Android - 如何使用DragShadowBuilder？

Question

我使用DragShadowBuilder.java，這個類是爲了一個樣本。

我不知道我怎麼可以用我的Activity，我應該送什麼參數constructorDrawableDragShadowBuilder的：

感謝的很多。

Answer 1

你要通過要拖動View，在DragShadowBuilder

DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view); 

構造函數，然後使用啓動拖動：

view.startDrag(data, shadowBuilder, view, 0); 

這裏是以下這個優秀的完整的示例tutorial：

import android.app.Activity; 
import android.content.ClipData; 
import android.graphics.drawable.Drawable; 
import android.os.Bundle; 
import android.view.DragEvent; 
import android.view.MotionEvent; 
import android.view.View; 
import android.view.View.DragShadowBuilder; 
import android.view.View.OnDragListener; 
import android.view.View.OnTouchListener; 
import android.view.ViewGroup; 
import android.widget.LinearLayout; 

public class MyActivity extends Activity { 



@Override 
public void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
setContentView(R.layout.main); 
    findViewById(R.id.myimage1).setOnTouchListener(new MyTouchListener()); 
findViewById(R.id.myimage2).setOnTouchListener(new MyTouchListener()); 
findViewById(R.id.myimage3).setOnTouchListener(new MyTouchListener()); 
findViewById(R.id.myimage4).setOnTouchListener(new MyTouchListener()); 
findViewById(R.id.topleft).setOnDragListener(new MyDragListener()); 
findViewById(R.id.topright).setOnDragListener(new MyDragListener()); 
findViewById(R.id.bottomleft).setOnDragListener(new MyDragListener()); 
findViewById(R.id.bottomright).setOnDragListener(new MyDragListener()); 

} 

private final class MyTouchListener implements OnTouchListener { 
public boolean onTouch(View view, MotionEvent motionEvent) { 
    if (motionEvent.getAction() == MotionEvent.ACTION_DOWN) { 
    ClipData data = ClipData.newPlainText("", ""); 
    DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view); 
    view.startDrag(data, shadowBuilder, view, 0); 
    view.setVisibility(View.INVISIBLE); 
    return true; 
    } else { 
    return false; 
    } 
} 
} 

class MyDragListener implements OnDragListener { 
Drawable enterShape = getResources().getDrawable(R.drawable.shape_droptarget); 
Drawable normalShape = getResources().getDrawable(R.drawable.shape); 

@Override 
public boolean onDrag(View v, DragEvent event) { 
    int action = event.getAction(); 
    switch (event.getAction()) { 
    case DragEvent.ACTION_DRAG_STARTED: 
    // do nothing 
    break; 
    case DragEvent.ACTION_DRAG_ENTERED: 
    v.setBackgroundDrawable(enterShape); 
    break; 
    case DragEvent.ACTION_DRAG_EXITED: 
    v.setBackgroundDrawable(normalShape); 
    break; 
    case DragEvent.ACTION_DROP: 
    // Dropped, reassign View to ViewGroup 
    View view = (View) event.getLocalState(); 
    ViewGroup owner = (ViewGroup) view.getParent(); 
    owner.removeView(view); 
    LinearLayout container = (LinearLayout) v; 
    container.addView(view); 
    view.setVisibility(View.VISIBLE); 
    break; 
    case DragEvent.ACTION_DRAG_ENDED: 
    v.setBackgroundDrawable(normalShape); 
    default: 
    break; 
    } 
    return true; 
    } 
} 
} 

Answer 2

I找到範例我的問題：

我StartActivity.java：

public class StartActivity extends Activity implements View.OnLongClickListener{ 

     @Override 
     protected void onCreate(Bundle savedInstanceState) { 
      super.onCreate(savedInstanceState); 
      setContentView(R.layout.activity_start); 
      findViewById(R.id.imgv).setOnLongClickListener(this); 
     } 

     @Override 
     public boolean onLongClick(View v) { 
      View.DragShadowBuilder shadowBuilder = new DrawableDragShadowBuilder(v, 
      getResources().getDrawable(R.drawable.ic_launcher)); 
      v.startDrag(null, shadowBuilder, ((ImageView) v).getDrawable(), 0); 
      return true; 
     } 
    } 

而且activity_start.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" 
    tools:context=".StartActivity"> 

    <ImageView 
     android:id="@+id/imgv" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:src="@drawable/ic_launcher"/> 

</RelativeLayout>