com.sun.glass.ui.monocle.LookaheadTouchFilter Maven / Gradle / Ivy
/*
* Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
package com.sun.glass.ui.monocle;
class LookaheadTouchFilter implements TouchFilter {
private TouchState previousState = new TouchState();
private TouchState tmpState = new TouchState();
private boolean assignIDs;
private enum FilterState {
/** No events processed yet */
CLEAN,
/**
* previousState contains an event that must be sent as is. This will
* happen when an event is the first to be processed on this pulse, or
* "Substantially different" means that two events differ in the number
* of touch points or in the IDs assigned to those points.
*/
PENDING_UNMODIFIABLE,
/**
* previousState contains an event that we are allowed to change before
* sending. An event can be modified if it is substantially different
* neither from the event that preceded it nor from the event that
* follows it.
*/
PENDING_MODIFIABLE
}
private FilterState filterState = FilterState.CLEAN;
/**
* Creates a new LookaheadTouchFilter
*
* @param assignIDs Sets whether or not we are asking the touch pipeline to
* assign touch point IDs
*/
LookaheadTouchFilter(boolean assignIDs) {
this.assignIDs = assignIDs;
}
@Override
public boolean filter(TouchState state) {
state.sortPointsByID();
switch (filterState) {
case CLEAN:
state.copyTo(previousState);
filterState = FilterState.PENDING_UNMODIFIABLE;
return true;
case PENDING_UNMODIFIABLE:
// send the previous state and hold the new state as pending
state.copyTo(tmpState);
previousState.copyTo(state);
tmpState.copyTo(previousState);
if (state.canBeFoldedWith(previousState, assignIDs)) {
filterState = FilterState.PENDING_MODIFIABLE;
}
return false;
case PENDING_MODIFIABLE:
if (state.canBeFoldedWith(previousState, assignIDs)) {
state.copyTo(previousState);
return true;
} else {
// send the previous state and hold the new state as pending
state.copyTo(tmpState);
previousState.copyTo(state);
tmpState.copyTo(previousState);
filterState = FilterState.PENDING_UNMODIFIABLE;
return false;
}
default:
return false;
}
}
@Override
public boolean flush(TouchState state) {
switch (filterState) {
case PENDING_MODIFIABLE:
case PENDING_UNMODIFIABLE:
previousState.copyTo(state);
filterState = FilterState.CLEAN;
return true;
default:
return false;
}
}
@Override
public int getPriority() {
return PRIORITY_PRE_ID + 1;
}
@Override
public String toString() {
return "Lookahead[previousState="
+ previousState
+ ",filterState=" + filterState
+ "]";
}
}