Develop Reference

Android OOM Error, Loading multiple images

I was looking at this answer over here, however it didn't really fix my problem.
For some reason the manifest.xml doesn't overwrite my changes, even though I deleted my build folder.
I am trying to load up 5 images on the screen, however even after optimizing them; they still run out of memory.
I was watching a video that teaches image scaling. It did solved a small portion of my problem. I am able to load my background image, however I wasn't able to load my other 4 images.
How can I optimize more efficiently? I was watching this video regards Bitmap optimization by Android, however I didn't understand much from it.
Here is my source code
MainActivity.java
package com.example.cliente.myapplication;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ImageView;
public class MainActivity extends AppCompatActivity {
private static final float BYTES_PER_PX = 4.0f;
ImageView backgroundImage, upImage, downImage, leftImage, alertImage;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
backgroundImage = findViewById(R.id.background_image);
loadImage(backgroundImage, R.drawable.background);
upImage = findViewById(R.id.up_arrow_image);
loadImage(upImage, R.drawable.up);
downImage = findViewById(R.id.down_arrow_image);
loadImage(downImage, R.drawable.down);
leftImage = findViewById(R.id.left_arrow_image);
loadImage(leftImage, R.drawable.left);
alertImage = findViewById(R.id.alert_image);
loadImage(alertImage, R.drawable.alert);
}
private void loadImage(ImageView image, int imgSrc) {
if (readBitmapInfo() > MemUtils.megabytesFree()) {
subSampleImage(image, 32);
} else {
image.setImageResource(imgSrc);
}
}
private float readBitmapInfo() {
final Resources res = this.getResources();
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(res, R.drawable.background, options);
final float imageHeight = options.outHeight;
final float imageWidth = options.outWidth;
return imageWidth * imageHeight * BYTES_PER_PX / MemUtils.BYTES_IN_MB;
}
private void subSampleImage(ImageView image, int powerOf2) {
if (powerOf2 < 1 || powerOf2 > 2) {
return;
}
final Resources res = this.getResources();
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = false;
options.inSampleSize = powerOf2;
final Bitmap map = BitmapFactory.decodeResource(res, R.drawable.background, options);
image.setImageBitmap(map);
}
}
MemUtils.java
package com.example.cliente.myapplication;
public class MemUtils {
public static final float BYTES_IN_MB = 1024.0f * 1024.0f;
public static float megabytesFree() {
final Runtime rt = Runtime.getRuntime();
final float bytesUsed = rt.totalMemory();
final float mbUsed = bytesUsed / BYTES_IN_MB;
final float mbFree = megabytesAvailable() - mbUsed;
return mbFree;
}
public static float megabytesAvailable() {
final Runtime rt = Runtime.getRuntime();
final float bytesAvailable = rt.maxMemory();
return bytesAvailable / BYTES_IN_MB;
}
}

So I had 2 errors to begin with.
OOM (out of memory) exception, thanks too #Chisko, I used a library called Picasso to solve my problem.
Another issue was Canvas: trying to draw too large... problem. Which I needed to move my images from drawable-mdpi to drawable-xxhdpi.
Here is the solution to my problem:
package com.example.cliente.myapplication;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ImageView;
import com.squareup.picasso.Picasso;
public class MainActivity extends AppCompatActivity {
ImageView backgroundImage, upImage, downImage, leftImage, alertImage;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
backgroundImage = findViewById(R.id.background_image);
Picasso.get().load(R.drawable.background).into(backgroundImage);
upImage = findViewById(R.id.up_arrow_image);
Picasso.get().load(R.drawable.up).into(upImage);
downImage = findViewById(R.id.down_arrow_image);
Picasso.get().load(R.drawable.down).into(downImage);
leftImage = findViewById(R.id.left_arrow_image);
Picasso.get().load(R.drawable.left).into(leftImage);
alertImage = findViewById(R.id.alert_image);
Picasso.get().load(R.drawable.alert).into(alertImage);
}
}

How to tell if an X and Y coordinate are inside my button?

