如何创建一个自定义的拖影？

我要达到什么样的：

我想创建一个拖放在Android的拖放功能。我想使用一个特定的布局，一拖影（从拖动对象本身不同）。

I want to create a drag and drop functionality in Android. I'd like to use a specific layout (different from the dragged object itself) as a drag shadow.

什么导致我收到代替：

无论是我的方法按预期工作 - 我最终没有明显的拖影都（虽然目标确实接收到滴）

Neither of my approaches works as expected - I end up with no visible drag shadow at all (although the target does receive the drop).

我的尝试：

我试过

• 充气 drag_item 布局中的活动，然后将它作为参数传递给阴影生成器的构造

• inflating the drag_item layout in the activity, then passing it as an argument to the shadow builder's constructor

和

• 膨胀的影子建筑工地 onDrawShadow 方法 drag_item 布局，然后在画布

• inflating the drag_item layout in the shadow builder's onDrawShadow method, then drawing it on the canvas

布局：

我的活动布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              xmlns:tools="http://schemas.android.com/tools"
              android:id="@+id/container"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              tools:context="com.example.app.DragDropTestActivity"
              tools:ignore="MergeRootFrame">
    <TextView
        android:id="@+id/tvReceiver"
        android:text="Drop here"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    <Button
        android:id="@+id/btnDragged"
        android:layout_height="wrap_content"
        android:text="Drag me"
        android:layout_width="match_parent"/>
</LinearLayout>

我要为一拖影使用的布局：

The layout I want to use as a drag shadow:

dragged_item.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="match_parent"
              android:layout_height="match_parent">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Dragged Item"/>
</LinearLayout>

来源$ C ​​$ C：

这里的code有两种方法（重presented由 1 ， BuilderOne 和 2 ， BuilderTwo ，分别）：

Here's the code with both approaches (represented by 1, BuilderOne and 2, BuilderTwo, respectively):

package com.example.app;

import android.graphics.Canvas;
import android.graphics.Point;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;

public class DragDropTestActivity extends ActionBarActivity
{
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_drag_drop_test);
        Button dragged = (Button) findViewById(R.id.btnDragged);

        dragged.setOnTouchListener(
            new View.OnTouchListener()
            {
                @Override
                public boolean onTouch(View v, MotionEvent event)
                {
                    if (event.getAction() != MotionEvent.ACTION_DOWN) {
                        return false;
                    }
                    LayoutInflater inflater = getLayoutInflater();

                    int approach = 1;    
                    // both approaches fail
                    switch (approach) {
                        case 1: {
                            View draggedItem = inflater.inflate(R.layout.dragged_item, null);
                            BuilderOne builder = new BuilderOne(draggedItem);
                            v.startDrag(null, builder, null, 0);
                            break;
                        }
                        case 2: {
                            BuilderTwo builder = new BuilderTwo(inflater, v);
                            v.startDrag(null, builder, null, 0);
                            break;
                        }
                    }

                    return true;
                }
            });
    }

我的 BuilderOne 类：

    public static class BuilderOne extends View.DragShadowBuilder
    {
        public BuilderOne(View view)
        {
            super(view);
        }

        @Override
        public void onProvideShadowMetrics(Point shadowSize, Point shadowTouchPoint)
        {
            super.onProvideShadowMetrics(
                shadowSize,
                shadowTouchPoint);
        }
    }

和 BuilderTwo 类：

    public static class BuilderTwo extends View.DragShadowBuilder
    {
        final LayoutInflater inflater;

        public BuilderTwo(LayoutInflater inflater, View view)
        {
            super(view);
            this.inflater = inflater;
        }

        @Override
        public void onProvideShadowMetrics(Point shadowSize, Point shadowTouchPoint)
        {
            super.onProvideShadowMetrics(
                shadowSize,
                shadowTouchPoint);
        }

        @Override
        public void onDrawShadow(Canvas canvas)
        {
            final View draggedItem = inflater.inflate(R.layout.dragged_item, null);
            if (draggedItem != null) {
                draggedItem.draw(canvas);
            }
        }
    }
}

问：

我该怎么办错了？

更新：

赏金补充说。