1 /* 2 * Copyright 2010, The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include "SkScalar.h" 18 19 SkScalar SkScalarInterpFunc(SkScalar searchKey, const SkScalar keys[], 20 const SkScalar values[], int length) { 21 SkASSERT(length > 0); 22 SkASSERT(keys != NULL); 23 SkASSERT(values != NULL); 24 #ifdef SK_DEBUG 25 for (int i = 1; i < length; i++) 26 SkASSERT(keys[i] >= keys[i-1]); 27 #endif 28 int right = 0; 29 while (right < length && searchKey > keys[right]) 30 right++; 31 // Could use sentinel values to eliminate conditionals, but since the 32 // tables are taken as input, a simpler format is better. 33 if (length == right) 34 return values[length-1]; 35 if (0 == right) 36 return values[0]; 37 // Otherwise, interpolate between right - 1 and right. 38 SkScalar rightKey = keys[right]; 39 SkScalar leftKey = keys[right-1]; 40 SkScalar fract = SkScalarDiv(searchKey-leftKey,rightKey-leftKey); 41 return SkScalarInterp(values[right-1], values[right], fract); 42 } 43