I have managed, with great difficulty, to make a bitmap overlay the screen. I can also get touch input, however it gets touch input for EVERYWHERE on the screen.
I want to know how I would be able to check if the touch was on my bitmap, which is visible on the screen.
The service and view class is below. I have thought and thought, but I couldn't think of a way to do it :(
package <package>;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.Rect;
import android.os.IBinder;
import android.support.v4.app.NotificationCompat;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.Toast;
public class MyService extends Service {
ButtonView mView;
Bitmap bit;
#Override
public IBinder onBind(Intent intent) {
return null;
}
#Override
public void onCreate() {
super.onCreate();
bit = BitmapFactory.decodeResource(getResources(), R.drawable.button);
NotificationCompat.Builder builder = new NotificationCompat.Builder(
this);
builder.setContentTitle("Ingress Tools Running");
builder.setContentText("Click to stop Ingress Tools");
builder.setSmallIcon(R.drawable.ic_launcher);
builder.setContentIntent(PendingIntent.getActivity(this, 0, new Intent(
this, StopActivity.class), 0));
NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
manager.notify(1, builder.build());
mView = new ButtonView(this, bit);
WindowManager.LayoutParams params = new WindowManager.LayoutParams(
WindowManager.LayoutParams.FILL_PARENT,
WindowManager.LayoutParams.FILL_PARENT,
WindowManager.LayoutParams.TYPE_PHONE,
WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
| WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL
| WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH,
PixelFormat.TRANSLUCENT);
params.gravity = Gravity.RIGHT;
params.setTitle("Load Average");
WindowManager wm = (WindowManager) getSystemService(WINDOW_SERVICE);
wm.addView(mView, params);
}
#Override
public void onDestroy() {
super.onDestroy();
Toast.makeText(getBaseContext(), "onDestroy", Toast.LENGTH_LONG).show();
if (mView != null) {
((WindowManager) getSystemService(WINDOW_SERVICE))
.removeView(mView);
mView = null;
}
}
}
class ButtonView extends ViewGroup {
private Paint mLoadPaint;
private Rect r;
private Bitmap bit;
public ButtonView(Context context, Bitmap bit) {
super(context);
Toast.makeText(context, "HUDView", Toast.LENGTH_LONG).show();
mLoadPaint = new Paint();
mLoadPaint.setAntiAlias(true);
mLoadPaint.setTextSize(10);
mLoadPaint.setARGB(255, 255, 0, 0);
r = new Rect();
r.set(380, 134, 468, 213);
this.bit = bit;
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
//canvas.drawColor(Color.BLACK);
canvas.drawBitmap(bit, 100, 100, null);
}
#Override
protected void onLayout(boolean arg0, int arg1, int arg2, int arg3, int arg4) {
}
#Override
public boolean onTouchEvent(MotionEvent event) {
int area = bit.getWidth() * bit.getHeight();
//if (event.getY() <= maxY && event.getX() <= maxX) {
Toast.makeText(getContext(), "Open tools: ", Toast.LENGTH_LONG)
.show();
//}
return true;
}
}

this works for any view
#Override
public boolean dispatchTouchEvent(MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_UP) {
if (inViewInBounds(myButtonView, (int) event.getRawX(), (int) event.getRawY())) {
// User moved outside bounds
Log.e("dispatchTouchEvent", "you touched inside button");
} else {
Log.e("dispatchTouchEvent", "you touched outside button");
}
}
return super.dispatchTouchEvent(event);
}
Rect outRect = new Rect();
int[] location = new int[2];
private boolean inViewInBounds(View view, int x, int y) {
view.getDrawingRect(outRect);
view.getLocationOnScreen(location);
outRect.offset(location[0], location[1]);
return outRect.contains(x, y);
}

