android - 拖放 ImageView 不起作用

Question

我的 RelativeLayout 有一张图片。我只是想让它在整个布局中都可以拖动。问题是每次我拖放时，它都会回到原来的位置。这是我的

drag_layout.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/mainView"
    android:background="@drawable/bg_animation"
    tools:context="com.example.activities.AnimationActivity">
    <ImageView
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:src="@drawable/ic_launcher"
        android:id="@+id/appLogo"
        android:layout_alignBottom="@+id/ba_cell_animation"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="47dp" />
</RelativeLayout>

AnimationActivity.java

public class AnimationActivity extends ActionBarActivity implements View.OnTouchListener, View.OnDragListener {

    static ImageView mLogo;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_animation);
        setTitle("Animation");
        Typeface mAnimPromptTF = Typeface.createFromAsset(getAssets(), "fonts/Jelloween - Machinato ExtraLight.ttf");
        Typeface mAnimBonusTF = Typeface.createFromAsset(getAssets(), "fonts/Jelloween - Machinato SemiBold Italic.ttf");
        mAnimPrompt = (TextView) findViewById(R.id.anim_prompt);
        mAnimBonus = (TextView) findViewById(R.id.anim_bonus);
        mAnimPrompt.setTypeface(mAnimPromptTF);
        mAnimBonus.setTypeface(mAnimBonusTF);

        mLogo = (ImageView) findViewById(R.id.appLogo);


        mLogo.setOnTouchListener(this);
        findViewById(R.id.mainView).setOnDragListener(this);

    }

    @Override
    public boolean onTouch(View v, MotionEvent e) {
        // TODO Auto-generated method stub
        if (e.getAction() == MotionEvent.ACTION_DOWN) {
            View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(v);
            v.startDrag(null, shadowBuilder, v, 0);
            v.setVisibility(View.INVISIBLE);
            return true;
        } else {
            return false;
        }
    }

    @Override
    public boolean onDrag(View v, DragEvent e) {
        // TODO Auto-generated method stub

        switch (e.getAction()) {
            case DragEvent.ACTION_DROP:
                View view = (View) e.getLocalState();
                ViewGroup from = (ViewGroup) view.getParent();
                from.removeView(view);
                RelativeLayout to = (RelativeLayout) v;
                to.addView(view);
                view.setVisibility(View.VISIBLE);

                break;

            //the drag point has entered the bounding box of the View
            case DragEvent.ACTION_DRAG_ENTERED:
                break;

            //the user has moved the drag shadow outside the bounding box of the View
            case DragEvent.ACTION_DRAG_EXITED:
                break;

            // the drag and drop operation has concluded.
            case DragEvent.ACTION_DRAG_ENDED:
                break;

            default:


                break;
        }

        return true;
    }

    @Override
    public void onBackPressed() {
        Intent intent = new Intent(this, MainActivity.class);
        startActivity(intent);
    }
}

我已经尝试了以下所有链接，但仍然不知道哪里出错了:

http://www.vogella.com/tutorials/AndroidDragAndDrop/article.html

http://codingjunkie.net/android-drag-and-drop-part1

http://tech-papers.org/android-drag-and-drop

我真的尝试了很多。

Answer 1

我终于找到了解决方案，请引用以下代码:就像这段代码一样简单。

@Override
    public boolean onTouch(View v, MotionEvent e) {

        switch (e.getAction()) {
            case MotionEvent.ACTION_DOWN:

                View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(v);
                v.startDrag(null, shadowBuilder, v, 0);
                return true;
        }

        return false;

    }

    @Override
    public boolean onDrag(View mainView, DragEvent e) {
        View view = (View) e.getLocalState();
        switch (e.getAction()) {
            case DragEvent.ACTION_DROP:
                view.setX(e.getX() - (view.getWidth() / 2));
                view.setY(e.getY() - (view.getHeight() / 2));
                view.invalidate();
                mainView.invalidate();
                return true;
            case DragEvent.ACTION_DRAG_STARTED:
                return true;

            case DragEvent.ACTION_DRAG_EXITED:
                break;

            case DragEvent.ACTION_DRAG_ENDED:
                mainView.invalidate();
                return true;

            default:


                break;
        }

        return true;
    }