java - 从Android屏幕上删除图像

Question

我正在制作一个 Android 游戏，一旦点击它们，就会从屏幕上删除一些掉落的图像。我想我也许可以使用一些类似的代码，如 doDraw() 方法中所示，一旦它们到达屏幕底部，就会删除它们，还会播放声音，并检查玩家的健康值。但我需要一点帮助。如果有人可以向我发布任何代码并向我解释这是如何完成的，我将非常感激!

这是我到目前为止使用的代码:

public class ExampleView extends SurfaceView implements SurfaceHolder.Callback
{
class ExampleThread extends Thread
{
    private ArrayList<Parachuter> parachuters;
    private Bitmap parachuter;
    private Paint black;

    private boolean running;

    private SurfaceHolder mSurfaceHolder;
    private Context mContext;
    private Context mContext1;
    private Handler mHandler;
    private Handler mHandler1;
    private GameScreenActivity mActivity;

    private long frameRate;
    private boolean loading;
    public float x;
    public float y;
    public MediaPlayer mp1;
    public int parachuterIndexToResetAndDelete;
    public int canvasGetWidth;
    public int livesLeftValue;

    public ExampleThread(SurfaceHolder sHolder, Context context, Handler handler)
    {
        mSurfaceHolder = sHolder;
        mHandler = handler;
        mHandler1 = handler;
        mContext = context;
        mActivity = (GameScreenActivity) context;

        parachuters = new ArrayList<Parachuter>();
        parachuter = BitmapFactory.decodeResource(getResources(), R.drawable.parachuteman);
        black = new Paint();
        black.setStyle(Paint.Style.FILL);
        black.setColor(Color.WHITE);

        running = true;

        // This equates to 26 frames per second.
        frameRate = (long) (1000 / 26);
        loading = true;
    }

    @Override
    public void run()
    {
        while (running)
        {
            Canvas c = null;
            try
            {
                c = mSurfaceHolder.lockCanvas();

                synchronized (mSurfaceHolder)
                {
                    long start = System.currentTimeMillis();
                    doDraw(c);
                    long diff = System.currentTimeMillis() - start;

                    if (diff < frameRate)
                        Thread.sleep(frameRate - diff);
                }
            } catch (InterruptedException e)
            {
            }
            finally
            {
                if (c != null)
                {
                    mSurfaceHolder.unlockCanvasAndPost(c);
                }
            }
        }
    }

    protected void doDraw(Canvas canvas)
    {
        canvas.drawRect(0, 0, canvas.getWidth(), canvas.getHeight(), black);
        canvasGetWidth = canvas.getWidth();

        //Draw
        for (int i = 0; i < parachuters.size(); i++)
        {
            canvas.drawBitmap(parachuter, parachuters.get(i).getX(), parachuters.get(i).getY(), null);
            parachuters.get(i).tick();
        }

        //Remove
        for (int i = 0; i < parachuters.size(); i++)
        {
        if (parachuters.get(i).getY() > canvas.getHeight()) {
            parachuters.remove(i);
            onPlaySound();
            checkLivesLeftValue();
        }
    }
    }


    private void checkLivesLeftValue() {
        Log.d("checkLivesLeftValue", "lives = " + livesLeftValue);
        // TODO Auto-generated method stub
        if (livesLeftValue == 3) {
            //Message to display: "You lost!
            Log.d("checkLivesLeftValue", "calling onMethod now");
            onMethod();
        }
        else {
            livesLeftValue = livesLeftValue + 1;
            Log.d("checkLivesLeftValue", "increased lives to " + livesLeftValue);
        }
    }
    public void onMethod() {
        mHandler.post(new Runnable() {
            @Override
            public void run() {
                Toast.makeText(getContext(), "You lost!", 15).show();
                livesLeftValue = 0;
                //Tell the user that he lost:
                android.content.Context ctx = mContext;
                Intent i = new Intent(ctx, playerLostMessageActivity.class);  
                i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                ctx.startActivity(i);
            }
        });
    } 

    public void onPlaySound()
    {
        try {
        mp1 = MediaPlayer.create(getContext(), R.raw.bombsound);
        mp1.start();
        } catch (Exception e) {
            e.printStackTrace();
            mp1.release();
        }
    }

    public boolean onTouchEvent(MotionEvent event)
    {
        if (event.getAction() != MotionEvent.ACTION_DOWN)
            return false;
        float x1 = event.getX();
        float y1 = event.getY();

        initiateDrawParachuters();

        return true;
    }

    public void initiateDrawParachuters()
    {
        drawParachuter1();
    }

    private void drawParachuter1() {
        // TODO Auto-generated method stub
        //Parachuter nr. 1
        x = 10;
        y = 40;

