| /* |
| * Copyright 2022 Google LLC |
| * |
| * 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. |
| */ |
| |
| #ifndef INK_STROKE_MODELER_STROKE_MODELER_H_ |
| #define INK_STROKE_MODELER_STROKE_MODELER_H_ |
| |
| #include <memory> |
| #include <vector> |
| |
| #include "absl/status/status.h" |
| #include "absl/status/statusor.h" |
| #include "absl/types/optional.h" |
| #include "ink_stroke_modeler/internal/position_modeler.h" |
| #include "ink_stroke_modeler/internal/prediction/input_predictor.h" |
| #include "ink_stroke_modeler/internal/stylus_state_modeler.h" |
| #include "ink_stroke_modeler/internal/wobble_smoother.h" |
| #include "ink_stroke_modeler/params.h" |
| #include "ink_stroke_modeler/types.h" |
| |
| namespace ink { |
| namespace stroke_model { |
| |
| // This class models a stroke from a raw input stream. The modeling is performed |
| // in several stages, which are delegated to component classes: |
| // - Wobble Smoothing: Dampens high-frequency noise from quantization error. |
| // - Position Modeling: Models the pen tip as a mass, connected by a spring, to |
| // a moving anchor. |
| // - Stylus State Modeling: Constructs stylus states for modeled positions by |
| // interpolating over the raw input. |
| // |
| // Additionally, this class provides prediction of the modeled stroke. |
| // |
| // StrokeModeler is completely unit-agnostic. That is, it doesn't matter what |
| // units or coordinate-system the input is given in; the output will be given in |
| // the same coordinate-system and units. |
| class StrokeModeler { |
| public: |
| // Clears any in-progress stroke, and initializes (or re-initializes) the |
| // model with the given parameters. Returns an error if the parameters are |
| // invalid. |
| absl::Status Reset(const StrokeModelParams &stroke_model_params); |
| |
| // Updates the model with a raw input, returning the generated results. Any |
| // previously generated results are stable, i.e. any previously returned |
| // Results are still valid. |
| // |
| // Returns an error if the the model has not yet been initialized (via Reset) |
| // or if the input stream is malformed (e.g decreasing time, Up event before |
| // Down event). |
| // |
| // If this does not return an error, the result will contain at least one |
| // Result, and potentially more than one if the inputs are slower than |
| // the minimum output rate. |
| absl::StatusOr<std::vector<Result>> Update(const Input &input); |
| |
| // Model the given input prediction without changing the internal model state. |
| // |
| // Returns an error if the the model has not yet been initialized (via Reset), |
| // or if there is no stroke in progress. The output is limited to results |
| // where the predictor has sufficient confidence, |
| absl::StatusOr<std::vector<Result>> Predict() const; |
| |
| private: |
| absl::StatusOr<std::vector<Result>> ProcessDownEvent(const Input &input); |
| absl::StatusOr<std::vector<Result>> ProcessMoveEvent(const Input &input); |
| absl::StatusOr<std::vector<Result>> ProcessUpEvent(const Input &input); |
| |
| std::unique_ptr<InputPredictor> predictor_; |
| |
| absl::optional<StrokeModelParams> stroke_model_params_; |
| |
| WobbleSmoother wobble_smoother_; |
| PositionModeler position_modeler_; |
| StylusStateModeler stylus_state_modeler_; |
| |
| struct InputAndCorrectedPosition { |
| Input input; |
| Vec2 corrected_position{0}; |
| }; |
| absl::optional<InputAndCorrectedPosition> last_input_; |
| }; |
| |
| } // namespace stroke_model |
| } // namespace ink |
| |
| #endif // INK_STROKE_MODELER_STROKE_MODELER_H_ |