Patch #1186744 (Common line-drawing function)

svn-id: r17842

1 files changed, 64 insertions, 0 deletions

diff --git a/graphics/primitives.cpp b/graphics/primitives.cpp
new file mode 100644
index 0000000000..f5c28a0cfd
--- /dev/null
+++ b/graphics/primitives.cpp
@@ -0,0 +1,64 @@
+/* ScummVM - Scumm Interpreter
+ * Copyright (C) 2002-2005 The ScummVM project
+ *
+ * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ *
+ * $Header$
+ */
+
+#include "common/stdafx.h"
+#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
+	bool steep = ABS(y1 - y0) > ABS(x1 - x0);
+
+	if (steep) {
+		SWAP(x0, y0);
+		SWAP(x1, y1);
+	}
+
+	int delta_x = ABS(x1 - x0);
+	int delta_y = ABS(y1 - y0);
+	int err = 0;
+	int delta_err = delta_y;
+	int x = x0;
+	int y = y0;
+
+	int x_step = (x0 < x1) ? 1 : -1;
+	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);
+	}
+}
+
+}	// End of namespace Graphics