Fix numerous errors in trapezoid rendering and wide line drawing algorithms

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3840 42af7a65-404d-4744-a932-0658087f49c3

4 files changed, 92 insertions, 51 deletions

diff --git a/nuttx/graphics/nxglib/fb/nxglib_filltrapezoid.c b/nuttx/graphics/nxglib/fb/nxglib_filltrapezoid.c
index 2f16b58ed..4f0c2f072 100644
--- a/nuttx/graphics/nxglib/fb/nxglib_filltrapezoid.c
+++ b/nuttx/graphics/nxglib/fb/nxglib_filltrapezoid.c
@@ -115,8 +115,8 @@ void NXGL_FUNCNAME(nxgl_filltrapezoid,NXGLIB_SUFFIX)(
 
   /* Get the top run position and the number of rows to draw */
 
-  x1 = trap->top.x1;
-  x2 = trap->top.x2;
+  x1    = trap->top.x1;
+  x2    = trap->top.x2;
 
   /* Calculate the number of rows to render */
 
@@ -133,6 +133,15 @@ void NXGL_FUNCNAME(nxgl_filltrapezoid,NXGLIB_SUFFIX)(
 
   if (y1 < bounds->pt1.y)
     {
+      /* Is the entire trapezoid "above" the clipping window? */
+
+      if (y2 < bounds->pt1.y)
+        {
+          /* Yes.. then do nothing */
+
+          return;
+        }
+
       /* Calculate the x values for the new top run */
 
       int dy = bounds->pt1.y - y1;
@@ -147,6 +156,15 @@ void NXGL_FUNCNAME(nxgl_filltrapezoid,NXGLIB_SUFFIX)(
 
   if (y2 > bounds->pt2.y)
     {
+      /* Is the entire trapezoid "below" the clipping window? */
+
+      if (y1 > bounds->pt2.y)
+        {
+          /* Yes.. then do nothing */
+
+          return;
+        }
+
       /* Clip and re-calculate the number of rows to render */
 
       y2     = bounds->pt2.y;
diff --git a/nuttx/graphics/nxglib/lcd/nxglib_filltrapezoid.c b/nuttx/graphics/nxglib/lcd/nxglib_filltrapezoid.c
index 0c8611088..970bbf829 100644
--- a/nuttx/graphics/nxglib/lcd/nxglib_filltrapezoid.c
+++ b/nuttx/graphics/nxglib/lcd/nxglib_filltrapezoid.c
@@ -124,14 +124,23 @@ void NXGL_FUNCNAME(nxgl_filltrapezoid,NXGLIB_SUFFIX)
 
   /* Calculate the slope of the left and right side of the trapezoid */
 
-  dy    = boty - topy;
-  dx1dy = b16divi((botx1 - topx1), dy);
-  dx2dy = b16divi((botx2 - topx2), dy);
+  dy     = boty - topy;
+  dx1dy  = b16divi((botx1 - topx1), dy);
+  dx2dy  = b16divi((botx2 - topx2), dy);
 
   /* Perform vertical clipping */
 
   if (topy < bounds->pt1.y)
     {
+      /* Is the entire trapezoid "above" the clipping window? */
+
+      if (boty < bounds->pt1.y)
+        {
+          /* Yes.. then do nothing */
+
+          return;
+        }
+
       /* Calculate the x values for the new top run */
 
       dy      = bounds->pt1.y - topy;
@@ -145,6 +154,15 @@ void NXGL_FUNCNAME(nxgl_filltrapezoid,NXGLIB_SUFFIX)
 
   if (boty > bounds->pt2.y)
     {
+      /* Is the entire trapezoid "below" the clipping window? */
+
+      if (topy > bounds->pt2.y)
+        {
+          /* Yes.. then do nothing */
+
+          return;
+        }
+
       /* Calculate the x values for the new bottom run */
 
       dy      = boty - bounds->pt2.y;
diff --git a/nuttx/graphics/nxglib/nxglib_runoffset.c b/nuttx/graphics/nxglib/nxglib_runoffset.c
index 31d0dd163..f66d73674 100644
--- a/nuttx/graphics/nxglib/nxglib_runoffset.c
+++ b/nuttx/graphics/nxglib/nxglib_runoffset.c
@@ -70,7 +70,7 @@
  * Name: nxgl_runoffset
  *
  * Description:
- *   Offset the run position by the specified dx, dy values.
+ *   Offset the run position by the specified (integer) dx, dy values.
  *
  ****************************************************************************/
 
