* libee/line.c:

+ ee_draw_thin_line().
  * test/demo.c:
    + Added a thin lines demo.

libee/ee.h

@@ -75,6 +75,7 @@ char ee_get_key(void);
 
 void ee_draw_circle(int, int, int, char);
 void ee_draw_line(int, int, int, int, char);
+void ee_draw_thin_line(int, int, int, int);
 
 int ee_rand(int, int);
 int ee_sqrt(int);

libee/line.c

@@ -38,6 +38,7 @@ struct line
 static void clip_line(struct line*);
 static uint8_t clip_bits(int, int);
 static void draw_solid_line(struct line*);
+static void draw_thin_line(struct line*);
 
 void ee_draw_line(int x1, int y1, int x2, int y2, char c)
 {
@@ -51,6 +52,17 @@ void ee_draw_line(int x1, int y1, int x2, int y2, char c)
     clip_line(&s);
 }
 
+void ee_draw_thin_line(int x1, int y1, int x2, int y2)
+{
+    struct line s;
+    s.x1 = x1;
+    s.y1 = y1;
+    s.x2 = x2;
+    s.y2 = y2;
+    s.draw = draw_thin_line;
+    clip_line(&s);
+}
+
 static void clip_line(struct line* s)
 {
     uint8_t bits1, bits2;
@@ -121,15 +133,14 @@ static uint8_t clip_bits(int x, int y)
 
 static void draw_solid_line(struct line* s)
 {
-    int x1 = s->x1;
-    int y1 = s->y1;
-    int x2 = s->x2;
-    int y2 = s->y2;
+    int x1, y1, x2, y2;
+    int dx, dy;
+    int xinc, yinc;
 
-    int dx = abs(x2-x1);
-    int dy = abs(y2-y1);
+    x1 = s->x1; y1 = s->y1; x2 = s->x2; y2 = s->y2;
 
-    int xinc, yinc;
+    dx = abs(x2 - x1);
+    dy = abs(y2 - y1);
 
     xinc = (x1 > x2) ? -1 : 1;
     yinc = (y1 > y2) ? -1 : 1;
@@ -182,3 +193,98 @@ static void draw_solid_line(struct line* s)
     }
 }
 
+static void draw_thin_line(struct line* s)
+{
+    char *charmapx, *charmapy;
+    int x1, y1, x2, y2;
+    int dx, dy;
+    int yinc;
+
+    if(s->x2 >= s->x1)
+    {
+        if(s->y1 > s->y2)
+            charmapx = ",'";
+        else
+            charmapx = "`.";
+        x1 = s->x1; y1 = s->y1; x2 = s->x2; y2 = s->y2;
+    }
+    else
+    {
+        if(s->y1 > s->y2)
+            charmapx = "`.";
+        else
+            charmapx = ",'";
+        x2 = s->x1; y2 = s->y1; x1 = s->x2; y1 = s->y2;
+    }
+
+    dx = abs(x2 - x1);
+    dy = abs(y2 - y1);
+
+    if(y1 > y2)
+    {
+        charmapy = ",'";
+        yinc = -1;
+    }
+    else
+    {
+        yinc = 1;
+        charmapy = "`.";
+    }
+
+    if(dx >= dy)
+    {
+        int dpr = dy << 1;
+        int dpru = dpr - (dx << 1);
+        int delta = dpr - dx;
+        int prev = 0;
+
+        for(; dx>=0; dx--)
+        {
+            ee_goto(x1, y1);
+            if(delta > 0)
+            {
+                ee_putchar(charmapy[1]);
+                x1++;
+                y1 += yinc;
+                delta += dpru;
+                prev = 1;
+            }
+            else
+            {
+                if(prev)
+                    ee_putchar(charmapy[0]);
+                else
+                    ee_putchar('-');
+                x1++;
+                delta += dpr;
+                prev = 0;
+            }
+        }
+    }
+    else
+    {
+        int dpr = dx << 1;
+        int dpru = dpr - (dy << 1);
+        int delta = dpr - dy;
+
+        for(; dy >= 0; dy--)
+        {
+            ee_goto(x1, y1);
+            if(delta > 0)
+            {
+                ee_putchar(charmapx[0]);
+                ee_putchar(charmapx[1]);
+                x1++;
+                y1 += yinc;
+                delta += dpru;
+            }
+            else
+            {
+                ee_putchar('|');
+                y1 += yinc;
+                delta += dpr;
+            }
+        }
+    }
+}
+

test/demo.c

@@ -29,6 +29,7 @@ static void display_menu(void);
 
 static void demo_dots(void);
 static void demo_lines(void);
+static void demo_thin_lines(void);
 static void demo_circles(void);
 static void demo_radar(void);
 
