Line data    Source code

       1             : /*
       2             :  * Copyright 2010 The Android Open Source Project
       3             :  *
       4             :  * Use of this source code is governed by a BSD-style license that can be
       5             :  * found in the LICENSE file.
       6             :  */
       7             : 
       8             : 
       9             : #include "SkMath.h"
      10             : #include "SkScalar.h"
      11             : 
      12           0 : SkScalar SkScalarInterpFunc(SkScalar searchKey, const SkScalar keys[],
      13             :                             const SkScalar values[], int length) {
      14           0 :     SkASSERT(length > 0);
      15           0 :     SkASSERT(keys != nullptr);
      16           0 :     SkASSERT(values != nullptr);
      17             : #ifdef SK_DEBUG
      18           0 :     for (int i = 1; i < length; i++)
      19           0 :         SkASSERT(keys[i] >= keys[i-1]);
      20             : #endif
      21           0 :     int right = 0;
      22           0 :     while (right < length && searchKey > keys[right])
      23           0 :         right++;
      24             :     // Could use sentinel values to eliminate conditionals, but since the
      25             :     // tables are taken as input, a simpler format is better.
      26           0 :     if (length == right)
      27           0 :         return values[length-1];
      28           0 :     if (0 == right)
      29           0 :         return values[0];
      30             :     // Otherwise, interpolate between right - 1 and right.
      31           0 :     SkScalar rightKey = keys[right];
      32           0 :     SkScalar leftKey = keys[right-1];
      33           0 :     SkScalar fract = (searchKey - leftKey) / (rightKey - leftKey);
      34           0 :     return SkScalarInterp(values[right-1], values[right], fract);
      35             : }