/*******************************************************************************
 * Copyright 2011 See AUTHORS file.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/

package com.badlogic.gdx.graphics.glutils;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Graphics.GraphicsType;
import com.badlogic.gdx.graphics.GL20;

/** To deal with HDPI monitors properly, use the glViewport and glScissor functions of this class instead of directly calling
 * OpenGL yourself. The logical coordinate system provided by the operating system may not have the same resolution as the actual
 * drawing surface to which OpenGL draws, also known as the backbuffer. This class will ensure, that you pass the correct values
 * to OpenGL for any function that expects backbuffer coordinates instead of logical coordinates.
 * 
 * @author badlogic */
public class HdpiUtils {
	/** Calls {@link GL20#glScissor(int, int, int, int)}, expecting the coordinates and sizes given in logical coordinates and
	 * automatically converts them to backbuffer coordinates, which may be bigger on HDPI screens. */
	public static void glScissor (int x, int y, int width, int height) {
		if (Gdx.graphics.getWidth() != Gdx.graphics.getBackBufferWidth()
			|| Gdx.graphics.getHeight() != Gdx.graphics.getBackBufferHeight()) {
			Gdx.gl.glScissor(toBackBufferX(x), toBackBufferY(y), toBackBufferX(width), toBackBufferY(height));
		} else {
			Gdx.gl.glScissor(x, y, width, height);
		}
	}

	/** Calls {@link GL20#glViewport(int, int, int, int)}, expecting the coordinates and sizes given in logical coordinates and
	 * automatically converts them to backbuffer coordinates, which may be bigger on HDPI screens. */
	public static void glViewport (int x, int y, int width, int height) {
		if (Gdx.graphics.getWidth() != Gdx.graphics.getBackBufferWidth()
			|| Gdx.graphics.getHeight() != Gdx.graphics.getBackBufferHeight()) {
			Gdx.gl.glViewport(toBackBufferX(x), toBackBufferY(y), toBackBufferX(width), toBackBufferY(height));
		} else {
			Gdx.gl.glViewport(x, y, width, height);
		}
	}
	
	/**
	 * Converts an x-coordinate given in backbuffer coordinates to
	 * logical screen coordinates.
	 */
	public static int toLogicalX(int backBufferX) {
		return (int)(backBufferX * Gdx.graphics.getWidth() / (float)Gdx.graphics.getBackBufferWidth());
	}

	/**
	 * Convers an y-coordinate given in backbuffer coordinates to
	 * logical screen coordinates
	 */
	public static int toLogicalY(int backBufferY) {
		return (int)(backBufferY * Gdx.graphics.getHeight() / (float)Gdx.graphics.getBackBufferHeight());
	}
	
	/**
	 * Converts an x-coordinate given in logical screen coordinates to
	 * backbuffer coordinates.
	 */
	public static int toBackBufferX(int logicalX) {
		return (int)(logicalX * Gdx.graphics.getBackBufferWidth() / (float)Gdx.graphics.getWidth());
	}

	/**
	 * Convers an y-coordinate given in backbuffer coordinates to
	 * logical screen coordinates
	 */
	public static int toBackBufferY(int logicalY) {
		return (int)(logicalY * Gdx.graphics.getBackBufferHeight() / (float)Gdx.graphics.getHeight());
	}
}