The Tor Browser: mobile/android/base/ScrollAnimator.java@fc2d59ddac77

     1 /* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-

     2 /* This Source Code Form is subject to the terms of the Mozilla Public

     3  * License, v. 2.0. If a copy of the MPL was not distributed with this file,

     4  * You can obtain one at http://mozilla.org/MPL/2.0/. */

     6 package org.mozilla.gecko;

     8 import java.util.Timer;

     9 import java.util.TimerTask;

    11 import org.mozilla.gecko.util.GamepadUtils;

    13 import android.view.InputDevice;

    14 import android.view.MotionEvent;

    15 import android.view.View;

    17 public class ScrollAnimator implements View.OnGenericMotionListener {

    18     private Timer mScrollTimer;

    19     private int mX;

    20     private int mY;

    22     // Assuming 60fps, this will make the view scroll once per frame

    23     static final long MS_PER_FRAME = 1000 / 60;

    25     // Maximum number of pixels that can be scrolled per frame

    26     static final float MAX_SCROLL = 0.075f * GeckoAppShell.getDpi();

    28     private class ScrollRunnable extends TimerTask {

    29         private View mView;

    31         public ScrollRunnable(View view) {

    32             mView = view;

    33         }

    35         @Override

    36         public final void run() {

    37             mView.scrollBy(mX, mY);

    38         }

    39     }

    41     @Override

    42     public boolean onGenericMotion(View view, MotionEvent event) {

    43         if ((event.getSource() & InputDevice.SOURCE_CLASS_JOYSTICK) != 0) {

    44             switch (event.getAction()) {

    45             case MotionEvent.ACTION_MOVE:

    46                 // Cancel the animation if the joystick is in a neutral position

    47                 if (GamepadUtils.isValueInDeadZone(event, MotionEvent.AXIS_X) &&

    48                         GamepadUtils.isValueInDeadZone(event, MotionEvent.AXIS_Y)) {

    49                     if (mScrollTimer != null) {

    50                         mScrollTimer.cancel();

    51                         mScrollTimer = null;

    52                     }

    53                     return true;

    54                 }

    56                 // Scroll with a velocity relative to the screen DPI

    57                 mX = (int) (event.getAxisValue(MotionEvent.AXIS_X) * MAX_SCROLL);

    58                 mY = (int) (event.getAxisValue(MotionEvent.AXIS_Y) * MAX_SCROLL);

    60                 // Start the timer; the view will continue to scroll as long as

    61                 // the joystick is not in the deadzone.

    62                 if (mScrollTimer == null) {

    63                     mScrollTimer = new Timer();

    64                     ScrollRunnable task = new ScrollRunnable(view);

    65                     mScrollTimer.scheduleAtFixedRate(task, 0, MS_PER_FRAME);

    66                 }

    68                 return true;

    69             }

    70         }

    72         return false;

    73     }

    75     /**

    76      * Cancels the running scroll animation if it is in progress.

    77      */

    78     public void cancel() {

    79         if (mScrollTimer != null) {

    80             mScrollTimer.cancel();

    81             mScrollTimer = null;

    82         }

    83     }

    84 }

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