Handle too many (or too large) paths in GrDefaultPathRenderer

PathGeoBuilder constructs the geometry with the same basic
technique as before, but allows interrupting the process
to emit multiple draws.

Original test case was 2000 non-AA stroked circles, which
created ~66000 vertices. That now renders, as do various
tests with a single large path (as well as filled paths).

Added a new set of 'AtLeast' allocators for vertex and index
data. These take a minimum size and a fallback size. If the
minimum size can be satisfied by an existing block, then
the caller gets *all* memory in that block, otherwise they
get a new block sized for the fallback amount. The previous
allocation scheme wasn't a good fit for the new use-case,
and because we don't usually need many verts, the flexible
approach seems appropriate.

TODO: I think that this could be extracted and re-used for
MSAA path renderer without too much work? I need to read
that code more carefully to make sure it lines up.

Re-land of: https://skia-review.googlesource.com/18360
Re-land of: https://skia-review.googlesource.com/18983

Bug: skia:6695
Change-Id: I09ac1273e5af67ed0e3e886de90e2970c3d0b239
Reviewed-on: https://skia-review.googlesource.com/19480
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/src/gpu/GrPathUtils.cpp b/src/gpu/GrPathUtils.cpp
index 6047e60258..b6711a0df4 100644
--- a/src/gpu/GrPathUtils.cpp
+++ b/src/gpu/GrPathUtils.cpp
@@ -10,7 +10,6 @@
 #include "GrTypes.h"
 #include "SkMathPriv.h"
 
-static const int MAX_POINTS_PER_CURVE = 1 << 10;
 static const SkScalar gMinCurveTol = 0.0001f;
 
 SkScalar GrPathUtils::scaleToleranceToSrc(SkScalar devTol,
@@ -44,7 +43,7 @@ uint32_t GrPathUtils::quadraticPointCount(const SkPoint points[], SkScalar tol)
 
     SkScalar d = points[1].distanceToLineSegmentBetween(points[0], points[2]);
     if (!SkScalarIsFinite(d)) {
-        return MAX_POINTS_PER_CURVE;
+        return kMaxPointsPerCurve;
     } else if (d <= tol) {
         return 1;
     } else {
@@ -54,7 +53,7 @@ uint32_t GrPathUtils::quadraticPointCount(const SkPoint points[], SkScalar tol)
         // 2^(log4(x)) = sqrt(x);
         SkScalar divSqrt = SkScalarSqrt(d / tol);
         if (((SkScalar)SK_MaxS32) <= divSqrt) {
-            return MAX_POINTS_PER_CURVE;
+            return kMaxPointsPerCurve;
         } else {
             int temp = SkScalarCeilToInt(divSqrt);
             int pow2 = GrNextPow2(temp);
@@ -64,7 +63,7 @@ uint32_t GrPathUtils::quadraticPointCount(const SkPoint points[], SkScalar tol)
             if (pow2 < 1) {
                 pow2 = 1;
             }
-            return SkTMin(pow2, MAX_POINTS_PER_CURVE);
+            return SkTMin(pow2, kMaxPointsPerCurve);
         }
     }
 }
@@ -104,13 +103,13 @@ uint32_t GrPathUtils::cubicPointCount(const SkPoint points[],
         points[2].distanceToLineSegmentBetweenSqd(points[0], points[3]));
     d = SkScalarSqrt(d);
     if (!SkScalarIsFinite(d)) {
-        return MAX_POINTS_PER_CURVE;
+        return kMaxPointsPerCurve;
     } else if (d <= tol) {
         return 1;
     } else {
         SkScalar divSqrt = SkScalarSqrt(d / tol);
         if (((SkScalar)SK_MaxS32) <= divSqrt) {
-            return MAX_POINTS_PER_CURVE;
+            return kMaxPointsPerCurve;
         } else {
             int temp = SkScalarCeilToInt(SkScalarSqrt(d / tol));
             int pow2 = GrNextPow2(temp);
@@ -120,7 +119,7 @@ uint32_t GrPathUtils::cubicPointCount(const SkPoint points[],
             if (pow2 < 1) {
                 pow2 = 1;
             }
-            return SkTMin(pow2, MAX_POINTS_PER_CURVE);
+            return SkTMin(pow2, kMaxPointsPerCurve);
         }
     }
 }