Consider using FrameLayout (or any other subclass of ViewGroup) instead of ViewGroup directly. Because your current implementation of onLayout method is not correct, which will lead you to problems with displaying of child views.
Now, closer to your question. You should ininitialize Rect and just store left, top, right and bottom position of your Bitmap. As I can see, currently you're initialized r variable, but not using it anywhere.
So, you can initialize it like this:
r = new Rect(100, 100, 100 + bit.getWidth(), 100 + bit.getHeight());
Now in onTouchEvent you can just check:
r.contains((int) event.getX(), (int) event.getY());

Rect rect = new Rect();
getHitRect(rect);
if (rect.contains((int) event.getX(), (int) event.getY())) {}
you can use getHitRect(Rect). it returns the Hit rectangle in parent's coordinates. Here the documentation

Use if statement with method if(r.contains(x, y)) on that button which you want to check. This method will return true, when x and y point is inside rectangle r. You can also make public method within that class, so you can access it outside ButtonView class with button object reference.

// We assume MotionEvent is from the direct View parent so we are in the same co-ordindate space
fun View.isWithinBounds(event: MotionEvent): Boolean {
val rect = Rect(x.roundToInt(), y.roundToInt(), (x + width).roundToInt(), (y + height).roundToInt())
return rect.contains(event.x.roundToInt(), event.y.roundToInt())
}

When the "touch event" happens, it's going through all view's tree.
F.e. if you have Linear layout and ImageView on it and user touchs the screen on ImageView, then touch event intercepts and firstly it'll be handled at LinearLayour and then at the ImageView.
If you want to block event f.e. on the bitmap, then you should override onTouchEvent for Bitmap and return true value. This will mean that you handled this event and it won't be available for LinearLayout.
image.setOnTouchListener( new View.OnTouchListener() {
#Override
public boolean onTouch(View view, MotionEvent motionEvent) {
return true; // attentively read documentation for onTouc interface
}
});

Showing result in Android layout

I'm totally new to this and am trying to figure out how to actually show the result of this little function in the layout of android. Have been searching and searching and I can't figure out exactly what it requires.
package com.example.proyectoparteb;
import java.io.IOException;
import java.io.RandomAccessFile;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
readUsage();
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
private float readUsage() {
try {
RandomAccessFile reader = new RandomAccessFile("/proc/stat", "r");
String load = reader.readLine();
String[] toks = load.split(" ");
long idle1 = Long.parseLong(toks[5]);
long cpu1 = Long.parseLong(toks[2]) + Long.parseLong(toks[3]) + Long.parseLong(toks[4])
+ Long.parseLong(toks[6]) + Long.parseLong(toks[7]) + Long.parseLong(toks[8]);
try {
Thread.sleep(360);
} catch (Exception e) {}
reader.seek(0);
load = reader.readLine();
reader.close();
toks = load.split(" ");
long idle2 = Long.parseLong(toks[5]);
long cpu2 = Long.parseLong(toks[2]) + Long.parseLong(toks[3]) + Long.parseLong(toks[4])
+ Long.parseLong(toks[6]) + Long.parseLong(toks[7]) + Long.parseLong(toks[8]);
return (float)(cpu2 - cpu1) / ((cpu2 + idle2) - (cpu1 + idle1));
} catch (IOException ex) {
ex.printStackTrace();
}
return 0;
}
}

Well, kind of a vague question but here is an example of something you could do.
Add a TextView to your layout in your main_activity.xml or whatever you have named it.
Set the id as #+id/myTextView.
In your code, import the TextView widget with:
import android.widget.TextView;
Then initialize it in your method:
TextView cpu = (TextView) findViewById(R.id.myTextView);
and set the text to something:
cpu.setText(readUsage().toString());
There you go. As with any language make sure you play around with stuff to learn it. You can use the eclipse graphical editor to add widgets and change properties like text size and colour etc.

How do i handle touch events properly in android?

