1 files changed, 74 insertions, 0 deletions
diff --git a/src/blitter/base.cpp b/src/blitter/base.cpp
new file mode 100644
index 000000000..b18e9c87a
--- /dev/null
+++ b/src/blitter/base.cpp
@@ -0,0 +1,74 @@
+/* $Id$ */
+
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD 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, version 2.
+ * OpenTTD 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 OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file base.cpp Implementation of the base for all blitters. */
+
+#include "../stdafx.h"
+#include "base.hpp"
+
+/**
+ * Draw a line with a given colour.
+ * @param video The destination pointer (video-buffer).
+ * @param x The x coordinate from where the line starts.
+ * @param y The y coordinate from where the line starts.
+ * @param x2 The x coordinate to where the line goes.
+ * @param y2 The y coordinate to where the lines goes.
+ * @param screen_width The width of the screen you are drawing in (to avoid buffer-overflows).
+ * @param screen_height The height of the screen you are drawing in (to avoid buffer-overflows).
+ * @param colour A 8bpp mapping colour.
+ */
+void Blitter::DrawLine(void *video, int x, int y, int x2, int y2, int screen_width, int screen_height, uint8 colour)
+{
+	int dy;
+	int dx;
+	int stepx;
+	int stepy;
+	int frac;
+
+	dy = (y2 - y) * 2;
+	if (dy < 0) {
+		dy = -dy;
+		stepy = -1;
+	} else {
+		stepy = 1;
+	}
+
+	dx = (x2 - x) * 2;
+	if (dx < 0) {
+		dx = -dx;
+		stepx = -1;
+	} else {
+		stepx = 1;
+	}
+
+	if (x >= 0 && y >= 0 && x < screen_width && y < screen_height) this->SetPixel(video, x, y, colour);
+	if (dx > dy) {
+		frac = dy - (dx / 2);
+		while (x != x2) {
+			if (frac >= 0) {
+				y += stepy;
+				frac -= dx;
+			}
+			x += stepx;
+			frac += dy;
+			if (x >= 0 && y >= 0 && x < screen_width && y < screen_height) this->SetPixel(video, x, y, colour);
+		}
+	} else {
+		frac = dx - (dy / 2);
+		while (y != y2) {
+			if (frac >= 0) {
+				x += stepx;
+				frac -= dy;
+			}
+			y += stepy;
+			frac += dx;
+			if (x >= 0 && y >= 0 && x < screen_width && y < screen_height) this->SetPixel(video, x, y, colour);
+		}
+	}
+}