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107 lines
3.7 KiB
107 lines
3.7 KiB
/* |
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* Copyright (C) 2012 The Android Open Source Project |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0 |
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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#ifndef _LIBINPUT_VELOCITY_CONTROL_H |
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#define _LIBINPUT_VELOCITY_CONTROL_H |
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#include <input/Input.h> |
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#include <input/VelocityTracker.h> |
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#include <utils/Timers.h> |
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namespace android { |
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/* |
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* Specifies parameters that govern pointer or wheel acceleration. |
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*/ |
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struct VelocityControlParameters { |
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// A scale factor that is multiplied with the raw velocity deltas |
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// prior to applying any other velocity control factors. The scale |
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// factor should be used to adapt the input device resolution |
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// (eg. counts per inch) to the output device resolution (eg. pixels per inch). |
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// |
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// Must be a positive value. |
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// Default is 1.0 (no scaling). |
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float scale; |
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// The scaled speed at which acceleration begins to be applied. |
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// This value establishes the upper bound of a low speed regime for |
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// small precise motions that are performed without any acceleration. |
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// |
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// Must be a non-negative value. |
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// Default is 0.0 (no low threshold). |
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float lowThreshold; |
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// The scaled speed at which maximum acceleration is applied. |
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// The difference between highThreshold and lowThreshold controls |
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// the range of speeds over which the acceleration factor is interpolated. |
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// The wider the range, the smoother the acceleration. |
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// |
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// Must be a non-negative value greater than or equal to lowThreshold. |
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// Default is 0.0 (no high threshold). |
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float highThreshold; |
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// The acceleration factor. |
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// When the speed is above the low speed threshold, the velocity will scaled |
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// by an interpolated value between 1.0 and this amount. |
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// |
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// Must be a positive greater than or equal to 1.0. |
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// Default is 1.0 (no acceleration). |
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float acceleration; |
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VelocityControlParameters() : |
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scale(1.0f), lowThreshold(0.0f), highThreshold(0.0f), acceleration(1.0f) { |
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} |
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VelocityControlParameters(float scale, float lowThreshold, |
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float highThreshold, float acceleration) : |
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scale(scale), lowThreshold(lowThreshold), |
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highThreshold(highThreshold), acceleration(acceleration) { |
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} |
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}; |
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/* |
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* Implements mouse pointer and wheel speed control and acceleration. |
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*/ |
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class VelocityControl { |
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public: |
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VelocityControl(); |
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/* Sets the various parameters. */ |
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void setParameters(const VelocityControlParameters& parameters); |
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/* Resets the current movement counters to zero. |
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* This has the effect of nullifying any acceleration. */ |
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void reset(); |
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/* Translates a raw movement delta into an appropriately |
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* scaled / accelerated delta based on the current velocity. */ |
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void move(nsecs_t eventTime, float* deltaX, float* deltaY); |
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private: |
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// If no movements are received within this amount of time, |
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// we assume the movement has stopped and reset the movement counters. |
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static const nsecs_t STOP_TIME = 500 * 1000000; // 500 ms |
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VelocityControlParameters mParameters; |
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nsecs_t mLastMovementTime; |
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VelocityTracker::Position mRawPosition; |
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VelocityTracker mVelocityTracker; |
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}; |
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} // namespace android |
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#endif // _LIBINPUT_VELOCITY_CONTROL_H
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