add line drawing of dotted and/or dashed lines (from gprint).

SCCS-vsn: local/ditroff/ditroff.old.okeeffe/driver/draw.c 1.3

diff --git a/usr/src/local/ditroff/ditroff.old.okeeffe/driver/draw.c b/usr/src/local/ditroff/ditroff.old.okeeffe/driver/draw.c
index 6d0f461..96ca6be 100644 (file)
--- a/usr/src/local/ditroff/ditroff.old.okeeffe/driver/draw.c
+++ b/usr/src/local/ditroff/ditroff.old.okeeffe/driver/draw.c
@@ -1,7 +1,7 @@
-/*     draw.c  1.2     83/09/14
+/*     draw.c  1.3     83/11/01

  *
  *     This file contains the functions for producing the graphics
  *
  *     This file contains the functions for producing the graphics

- *   images in the varian/versatec drivers for ditroff.
+ *   images in the canon/imagen driver for ditroff.

  */
 
 
  */
 
 


@@ -41,8 +41,9 @@ extern putint();
 
 #define START  1
 #define POINT  0
 
 #define START  1
 #define POINT  0

-#define xbound(x)      (x < 0 ? 0 : x > MAXX ? MAXX : x)
-#define ybound(y)      (y < 0 ? 0 : y > MAXY ? MAXY : y)
+/* the imagen complains if a path is drawn at < 1, or > limit, so truncate. */
+#define xbound(x)      (x < 1 ? 1 : x > MAXX ? MAXX : x)
+#define ybound(y)      (y < 1 ? 1 : y > MAXY ? MAXY : y)

 
 
 int    linethickness = -1;     /* number of pixels wide to make lines */
 
 
 int    linethickness = -1;     /* number of pixels wide to make lines */


@@ -633,16 +634,14 @@ int numpoints;
 
 
 /*----------------------------------------------------------------------------
 
 
 /*----------------------------------------------------------------------------

- | Routine:    HGtline(xstart, ystart, xend, yend)
+ | Routine:    line(xstart, ystart, xend, yend)

  |
  | Results:    Creates a drawing path and draws the line.  If the line falls
  |             off the end of the page, a crude clipping is done:  truncating
  |             the offending ordinate.
  |
  | Results:    Creates a drawing path and draws the line.  If the line falls
  |             off the end of the page, a crude clipping is done:  truncating
  |             the offending ordinate.

- |
- | Bugs:       Does NOTHING about line style yet...

  *----------------------------------------------------------------------------*/
 
  *----------------------------------------------------------------------------*/
 

-HGtline(x0, y0, x1, y1)
+line(x0, y0, x1, y1)

 int x0, y0, x1, y1;
 {
     byte(ASPATH);              /* send the coordinates first */
 int x0, y0, x1, y1;
 {
     byte(ASPATH);              /* send the coordinates first */


@@ -653,4 +652,104 @@ int x0, y0, x1, y1;
     word(ybound(y1));
     byte(ADRAW);               /* now draw it */
     byte(15);          /* black */
     word(ybound(y1));
     byte(ADRAW);               /* now draw it */
     byte(15);          /* black */

-}  /* end HGtline */
+}  /* end line */
+
+
+/*----------------------------------------------------------------------------*
+ | Routine:    change (x_position, y_position, visible_flag)
+ |
+ | Results:    As HGtline passes from the invisible to visible (or vice
+ |             versa) portion of a line, change is called to either draw
+ |             the line, or initialize the beginning of the next one.
+ |             Change calls line to draw segments if visible_flag is set
+ |             (which means we're leaving a visible area).
+ *----------------------------------------------------------------------------*/
+
+change (x, y, vis)
+register int x;
+register int y;
+register int vis;
+{
+    static int xorg;
+    static int yorg;
+
+    if (vis)           /* leaving a visible area, draw it. */
+       line (xorg, yorg, x, y);
+    else {             /* otherwise, we're entering one, remember beginning */
+       xorg = x;
+       yorg = y;
+    }
+}
+
+
+/*----------------------------------------------------------------------------
+ | Routine:    HGtline (xstart, ystart, xend, yend)
+ |
+ | Results:    Draws a line from (x0,y0) to (x1,y1) using line(x0,y0,x1,y1)
+ |             to place individual segments of dotted or dashed lines.
+ *----------------------------------------------------------------------------*/
+
+HGtline(x0, y0, x1, y1)
+register int x0;
+register int y0;
+int x1;
+int y1;
+{
+    register int dx;
+    register int dy;
+    register int res1;
+    register int visible;
+    int res2;
+    int xinc;
+    int yinc;
+    int slope;
+
+
+    if (linmod == -1) {
+       line(x0, y0, x1, y1);
+       return;
+    }
+    xinc = 1;
+    yinc = 1;
+    if ((dx = x1-x0) < 0) {
+        xinc = -1;
+        dx = -dx;
+    }
+    if ((dy = y1-y0) < 0) {
+        yinc = -1;
+        dy = -dy;
+    }
+    slope = xinc*yinc;
+    res1 = 0;
+    res2 = 0;
+    visible = 0;
+    if (dx >= dy) 
+        while (x0 != x1) {
+            if((((x0+slope*y0)&linmod)&&1)^visible) {
+               change(x0, y0, visible);
+               visible = !visible;
+           }
+            if (res1 > res2) {
+                res2 += dx - res1;
+                res1 = 0;
+                y0 += yinc;
+            }
+            res1 += dy;
+            x0 += xinc;
+        } 
+    else 
+        while (y0 != y1) {
+            if((((x0+slope*y0)&linmod)&&1)^visible) {
+               change(x0, y0, visible);
+               visible = !visible;
+           }
+            if (res1 > res2) {
+                res2 += dy - res1;
+                res1 = 0;
+                x0 += xinc;
+            }
+            res1 += dx;
+            y0 += yinc;
+        }
+    if(visible) change(x1, y1, 1);
+}