Scope of the project
When a user touches the Android screen with two fingers, draw a "Frame" at each touch location with a "cursor" for each frame. Each frame is a custom slider that the cursor will move up and down. All the way up will be 100%, middle will be 0% and all the way down will be -100%. This will be used to control small motors, similar to tank turning, each touch controls a separate motor (sending signals over bluetooth). After a two touch and everything is drawn, I want to be able to lift off either finger, BUT keep the cursor at what ever location it was last at, while the other finger is free to move its cursor. When the last finger is lifted off, everything "hides" and resets to 0%.
Functionality Wanted
On two finger touch, draw separate .pngs under the touch location
After the frames and cursors are drawn, keep track of where they are relative to the frame to determine the percentage.
If a finger is lifted off, keep that fingers cursor at last known location, but the other finger can move it's cursor. Also if the finger is put back down it should be able to move its cursor again.
If both fingers are lifted off of the screen, hide everything and reset percentages to 0%
Functionality Obtained
I can draw the frames and cursors on multitouch
Positions and percentages work fine
Cursors do move properly
What doesn't work
I am unsure if I should have one custom class that handles both touch event or if i should have 2 instances of the custom class each handling their own touch events (I have tried both, the only way i get any "real" functionality is with 1 custom class handling both touch events, the other way doesn't work as intended)
When I only have 1 custom class, It works great, but I have it "hide" everything if both fingers are not on the screen, and sometimes android registers that I have lifted a finger off the screen and this causes me a lot of issues when the frames hide then re appear in a different location
When I use 2 custom classes I touch each custom class would have its own touch event, and i wouldn't have to worry about multitouch if i split the classes evenly between the screen. This was not the case, still need to deal with multitouch
Can someone explain to me how android handles their touch events. from what I have done, it seems if i lay down finger 1, the finger 2, the first finger will register a "ACTION_DOWN" and the second will register a "ACTION_POINTER_2_DOWN", BUT if i life off my first finger, my second finger is "demoted" and now all of the events my second finger registers does not related to "ACTION_POINTER_2" and instead will be "ACTION_DOWN, ACTION_UP, etc". Is this correct?
TouchUI.java
package com.robota.android;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.widget.ImageView;
public class TouchUI extends ImageView {
public static final String LEFT_TOUCHUI = "com.robota.android:id/leftTouchUI";
public static final String RIGHT_TOUCHUI = "com.robota.android:id/rightTouchUI";
private String whoAmI = new String();
private MyPoints framePts = new MyPoints();
private MyPoints cursorPts = new MyPoints();
private Bitmap frame;
private Bitmap cursor;
private int frameWidth;
private int frameHeight;
private int cursorHeight;
private boolean pointerDown = false;
private int dy;
public TouchUI(final Context context, final AttributeSet as){
super(context, as);
Log.d("TouchUI", getResources().getResourceName(this.getId()));
whoAmI = new String(getResources().getResourceName(this.getId()));
if(whoAmI.equals(LEFT_TOUCHUI)){
frame = BitmapFactory.decodeResource(getResources(), R.drawable.tank_left);
}else if(whoAmI.equals(RIGHT_TOUCHUI)){
frame = BitmapFactory.decodeResource(getResources(), R.drawable.tank_right);
}
cursor = BitmapFactory.decodeResource(getResources(), R.drawable.cursor);
frameWidth = frame.getWidth();
frameHeight = frame.getHeight();
cursorHeight = cursor.getHeight();
}
public void determinePointers(int x, int y){
framePts.setOrigin(x-frameWidth/2, y-frameHeight/2);
cursorPts.setOrigin(x-frameWidth/2, y-frameHeight/2);
}
#Override
public boolean onTouchEvent(MotionEvent e){
int x = 0;
int y = 0;
Log.d("TouchUI", ">>>>> " + whoAmI);
if(e.getAction() == MotionEvent.ACTION_DOWN){
determinePointers(x,y);
pointerDown = true;
}else if(e.getAction() == MotionEvent.ACTION_UP){
pointerDown = false;
}else if(e.getAction() == MotionEvent.ACTION_MOVE){
dy = (int)e.getY()-framePts.getY();
if(dy <= 0){
dy=0;
}else if(dy+cursorHeight/2 >= frameHeight){
dy=frameHeight;
}
sendMotorSpeed(dy);
}
return true;
}
public void sendMotorSpeed(int dy){
float motor = dy;
motor-=frameHeight;
motor*=-1;
motor = (motor/frameHeight)*255;
PacketController.updateMotorSpeeds(whoAmI, (int)motor);
}
public void onDraw(Canvas canvas){
if(pointerDown){//twoDown){
canvas.drawBitmap(frame, framePts.getX(), framePts.getY(), null);
canvas.drawBitmap(cursor, cursorPts.getX(), (cursorPts.getY()+dy), null);
}
invalidate();
}
private class MyPoints{
private int x = -100;
private int y = -100;
private int deltaY = 0;;
public MyPoints(){
this.x = 0;
this.y = 0;
}
public int getX(){
