Mega Code Archive
Using MotionEvent
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/*
* Copyright (C) 2010 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 app.test;
import android.app.Activity;
import android.os.Bundle;
import android.view.ViewGroup;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.content.Context;
import android.os.Build;
import android.util.Log;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
abstract class VersionedGestureDetector {
private static final String TAG = "VersionedGestureDetector";
OnGestureListener mListener;
public static VersionedGestureDetector newInstance(Context context,
OnGestureListener listener) {
final int sdkVersion = Integer.parseInt(Build.VERSION.SDK);
VersionedGestureDetector detector = null;
if (sdkVersion < Build.VERSION_CODES.ECLAIR) {
detector = new CupcakeDetector();
} else if (sdkVersion < Build.VERSION_CODES.FROYO) {
detector = new EclairDetector();
} else {
detector = new FroyoDetector(context);
}
Log.d(TAG, "Created new " + detector.getClass());
detector.mListener = listener;
return detector;
}
public abstract boolean onTouchEvent(MotionEvent ev);
public interface OnGestureListener {
public void onDrag(float dx, float dy);
public void onScale(float scaleFactor);
}
private static class CupcakeDetector extends VersionedGestureDetector {
float mLastTouchX;
float mLastTouchY;
float getActiveX(MotionEvent ev) {
return ev.getX();
}
float getActiveY(MotionEvent ev) {
return ev.getY();
}
boolean shouldDrag() {
return true;
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN: {
mLastTouchX = getActiveX(ev);
mLastTouchY = getActiveY(ev);
break;
}
case MotionEvent.ACTION_MOVE: {
final float x = getActiveX(ev);
final float y = getActiveY(ev);
if (shouldDrag()) {
mListener.onDrag(x - mLastTouchX, y - mLastTouchY);
}
mLastTouchX = x;
mLastTouchY = y;
break;
}
}
return true;
}
}
private static class EclairDetector extends CupcakeDetector {
private static final int INVALID_POINTER_ID = -1;
private int mActivePointerId = INVALID_POINTER_ID;
private int mActivePointerIndex = 0;
@Override
float getActiveX(MotionEvent ev) {
return ev.getX(mActivePointerIndex);
}
@Override
float getActiveY(MotionEvent ev) {
return ev.getY(mActivePointerIndex);
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
mActivePointerId = ev.getPointerId(0);
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
mActivePointerId = INVALID_POINTER_ID;
break;
case MotionEvent.ACTION_POINTER_UP:
final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK)
>> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = ev.getPointerId(pointerIndex);
if (pointerId == mActivePointerId) {
// This was our active pointer going up. Choose a new
// active pointer and adjust accordingly.
final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
mActivePointerId = ev.getPointerId(newPointerIndex);
mLastTouchX = ev.getX(newPointerIndex);
mLastTouchY = ev.getY(newPointerIndex);
}
break;
}
mActivePointerIndex = ev.findPointerIndex(mActivePointerId);
return super.onTouchEvent(ev);
}
}
private static class FroyoDetector extends EclairDetector {
private ScaleGestureDetector mDetector;
public FroyoDetector(Context context) {
mDetector = new ScaleGestureDetector(context,
new ScaleGestureDetector.SimpleOnScaleGestureListener() {
@Override public boolean onScale(ScaleGestureDetector detector) {
mListener.onScale(detector.getScaleFactor());
return true;
}
});
}
@Override
boolean shouldDrag() {
return !mDetector.isInProgress();
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
mDetector.onTouchEvent(ev);
return super.onTouchEvent(ev);
}
}
}
class TouchExampleView extends View {
private Drawable mIcon;
private float mPosX;
private float mPosY;
private VersionedGestureDetector mDetector;
private float mScaleFactor = 1.f;
public TouchExampleView(Context context) {
this(context, null, 0);
}
public TouchExampleView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public TouchExampleView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mIcon = context.getResources().getDrawable(R.drawable.icon);
mIcon.setBounds(0, 0, mIcon.getIntrinsicWidth(), mIcon.getIntrinsicHeight());
mDetector = VersionedGestureDetector.newInstance(context, new GestureCallback());
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
mDetector.onTouchEvent(ev);
return true;
}
@Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save();
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
mIcon.draw(canvas);
canvas.restore();
}
private class GestureCallback implements VersionedGestureDetector.OnGestureListener {
public void onDrag(float dx, float dy) {
mPosX += dx;
mPosY += dy;
invalidate();
}
public void onScale(float scaleFactor) {
mScaleFactor *= scaleFactor;
// Don't let the object get too small or too large.
mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 5.0f));
invalidate();
}
}
}
public class Test extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
TouchExampleView view = new TouchExampleView(this);
view.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.MATCH_PARENT));
setContentView(view);
}
}
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