Canvas * canvas = luax_checkcanvas(L, 1);
+		const char * minstr = luaL_checkstring(L, 2);
+		const char * magstr = luaL_checkstring(L, 3);
+
+		Image::Filter f;
+		if (!Image::getConstant(minstr, f.min))
+			return luaL_error(L, "Invalid min filter mode: %s", minstr);
+		if (!Image::getConstant(magstr, f.mag))
+			return luaL_error(L, "Invalid max filter mode: %s", magstr);
+
+		canvas->setFilter(f);
+		return 0;
+	}
+
+	int w_Canvas_getFilter(lua_State * L)
+	{
+		Canvas * canvas = luax_checkcanvas(L, 1);
+		Image::Filter f = canvas->getFilter();
+
+		const char * minstr;
+		const char * magstr;
+		Image::getConstant(f.min, minstr);
+		Image::getConstant(f.mag, magstr);
+
+		lua_pushstring(L, minstr);
+		lua_pushstring(L, magstr);
+
+		return 2;
+	}
+
+	int w_Canvas_setWrap(lua_State * L)
+	{
+		Canvas * canvas = luax_checkcanvas(L, 1);
+		const char * wrap_s = luaL_checkstring(L, 2);
+		const char * wrap_t = luaL_checkstring(L, 3);
+
+		Image::Wrap w;
+		if (!Image::getConstant(wrap_s, w.s))
+			return luaL_error(L, "Invalid wrap mode: %s", wrap_s);
+		if (!Image::getConstant(wrap_t, w.t))
+			return luaL_error(L, "Invalid wrap mode: %s", wrap_t);
+
+		canvas->setWrap(w);
+		return 0;
+	}
+
+	int w_Canvas_getWrap(lua_State * L)
+	{
+		Canvas * canvas = luax_checkcanvas(L, 1);
+		Image::Wrap w = canvas->getWrap();
+
+		const char * wrap_s;
+		const char * wrap_t;
+		Image::getConstant(w.s, wrap_s);
+		Image::getConstant(w.t, wrap_t);
+
+		lua_pushstring(L, wrap_s);
+		lua_pushstring(L, wrap_t);
+
+		return 2;
+	}
+
+	int w_Canvas_clear(lua_State * L)
+	{
+		Canvas * canvas = luax_checkcanvas(L, 1);
+		Color c;
+		if (lua_isnoneornil(L, 2)) {
+			c.r = 0;
+			c.g = 0;
+			c.b = 0;
+			c.a = 0;
+		} else if (lua_istable(L, 2)) {
+			lua_pushinteger(L, 1);
+			lua_gettable(L, 2);
+			c.r = (unsigned char)luaL_checkint(L, -1);
+			lua_pushinteger(L, 2);
+			lua_gettable(L, 2);
+			c.g = (unsigned char)luaL_checkint(L, -1);
+			lua_pushinteger(L, 3);
+			lua_gettable(L, 2);
+			c.b = (unsigned char)luaL_checkint(L, -1);
+			lua_pushinteger(L, 4);
+			lua_gettable(L, 2);
+			c.g = (unsigned char)luaL_optint(L, -1, 255);
+			lua_pop(L, 4);
+		} else {
+			c.r = (unsigned char)luaL_checkint(L, 2);
+			c.g = (unsigned char)luaL_checkint(L, 3);
+			c.b = (unsigned char)luaL_checkint(L, 4);
+			c.a = (unsigned char)luaL_optint(L, 5, 255);
+		}
+		canvas->clear(c);
+
+		return 0;
+	}
+
+	static const luaL_Reg functions[] = {
+		{ "renderTo", w_Canvas_renderTo },
+		{ "getImageData", w_Canvas_getImageData },
+		{ "setFilter", w_Canvas_setFilter },
+		{ "getFilter", w_Canvas_getFilter },
+		{ "setWrap", w_Canvas_setWrap },
+		{ "getWrap", w_Canvas_getWrap },
+		{ "clear", w_Canvas_clear },
+		{ 0, 0 }
+	};
+
+	int luaopen_canvas(lua_State * L)
+	{
+		return luax_register_type(L, "Canvas", functions);
+	}
+
+} // opengl
+} // graphics
+} // love