@@ -79,7 +79,7 @@ void nxgl_runoffset(FAR struct nxgl_run_s *dest,
                     nxgl_coord_t dx, nxgl_coord_t dy)
 {
   b16_t b16dx = itob16(dx);
-  dest->x1  += b16dx;
-  dest->x2  += b16dx;
-  dest->y   += dy;
+  dest->x1    = src->x1 + b16dx;
+  dest->x2    = src->x2 + b16dx;
+  dest->y     = src->y  + dy;
 }
diff --git a/nuttx/graphics/nxglib/nxglib_splitline.c b/nuttx/graphics/nxglib/nxglib_splitline.c
index 7be9cc115..eb2906e3f 100644
--- a/nuttx/graphics/nxglib/nxglib_splitline.c
+++ b/nuttx/graphics/nxglib/nxglib_splitline.c
@@ -112,15 +112,16 @@ int nxgl_splitline(FAR struct nxgl_vector_s *vector,
                    nxgl_coord_t linewidth)
 {
   struct nxgl_vector_s line;
-  struct nxgl_point_s pt;
   nxgl_coord_t iheight;
   nxgl_coord_t iwidth;
+  nxgl_coord_t iy;
   nxgl_coord_t triheight;
-  nxgl_coord_t adjwidth;
-  nxgl_coord_t xoffset;
-  nxgl_coord_t halfoffset;
   nxgl_coord_t halfheight;
+  b16_t adjwidth;
+  b16_t xoffset;
+  b16_t halfoffset;
   b16_t angle;
+  b16_t b16x;
 
   /* First, check the linewidth */
 
@@ -226,13 +227,17 @@ int nxgl_splitline(FAR struct nxgl_vector_s *vector,
 
   angle        = b16atan2(itob16(iheight), itob16(iwidth));
   triheight    = b16toi(linewidth * b16cos(angle));
-  adjwidth     = b16toi(b16divb16(itob16(linewidth), b16sin(angle)));
-  xoffset      = (linewidth * linewidth + (adjwidth >> 1)) / adjwidth;
+  adjwidth     = b16divb16(itob16(linewidth), b16sin(angle));
+  xoffset      = itob16(linewidth * linewidth);
+  xoffset      = b16divb16(xoffset, adjwidth);
 
   halfoffset   = (xoffset   >> 1);
   halfheight   = (triheight >> 1);
 
-  /* Return the top triangle (if there is one) */
+  /* Return the top triangle (if there is one).  NOTE that the horizontal
+   * (z) positions are represented with 16 bits of fraction.  The vertical
+   * (y) positions, on the other hand, are integer.
+   */
 
   if (triheight > 0)
     {
@@ -240,53 +245,53 @@ int nxgl_splitline(FAR struct nxgl_vector_s *vector,
         {
           /* Line is going "south east" */
 
-          pt.x = line.pt1.x - halfoffset;
-          pt.y = line.pt1.y + halfheight;
+          b16x = itob16(line.pt1.x) - halfoffset;
+          iy   = line.pt1.y + halfheight;
 
