Commit 74916997ded864cb6eb91452c2eaa08f54e5f929
2014-10-29T22:24:24
Unify hypotenuse approximations. * include/internal/ftcalc.h (FT_HYPOT): Move macro from here... * include/internal/ftobjs.h: ... to here, next to required `FT_ABS'. * src/smooth/ftgrays.c (gray_render_cubic): Use it here.
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diff --git a/ChangeLog b/ChangeLog
index 069fe4f..78dd95e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2014-10-29 Alexei Podtelezhnikov <apodtele@gmail.com>
+
+ Unify hypotenuse approximations.
+
+ * include/internal/ftcalc.h (FT_HYPOT): Move macro from here...
+ * include/internal/ftobjs.h: ... to here, next to required `FT_ABS'.
+ * src/smooth/ftgrays.c (gray_render_cubic): Use it here.
+
2014-10-25 Werner Lemberg <wl@gnu.org>
[cff] Test valid darkening parameter macros in `ftoption.h'.
diff --git a/include/internal/ftcalc.h b/include/internal/ftcalc.h
index 1d83d50..d4023fa 100644
--- a/include/internal/ftcalc.h
+++ b/include/internal/ftcalc.h
@@ -314,7 +314,7 @@ FT_BEGIN_HEADER
/*
* Return TRUE if a corner is flat or nearly flat. This is equivalent to
- * saying that the corner point is close to its neighbors, or inside an
+ * saying that the corner point is close to its neighbors, or inside an
* ellipse defined by the neighbor focal points to be more precise.
*/
FT_BASE( FT_Int )
@@ -362,18 +362,6 @@ FT_BEGIN_HEADER
FT_Fixed y );
- /*
- * Approximate sqrt(x*x+y*y) using the `alpha max plus beta min'
- * algorithm. We use alpha = 1, beta = 3/8, giving us results with a
- * largest error less than 7% compared to the exact value.
- */
-#define FT_HYPOT( x, y ) \
- ( x = FT_ABS( x ), \
- y = FT_ABS( y ), \
- x > y ? x + ( 3 * y >> 3 ) \
- : y + ( 3 * x >> 3 ) )
-
-
#if 0
/*************************************************************************/
diff --git a/include/internal/ftobjs.h b/include/internal/ftobjs.h
index faa37f8..b45a5ed 100644
--- a/include/internal/ftobjs.h
+++ b/include/internal/ftobjs.h
@@ -72,6 +72,16 @@ FT_BEGIN_HEADER
#define FT_ABS( a ) ( (a) < 0 ? -(a) : (a) )
+ /*
+ * Approximate sqrt(x*x+y*y) using the `alpha max plus beta min'
+ * algorithm. We use alpha = 1, beta = 3/8, giving us results with a
+ * largest error less than 7% compared to the exact value.
+ */
+#define FT_HYPOT( x, y ) \
+ ( x = FT_ABS( x ), \
+ y = FT_ABS( y ), \
+ x > y ? x + ( 3 * y >> 3 ) \
+ : y + ( 3 * x >> 3 ) )
#define FT_PAD_FLOOR( x, n ) ( (x) & ~((n)-1) )
#define FT_PAD_ROUND( x, n ) FT_PAD_FLOOR( (x) + ((n)/2), n )
diff --git a/src/smooth/ftgrays.c b/src/smooth/ftgrays.c
index 27be966..94c5462 100644
--- a/src/smooth/ftgrays.c
+++ b/src/smooth/ftgrays.c
@@ -1091,37 +1091,10 @@ typedef ptrdiff_t FT_PtrDist;
/* dx and dy are x and y components of the P0-P3 chord vector. */
- dx = arc[3].x - arc[0].x;
- dy = arc[3].y - arc[0].y;
-
- /* L is an (under)estimate of the Euclidean distance P0-P3. */
- /* */
- /* If dx >= dy, then r = sqrt(dx^2 + dy^2) can be overestimated */
- /* with least maximum error by */
- /* */
- /* r_upperbound = dx + (sqrt(2) - 1) * dy , */
- /* */
- /* where sqrt(2) - 1 can be (over)estimated by 107/256, giving an */
- /* error of no more than 8.4%. */
- /* */
- /* Similarly, some elementary calculus shows that r can be */
- /* underestimated with least maximum error by */
- /* */
- /* r_lowerbound = sqrt(2 + sqrt(2)) / 2 * dx */
- /* + sqrt(2 - sqrt(2)) / 2 * dy . */
- /* */
- /* 236/256 and 97/256 are (under)estimates of the two algebraic */
- /* numbers, giving an error of no more than 8.1%. */
-
- dx_ = FT_ABS( dx );
- dy_ = FT_ABS( dy );
-
- /* This is the same as */
- /* */
- /* L = ( 236 * FT_MAX( dx_, dy_ ) */
- /* + 97 * FT_MIN( dx_, dy_ ) ) >> 8; */
- L = ( dx_ > dy_ ? 236 * dx_ + 97 * dy_
- : 97 * dx_ + 236 * dy_ ) >> 8;
+ dx = dx_ = arc[3].x - arc[0].x;
+ dy = dy_ = arc[3].y - arc[0].y;
+
+ L = FT_HYPOT( dx_, dy_ );
/* Avoid possible arithmetic overflow below by splitting. */
if ( L > 32767 )