我想做一个简单的控件:一个里面有视图的容器。如果我触摸容器并移动手指,我想让视图跟着我的手指移动。

我应该使用什么样的容器(布局)?如何做到这一点?

我不需要使用一个表面,但一个简单的布局。


当前回答

和@Alex Karshin的答案一样,我做了一点改变。

public class MovingObject implements OnTouchListener {
private RelativeLayout.LayoutParams lParams;
private PointF viewPoint, prePoint, currPoint;

public MovingObject() {
    lParams = null;
    viewPoint = new PointF();
    prePoint = new PointF();
    currPoint = new PointF();
}

public boolean onTouch(View view, MotionEvent event) {
    switch (event.getAction() & MotionEvent.ACTION_MASK) {
    case MotionEvent.ACTION_DOWN:
        viewPoint.set(view.getX(), view.getY());
        prePoint.set(event.getRawX(), event.getRawY());
        lParams = (RelativeLayout.LayoutParams) view.getLayoutParams();
        break;
    case MotionEvent.ACTION_UP:
        break;
    case MotionEvent.ACTION_POINTER_DOWN:
        break;
    case MotionEvent.ACTION_POINTER_UP:
        break;
    case MotionEvent.ACTION_MOVE:
        currPoint.set(event.getRawX(), event.getRawY());
        moveToCurrentPoint(view);
        break;
    }
    view.invalidate();
    return true;
}

private void moveToCurrentPoint(View view) {
    float dx = currPoint.x - prePoint.x - prePoint.x + viewPoint.x;
    float dy = currPoint.y - prePoint.y - prePoint.y + viewPoint.y;
    lParams.leftMargin = (int) (prePoint.x + dx);
    lParams.topMargin = (int) (prePoint.y + dy);
    view.setLayoutParams(lParams);
}
}

其他回答

按照@Andrew方法,如果你想要移动视图的中心,你只需要减去视图的一半高度和一半宽度。

float dX, dY;

@Override
public boolean onTouchEvent(View view, MotionEvent event) {
    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            dX = view.getX() - event.getRawX();
            dY = view.getY() - event.getRawY();
            break;
        case MotionEvent.ACTION_MOVE:
            view.animate()
                .x(event.getRawX() + dX - (view.getWidth() / 2f))
                .y(event.getRawY() + dY - (view.getHeight() / 2f))
                .setDuration(0)
                .start();
            break;
        default:
            return false;
    }
    return true;
}     

kotlin的简单代码:

var dx = 0f
var dy = 0f

private fun setMyViewListener(): OnTouchListener {
    return OnTouchListener { view, event ->

        when (event.action) {
            MotionEvent.ACTION_DOWN -> {
                dx = view.x - event.rawX
                dx = view.y - event.rawY
            }
            MotionEvent.ACTION_MOVE -> view.animate()
                    .x(event.rawX + dx)
                    //.y(event.rawY + dy) // uncomment this line to move y
                    .setDuration(0)
                    .start()
        }

        true
    }
}

然后像这样调用它:

var myView = findViewById<ConstraintLayout>(R.id.myView)
myView.setOnTouchListener(setMyViewListener())

改变了一点由@Vyacheslav Shylkin提供的解决方案,以删除手动输入数字的依赖性。

import android.app.Activity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewTreeObserver;
import android.widget.ImageView;
import android.widget.RelativeLayout;

public class MainActivity extends Activity implements View.OnTouchListener
{
    private int       _xDelta;
    private int       _yDelta;
    private int       _rightMargin;
    private int       _bottomMargin;
    private ImageView _floatingView;

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

        this._floatingView = (ImageView) findViewById(R.id.textView);

        this._floatingView.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener()
        {
            @Override
            public boolean onPreDraw()
            {
                if (_floatingView.getViewTreeObserver().isAlive())
                    _floatingView.getViewTreeObserver().removeOnPreDrawListener(this);

                updateLayoutParams(_floatingView);
                return false;
            }
        });

        this._floatingView.setOnTouchListener(this);
    }

    private void updateLayoutParams(View view)
    {
        this._rightMargin = -view.getMeasuredWidth();
        this._bottomMargin = -view.getMeasuredHeight();

        RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(view.getMeasuredWidth(), view.getMeasuredHeight());
        layoutParams.bottomMargin = this._bottomMargin;
        layoutParams.rightMargin = this._rightMargin;

        view.setLayoutParams(layoutParams);
    }

    @Override
    public boolean onTouch(View view, MotionEvent event)
    {
        if (view == this._floatingView)
        {
            final int X = (int) event.getRawX();
            final int Y = (int) event.getRawY();

            switch (event.getAction() & MotionEvent.ACTION_MASK)
            {
                case MotionEvent.ACTION_DOWN:
                    RelativeLayout.LayoutParams lParams = (RelativeLayout.LayoutParams) view.getLayoutParams();
                    this._xDelta = X - lParams.leftMargin;
                    this._yDelta = Y - lParams.topMargin;
                    break;

                case MotionEvent.ACTION_MOVE:
                    RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) view.getLayoutParams();
                    layoutParams.leftMargin = X - this._xDelta;
                    layoutParams.topMargin = Y - this._yDelta;
                    layoutParams.rightMargin = this._rightMargin;
                    layoutParams.bottomMargin = this._bottomMargin;
                    view.setLayoutParams(layoutParams);
                    break;
            }

            return true;
        }
        else
        {
            return false;
        }
    }
}

//如果你想移动你的相机或任何东西,然后按照下面的方法来做 //我在相机上实现的情况下,你可以应用它在任何你想要的

public class VideoCallActivity extends AppCompatActivity implements 
  View.OnTouchListener {
 FrameLayout myLayout1;

@SuppressLint("ClickableViewAccessibility")
@Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
  //in the frame layout I am setting my camera
   myLayout1.setOnTouchListener(this);
  
  }

   float dX, dY;

@Override
public boolean onTouch(View view, MotionEvent event) {
    switch (event.getAction()) {
 //this is your code
        case MotionEvent.ACTION_DOWN:
            dX = view.getX() - event.getRawX();
            dY = view.getY() - event.getRawY();
            break;
        case MotionEvent.ACTION_MOVE:
            view.animate()
                    .x(event.getRawX() + dX)
                    .y(event.getRawY() + dY)
                    .setDuration(0)
                    .start();
            break;
        default:
            return false;
    }
    return true;
}

在Kotlin中实现相同

    rightPanel.setOnTouchListener(View.OnTouchListener { view, event ->
        when (event?.action) {
            MotionEvent.ACTION_DOWN -> {

                rightDX = view!!.x - event.rawX
                // rightDY = view!!.getY() - event.rawY;

            }
            MotionEvent.ACTION_MOVE -> {

                var displacement = event.rawX + rightDX

                view!!.animate()
                        .x(displacement)
                        // .y(event.getRawY() + rightDY)
                        .setDuration(0)
                        .start()
            }
            else -> { // Note the block
                return@OnTouchListener false
            }
        }
        true
 })