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/*
* Copyright 2010, The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "SkScalar.h"
SkScalar SkScalarInterpFunc(SkScalar searchKey, const SkScalar keys[],
const SkScalar values[], int length) {
SkASSERT(length > 0);
SkASSERT(keys != NULL);
SkASSERT(values != NULL);
#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 = SkScalarDiv(searchKey-leftKey,rightKey-leftKey);
return SkScalarInterp(values[right-1], values[right], fract);
}
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