michael@0: /* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
michael@0:  * You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: package org.mozilla.gecko;
michael@0: 
michael@0: import java.util.Timer;
michael@0: import java.util.TimerTask;
michael@0: 
michael@0: import org.mozilla.gecko.util.GamepadUtils;
michael@0: 
michael@0: import android.view.InputDevice;
michael@0: import android.view.MotionEvent;
michael@0: import android.view.View;
michael@0: 
michael@0: public class ScrollAnimator implements View.OnGenericMotionListener {
michael@0:     private Timer mScrollTimer;
michael@0:     private int mX;
michael@0:     private int mY;
michael@0: 
michael@0:     // Assuming 60fps, this will make the view scroll once per frame
michael@0:     static final long MS_PER_FRAME = 1000 / 60;
michael@0: 
michael@0:     // Maximum number of pixels that can be scrolled per frame
michael@0:     static final float MAX_SCROLL = 0.075f * GeckoAppShell.getDpi();
michael@0: 
michael@0:     private class ScrollRunnable extends TimerTask {
michael@0:         private View mView;
michael@0: 
michael@0:         public ScrollRunnable(View view) {
michael@0:             mView = view;
michael@0:         }
michael@0: 
michael@0:         @Override
michael@0:         public final void run() {
michael@0:             mView.scrollBy(mX, mY);
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     @Override
michael@0:     public boolean onGenericMotion(View view, MotionEvent event) {
michael@0:         if ((event.getSource() & InputDevice.SOURCE_CLASS_JOYSTICK) != 0) {
michael@0:             switch (event.getAction()) {
michael@0:             case MotionEvent.ACTION_MOVE:
michael@0:                 // Cancel the animation if the joystick is in a neutral position
michael@0:                 if (GamepadUtils.isValueInDeadZone(event, MotionEvent.AXIS_X) &&
michael@0:                         GamepadUtils.isValueInDeadZone(event, MotionEvent.AXIS_Y)) {
michael@0:                     if (mScrollTimer != null) {
michael@0:                         mScrollTimer.cancel();
michael@0:                         mScrollTimer = null;
michael@0:                     }
michael@0:                     return true;
michael@0:                 }
michael@0: 
michael@0:                 // Scroll with a velocity relative to the screen DPI
michael@0:                 mX = (int) (event.getAxisValue(MotionEvent.AXIS_X) * MAX_SCROLL);
michael@0:                 mY = (int) (event.getAxisValue(MotionEvent.AXIS_Y) * MAX_SCROLL);
michael@0: 
michael@0:                 // Start the timer; the view will continue to scroll as long as
michael@0:                 // the joystick is not in the deadzone.
michael@0:                 if (mScrollTimer == null) {
michael@0:                     mScrollTimer = new Timer();
michael@0:                     ScrollRunnable task = new ScrollRunnable(view);
michael@0:                     mScrollTimer.scheduleAtFixedRate(task, 0, MS_PER_FRAME);
michael@0:                 }
michael@0: 
michael@0:                 return true;
michael@0:             }
michael@0:         }
michael@0: 
michael@0:         return false;
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Cancels the running scroll animation if it is in progress.
michael@0:      */
michael@0:     public void cancel() {
michael@0:         if (mScrollTimer != null) {
michael@0:             mScrollTimer.cancel();
michael@0:             mScrollTimer = null;
michael@0:         }
michael@0:     }
michael@0: }