From d5cc42f1c233a45abb879818af503ec7b91c6f34 Mon Sep 17 00:00:00 2001
From: Walter van Niftrik
Date: Thu, 3 Mar 2016 19:17:49 +0100
Subject: ADL: Make frame buffer linear

---
 engines/adl/hires1.cpp | 40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

(limited to 'engines/adl/hires1.cpp')

diff --git a/engines/adl/hires1.cpp b/engines/adl/hires1.cpp
index 54351911fc..04df01ecd4 100644
--- a/engines/adl/hires1.cpp
+++ b/engines/adl/hires1.cpp
@@ -216,10 +216,10 @@ void HiRes1Engine::drawPic(Common::ReadStream &stream, Common::Point pos) {
 			y = 160;
 
 		if (bNewLine) {
-			_display->drawPixel(x, y, 0x7f);
+			_display->putPixel(Common::Point(x, y), 0x7f);
 			bNewLine = false;
 		} else {
-			_display->drawLine(Common::Point(oldX, oldY), Common::Point(x, y), 0x7f);
+			drawLine(Common::Point(oldX, oldY), Common::Point(x, y), 0x7f);
 		}
 
 		oldX = x;
@@ -455,6 +455,42 @@ uint HiRes1Engine::getEngineMessage(EngineMessage msg) {
 	}
 }
 
+void HiRes1Engine::drawLine(Common::Point p1, Common::Point p2, byte color) {
+	int16 deltaX = p2.x - p1.x;
+	byte dir = deltaX >> 8;
+
+	if (deltaX < 0)
+		deltaX = -deltaX;
+
+	int16 err = deltaX;
+
+	int16 deltaY = p2.y - p1.y - 1;
+	dir >>= 1;
+	if (deltaY >= 0) {
+		deltaY = -deltaY - 2;
+		dir |= 0x80;
+	}
+
+	int16 steps = deltaY - deltaX;
+
+	err += deltaY + 1;
+
+	while (1) {
+		_display->putPixel(p1, color);
+
+		if (++steps == 0)
+			return;
+
+		if (err < 0) {
+			p1.y += (dir & 0x80 ? 1 : -1);
+			err += deltaX;
+		} else {
+			p1.x += (dir & 0x40 ? -1 : 1);
+			err += deltaY + 1;
+		}
+	}
+}
+
 AdlEngine *HiRes1Engine__create(OSystem *syst, const AdlGameDescription *gd) {
 	return new HiRes1Engine(syst, gd);
 }
-- 
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