在Android中使用来自Recyclerview（内部的所有项目）的iText创建PDF文件？

Question

您好我正在尝试使用库iText从Recyclerview创建PDF输出文件。经过几个小时的奋斗，我能够从recylerview创建PDF。

以下是我用来创建PDF的类

主类代码

     private void getPrint() {


    ArrayList<View> viewArrayList = mAdapter.getPrintView(); // A function from Adapter class which returns ArrayList of VIEWS
    Document document = new Document(PageSize.A4);
    final File file = new File(getStorageDir("PDF"), "print.pdf");
    try {
        PdfWriter.getInstance(document, new FileOutputStream(file));
    } catch (DocumentException | FileNotFoundException e) {
        e.printStackTrace();
    }

    for (int im = 0; im < viewArrayList.size(); im++) {
        // Iterate till the last of the array list and add each view individually to the document.
        try {
            viewArrayList.get(im).buildDrawingCache();         //Adding the content to the document
            Bitmap bmp = viewArrayList.get(im).getDrawingCache();
            ByteArrayOutputStream stream = new ByteArrayOutputStream();
            bmp.compress(Bitmap.CompressFormat.PNG, 100, stream);
            Image image = Image.getInstance(stream.toByteArray());
            image.scalePercent(70);
            image.setAlignment(Image.MIDDLE);
            if (!document.isOpen()) {
                document.open();
            }
            document.add(image);

        } catch (Exception ex) {
            Log.e("TAG-ORDER PRINT ERROR", ex.getMessage());
        }
    }

    if (document.isOpen()) {
        document.close();
    }

    AlertDialog.Builder builder = new AlertDialog.Builder(Index.this);
    builder.setTitle("Success")
            .setMessage("PDF File Generated Successfully.")
            .setIcon(android.R.drawable.ic_dialog_alert)
            .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int whichButton) {
                    Intent intent = new Intent(Intent.ACTION_VIEW);
                    intent.setDataAndType(Uri.fromFile(file), "application/pdf");
                    intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
                    startActivity(intent);
                }

            }).show();

}

常见的RecyclerView适配器类

    public class RecyclerAdapter<T, VM extends ViewDataBinding> extends RecyclerView.Adapter<RecyclerAdapter.RecyclerViewHolder> {
private final Context context;
private ArrayList<T> items;
private int layoutId;
private RecyclerCallback<VM, T> bindingInterface;
private static ArrayList<View> mPrintView = new ArrayList<>();

public RecyclerAdapter(Context context, ArrayList<T> items, int layoutId, RecyclerCallback<VM, T> bindingInterface) {
    this.items = items;
    this.context = context;
    this.layoutId = layoutId;
    this.bindingInterface = bindingInterface;
}

public class RecyclerViewHolder extends RecyclerView.ViewHolder {

    VM binding;

    public RecyclerViewHolder(View view) {
        super(view);
        binding = DataBindingUtil.bind(view);
    }

    public void bindData(T model) {
        bindingInterface.bindData(binding, model);
        binding.executePendingBindings();
    }

}

@Override
public RecyclerViewHolder onCreateViewHolder(ViewGroup parent,
                                             int viewType) {
    View v = LayoutInflater.from(parent.getContext())
            .inflate(layoutId, parent, false);
    return new RecyclerViewHolder(v);
}

@Override
public void onBindViewHolder(RecyclerAdapter.RecyclerViewHolder holder, int position) {
    T item = items.get(position);
    Log.e("PRINT ", holder.binding.getRoot().getId() + "");
    mPrintView.add(holder.binding.getRoot());
    holder.bindData(item);

}

@Override
public int getItemCount() {
    if (items == null) {
        return 0;
    }
    return items.size();
}

public static ArrayList<View> getPrintView() {
    return mPrintView;
}

}

我使用名为mPrintView的Arraylist来保存RecylerView中的视图。当USER滚动recylerview UP和DOWM多次时，ArrayList中的数据变得重复，就会出现问题

以下是PDF转换后得到的结果图像

案例1：当用户仅滚动一次时

案例2：当用户多次向上和向下滚动时

在上图中，您可以注意到Apple已被复制

任何帮助表示赞赏

Answer 1

你救了我的一天。但我必须改变这一行：

image.scalePercent(70);
image.setAlignment(Image.MIDDLE);

