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] >= 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