Thứ Ba, 17 tháng 7, 2012

Implement GestureDetector/OnGestureListener to detect Fling, and ObjectAnimator for ImageView

0
15:50
In this exercise, I will implement GestureDetector with OnGestureListener for a ImageView of icon. Once the user fling on the icon, it will be moved (animated using ObjectAnimator).



package com.example.androidanimatefling;

import android.os.Bundle;
import android.animation.ObjectAnimator;
import android.app.Activity;
import android.util.DisplayMetrics;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.view.GestureDetector.OnGestureListener;
import android.view.View.OnTouchListener;
import android.widget.FrameLayout;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends Activity {

TextView info;
ImageView flingObj;
FrameLayout mainScreen;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

info = (TextView)findViewById(R.id.info);
flingObj = (ImageView)findViewById(R.id.flingobject);
mainScreen = (FrameLayout)findViewById(R.id.mainscreen);

final GestureDetector myGesture = new GestureDetector(this, new MyOnGestureListener());

flingObj.setOnTouchListener(new OnTouchListener(){

@Override
public boolean onTouch(View v, MotionEvent event) {
return myGesture.onTouchEvent(event);
}});

flingObj.setClickable(true);

}

class MyOnGestureListener implements OnGestureListener{

int MIN_DIST = 100;

@Override
public boolean onDown(MotionEvent arg0) {
// TODO Auto-generated method stub
return false;
}

@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
float e1X = e1.getX();
float e1Y = e1.getY();
float e2X = e2.getX();
float e2Y = e2.getY();
float distX = e2X - e1X;
float distY = e2Y - e1Y;

info.setText(
"e1X e1Y : " + String.valueOf(e1X) + " : " + String.valueOf(e1Y) + "\n" +
"e2X e2Y : " + String.valueOf(e2X) + " : " + String.valueOf(e2Y) + "\n" +
"velocityX : " + String.valueOf(velocityX) + "\n" +
"velocityY : " + String.valueOf(velocityY));

//Get the Y OFfset
DisplayMetrics displayMetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
int offsetY = displayMetrics.heightPixels - mainScreen.getMeasuredHeight();

int[] location = new int[2];
flingObj.getLocationOnScreen(location);
float orgX = location[0];
float orgY = location[1] - offsetY;

float stopX = orgX + distX;
float stopY = orgY + distY;

if (distX > MIN_DIST) {
//Fling Right
ObjectAnimator flingAnimator = ObjectAnimator.ofFloat(flingObj, "translationX", orgX, stopX);
flingAnimator.setDuration(1000);
flingAnimator.start();
}else if(distX < - MIN_DIST){
//Fling Left
ObjectAnimator flingAnimator = ObjectAnimator.ofFloat(flingObj, "translationX", orgX, stopX);
flingAnimator.setDuration(1000);
flingAnimator.start();
}else if (distY > MIN_DIST) {
//Fling Down
ObjectAnimator flingAnimator = ObjectAnimator.ofFloat(flingObj, "translationY", orgY, stopY);
flingAnimator.setDuration(1000);
flingAnimator.start();
}else if(distY < - MIN_DIST){
//Fling Up
ObjectAnimator flingAnimator = ObjectAnimator.ofFloat(flingObj, "translationY", orgY, stopY);
flingAnimator.setDuration(1000);
flingAnimator.start();
}

return true;
}

@Override
public void onLongPress(MotionEvent e) {
// TODO Auto-generated method stub

}

@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2,
float distanceX, float distanceY) {
// TODO Auto-generated method stub
return false;
}

@Override
public void onShowPress(MotionEvent e) {
// TODO Auto-generated method stub

}

@Override
public boolean onSingleTapUp(MotionEvent e) {
// TODO Auto-generated method stub
return false;
}};

}


<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/mainscreen">

<TextView
android:id="@+id/info"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>

<ImageView
android:id="@+id/flingobject"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="@dimen/padding_medium"
android:src="@drawable/ic_launcher"
tools:context=".MainActivity" />

</FrameLayout>


In order to use android.animation.ObjectAnimator, minSdkVersion="11" is needed.

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