SkPatchGrid bench

src/utils/SkPatchUtils.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkPatchUtils.h"
 
 #include "SkColorPriv.h"
@@ skipping 186 matching lines @@
     points[1] = cubics[kRightP1_CubicCtrlPts];
     points[2] = cubics[kRightP2_CubicCtrlPts];
     points[3] = cubics[kRightP3_CubicCtrlPts];
 }
 
 bool SkPatchUtils::getVertexData(SkPatchUtils::VertexData* data, const SkPoint cubics[12],
                    const SkColor colors[4], const SkPoint texCoords[4], int lodX, int lodY) {
     if (lodX < 1 || lodY < 1 || NULL == cubics || NULL == data) {
         return false;
     }
-    
-    // number of indices is limited by size of uint16_t, so we clamp it to avoid overflow
-    data->fVertexCount = SkMin32((lodX + 1) * (lodY + 1), 65536);
-    lodX  = SkMin32(lodX, 255);
-    lodY  = SkMin32(lodY, 255);
+
+    // check for overflow in multiplication
+    const int64_t lodX64 = (lodX + 1),
+                   lodY64 = (lodY + 1),
+                   mult64 = lodX64 * lodY64;
+    if (mult64 > SK_MaxS32) {
+        return false;
+    }
+    data->fVertexCount = SkToS32(mult64);
+
+    // it is recommended to generate draw calls of no more than 65536 indices, so we never generate
+    // more than 60000 indices. To accomplish that we resize the LOD and vertex count
+    if (data->fVertexCount > 10000 || lodX > 200 || lodY > 200) {
+        SkScalar weightX = static_cast<SkScalar>(lodX) / (lodX + lodY);
+        SkScalar weightY = static_cast<SkScalar>(lodY) / (lodX + lodY);
+
+        // 200 comes from the 100 * 2 which is the max value of vertices because of the limit of
+        // 60000 indices ( sqrt(60000 / 6) that comes from data->fIndexCount = lodX * lodY * 6)
+        lodX = static_cast<int>(weightX * 200);
+        lodY = static_cast<int>(weightY * 200);
+        data->fVertexCount = (lodX + 1) * (lodY + 1);
+    }
     data->fIndexCount = lodX * lodY * 6;
     
     data->fPoints = SkNEW_ARRAY(SkPoint, data->fVertexCount);
     data->fIndices = SkNEW_ARRAY(uint16_t, data->fIndexCount);
     
     // if colors is not null then create array for colors
     SkPMColor colorsPM[kNumCorners];
     if (NULL != colors) {
         // premultiply colors to avoid color bleeding.
         for (int i = 0; i < kNumCorners; i++) {
@@ skipping 93 matching lines @@
                 data->fIndices[i + 4] = data->fIndices[i + 2];
                 data->fIndices[i + 5] = (x + 1) * stride + y;
             }
             v = SkScalarClampMax(v + 1.f / lodY, 1);
         }
         u = SkScalarClampMax(u + 1.f / lodX, 1);
     }
     return true;
 
 }