        Parachuter p = new Parachuter(x, y);
        parachuters.add(p);
        drawParachuter2();
    }

    private void drawParachuter2() {
        // TODO Auto-generated method stub
        //Parachuter nr. 2
        x = 50;
        y = 80;

        Parachuter p = new Parachuter(x, y);
        parachuters.add(p);
        drawParachuter3();
    }

    private void drawParachuter3() {
        // TODO Auto-generated method stub
        //Parachuter nr. 3
        x = 90;
        y = 120;

        Parachuter p = new Parachuter(x, y);
        parachuters.add(p);
        drawParachuter4();
    }

    private void drawParachuter4() {
        // TODO Auto-generated method stub
        //Parachuter nr. 4
        x = 140;
        y = 150;

        Parachuter p = new Parachuter(x, y);
        parachuters.add(p);
        drawParachuter5();
    }

    private void drawParachuter5() {
        // TODO Auto-generated method stub
        //Parachuter nr. 5
        x = 190;
        y = 170;

        Parachuter p = new Parachuter(x, y);
        parachuters.add(p);
        drawParachuter6();
    }

    private void drawParachuter6() {
        // TODO Auto-generated method stub
        //Parachuter nr. 6
        x = 240;
        y = 180;

        Parachuter p = new Parachuter(x, y);
        parachuters.add(p);
        drawParachuter7();
    }

    private void drawParachuter7() {
        // TODO Auto-generated method stub
        //Parachuter nr. 6
        x = 290;
        y = 180;

        Parachuter p = new Parachuter(x, y);
        parachuters.add(p);
    }

    public void drawParachuters()
    {
            Parachuter p = new Parachuter(x, y);
            parachuters.add(p);
            Toast.makeText(getContext(), "x=" + x + " y=" + y, 15).show();
    }

    public void setRunning(boolean bRun)
    {
        running = bRun;
    }

    public boolean getRunning()
    {
        return running;
    }
}

/** Handle to the application context, used to e.g. fetch Drawables. */
private Context mContext;

/** Pointer to the text view to display "Paused.." etc. */
private TextView mStatusText;

/** The thread that actually draws the animation */
private ExampleThread eThread;

public ExampleView(Context context)
{
    super(context);

    // register our interest in hearing about changes to our surface
    SurfaceHolder holder = getHolder();
    holder.addCallback(this);

    // create thread only; it's started in surfaceCreated()
    eThread = new ExampleThread(holder, context, new Handler()
    {
        @Override
        public void handleMessage(Message m)
        {
           // mStatusText.setVisibility(m.getData().getInt("viz"));
           // mStatusText.setText(m.getData().getString("text"));
        }
    });

    setFocusable(true);
}

@Override
public boolean onTouchEvent(MotionEvent event)
{
    return eThread.onTouchEvent(event);
}

public ExampleThread getThread()
{
    return eThread;
}

@Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3)
{
    // TODO Auto-generated method stub
}

public void surfaceCreated(SurfaceHolder holder)
{
    if (eThread.getState() == Thread.State.TERMINATED)
    {
        eThread = new ExampleThread(getHolder(), getContext(), getHandler());
        eThread.start();
    }
    else
    {
        eThread.start();
    }
}

@Override
public void surfaceDestroyed(SurfaceHolder holder)
{
    boolean retry = true;
    eThread.setRunning(false);

    while (retry)
    {
        try
        {
            eThread.join();
            retry = false;
        }
        catch (InterruptedException e)
        {
        }
    }
}
}

降落伞类触及 boolean 值:

    public boolean isTouched() {
    return touched;
}

public void setTouched(boolean touched) {
    this.touched = touched;
}

Answer 1

当降落伞被触摸时，您只需在 Parachuter 类中设置一个 boolean 值，表示它现在已经死亡并且应该被删除。然后，您可以将 onDraw 删除部分更改为如下所示。

   for (int i = 0; i < parachuters.size(); i++)
    {
    if (parachuters.get(i).getY() > canvas.getHeight()) {
        parachuters.remove(i);
        onPlaySound();
        checkLivesLeftValue();
    } else if(parachuters.get(i).isDead) {
        parachuters.remove(i);
    }