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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 #package_name#;
import android.app.Activity;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.ImageView;
import #ManifestPackageName#.R;
public class #class_name# extends Activity {
private ImageView imgView;
//available operations
private final int MOVE = 1;
private final int ZOOM = 2;
private int action = 0;
PointF startPoint = new PointF();
PointF centerPoint = new PointF();
//holds previous state information
private double prevDist = 0;
private Matrix curMatrix = new Matrix();
private Matrix auxMatrix = new Matrix();
//Minimum distance between fingers
private Double MIN_DISTANCE;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.#layout_name#multitouch_event/multitouchlayout.xml#);
// convert dip measurements to pixels. Screen independent value.
final float scale = getResources().getDisplayMetrics().density;
MIN_DISTANCE = (double) ( 15.0f * scale + 0.5f );
//loads image view
imgView = (ImageView) findViewById(R.id.img01);
imgView.setImageMatrix(curMatrix);
imgView.setImageResource(R.drawable.#drawable_name#multitouch_event/multitouch.jpg#);
imgView.setVisibility(View.VISIBLE);
imgView.setOnTouchListener(new OnTouchListener(){
public boolean onTouch(View v, MotionEvent event) {
ImageView view = (ImageView)v;
//get the 8 bits that represents the action itself
int eventType = event.getAction() & MotionEvent.ACTION_MASK;
switch (eventType) {
//first touch
case MotionEvent.ACTION_DOWN:
action = MOVE;
auxMatrix.set(curMatrix);
startPoint.set(event.getX(), event.getY());
break;
//second touch
case MotionEvent.ACTION_POINTER_DOWN:
prevDist = distance(event);
if (prevDist > MIN_DISTANCE) {
action = ZOOM;
auxMatrix.set(curMatrix);
//used to center the image
centerPoint = mean(event);
}
break;
//movement event
case MotionEvent.ACTION_MOVE:
//using one finger we drag the image
if (action == MOVE) {
curMatrix.set(auxMatrix);
//moves the image
curMatrix.postTranslate(event.getX() - startPoint.x,
event.getY() - startPoint.y);
}
//using two fingers, zoom in or out and rotate the image
else if (action == ZOOM)
{
double curDist = distance(event);
if (curDist > MIN_DISTANCE) {
curMatrix.set(auxMatrix);
//relation between fingers distance
Double scale = curDist / prevDist;
//resize image keeping its center position
curMatrix.postScale(scale.floatValue(), scale.floatValue(),
centerPoint.x, centerPoint.y);
}
}
break;
}
//apply changes
view.setImageMatrix(curMatrix);
return true;
}});
}
/*distance between the two fingers of dual touch event*/
private double distance(MotionEvent event) {
float dy = event.getY(1) - event.getY(0);
float dx = event.getX(1) - event.getX(0);
dx *= dx;
dy *= dy;
return Math.sqrt(dx + dy);
}
/*evaluates the center point*/
private PointF mean(MotionEvent event) {
PointF point = new PointF();
float dy = event.getY(1) + event.getY(0);
float dx = event.getX(1) + event.getX(0);
point.set(dx / 2, dy / 2);
return point;
}
}
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