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 0 : SkScalar SkScalarInterpFunc(SkScalar searchKey, const SkScalar keys[],
14 : const SkScalar values[], int length) {
15 0 : SkASSERT(length > 0);
16 0 : SkASSERT(keys != NULL);
17 0 : SkASSERT(values != NULL);
18 : #ifdef SK_DEBUG
19 0 : for (int i = 1; i < length; i++)
20 0 : SkASSERT(keys[i] >= keys[i-1]);
21 : #endif
22 0 : int right = 0;
23 0 : while (right < length && searchKey > keys[right])
24 0 : right++;
25 : // Could use sentinel values to eliminate conditionals, but since the
26 : // tables are taken as input, a simpler format is better.
27 0 : if (length == right)
28 0 : return values[length-1];
29 0 : if (0 == right)
30 0 : return values[0];
31 : // Otherwise, interpolate between right - 1 and right.
32 0 : SkScalar rightKey = keys[right];
33 0 : SkScalar leftKey = keys[right-1];
34 0 : SkScalar fract = SkScalarDiv(searchKey-leftKey,rightKey-leftKey);
35 0 : return SkScalarInterp(values[right-1], values[right], fract);
36 : }
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