OntouchListener跨按钮拖动

Question

I am developing a piano app for android. I am trying to implement OnTouchListener for all the 8 buttons that I have in my activity. So, when the user drags or swipes his finger I want all the buttons to play the sound. I think the picture below explains it better.

See? When the user will place his hand on the first button and then drag till the last button, I want all the 8 buttons to play the song. But I am not able to achieve it. The below java code works only for the first button but the rest of the 7 buttons don't get pressed.

Here it is:

@Override
public boolean onTouch(View v, MotionEvent event) {
    switch(v.getID())
    {
        case(R.id.btn1):
        //play button 1 sound
        break;

        case(R.id.btn2):
        //play button 2 sound
        break;

        case(R.id.btn3):
        //play button 3 sound
        break;

        case(R.id.btn4):
        //play button 4 sound
        break;

        case(R.id.btn5):
        //play button 1 sound
        break;

        case(R.id.btn6):
        //play button 6 sound
        break;

        case(R.id.btn7):
        //play button 7 sound
        break;

        case(R.id.btn8):
        //play button 8 sound
        break;
        }          
    return true;
    }

I have already seen this question and this as well but couldn't find an answer there.

Please help me out. Thank you for you time!

Answer 1

You should implement onTouchListner on the layout which contains the piano buttons

The idea is to get all piano buttons positions on the screen (x , y) after render them.

then get touch position by using getX() and getY() methods.

At this point you can handle it by checking if the touch x and y is between the view start and

end x and y, then play the sound of the view.

At this example i'am using soundpool and pitch to play different sounds (i know that it's not the perfect way), and i'm also working on x factor only because i'm using piano white keys only.

import android.app.Activity;
import android.media.*;
import android.os.Bundle;
import android.view.*;
import android.widget.*;

import java.util.ArrayList;
import java.util.List;


public class MainActivity extends Activity
{

    //The layout that holds the piano keys.
    LinearLayout pianoKeysContainer;

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

        pianoKeysContainer = (LinearLayout) findViewById(R.id.key_container);
        pianoKeysContainer.setOnTouchListener(onYourViewTouchListener);
    }


    //Here we load the view positions after render it and fill the array with the positions
    private List<Integer> positionsLeft_whiteKeys  = new ArrayList<Integer>();
    private List<Integer> positionsRight_whiteKeys = new ArrayList<Integer>();

    public void onWindowFocusChanged(boolean hasFocus)
    {
        super.onWindowFocusChanged(hasFocus);

        for (int i = 0; i < pianoKeysContainer.getChildCount(); i++)
        {
            //positionsLeft_whiteKeys holds the start x of each view.
            positionsLeft_whiteKeys.add(pianoKeysContainer.getChildAt(i).getLeft());
            //positionsRight_whiteKeys holds the end x of each view.
            positionsRight_whiteKeys.add(pianoKeysContainer.getChildAt(i).getRight());
        }
    }

    public View.OnTouchListener onYourViewTouchListener = new View.OnTouchListener()
    {
        float positionX;
        FrameLayout pianoKey;
        FrameLayout lastPlayedKey;
        ArrayList<FrameLayout> pressedKeys = new ArrayList<FrameLayout>();

        @Override
        public boolean onTouch(View view, MotionEvent motionEvent)
        {

            positionX = motionEvent.getX();

            float pitch;

            //Looping on the child of the layout which contains the piano keys
            for (int x = 0; x < ((LinearLayout) view).getChildCount(); x++)
            {
                // Calculating the pitch to get good chords
                pitch = (float) Math.pow(Math.pow(2.0, 1 / 12.0), (float) x);

                pianoKey = (FrameLayout) ((LinearLayout) view).getChildAt(x);

                if (positionsLeft_whiteKeys.size() >= 0 && positionsRight_whiteKeys.size() >= 0)
                {
                    if (positionX > positionsLeft_whiteKeys.get(x) && positionX < positionsRight_whiteKeys.get(x))
                    {
                        pianoKey = (FrameLayout) ((LinearLayout) view).getChildAt(x);