有了这个 ：

float scaler = ((document.getPageSize().getWidth() - document.leftMargin()
                    - document.rightMargin() - 0) / image.getWidth()) * 100; // 0 means you have no indentation. If you have any, change it.
            image.scalePercent(scaler);
            image.setAlignment(com.itextpdf.text.Image.ALIGN_CENTER | com.itextpdf.text.Image.ALIGN_TOP);

非常感谢

Answer 2

经过几个小时的追踪和错误，我找到了答案。我正在分享代码片段，因为它可能对其他人有帮助

     public void generatePDF(RecyclerView view) {

    RecyclerView.Adapter adapter = view.getAdapter();
    Bitmap bigBitmap = null;
    if (adapter != null) {
        int size = adapter.getItemCount();
        int height = 0;
        Paint paint = new Paint();
        int iHeight = 0;
        final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);

        // Use 1/8th of the available memory for this memory cache.
        final int cacheSize = maxMemory / 8;
        LruCache<String, Bitmap> bitmaCache = new LruCache<>(cacheSize);
        for (int i = 0; i < size; i++) {
            RecyclerView.ViewHolder holder = adapter.createViewHolder(view, adapter.getItemViewType(i));
            adapter.onBindViewHolder(holder, i);
            holder.itemView.measure(View.MeasureSpec.makeMeasureSpec(view.getWidth(), View.MeasureSpec.EXACTLY),
                    View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));
            holder.itemView.layout(0, 0, holder.itemView.getMeasuredWidth(), holder.itemView.getMeasuredHeight());
            holder.itemView.setDrawingCacheEnabled(true);
            holder.itemView.buildDrawingCache();
            Bitmap drawingCache = holder.itemView.getDrawingCache();
            if (drawingCache != null) {

                bitmaCache.put(String.valueOf(i), drawingCache);
            }

            height += holder.itemView.getMeasuredHeight();
        }

        bigBitmap = Bitmap.createBitmap(view.getMeasuredWidth(), height, Bitmap.Config.ARGB_8888);
        Canvas bigCanvas = new Canvas(bigBitmap);
        bigCanvas.drawColor(Color.WHITE);

        Document document = new Document(PageSize.A4);
        final File file = new File(getStorageDir("PDF"), "print.pdf");
        try {
            PdfWriter.getInstance(document, new FileOutputStream(file));
        } catch (DocumentException | FileNotFoundException e) {
            e.printStackTrace();
        }

        for (int i = 0; i < size; i++) {

            try {
                //Adding the content to the document
                Bitmap bmp = bitmaCache.get(String.valueOf(i));
                ByteArrayOutputStream stream = new ByteArrayOutputStream();
                bmp.compress(Bitmap.CompressFormat.PNG, 100, stream);
                Image image = Image.getInstance(stream.toByteArray());
                 float scaler = ((document.getPageSize().getWidth() - document.leftMargin()
                - document.rightMargin() - 0) / image.getWidth()) * 100; // 0 means you have no indentation. If you have any, change it.
                image.scalePercent(scaler);
                image.setAlignment(com.itextpdf.text.Image.ALIGN_CENTER | com.itextpdf.text.Image.ALIGN_TOP);
                if (!document.isOpen()) {
                    document.open();
                }
                document.add(image);

            } catch (Exception ex) {
                Log.e("TAG-ORDER PRINT ERROR", ex.getMessage());
            }
        }

        if (document.isOpen()) {
            document.close();
        }
        // Set on UI Thread
        runOnUiThread(new Runnable() {
            @Override
            public void run() {

                AlertDialog.Builder builder = new AlertDialog.Builder(Index.this);
                builder.setTitle("Success")
                        .setMessage("PDF File Generated Successfully.")
                        .setIcon(android.R.drawable.ic_dialog_alert)
                        .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int whichButton) {
                                Intent intent = new Intent(Intent.ACTION_VIEW);
                                intent.setDataAndType(Uri.fromFile(file), "application/pdf");
                                intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
                                startActivity(intent);
                            }

                        }).show();
            }
        });

    }

}