Android 在活动和视图类之间传递值

在

DravingView

中，从

onTouchEvent

传递X和Y坐标时遇到问题；我想在

MainActivity

中显示这些值。我尝试使用初始和捆绑方法，但我做了一些错误的事情

DrawingView.java

public class DrawingView extends View {


private Bitmap cacheBitmap;

private Canvas cacheCanvas;

private Paint paint;

private Paint BitmapPaint;

private Path path;

private int height;

private int width;

/** Last saved X-coordinate */
private float pX;
/** Last saved Y-coordinate*/
private float pY;

/** Initial color */
private int paintColor = Color.BLACK;

private static Paint.Style paintStyle = Paint.Style.STROKE;
/** Paint Point size */
private static int paintWidth = 8;

private Canvas canvas;




/** get the height and width */
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    height = h;
    width = w;
    init();
}

private void init(){
    cacheBitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);
    cacheCanvas = new Canvas(cacheBitmap);
    paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    path = new Path();
    BitmapPaint = new Paint();
    updatePaint();
}

private void updatePaint(){
    paint.setColor(paintColor);
    paint.setStyle(paintStyle);
    paint.setStrokeWidth(paintWidth);
}

public DrawingView(Context context, AttributeSet attrs) {
    super(context, attrs);
}

public DrawingView(Context context){
    super(context);
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    int action = event.getAction();


    switch (action) {
        case MotionEvent.ACTION_DOWN:
            path.moveTo(event.getX(), event.getY());
            pX = event.getX();
            pY = event.getY();
            break;
        case MotionEvent.ACTION_MOVE:
            path.quadTo(pX, pY, event.getX(), event.getY());
            pX = event.getX();
            pY = event.getY();


            break;
        case MotionEvent.ACTION_UP:
            cacheCanvas.drawPath(path, paint);
            path.reset();
            break;
    }


    invalidate();

    return true;
}

@Override
protected void onDraw(Canvas canvas) {
    this.canvas = canvas;
    BitmapPaint = new Paint();
    canvas.drawBitmap(cacheBitmap, 0,0, BitmapPaint);
    canvas.drawPath(path, paint);

}


public void setColor(int color){
    paintColor = color;
    updatePaint();
}


public void setPaintWidth(int width){
    paintWidth = width;
    updatePaint();
}

public static final int PEN = 1;
public static final int PAIL = 2;


public void setStyle(int style){
    switch(style){
        case PEN:
            paintStyle = Paint.Style.STROKE;
            break;
        case PAIL:
            paintStyle = Paint.Style.FILL;
            break;
    }
    updatePaint();
}

/** clear your drawing*/
public void clearScreen(){
    if(canvas != null){
        Paint backPaint = new Paint();
        backPaint.setColor(Color.WHITE);
        canvas.drawRect(new Rect(0, 0, width, height), backPaint);
        cacheCanvas.drawRect(new Rect(0, 0, width, height), backPaint);
    }
    invalidate();
}
}

MainActivity.java

public class MainActivity extends ActionBarActivity {

private DrawingView drawView;
private ImageButton currPaint;

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

    drawView = (DrawingView)findViewById(R.id.drawing);



    //LinearLayout paintLayout = (LinearLayout)findViewById(R.id.paint_colors);
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

public void openMenuBack(View view) {

    Intent intent = new Intent(this, MainActivityMenu.class);
    startActivity(intent);


}


public void openNew(View view) {

    Intent intent = new Intent(this, MainActivity.class);
    startActivity(intent);

}
}

---

您可以做的是创建一个接口，mainActivity将实现该接口

public interface MyDrawingViewInterface {
  public void onActionFinished(int movedX, int movedY);
}

然后您的MainActivity将实现此接口：

public class MainActivity extends ActionBarActivity implements MyDrawingViewInterface{
 /* All your other stuff */
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    drawView = (DrawingView)findViewById(R.id.drawing);
    drawView.setViewListener(this);



    //LinearLayout paintLayout = (LinearLayout)findViewById(R.id.paint_colors);
  }

  @Override
  public void onActionFinished(int movedX, int movedY) {
    /*Print it wherever you want here */
  }
}

最后，您的DrawView也会随之更改（请注意新变量和对ACTION_UP的调用）：

---

问题是什么，您是否有一些信息或意外结果？

public class DrawingView extends View {
  private MyDrawingInterface mInterface;


  public void setViewListener(MyDrawingView interface) {
    mInterface = interface;
  }


@Override
public boolean onTouchEvent(MotionEvent event) {
    int action = event.getAction();


    switch (action) {
        case MotionEvent.ACTION_DOWN:
            path.moveTo(event.getX(), event.getY());
            pX = event.getX();
            pY = event.getY();
            break;
        case MotionEvent.ACTION_MOVE:
            path.quadTo(pX, pY, event.getX(), event.getY());
            pX = event.getX();
            pY = event.getY();


            break;
        case MotionEvent.ACTION_UP:
            cacheCanvas.drawPath(path, paint);
            path.reset();

            mInterface.onActionFinished(pX, pY);

            break;
    }


    invalidate();

    return true;
}
}