1 2 /* 3 * Copyright 2010 The Android Open Source Project 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 9 10 #include "SkMath.h" 11 #include "SkScalar.h" 12 13 SkScalar SkScalarInterpFunc(SkScalar searchKey, const SkScalar keys[], 14 const SkScalar values[], int length) { 15 SkASSERT(length > 0); 16 SkASSERT(keys != NULL); 17 SkASSERT(values != NULL); 18 #ifdef SK_DEBUG 19 for (int i = 1; i < length; i++) 20 SkASSERT(keys[i] >= keys[i-1]); 21 #endif 22 int right = 0; 23 while (right < length && searchKey > keys[right]) 24 right++; 25 // Could use sentinel values to eliminate conditionals, but since the 26 // tables are taken as input, a simpler format is better. 27 if (length == right) 28 return values[length-1]; 29 if (0 == right) 30 return values[0]; 31 // Otherwise, interpolate between right - 1 and right. 32 SkScalar rightKey = keys[right]; 33 SkScalar leftKey = keys[right-1]; 34 SkScalar fract = SkScalarDiv(searchKey-leftKey,rightKey-leftKey); 35 return SkScalarInterp(values[right-1], values[right], fract); 36 } 37
