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 SkScalar 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] >= keys[i-1]); 20 #endif 21 int right = 0; 22 while (right < length && searchKey > keys[right]) 23 right++; 24 // Could use sentinel values to eliminate conditionals, but since the 25 // tables are taken as input, a simpler format is better. 26 if (length == right) 27 return values[length-1]; 28 if (0 == right) 29 return values[0]; 30 // Otherwise, interpolate between right - 1 and right. 31 SkScalar rightKey = keys[right]; 32 SkScalar leftKey = keys[right-1]; 33 SkScalar fract = (searchKey - leftKey) / (rightKey - leftKey); 34 return SkScalarInterp(values[right-1], values[right], fract); 35 } 36
