blob: 87a5073e14655744571ebfcf5bfbddbb6e4558d7 [file] [log] [blame]
/*
* Copyright 2010 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkMath.h"
#include "SkScalar.h"
SkScalar SkScalarInterpFunc(SkScalar searchKey, const SkScalar keys[],
const SkScalar values[], int length) {
SkASSERT(length > 0);
SkASSERT(keys != nullptr);
SkASSERT(values != nullptr);
#ifdef SK_DEBUG
for (int i = 1; i < length; i++)
SkASSERT(keys[i] >= keys[i-1]);
#endif
int right = 0;
while (right < length && searchKey > keys[right])
right++;
// Could use sentinel values to eliminate conditionals, but since the
// tables are taken as input, a simpler format is better.
if (length == right)
return values[length-1];
if (0 == right)
return values[0];
// Otherwise, interpolate between right - 1 and right.
SkScalar rightKey = keys[right];
SkScalar leftKey = keys[right-1];
SkScalar fract = (searchKey - leftKey) / (rightKey - leftKey);
return SkScalarInterp(values[right-1], values[right], fract);
}