@@ -73,9 +74,13 @@ int main(int argc, char **argv)
                 break;
             case '3':
                 ee_clear();
-                demo = demo_circles;
+                demo = demo_thin_lines;
                 break;
             case '4':
+                ee_clear();
+                demo = demo_circles;
+                break;
+            case '5':
                 ee_clear();
                 demo = demo_radar;
                 break;
@@ -114,9 +119,11 @@ static void display_menu(void)
     ee_goto(4, 7);
     ee_putstr("2: lines demo");
     ee_goto(4, 8);
-    ee_putstr("3: circles demo");
+    ee_putstr("3: thin lines demo");
     ee_goto(4, 9);
-    ee_putstr("4: radar demo");
+    ee_putstr("4: circles demo");
+    ee_goto(4, 10);
+    ee_putstr("5: radar demo");
 
     ee_goto(4, yo - 2);
     ee_putstr("q: quit");
@@ -126,14 +133,15 @@ static void display_menu(void)
 
 static void demo_dots(void)
 {
+    int xmax = ee_get_width() - 1;
+    int ymax = ee_get_height() - 1;
     int i;
 
-    for(i=1000; i--;)
+    for(i = 1000; i--;)
     {
         /* Putpixel */
         ee_color(ee_rand(1, 10));
-        ee_goto(ee_rand(0, ee_get_width() - 1),
-                ee_rand(0, ee_get_height() - 1));
+        ee_goto(ee_rand(0, xmax), ee_rand(0, ymax));
         ee_putchar('#');
     }
     ee_refresh();
@@ -141,46 +149,65 @@ static void demo_dots(void)
 
 static void demo_lines(void)
 {
+    int w = ee_get_width();
+    int h = ee_get_height();
+
     /* Draw lines */
     ee_color(ee_rand(1, 10));
     if(clipping)
     {
-        ee_draw_line(ee_rand(- ee_get_width(), 2 * ee_get_width()),
-                     ee_rand(- ee_get_height(), 2 * ee_get_height()),
-                     ee_rand(- ee_get_width(), 2 * ee_get_width()),
-                     ee_rand(- ee_get_height(), 2 * ee_get_height()),
-                     '#');
+        ee_draw_line(ee_rand(- w, 2 * w), ee_rand(- h, 2 * h),
+                     ee_rand(- w, 2 * w), ee_rand(- h, 2 * h), '#');
     }
     else
     {
-        ee_draw_line(ee_rand(0, ee_get_width()),
-                     ee_rand(0, ee_get_height()),
-                     ee_rand(0, ee_get_width()),
-                     ee_rand(0, ee_get_height()),
-                     '*');
+        ee_draw_line(ee_rand(0, w - 1), ee_rand(0, h - 1),
+                     ee_rand(0, w - 1), ee_rand(0, h - 1), '*');
+    }
+    ee_refresh();
+}
+
+static void demo_thin_lines(void)
+{
+    int w = ee_get_width();
+    int h = ee_get_height();
+
+    /* Draw lines */
+    ee_color(ee_rand(1, 10));
+    if(clipping)
+    {
+        ee_draw_thin_line(ee_rand(- w, 2 * w), ee_rand(- h, 2 * h),
+                          ee_rand(- w, 2 * w), ee_rand(- h, 2 * h));
+    }
+    else
+    {
+        ee_draw_thin_line(ee_rand(0, w), ee_rand(0, h),
+                          ee_rand(0, w), ee_rand(0, h));
     }
     ee_refresh();
 }
 
 static void demo_circles(void)
 {
+    int w = ee_get_width();
+    int h = ee_get_height();
+
     /* Draw circles */
     if(clipping)
     {
         ee_color(ee_rand(1, 10));
-        ee_draw_circle(ee_rand(- ee_get_width(), 2 * ee_get_width()),
-                       ee_rand(- ee_get_height(), 2 * ee_get_height()),
-                       ee_rand(0, ee_get_width() + ee_get_height()) / 2,
+        ee_draw_circle(ee_rand(- w, 2 * w),
+                       ee_rand(- h, 2 * h),
+                       ee_rand(0, (w + h) / 2),
                        '#');
     }
     else
     {
-        int x = ee_rand(0, ee_get_width());
-        int y = ee_rand(0, ee_get_height());
-        int r = ee_rand(0, (ee_get_width() + ee_get_height()) / 2);
+        int x = ee_rand(0, w);
+        int y = ee_rand(0, h);
+        int r = ee_rand(0, (w + h) / 2);
 
-        if(x - r < 0 || x + r >= ee_get_width() ||
-           y - r < 0 || y + r >= ee_get_height())
+        if(x - r < 0 || x + r >= w || y - r < 0 || y + r >= h)
         {
             demo_circles();
             return;