More code restructuring.

Move all love.graphics functionality that doesn’t call OpenGL out of the OpenGL backend Graphics class.

--HG--
branch : minor

src/modules/graphics/Canvas.h

@@ -0,0 +1,65 @@
+/**
+* Copyright (c) 2006-2016 LOVE Development Team
+*
+* This software is provided 'as-is', without any express or implied
+* warranty.  In no event will the authors be held liable for any damages
+* arising from the use of this software.
+*
+* Permission is granted to anyone to use this software for any purpose,
+* including commercial applications, and to alter it and redistribute it
+* freely, subject to the following restrictions:
+*
+* 1. The origin of this software must not be misrepresented; you must not
+*    claim that you wrote the original software. If you use this software
+*    in a product, an acknowledgment in the product documentation would be
+*    appreciated but is not required.
+* 2. Altered source versions must be plainly marked as such, and must not be
+*    misrepresented as being the original software.
+* 3. This notice may not be removed or altered from any source distribution.
+**/
+
+#pragma once
+
+#include "image/Image.h"
+#include "image/ImageData.h"
+#include "Texture.h"
+
+namespace love
+{
+namespace graphics
+{
+
+class Graphics;
+
+class Canvas : public Texture
+{
+public:
+
+	static love::Type type;
+
+	struct Settings
+	{
+		PixelFormat format = PIXELFORMAT_NORMAL;
+		float pixeldensity = 1.0f;
+		int msaa = 0;
+	};
+
+	Canvas();
+	virtual ~Canvas();
+
+	virtual love::image::ImageData *newImageData(love::image::Image *module, int x, int y, int w, int h) = 0;
+
+	virtual int getMSAA() const = 0;
+	virtual int getRequestedMSAA() const = 0;
+	virtual ptrdiff_t getMSAAHandle() const = 0;
+
+	static int canvasCount;
+
+private:
+
+	void drawv(Graphics *gfx, const Matrix4 &t, const Vertex *v) override;
+	
+}; // Canvas
+
+} // graphics
+} // love