/*
* Copyright (C) 2012 Google Inc. All rights reserved.
*
* 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.
*/
// BACKPORTED FROM ANDROID PUBLIC REPOSITORY
package com.example.google.tv.anymotelibrary.touch;
import android.view.MotionEvent;
/**
* Detects transformation gestures involving more than one pointer
* ("multitouch") using the supplied {@link MotionEvent}s. The
* {@link OnScaleGestureListener} callback will notify users when a particular
* gesture event has occurred. This class should only be used with
* {@link MotionEvent}s reported via touch. To use this class:
* <ul>
* <li>Create an instance of the {@code ScaleGestureDetector} for your
* {@link View}
* <li>In the {@link View#onTouchEvent(MotionEvent)} method ensure you call
* {@link #onTouchEvent(MotionEvent)}. The methods defined in your callback will
* be executed when the events occur.
* </ul>
*/
public interface ScaleGestureDetector {
/**
* The listener for receiving notifications when gestures occur. If you want
* to listen for all the different gestures then implement this interface.
* If you only want to listen for a subset it might be easier to extend
* {@link SimpleOnScaleGestureListener}. An application will receive events
* in the following order:
* <ul>
* <li>One {@link OnScaleGestureListener#onScaleBegin(ScaleGestureDetector)}
* <li>Zero or more
* {@link OnScaleGestureListener#onScale(ScaleGestureDetector)}
* <li>One {@link OnScaleGestureListener#onScaleEnd(ScaleGestureDetector)}
* </ul>
*/
public interface OnScaleGestureListener {
/**
* Responds to scaling events for a gesture in progress. Reported by
* pointer motion.
*
* @param detector The detector reporting the event - use this to
* retrieve extended info about event state.
* @return Whether or not the detector should consider this event as
* handled. If an event was not handled, the detector will
* continue to accumulate movement until an event is handled.
* This can be useful if an application, for example, only wants
* to update scaling factors if the change is greater than 0.01.
*/
public boolean onScale(ScaleGestureDetector detector);
/**
* Responds to the beginning of a scaling gesture. Reported by new
* pointers going down.
*
* @param detector The detector reporting the event - use this to
* retrieve extended info about event state.
* @return Whether or not the detector should continue recognizing this
* gesture. For example, if a gesture is beginning with a focal
* point outside of a region where it makes sense,
* onScaleBegin() may return false to ignore the rest of the
* gesture.
*/
public boolean onScaleBegin(ScaleGestureDetector detector);
/**
* Responds to the end of a scale gesture. Reported by existing pointers
* going up. Once a scale has ended,
* {@link ScaleGestureDetector#getFocusX()} and
* {@link ScaleGestureDetector#getFocusY()} will return the location of
* the pointer remaining on the screen.
*
* @param detector The detector reporting the event - use this to
* retrieve extended info about event state.
*/
public void onScaleEnd(ScaleGestureDetector detector);
}
/**
* A convenience class to extend when you only want to listen for a subset
* of scaling-related events. This implements all methods in
* {@link OnScaleGestureListener} but does nothing.
* {@link OnScaleGestureListener#onScale(ScaleGestureDetector)} returns
* {@code false} so that a subclass can retrieve the accumulated scale
* factor in an overridden onScaleEnd.
* {@link OnScaleGestureListener#onScaleBegin(ScaleGestureDetector)} returns
* {@code true}.
*/
public static class SimpleOnScaleGestureListener
implements OnScaleGestureListener {
public boolean onScale(ScaleGestureDetector detector) {
return false;
}
public boolean onScaleBegin(ScaleGestureDetector detector) {
return true;
}
public void onScaleEnd(ScaleGestureDetector detector) {
// Intentionally empty
}
}
/**
* Returns {@code true} if a two-finger scale gesture is in progress.
*
* @return {@code true} if a scale gesture is in progress, {@code false}
* otherwise.
*/
public boolean isInProgress();
/**
* Get the X coordinate of the current gesture's focal point. If a gesture
* is in progress, the focal point is directly between the two pointers
* forming the gesture. If a gesture is ending, the focal point is the
* location of the remaining pointer on the screen. If
* {@link #isInProgress()} would return false, the result of this function
* is undefined.
*
* @return X coordinate of the focal point in pixels.
*/
public float getFocusX();
/**
* Get the Y coordinate of the current gesture's focal point. If a gesture
* is in progress, the focal point is directly between the two pointers
* forming the gesture. If a gesture is ending, the focal point is the
* location of the remaining pointer on the screen. If
* {@link #isInProgress()} would return false, the result of this function
* is undefined.
*
* @return Y coordinate of the focal point in pixels.
*/
public float getFocusY();
/**
* Return the current distance between the two pointers forming the gesture
* in progress.
*
* @return Distance between pointers in pixels.
*/
public float getCurrentSpan();
/**
* Return the previous distance between the two pointers forming the gesture
* in progress.
*
* @return Previous distance between pointers in pixels.
*/
public float getPreviousSpan();
/**
* Return the scaling factor from the previous scale event to the current
* event. This value is defined as ({@link #getCurrentSpan()} /
* {@link #getPreviousSpan()}).
*
* @return The current scaling factor.
*/
public float getScaleFactor();
/**
* Return the time difference in milliseconds between the previous accepted
* scaling event and the current scaling event.
*
* @return Time difference since the last scaling event in milliseconds.
*/
public long getTimeDelta();
/**
* Return the event time of the current event being processed.
*
* @return Current event time in milliseconds.
*/
public long getEventTime();
public boolean onTouchEvent(MotionEvent event);
}