1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/widget/gonk/libui/VelocityControl.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,107 @@
1.4 +/*
1.5 + * Copyright (C) 2012 The Android Open Source Project
1.6 + *
1.7 + * Licensed under the Apache License, Version 2.0 (the "License");
1.8 + * you may not use this file except in compliance with the License.
1.9 + * You may obtain a copy of the License at
1.10 + *
1.11 + * http://www.apache.org/licenses/LICENSE-2.0
1.12 + *
1.13 + * Unless required by applicable law or agreed to in writing, software
1.14 + * distributed under the License is distributed on an "AS IS" BASIS,
1.15 + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
1.16 + * See the License for the specific language governing permissions and
1.17 + * limitations under the License.
1.18 + */
1.19 +
1.20 +#ifndef _ANDROIDFW_VELOCITY_CONTROL_H
1.21 +#define _ANDROIDFW_VELOCITY_CONTROL_H
1.22 +
1.23 +#include "Input.h"
1.24 +#include "VelocityTracker.h"
1.25 +#include <utils/Timers.h>
1.26 +
1.27 +namespace android {
1.28 +
1.29 +/*
1.30 + * Specifies parameters that govern pointer or wheel acceleration.
1.31 + */
1.32 +struct VelocityControlParameters {
1.33 + // A scale factor that is multiplied with the raw velocity deltas
1.34 + // prior to applying any other velocity control factors. The scale
1.35 + // factor should be used to adapt the input device resolution
1.36 + // (eg. counts per inch) to the output device resolution (eg. pixels per inch).
1.37 + //
1.38 + // Must be a positive value.
1.39 + // Default is 1.0 (no scaling).
1.40 + float scale;
1.41 +
1.42 + // The scaled speed at which acceleration begins to be applied.
1.43 + // This value establishes the upper bound of a low speed regime for
1.44 + // small precise motions that are performed without any acceleration.
1.45 + //
1.46 + // Must be a non-negative value.
1.47 + // Default is 0.0 (no low threshold).
1.48 + float lowThreshold;
1.49 +
1.50 + // The scaled speed at which maximum acceleration is applied.
1.51 + // The difference between highThreshold and lowThreshold controls
1.52 + // the range of speeds over which the acceleration factor is interpolated.
1.53 + // The wider the range, the smoother the acceleration.
1.54 + //
1.55 + // Must be a non-negative value greater than or equal to lowThreshold.
1.56 + // Default is 0.0 (no high threshold).
1.57 + float highThreshold;
1.58 +
1.59 + // The acceleration factor.
1.60 + // When the speed is above the low speed threshold, the velocity will scaled
1.61 + // by an interpolated value between 1.0 and this amount.
1.62 + //
1.63 + // Must be a positive greater than or equal to 1.0.
1.64 + // Default is 1.0 (no acceleration).
1.65 + float acceleration;
1.66 +
1.67 + VelocityControlParameters() :
1.68 + scale(1.0f), lowThreshold(0.0f), highThreshold(0.0f), acceleration(1.0f) {
1.69 + }
1.70 +
1.71 + VelocityControlParameters(float scale, float lowThreshold,
1.72 + float highThreshold, float acceleration) :
1.73 + scale(scale), lowThreshold(lowThreshold),
1.74 + highThreshold(highThreshold), acceleration(acceleration) {
1.75 + }
1.76 +};
1.77 +
1.78 +/*
1.79 + * Implements mouse pointer and wheel speed control and acceleration.
1.80 + */
1.81 +class VelocityControl {
1.82 +public:
1.83 + VelocityControl();
1.84 +
1.85 + /* Sets the various parameters. */
1.86 + void setParameters(const VelocityControlParameters& parameters);
1.87 +
1.88 + /* Resets the current movement counters to zero.
1.89 + * This has the effect of nullifying any acceleration. */
1.90 + void reset();
1.91 +
1.92 + /* Translates a raw movement delta into an appropriately
1.93 + * scaled / accelerated delta based on the current velocity. */
1.94 + void move(nsecs_t eventTime, float* deltaX, float* deltaY);
1.95 +
1.96 +private:
1.97 + // If no movements are received within this amount of time,
1.98 + // we assume the movement has stopped and reset the movement counters.
1.99 + static const nsecs_t STOP_TIME = 500 * 1000000; // 500 ms
1.100 +
1.101 + VelocityControlParameters mParameters;
1.102 +
1.103 + nsecs_t mLastMovementTime;
1.104 + VelocityTracker::Position mRawPosition;
1.105 + VelocityTracker mVelocityTracker;
1.106 +};
1.107 +
1.108 +} // namespace android
1.109 +
1.110 +#endif // _ANDROIDFW_VELOCITY_CONTROL_H
