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/*
* Copyright (C) 2012 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 android.view;
import android.os.Handler;
import android.os.Handler.Callback;
import android.os.Message;
import android.os.SystemClock;
import android.os.SystemProperties;
/**
* This class creates trackball events from touchpad events.
*
* @see ViewRootImpl
*/
class SimulatedTrackball {
// Maximum difference in milliseconds between the down and up of a touch
// event for it to be considered a tap
// TODO:Read this value from a configuration file
private static final int MAX_TAP_TIME = 250;
private static final int FLICK_MSG_ID = 313;
// The position of the previous touchpad event
private float mLastTouchpadXPosition;
private float mLastTouchpadYPosition;
// Where the touchpad was initially pressed
private float mTouchpadEnterXPosition;
private float mTouchpadEnterYPosition;
// When the most recent ACTION_HOVER_ENTER occurred
private long mLastTouchPadStartTimeMs = 0;
// When the most recent direction key was sent
private long mLastTouchPadKeySendTimeMs = 0;
// When the most recent touch event of any type occurred
private long mLastTouchPadEventTimeMs = 0;
// How quickly keys were sent;
private int mKeySendRateMs = 0;
private int mLastKeySent;
// Last movement in device screen pixels
private float mLastMoveX = 0;
private float mLastMoveY = 0;
// Offset from the initial touch. Gets reset as direction keys are sent.
private float mAccumulatedX;
private float mAccumulatedY;
// Change in position allowed during tap events
private float mTouchSlop;
private float mTouchSlopSquared;
// Has the TouchSlop constraint been invalidated
private boolean mAlwaysInTapRegion = true;
// Most recent event. Used to determine what device sent the event.
private MotionEvent mRecentEvent;
// TODO: Currently using screen dimensions tuned to a Galaxy Nexus, need to
// read this from a config file instead
private int mDistancePerTick;
private int mDistancePerTickSquared;
// Highest rate that the flinged events can occur at before dying out
private int mMaxRepeatDelay;
// The square of the minimum distance needed for a flick to register
private int mMinFlickDistanceSquared;
// How quickly the repeated events die off
private float mFlickDecay;
public SimulatedTrackball() {
mDistancePerTick = SystemProperties.getInt("persist.vr_dist_tick", 64);
mDistancePerTickSquared = mDistancePerTick * mDistancePerTick;
mMaxRepeatDelay = SystemProperties.getInt("persist.vr_repeat_delay", 300);
mMinFlickDistanceSquared = SystemProperties.getInt("persist.vr_min_flick", 20);
mMinFlickDistanceSquared *= mMinFlickDistanceSquared;
mFlickDecay = Float.parseFloat(SystemProperties.get(
"persist.sys.vr_flick_decay", "1.3"));
mTouchSlop = ViewConfiguration.getTouchSlop();
mTouchSlopSquared = mTouchSlop * mTouchSlop;
}
private final Handler mHandler = new Handler(new Callback() {
@Override
public boolean handleMessage(Message msg) {
if (msg.what != FLICK_MSG_ID)
return false;
final long time = SystemClock.uptimeMillis();
ViewRootImpl viewroot = (ViewRootImpl) msg.obj;
// Send the key
viewroot.enqueueInputEvent(new KeyEvent(time, time,
KeyEvent.ACTION_DOWN, msg.arg2, 0, mRecentEvent.getMetaState(),
mRecentEvent.getDeviceId(), 0,
KeyEvent.FLAG_FALLBACK, mRecentEvent.getSource()));
viewroot.enqueueInputEvent(new KeyEvent(time, time,
KeyEvent.ACTION_UP, msg.arg2, 0, mRecentEvent.getMetaState(),
mRecentEvent.getDeviceId(), 0,
KeyEvent.FLAG_FALLBACK, mRecentEvent.getSource()));
Message msgCopy = Message.obtain(msg);
// Increase the delay by the decay factor
msgCopy.arg1 = (int) Math.ceil(mFlickDecay * msgCopy.arg1);
if (msgCopy.arg1 <= mMaxRepeatDelay) {
// Send the key again in arg1 milliseconds
mHandler.sendMessageDelayed(msgCopy, msgCopy.arg1);
}
return false;
}
});
public void updateTrackballDirection(ViewRootImpl viewroot, MotionEvent event) {
// Store what time the touchpad event occurred
