How do I handle touch events in android correctly?

Project Scope

When the user touches the Android screen with two fingers, draw a “Frame” at each touch point using the “cursor” for each frame. Each frame is a custom slider that moves the cursor up and down. All the way will be 100%, the average will be 0%, and all the way down - 100%. This will be used to control small engines, like turning a tank, each touch controls a separate engine (transmitting signals via bluetooth). After two touches and everything drawn, I want to be able to rise with one finger, BUT to keep the cursor in that place that it is the last time, while the other finger is free to move its cursor. When the last finger is removed, everything “hides” and is reset to 0%.

Required functionality

• Touch with two fingers, draw separate .png in the touch area.
• After frames and cursors are drawn, track where they relate to the frame to determine the percentage.
• If the finger is removed, hold the cursor in a known place, but the other finger can move the cursor. Also, if the finger is laid back, it should again move the cursor.
• If both fingers are removed from the screen, hide everything and reset percent to 0%

Functionality Achieved

• I can draw frames and cursors on multitouch
• Positions and percentages work fine
• Cursors move correctly

What does not work

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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( )

    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 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));
        }
    }
};
}

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