return this.x;
}
public int getY(){
return this.y;
}
public void setOrigin(int x, int y){
this.x = x;
this.y = y;
}
public int getDeltaY(){
return deltaY;
}
public void setDeltaY(int newY){
deltaY = (newY-y);
Log.d("TouchUI", "DY: " + deltaY);
}
}
}
Main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/parentLayout"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical">
<LinearLayout android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.robota.android.TouchUI xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/leftTouchUI"
android:background="#0000"
android:layout_height="match_parent"
android:layout_width="wrap_content"
android:layout_weight="1">
</com.robota.android.TouchUI>
<com.robota.android.TouchUI xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/rightTouchUI"
android:background="#0000"
android:layout_height="match_parent"
android:layout_width="wrap_content"
android:layout_weight="1">
</com.robota.android.TouchUI>
</LinearLayout>
RobotController.java (Main Activity Class)
package com.robota.android;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.ActivityNotFoundException;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.Window;
import android.widget.ScrollView;
import android.widget.TextView;
import android.widget.Toast;
public class RobotController extends Activity {
// Tag used to keep track of class in the Log
private static final String TAG = "robotController_new";
// Boolean to debugging
private static final boolean D = true;
// Intent request codes
private static final int DISCONNECT_DEVICE = 1;
private static final int CONNECT_DEVICE = 2;
private static final int REQUEST_ENABLE_BT = 3;
// Handler Codes
public static final int MESSAGE_READ = 1;
public static final int MESSAGE_WRITE = 2;
// Local Bluetooth Adapter
private BluetoothAdapter bluetoothAdapter = null;
// Bluetooth Discovery and Datahandler
private BluetoothComm btComm = null;
// Debug's TextView, this is where strings will be written to display
private TextView tv;
private ScrollView sv;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
if(D) Log.d(TAG, "++ON CREATE++");
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.main);
bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if(bluetoothAdapter == null){
if(D) Log.d(TAG, "NO BLUETOOTH DEVICE");
Toast.makeText(this, "Bluetooth is not available", Toast.LENGTH_SHORT).show();
finish();
return;
}
PacketController.controller = this;
}
public void onStart(){
super.onStart();
if(D) Log.d(TAG, "++ON START++");
if(!bluetoothAdapter.isEnabled()){
Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableIntent, REQUEST_ENABLE_BT);
}else{
// Start BluetoothComm
if(btComm == null){
setupComm();
}
}
}
/**
* Creates new Bluetooth Communication
*/
private void setupComm(){
if(D) Log.d(TAG, "+++setupComm+++");
btComm = new BluetoothComm(this, handler);
}
private void connectDevice(Intent data){
if(D) Log.d(TAG, "+++connectDevice+++");
String addr = data.getExtras()
.getString(DeviceListActivity.EXTRA_DEVICE_ADDRESS);
BluetoothDevice device = bluetoothAdapter.getRemoteDevice(addr);
if(D) Log.d(TAG,"REMOTE ADDR: "+ addr);
btComm.connect(device);
}
private void disconnectDevice(){
if(D) Log.d(TAG, "---disconnectDevice---");
if(btComm.getState() == btComm.STATE_CONNECTED){
btComm.disconnect();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu)
{
//super.onCreateOptionsMenu(menu);
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
Intent serverIntent = null;
switch(item.getItemId()){
case R.id.insecure_connect_scan:
// Launch the DeviceListActivity to see devices and do scan
serverIntent = new Intent(this, DeviceListActivity.class);
try{
startActivityForResult(serverIntent, CONNECT_DEVICE);
}catch(ActivityNotFoundException activityNotFound){
Log.e(TAG, "Could not start DeviceListActivity(Insecure)");
}
return true;
}
return false;
}
#Override
public void onActivityResult(int requestCode, int resultCode, Intent data){
switch(requestCode){
case CONNECT_DEVICE:
if(resultCode == Activity.RESULT_OK){
connectDevice(data);
}
break;
case DISCONNECT_DEVICE:
if(resultCode == Activity.RESULT_OK){
disconnectDevice();
}
break;
}
}
public Handler getHandler(){
return this.handler;
}
public BluetoothComm getBtComm(){
return this.btComm;
}
// The Handler that gets information back from the BluetoothChatService
private final Handler handler = new Handler() {
#Override
public void handleMessage(Message msg) {
if(D) Log.d(TAG, "check message");
switch (msg.what) {
case MESSAGE_READ:
if(D) Log.d(TAG, "trying to read message");
byte[] readBuf = (byte[]) msg.obj;
// construct a string from the valid bytes in the buffer
String readMessage = new String(readBuf, 0, msg.arg1);
if(D) Log.d(TAG, "bytes: " + readBuf + " arg1: " + msg.arg1 + " Message: " + readMessage);
tv.append(readMessage);
break;
case MESSAGE_WRITE:
if(D) Log.d(TAG, "trying to send message");
String sendMessage = new String(String.valueOf(msg.obj));
}
}
};
}
Any other classes not listed I didn't believe needed to be, but if they are needed please let me know.
Any help is much appreciated

