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      1 /*
      2  * Copyright 2017 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include "LinearRamp.h"
     18 
     19 bool LinearRamp::isRamping() {
     20     float target = mTarget.load();
     21     if (target != mLevelTo) {
     22         // Update target. Continue from previous level.
     23         mLevelTo = target;
     24         mRemaining = mLengthInFrames;
     25         return true;
     26     } else {
     27         return mRemaining > 0;
     28     }
     29 }
     30 
     31 bool LinearRamp::nextSegment(int32_t frames, float *levelFrom, float *levelTo) {
     32     bool ramping = isRamping();
     33     *levelFrom = mLevelFrom;
     34     if (ramping) {
     35         float level;
     36         if (frames >= mRemaining) {
     37             level = mLevelTo;
     38             mRemaining = 0;
     39         } else {
     40             // Interpolate to a point along the full ramp.
     41             level = mLevelFrom + (frames * (mLevelTo - mLevelFrom) / mRemaining);
     42             mRemaining -= frames;
     43         }
     44         mLevelFrom = level; // for next ramp
     45         *levelTo = level;
     46     } else {
     47         *levelTo = mLevelTo;
     48     }
     49     return ramping;
     50 }