From 020c06031142c047e175695e59fc26d50f16f4dc Mon Sep 17 00:00:00 2001
From: Sam Hocevar <sam@hocevar.net>
Date: Sun, 9 Nov 2003 16:34:23 +0000
Subject: [PATCH]   * libee/line.c: Implemented ee_draw_line.

---
 libee/Makefile.am |   8 ++-
 libee/ee.h        |   2 +
 libee/line.c      | 153 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 162 insertions(+), 1 deletion(-)
 create mode 100644 libee/line.c

diff --git a/libee/Makefile.am b/libee/Makefile.am
index e7e769b..b5c2098 100644
--- a/libee/Makefile.am
+++ b/libee/Makefile.am
@@ -15,6 +15,12 @@ CPPFLAGS_ncurses = -DUSE_NCURSES
 endif
 
 lib_LIBRARIES = libee.a
-libee_a_SOURCES = ee.c ee.h io.c math.c
+libee_a_SOURCES = \
+	ee.c \
+	ee.h \
+	io.c \
+	line.c \
+	math.c \
+	$(NULL)
 libee_a_CPPFLAGS = $(CPPFLAGS_slang) $(CPPFLAGS_ncurses)
 
diff --git a/libee/ee.h b/libee/ee.h
index 25cbbee..15800db 100644
--- a/libee/ee.h
+++ b/libee/ee.h
@@ -73,6 +73,8 @@ void ee_end(void);
 
 char ee_get_key(void);
 
+void ee_draw_line(int, int, int, int, char);
+
 int ee_rand(int, int);
 int ee_sqrt(int);
 
diff --git a/libee/line.c b/libee/line.c
new file mode 100644
index 0000000..5fd9963
--- /dev/null
+++ b/libee/line.c
@@ -0,0 +1,153 @@
+/*
+ *   libee         ASCII-Art library
+ *   Copyright (c) 2002, 2003 Sam Hocevar <sam@zoy.org>
+ *                 All Rights Reserved
+ *
+ *   $Id$
+ *
+ *   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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "config.h"
+
+#include <inttypes.h>
+#include <stdlib.h>
+
+#include "ee.h"
+
+static uint8_t clip_bits(int, int);
+static void _ee_draw_line(int, int, int, int, char);
+
+void ee_draw_line(int x1, int y1, int x2, int y2, char c)
+{
+    uint8_t bits1, bits2;
+
+    bits1 = clip_bits(x1, y1);
+    bits2 = clip_bits(x2, y2);
+
+    if(bits1 & bits2)
+        return;
+
+    if(bits1 == 0)
+    {
+        if(bits2 == 0)
+            _ee_draw_line(x1, y1, x2, y2, c);
+        else
+            ee_draw_line(x2, y2, x1, y1, c);
+
+        return;
+    }
+
+    if(bits1 & (1<<0))
+    {
+        y1 = y2 - (x2-0) * (y2-y1) / (x2-x1);
+        x1 = 0;
+    }
+    else if( bits1 & (1<<1) )
+    {
+        int xmax = ee_get_width() - 1;
+        y1 = y2 - (x2-xmax) * (y2-y1) / (x2-x1);
+        x1 = xmax;
+    }
+    else if( bits1 & (1<<2) )
+    {
+        x1 = x2 - (y2-0) * (x2-x1) / (y2-y1);
+        y1 = 0;
+    }
+    else if( bits1 & (1<<3) )
+    {
+        int ymax = ee_get_height() - 1;
+        x1 = x2 - (y2-ymax) * (x2-x1) / (y2-y1);
+        y1 = ymax;
+    }
+
+    ee_draw_line(x1, y1, x2, y2, c);
+}
+
+static void _ee_draw_line(int x1, int y1, int x2, int y2, char c)
+{
+    int dx = abs(x2-x1);
+    int dy = abs(y2-y1);
+
+    int xinc, yinc;
+
+    xinc = (x1 > x2) ? -1 : 1;
+    yinc = (y1 > y2) ? -1 : 1;
+
+    if(dx >= dy)
+    {
+        int dpr = dy << 1;
+        int dpru = dpr - (dx << 1);
+        int delta = dpr - dx;
+
+        for(; dx>=0; dx--)
+        {
+            ee_goto(x1, y1);
+            ee_putchar(c);
+            if(delta > 0)
+            {
+                x1 += xinc;
+                y1 += yinc;
+                delta += dpru;
+            }
+            else
+            {
+                x1 += xinc;
+                delta += dpr;
+            }
+        }
+    }
+    else
+    {
+        int dpr = dx << 1;
+        int dpru = dpr - (dy << 1);
+        int delta = dpr - dy;
+
+        for(; dy >= 0; dy--)
+        {
+            ee_goto(x1, y1);
+            ee_putchar(c);
+            if(delta > 0)
+            {
+                x1 += xinc;
+                y1 += yinc;
+                delta += dpru;
+            }
+            else
+            {
+                y1 += yinc;
+                delta += dpr;
+            }
+        }
+    }
+}
+
+static uint8_t clip_bits(int x, int y)
+{
+    uint8_t b = 0;
+
+    if(x < 0)
+        b |= (1<<0);
+    else if(x >= ee_get_width())
+        b |= (1<<1);
+
+    if(y < 0)
+        b |= (1<<2);
+    else if(y >= ee_get_height())
+        b |= (1<<3);
+
+    return b;
+}
+