You're going to need to save the pointerId's of each point and compare them to the new Id's given with each MotionEvent. It's slightly tricky to explain, so I'll point you to this ADB Post that explains it much better than I could. Long story short? Multitouch can be tricksy, but it's not as bad as it looks at first glance.

Android: roatating images in a loop

I am trying with no success to modify the code example from:
http://www.inter-fuser.com/2009/08/android-animations-3d-flip.html
so it will rotate the images in a loop, when clicking on the image once. (second click should pause).
I tried using Handler and threading but cannot update the view since only the main thread can update UI.
Exception I get from the code below:
android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
[in 'image1.startAnimation(rotation);' ('applyRotation(0, 90);' from the main thread)]
package com.example.flip3d;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.animation.AccelerateInterpolator;
import android.widget.ImageView;
public class Flip3d extends Activity {
private ImageView image1;
private ImageView image2;
private boolean isFirstImage = true;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
image1 = (ImageView) findViewById(R.id.image01);
image2 = (ImageView) findViewById(R.id.image02);
image2.setVisibility(View.GONE);
image1.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
if (isFirstImage) {
applyRotation(0, 90);
isFirstImage = !isFirstImage;
} else {
applyRotation(0, -90);
isFirstImage = !isFirstImage;
}
}
});
}
private void applyRotation(float start, float end) {
// Find the center of image
final float centerX = image1.getWidth() / 2.0f;
final float centerY = image1.getHeight() / 2.0f;
// Create a new 3D rotation with the supplied parameter
// The animation listener is used to trigger the next animation
final Flip3dAnimation rotation =
new Flip3dAnimation(start, end, centerX, centerY);
rotation.setDuration(500);
rotation.setFillAfter(true);
rotation.setInterpolator(new AccelerateInterpolator());
rotation.setAnimationListener(new DisplayNextView(isFirstImage, image1, image2));
if (isFirstImage)
{
image1.startAnimation(rotation);
} else {
image2.startAnimation(rotation);
}
}
}
How can I manage to update the UI and control the rotation within onClick listener?
Thank you,
Oakist

Try wrapping the UI code in runOnUIThread()