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 "include/core/SkMath.h" 10#include "include/core/SkScalar.h" 11 12SkScalar SkScalarInterpFunc(SkScalar searchKey, const SkScalar keys[], 13 const SkScalar values[], int length) { 14 SkASSERT(length > 0); 15 SkASSERT(keys != nullptr); 16 SkASSERT(values != nullptr); 17#ifdef SK_DEBUG 18 for (int i = 1; i < length; i++) { 19 SkASSERT(keys[i-1] <= keys[i]); 20 } 21#endif 22 int right = 0; 23 while (right < length && keys[right] < searchKey) { 24 ++right; 25 } 26 // Could use sentinel values to eliminate conditionals, but since the 27 // tables are taken as input, a simpler format is better. 28 if (right == length) { 29 return values[length-1]; 30 } 31 if (right == 0) { 32 return values[0]; 33 } 34 // Otherwise, interpolate between right - 1 and right. 35 SkScalar leftKey = keys[right-1]; 36 SkScalar rightKey = keys[right]; 37 SkScalar fract = (searchKey - leftKey) / (rightKey - leftKey); 38 return SkScalarInterp(values[right-1], values[right], fract); 39} 40