blob: 316cae4ce779c6d85d88670283e3d413400211c6 [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 "include/core/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-1] <= keys[i]);
}
#endif
int right = 0;
while (right < length && keys[right] < searchKey) {
++right;
}
// Could use sentinel values to eliminate conditionals, but since the
// tables are taken as input, a simpler format is better.
if (right == length) {
return values[length-1];
}
if (right == 0) {
return values[0];
}
// Otherwise, interpolate between right - 1 and right.
SkScalar leftKey = keys[right-1];
SkScalar rightKey = keys[right];
SkScalar fract = (searchKey - leftKey) / (rightKey - leftKey);
return SkScalarInterp(values[right-1], values[right], fract);
}