[freetype2] smooth_malloc c8ab9dadf: [smooth] Estimate of the rendering pool size.

[Werner Lemberg]

branch: smooth_malloc
commit c8ab9dadf42ff79c259ad8b42b5bfed75d7a71ad
Author: Alexei Podtelezhnikov <apodtele@gmail.com>
Commit: Alexei Podtelezhnikov <apodtele@gmail.com>

    [smooth] Estimate of the rendering pool size.
    
    The estimate is based on the taxi perimeter with extra space added
    for local extrema.
    
    * src/smooth/ftgrays.c (gray_taxi): New function for the perimeter.
    (gray_convert_glyph): Updated, banding suppressed.
---
 src/smooth/ftgrays.c | 56 +++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 45 insertions(+), 11 deletions(-)

diff --git a/src/smooth/ftgrays.c b/src/smooth/ftgrays.c
index fabb986ab..aef6a5509 100644
--- a/src/smooth/ftgrays.c
+++ b/src/smooth/ftgrays.c
@@ -1920,6 +1920,39 @@ typedef ptrdiff_t  FT_PtrDist;
   )
 
 
+  static long
+  gray_taxi( RAS_ARG )
+  {
+    FT_Outline*  outline = &ras.outline;
+    short        c, p, first, last;
+    FT_Vector    u, v;
+    FT_Pos       taxi;
+
+
+    taxi = 0;
+    last = -1;
+    for ( c = 0; c < outline->n_contours; c++ )
+    {
+      first = last + 1;
+      last = outline->contours[c];
+
+      u = outline->points[last];
+      for ( p = first; p <= last; p++ )
+      {
+        v = outline->points[p];
+
+        taxi += v.x > u.x ? v.x - u.x : u.x - v.x;
+        taxi += v.y > u.y ? v.y - u.y : u.y - v.y;
+
+        u = v;
+      }
+    }
+
+    /* adding the number of local extrema might be worth it but is hard */
+    return  taxi >> 6;
+  }
+
+
   static int
   gray_convert_glyph_inner( RAS_ARG_
                             int  continued )
@@ -1935,7 +1968,7 @@ typedef ptrdiff_t  FT_PtrDist;
       if ( continued )
         FT_Trace_Enable();
 
-      FT_TRACE7(( "band [%d..%d]: %td cell%s remaining/\n",
+      FT_TRACE7(( "band [%d..%d]: %td cell%s remaining\n",
                   ras.min_ey,
                   ras.max_ey,
                   ras.cell_null - ras.cell_free,
@@ -1964,7 +1997,8 @@ typedef ptrdiff_t  FT_PtrDist;
 
     TCell*   buffer;
     size_t   height = (size_t)( yMax - yMin );
-    size_t   n = FT_MAX_GRAY_POOL / 8;
+    size_t   n;
+    long     size;
     TCoord   y;
     TCoord   bands[32];  /* enough to accommodate bisections */
     TCoord*  band;
@@ -1972,11 +2006,18 @@ typedef ptrdiff_t  FT_PtrDist;
     int  continued = 0;
 
 
-    if ( FT_QNEW_ARRAY ( buffer, FT_MAX_GRAY_POOL ) )
+    size = gray_taxi( RAS_VAR ) +
+           height * sizeof ( PCell ) / sizeof ( TCell ) +
+           9;  /* empirical extra for local extrema */
+
+    if ( FT_QNEW_ARRAY ( buffer, size ) )
       return error;
 
+    FT_TRACE7(( "Allocated %ld cells (%ld bytes)\n",
+                size, size * sizeof ( TCell ) ));
+
     /* Initialize the null cell at the end of the poll. */
-    ras.cell_null        = buffer + FT_MAX_GRAY_POOL - 1;
+    ras.cell_null        = buffer + size - 1;
     ras.cell_null->x     = CELL_MAX_X_VALUE;
     ras.cell_null->area  = 0;
     ras.cell_null->cover = 0;
@@ -1985,13 +2026,6 @@ typedef ptrdiff_t  FT_PtrDist;
     /* set up vertical bands */
     ras.ycells     = (PCell*)buffer;
 
-    if ( height > n )
-    {
-      /* two divisions rounded up */
-      n       = ( height + n - 1 ) / n;
-      height  = ( height + n - 1 ) / n;
-    }
-
     for ( y = yMin; y < yMax; )
     {
       ras.min_ey = y;