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/*
* Copyright (C) 2016 The Android Open Source Project
*
* 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.
*/
package org.chromium.latency.walt;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;
public class TouchCatcherView extends View {
private Paint linePaint = new Paint();
private Paint centerLinePaint = new Paint(); // for positioning the laser
private WaltDevice waltDevice;
private boolean isAnimated = false;
private double animationAmplitude = 0.4; // Fraction of view height
private double lineLength = 0.6; // Fraction of view width
public final int animationPeriod_us = 1000000;
public void startAnimation() {
isAnimated = true;
invalidate();
}
public void stopAnimation() {
isAnimated = false;
invalidate();
}
public TouchCatcherView(Context context, AttributeSet attrs) {
super(context, attrs);
waltDevice = WaltDevice.getInstance(context);
initialisePaint();
}
private void initialisePaint() {
float density = getResources().getDisplayMetrics().density;
float lineWidth = 10f * density;
float centerLineWidth = 3f * density;
linePaint.setColor(Color.GREEN);
linePaint.setStrokeWidth(lineWidth);
centerLinePaint.setColor(Color.GREEN);
centerLinePaint.setStrokeWidth(centerLineWidth);
}
public static double markerPosition(long t_us, int period_us) {
// Normalized time within a period, goes from 0 to 1
double t = (t_us % period_us) / (double) period_us;
// Triangular wave with unit amplitude
// 1| * *
// | * * *
// 0-----*-------*---|---*-----> t
// | * * 1 *
// -1| * *
double y_tri = -1 + 4 * Math.abs(t - 0.5);
// Apply some smoothing to get a feeling of deceleration and acceleration at the edges.
// f(y) = y / {1 + exp(b(|y|-1))/(b-1)}
// This is inspired by Fermi function and adjusted to have continuous derivative at extrema.
// b = beta is a dimensionless smoothing parameter, value selected by experimentation.
// Higher value gives less smoothing = closer to original triangular wave.
double beta = 4;
double y_smooth = y_tri / (1 + Math.exp(beta*(Math.abs(y_tri)-1))/(beta - 1));
return y_smooth;
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if (!isAnimated) return;
int h = getHeight();
double normPos = markerPosition(waltDevice.clock.micros(), animationPeriod_us);
int pos = (int) (h * (0.5 + animationAmplitude * normPos));
int centerPos = (int) (h * 0.5);
// Log.i("AnimatedView", "Pos is " + pos);
int w = getWidth();
int lineStart = (int) (w * (1 - lineLength) / 2);
int lineEnd = (int) (w * (1 + lineLength) / 2);
canvas.drawLine(0, centerPos, lineStart, centerPos, centerLinePaint);
canvas.drawLine(lineEnd, centerPos, w - 1, centerPos, centerLinePaint);
canvas.drawLine(lineStart, pos, lineEnd, pos, linePaint);
// Run every frame
invalidate();
}
}
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