将列表视图项转换为单个位图图像

参考这个主题：Android 获取所有 ListView 项目的屏幕截图 https://stackoverflow.com/questions/12742343/android-get-screenshot-of-all-listview-items

我想做类似的事情，但我有自定义适配器，它在这段代码中抛出 NullPointerException 错误：

childView.measure(MeasureSpec.makeMeasureSpec(_listView.getWidth(),    MeasureSpec.EXACTLY),MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));

我的自定义适配器：

public class InvoiceListAdapter extends BaseAdapter {

  ArrayList<Object> _itemList;
  public Activity _context;
  public LayoutInflater _inflater;
  BarCodeGenerator Generator = new BarCodeGenerator();


  public InvoiceListAdapter(Activity context,ArrayList<Object> itemList)
  {
      super();
      this._context=context;
      this._itemList=itemList;
      this._inflater=(LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

  }
@Override
public int getCount() {
    // TODO Auto-generated method stub
    return _itemList.size();
}

@Override
public Object getItem(int position) {
    // TODO Auto-generated method stub
    return _itemList.get(position);
}

@Override
public long getItemId(int position) {
    // TODO Auto-generated method stub
    return 0;
}

public static class ViewHolder
{
 TextView ProductName;
 TextView Qnt;
 ImageView Barcode;
 TextView BarcodeFormat;
 Button Del;

}



@Override
public View getView(final int position, View convertView, ViewGroup parent) {

    ViewHolder holder;
     if(convertView==null)
        {
            holder = new ViewHolder();
            convertView = _inflater.inflate(R.layout.custom_row_view, null);


            holder.ProductName = (TextView) convertView.findViewById(R.id.txt_CRow_ProdName);
            holder.Qnt = (TextView) convertView.findViewById(R.id.txt_CRow_Qnt);
            holder.Del = (Button) convertView.findViewById(R.id.btn_CRow_Delete);
            holder.Barcode = (ImageView) convertView.findViewById(R.id.Img_CRow_Barcode);
            /*-----------------------------Deleting Item with Button--------------------*/
            holder.Del.setTag(holder);


            convertView.setTag(holder);
        }
        else
        {
            holder=(ViewHolder)convertView.getTag();
        }

        AnItem Item = (AnItem) _itemList.get(position);

        holder.ProductName.setText(Item.getProductName());
        holder.Qnt.setText(Item.getQnt());
        holder.Barcode.setImageBitmap(Generator.Generate(Item.getProductName(), BarcodeFormat.valueOf(Item.getBarcode() ),500,200 ) ); 

        holder.Del.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(_context,"Item Deleted!: "+position, Toast.LENGTH_SHORT).show();

                _itemList.remove(position);  
                notifyDataSetChanged();

                // TODO Auto-generated method stub

            }
        });

        return convertView;


}

}

我的自定义行：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:orientation="vertical">

<TextView
android:id="@+id/txt_CRow_ProdName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:hint="@string/ProductName"
android:textSize="16sp"
android:textStyle="bold" />

<Button
android:id="@+id/btn_CRow_Delete"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:focusable="false"
android:text="@string/Delete"
android:textSize="12sp"/>

<TextView
android:id="@+id/txt_CRow_Qnt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/Img_CRow_Barcode"
android:hint="@string/Qnt"
android:textSize="12sp"
android:textStyle="bold" />

<ImageView
android:id="@+id/Img_CRow_Barcode"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/txt_CRow_ProdName"
android:layout_centerVertical="true"
android:layout_toLeftOf="@+id/btn_CRow_Delete"
android:layout_alignParentLeft="true"
 />

</RelativeLayout>

感谢您的帮助。

您可以从任何视图获取位图，如下所示：

public static Bitmap getBitmapFromView(View view) {
    Bitmap returnedBitmap = Bitmap.createBitmap(view.getWidth(), view.getHeight(), Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(returnedBitmap);
    Drawable bgDrawable = view.getBackground();
    if (bgDrawable != null)
        bgDrawable.draw(canvas);
    else
        canvas.drawColor(Color.WHITE);
    view.draw(canvas);
    return returnedBitmap;
}