final long time = SystemClock.uptimeMillis();
switch (event.getAction()) {
case MotionEvent.ACTION_HOVER_ENTER:
mLastTouchPadStartTimeMs = time;
mAlwaysInTapRegion = true;
mTouchpadEnterXPosition = event.getX();
mTouchpadEnterYPosition = event.getY();
mAccumulatedX = 0;
mAccumulatedY = 0;
mLastMoveX = 0;
mLastMoveY = 0;
// Clear any flings
mHandler.removeMessages(FLICK_MSG_ID);
break;
case MotionEvent.ACTION_HOVER_MOVE:
// Determine whether the move is slop or an intentional move
float deltaX = event.getX() - mTouchpadEnterXPosition;
float deltaY = event.getY() - mTouchpadEnterYPosition;
if (mTouchSlopSquared < deltaX * deltaX + deltaY * deltaY) {
mAlwaysInTapRegion = false;
}
// Find the difference in position between the two most recent
// touchpad events
mLastMoveX = event.getX() - mLastTouchpadXPosition;
mLastMoveY = event.getY() - mLastTouchpadYPosition;
mAccumulatedX += mLastMoveX;
mAccumulatedY += mLastMoveY;
float mAccumulatedXSquared = mAccumulatedX * mAccumulatedX;
float mAccumulatedYSquared = mAccumulatedY * mAccumulatedY;
// Determine if we've moved far enough to send a key press
if (mAccumulatedXSquared > mDistancePerTickSquared ||
mAccumulatedYSquared > mDistancePerTickSquared) {
float dominantAxis;
float sign;
boolean isXAxis;
int key;
int repeatCount = 0;
// Determine dominant axis
if (mAccumulatedXSquared > mAccumulatedYSquared) {
dominantAxis = mAccumulatedX;
isXAxis = true;
} else {
dominantAxis = mAccumulatedY;
isXAxis = false;
}
// Determine sign of axis
sign = (dominantAxis > 0) ? 1 : -1;
// Determine key to send
if (isXAxis) {
key = (sign == 1) ? KeyEvent.KEYCODE_DPAD_RIGHT :
KeyEvent.KEYCODE_DPAD_LEFT;
} else {
key = (sign == 1) ? KeyEvent.KEYCODE_DPAD_DOWN : KeyEvent.KEYCODE_DPAD_UP;
}
// Send key until maximum distance constraint is satisfied
while (dominantAxis * dominantAxis > mDistancePerTickSquared) {
repeatCount++;
dominantAxis -= sign * mDistancePerTick;
viewroot.enqueueInputEvent(new KeyEvent(time, time,
KeyEvent.ACTION_DOWN, key, 0, event.getMetaState(),
event.getDeviceId(), 0, KeyEvent.FLAG_FALLBACK, event.getSource()));
viewroot.enqueueInputEvent(new KeyEvent(time, time,
KeyEvent.ACTION_UP, key, 0, event.getMetaState(),
event.getDeviceId(), 0, KeyEvent.FLAG_FALLBACK, event.getSource()));
}
// Save new axis values
mAccumulatedX = isXAxis ? dominantAxis : 0;
mAccumulatedY = isXAxis ? 0 : dominantAxis;
mLastKeySent = key;
mKeySendRateMs = (int) ((time - mLastTouchPadKeySendTimeMs) / repeatCount);
mLastTouchPadKeySendTimeMs = time;
}
break;
case MotionEvent.ACTION_HOVER_EXIT:
if (time - mLastTouchPadStartTimeMs < MAX_TAP_TIME && mAlwaysInTapRegion) {
// Trackball Down
MotionEvent trackballEvent = MotionEvent.obtain(mLastTouchPadStartTimeMs, time,
MotionEvent.ACTION_DOWN, 0, 0, 0, 0, event.getMetaState(),
10f, 10f, event.getDeviceId(), 0);
trackballEvent.setSource(InputDevice.SOURCE_CLASS_TRACKBALL);
viewroot.enqueueInputEvent(trackballEvent);
// Trackball Release
trackballEvent = MotionEvent.obtain(mLastTouchPadStartTimeMs, time,
MotionEvent.ACTION_UP, 0, 0, 0, 0, event.getMetaState(),
10f, 10f, event.getDeviceId(), 0);
trackballEvent.setSource(InputDevice.SOURCE_CLASS_TRACKBALL);
viewroot.enqueueInputEvent(trackballEvent);
} else {
float xMoveSquared = mLastMoveX * mLastMoveX;
float yMoveSquared = mLastMoveY * mLastMoveY;
// Determine whether the last gesture was a fling.
if (mMinFlickDistanceSquared <= xMoveSquared + yMoveSquared &&
time - mLastTouchPadEventTimeMs <= MAX_TAP_TIME &&
mKeySendRateMs <= mMaxRepeatDelay && mKeySendRateMs > 0) {
Message message = Message.obtain(mHandler, FLICK_MSG_ID,
mKeySendRateMs, mLastKeySent, viewroot);
mRecentEvent = event;
mHandler.sendMessageDelayed(message, mKeySendRateMs);
}
}
break;
}
// Store touch event position and time
mLastTouchPadEventTimeMs = time;
mLastTouchpadXPosition = event.getX();
mLastTouchpadYPosition = event.getY();
}
}
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