| // Copyright 2016 The Fuchsia Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "lib/media/timeline/timeline_function.h" |
| |
| #include <limits> |
| #include <utility> |
| |
| #include "lib/fxl/logging.h" |
| |
| namespace media { |
| |
| // static |
| int64_t TimelineFunction::Apply( |
| int64_t subject_time, int64_t reference_time, |
| TimelineRate rate, // subject_delta / reference_delta |
| int64_t reference_input) { |
| return rate.Scale(reference_input - reference_time) + subject_time; |
| } |
| |
| // static |
| TimelineFunction TimelineFunction::Compose(const TimelineFunction& bc, |
| const TimelineFunction& ab, |
| bool exact) { |
| // TODO(dalesat): Improve this implementation. |
| // This particular approach to composing two timeline functions comprimises |
| // range and accuracy (in some cases) for simplicity. It should be replaced |
| // with something that provides maximum range and accuracy without adding a |
| // lot of runtime cost. |
| return TimelineFunction(bc.Apply(ab.subject_time()), ab.reference_time(), |
| TimelineRate::Product(ab.rate(), bc.rate(), exact)); |
| } |
| |
| } // namespace media |
