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
SkScalarInterpFunc(SkScalar searchKey,const SkScalar keys[],const SkScalar values[],int length)13 SkScalar SkScalarInterpFunc(SkScalar searchKey, const SkScalar keys[],
14 const SkScalar values[], int length) {
15 SkASSERT(length > 0);
16 SkASSERT(keys != nullptr);
17 SkASSERT(values != nullptr);
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 = (searchKey - leftKey) / (rightKey - leftKey);
35 return SkScalarInterp(values[right-1], values[right], fract);
36 }
37