scummvm/graphics/primitives.cpp

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#include "common/util.h"

namespace Graphics {

void drawLine(int x0, int y0, int x1, int y1, int color, void (*plotProc)(int, int, int, void *), void *data) {
	// Bresenham's line algorithm, as described by Wikipedia
	const bool steep = ABS(y1 - y0) > ABS(x1 - x0);

	if (steep) {
		SWAP(x0, y0);
		SWAP(x1, y1);
	}

	const int delta_x = ABS(x1 - x0);
	const int delta_y = ABS(y1 - y0);
	const int delta_err = delta_y;
	int x = x0;
	int y = y0;
	int err = 0;

	const int x_step = (x0 < x1) ? 1 : -1;
	const int y_step = (y0 < y1) ? 1 : -1;

	if (steep)
		(*plotProc)(y, x, color, data);
	else
		(*plotProc)(x, y, color, data);

	while (x != x1) {
		x += x_step;
		err += delta_err;
		if (2 * err > delta_x) {
			y += y_step;
			err -= delta_x;
		}
		if (steep)
			(*plotProc)(y, x, color, data);
		else
			(*plotProc)(x, y, color, data);
	}
}

void drawThickLine(int x0, int y0, int x1, int y1, int penX, int penY, int color, void (*plotProc)(int, int, int, void *), void *data) {
	assert(penX > 0 && penY > 0);

	// Shortcut
	if (penX == 1 && penY == 1) {
		drawLine(x0, y0, x1, y1, color, plotProc, data);
		return;
	}

	// TODO: Optimize this. It currently is a very naive way of handling
	// thick lines since quite often it will be drawing to the same pixel
	// multiple times.
	for (int x = 0; x < penX; x++)
		for (int y = 0; y < penY; y++)
			drawLine(x0 + x, y0 + y, x1 + x, y1 + y, color, plotProc, data);
}

}	// End of namespace Graphics