-          traps[0].top.x1 = pt.x + xoffset;
+          traps[0].top.x1 = b16x + xoffset;
           traps[0].top.x2 = traps[0].top.x1;
-          traps[0].top.y  = pt.y - triheight + 1;
-          traps[0].bot.x1 = pt.x;
-          traps[0].bot.x2 = pt.x + adjwidth - 1;
-          traps[0].bot.y  = pt.y;
-
-          pt.x = line.pt2.x + halfoffset;
-          pt.y = line.pt2.y - halfheight;
-
-          traps[2].top.x1 = pt.x - adjwidth + 1;
-          traps[2].top.x2 = pt.x;
-          traps[2].top.y  = pt.y;
-          traps[2].bot.x1 = pt.x - xoffset;
+          traps[0].top.y  = iy - triheight + 1;
+          traps[0].bot.x1 = b16x;
+          traps[0].bot.x2 = b16x + adjwidth - b16ONE;
+          traps[0].bot.y  = iy;
+
+          b16x = itob16(line.pt2.x) + halfoffset;
+          iy   = itob16(line.pt2.y) - halfheight;
+
+          traps[2].top.x1 = b16x - adjwidth + b16ONE;
+          traps[2].top.x2 = b16x;
+          traps[2].top.y  = iy;
+          traps[2].bot.x1 = b16x - xoffset;
           traps[2].bot.x2 = traps[2].bot.x1;
-          traps[2].bot.y  = pt.y + triheight - 1;
+          traps[2].bot.y  = iy + triheight - 1;
         }
       else
         {
           /* Line is going "south west" */
 
-          pt.x = line.pt1.x + halfoffset;
-          pt.y = line.pt1.y + halfheight;
+          b16x = itob16(line.pt1.x) + halfoffset;
+          iy   = itob16(line.pt1.y) + halfheight;
 
-          traps[0].top.x1 = pt.x - xoffset;
+          traps[0].top.x1 = b16x - xoffset;
           traps[0].top.x2 = traps[0].top.x1;
-          traps[0].top.y  = pt.y - triheight + 1;
-          traps[0].bot.x1 = pt.x - adjwidth + 1;
-          traps[0].bot.x2 = pt.x;
-          traps[0].bot.y  = pt.y;
-
-          pt.x = line.pt2.x - halfoffset;
-          pt.y = line.pt2.y - halfheight;
-
-          traps[2].top.x1 = pt.x;
-          traps[2].top.x2 = pt.x + adjwidth - 1;
-          traps[2].top.y  = pt.y;
-          traps[2].bot.x1 = pt.x + xoffset;
+          traps[0].top.y  = iy - triheight + 1;
+          traps[0].bot.x1 = b16x - adjwidth + b16ONE;
+          traps[0].bot.x2 = b16x;
+          traps[0].bot.y  = iy;
+
+          b16x = itob16(line.pt2.x) - halfoffset;
+          iy   = itob16(line.pt2.y) - halfheight;
+
+          traps[2].top.x1 = b16x;
+          traps[2].top.x2 = b16x + adjwidth - b16ONE;
+          traps[2].top.y  = iy;
+          traps[2].bot.x1 = b16x + xoffset;
           traps[2].bot.x2 = traps[2].bot.x1;
-          traps[2].bot.y  = pt.y + triheight - 1;
+          traps[2].bot.y  = iy + triheight - 1;
         }
 
       /* The center parallelogram is the horizontal edge of each triangle.
-       * Note the minor inefficency: that horizontal edge is drawn twice.
+       * Note the minor inefficency: that horizontal edges are drawn twice.
        */
 
       traps[1].top.x1 = traps[0].bot.x1;
@@ -304,11 +309,11 @@ int nxgl_splitline(FAR struct nxgl_vector_s *vector,
    * bottom.  Just return the center parallelogram.
    */
 
-  traps[1].top.x1 = line.pt1.x - halfoffset;
+  traps[1].top.x1 = itob16(line.pt1.x) - halfoffset;
   traps[1].top.x2 = traps[1].top.x1 + adjwidth - 1;
   traps[1].top.y  = line.pt1.y;
  
-  traps[1].bot.x1 = line.pt2.x - halfoffset;
+  traps[1].bot.x1 = itob16(line.pt2.x) -  halfoffset;
   traps[1].bot.x2 = traps[1].bot.x1 + adjwidth - 1;
   traps[1].bot.y  = line.pt2.y;
   return 1;