                        if (pianoKey != null)
                        {
                            pianoKey.setBackgroundResource(R.drawable.piano_key_pressed);
                            pressedKeys.add(pianoKey);
                        }
                        if (lastPlayedKey != pianoKey)
                            playKey(pitch);

                        lastPlayedKey = pianoKey;
                        break;
                    }

                    if (lastPlayedKey != null)
                    {
                        pianoKey.setBackgroundResource(R.drawable.piano_key);
                        lastPlayedKey.setBackgroundResource(R.drawable.piano_key);

                    }
                }
            }

            if (motionEvent.getAction() == MotionEvent.ACTION_UP)
            {
                lastPlayedKey = null;

                for (FrameLayout pressedKey : pressedKeys)
                {
                    pressedKey.setBackgroundResource(R.drawable.piano_key);
                }


            }

            return false;
        }
    };


    //This is sound play method
    SoundPool   sp = new SoundPool(1, AudioManager.STREAM_MUSIC, 1);
    public void playKey(final float pitch)
    {

        //here you should store your piano sound at res/raw then load it
        sp.load(this, R.raw.piano, 1);

        sp.setOnLoadCompleteListener(new SoundPool.OnLoadCompleteListener()
        {
            @Override
            public void onLoadComplete(SoundPool soundPool, int i, int i2)
            {
                soundPool.play(i, 0.99f, 0.99f, 1, 0, pitch);
            }
        });
    }

}

And this is the xml file (main.xml)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="match_parent"
              android:layout_height="match_parent">

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:clickable="true"
        android:id="@+id/key_container">

        <FrameLayout
            android:layout_height="match_parent"
            android:layout_marginRight="2dp"
            android:layout_width="48dp"
            android:background="@drawable/piano_key"/>

        <FrameLayout
            android:layout_height="match_parent"
            android:layout_marginRight="2dp"
            android:layout_width="48dp"
            android:background="@drawable/piano_key"/>

        <FrameLayout
            android:layout_height="match_parent"
            android:layout_marginRight="2dp"
            android:layout_width="48dp"
            android:background="@drawable/piano_key"/>

        <FrameLayout
            android:layout_height="match_parent"
            android:layout_marginRight="2dp"
            android:layout_width="48dp"
            android:background="@drawable/piano_key"/>

        <FrameLayout
            android:layout_height="match_parent"
            android:layout_marginRight="2dp"
            android:layout_width="48dp"
            android:background="@drawable/piano_key"
            />

        <FrameLayout
            android:layout_height="match_parent"
            android:layout_marginRight="2dp"
            android:layout_width="48dp"
            android:background="@drawable/piano_key"/>

        <FrameLayout
            android:layout_height="match_parent"
            android:layout_marginRight="2dp"
            android:layout_width="48dp"
            android:background="@drawable/piano_key"/>

        <FrameLayout
            android:layout_height="match_parent"
            android:layout_marginRight="2dp"
            android:layout_width="48dp"
            android:background="@drawable/piano_key"/>

        <FrameLayout
            android:layout_height="match_parent"
            android:layout_marginRight="2dp"
            android:layout_width="48dp"
            android:background="@drawable/piano_key"/>

        <FrameLayout
            android:layout_height="match_parent"
            android:layout_marginRight="2dp"
            android:layout_width="48dp"
            android:background="@drawable/piano_key"/>

        <FrameLayout
            android:layout_height="match_parent"
            android:layout_marginRight="2dp"
            android:layout_width="48dp"
            android:background="@drawable/piano_key"/>

        <FrameLayout
            android:layout_height="match_parent"
            android:layout_marginRight="2dp"
            android:layout_width="48dp"
            android:background="@drawable/piano_key"/>

    </LinearLayout>


</LinearLayout>

Note: the only thing you should do to complete the example is to put you piano key image (pressed and not pressed) and put the piano sound at res/raw