PdfRendererBasicFragment.java

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/*
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 * Copyright (C) 2014 The Android Open Source Project
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 *
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 * Licensed under the Apache License, Version 2.0 (the "License");
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 * you may not use this file except in compliance with the License.
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 * You may obtain a copy of the License at
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 *
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 *      http://www.apache.org/licenses/LICENSE-2.0
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 *
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 * Unless required by applicable law or agreed to in writing, software
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 * distributed under the License is distributed on an "AS IS" BASIS,
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 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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 * See the License for the specific language governing permissions and
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 * limitations under the License.
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 */
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package com.example.android.pdfrendererbasic;
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import android.app.Activity;
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import android.app.Fragment;
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import android.content.Context;
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import android.graphics.Bitmap;
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import android.graphics.pdf.PdfRenderer;
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import android.os.Bundle;
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import android.os.ParcelFileDescriptor;
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import android.view.LayoutInflater;
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import android.view.View;
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import android.view.ViewGroup;
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import android.widget.Button;
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import android.widget.ImageView;
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import android.widget.Toast;
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import java.io.File;
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import java.io.FileOutputStream;
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import java.io.IOException;
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import java.io.InputStream;
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/**
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 * This fragment has a big {@ImageView} that shows PDF pages, and 2 {@link android.widget.Button}s to move between
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 * pages. We use a {@link android.graphics.pdf.PdfRenderer} to render PDF pages as {@link android.graphics.Bitmap}s.
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 */
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public class PdfRendererBasicFragment extends Fragment implements View.OnClickListener {
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    /**
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     * Key string for saving the state of current page index.
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     */
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    private static final String STATE_CURRENT_PAGE_INDEX = "current_page_index";
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    /**
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     * The filename of the PDF.
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     */
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    private static final String FILENAME = "sample.pdf";
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    /**
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     * File descriptor of the PDF.
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     */
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    private ParcelFileDescriptor mFileDescriptor;
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    /**
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     * {@link android.graphics.pdf.PdfRenderer} to render the PDF.
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     */
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    private PdfRenderer mPdfRenderer;
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    /**
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     * Page that is currently shown on the screen.
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     */
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    private PdfRenderer.Page mCurrentPage;
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    /**
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     * {@link android.widget.ImageView} that shows a PDF page as a {@link android.graphics.Bitmap}
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     */
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    private ImageView mImageView;
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    /**
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     * {@link android.widget.Button} to move to the previous page.
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     */
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    private Button mButtonPrevious;
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    /**
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     * {@link android.widget.Button} to move to the next page.
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     */
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    private Button mButtonNext;
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    public PdfRendererBasicFragment() {
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    }
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    @Override
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    public View onCreateView(LayoutInflater inflater, ViewGroup container,
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                             Bundle savedInstanceState) {
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        return inflater.inflate(R.layout.fragment_pdf_renderer_basic, container, false);
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    }
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    @Override
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    public void onViewCreated(View view, Bundle savedInstanceState) {
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        super.onViewCreated(view, savedInstanceState);
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        // Retain view references.
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        mImageView = (ImageView) view.findViewById(R.id.image);
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        mButtonPrevious = (Button) view.findViewById(R.id.previous);
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        mButtonNext = (Button) view.findViewById(R.id.next);
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        // Bind events.
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        mButtonPrevious.setOnClickListener(this);
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        mButtonNext.setOnClickListener(this);
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        // Show the first page by default.
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        int index = 0;
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        // If there is a savedInstanceState (screen orientations, etc.), we restore the page index.
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        if (null != savedInstanceState) {
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            index = savedInstanceState.getInt(STATE_CURRENT_PAGE_INDEX, 0);
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        }
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        showPage(index);
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    }
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    @Override
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    public void onAttach(Activity activity) {
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        super.onAttach(activity);
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        try {
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            openRenderer(activity);
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        } catch (IOException e) {
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            e.printStackTrace();
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            Toast.makeText(activity, "Error! " + e.getMessage(), Toast.LENGTH_SHORT).show();
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            activity.finish();
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        }
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    }
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    @Override
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    public void onDetach() {
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        try {
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            closeRenderer();
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        } catch (IOException e) {
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            e.printStackTrace();
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        }
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        super.onDetach();
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    }
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    @Override
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    public void onSaveInstanceState(Bundle outState) {
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        super.onSaveInstanceState(outState);
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        if (null != mCurrentPage) {
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            outState.putInt(STATE_CURRENT_PAGE_INDEX, mCurrentPage.getIndex());
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        }
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    }
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    /**
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     * Sets up a {@link android.graphics.pdf.PdfRenderer} and related resources.
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     */
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    private void openRenderer(Context context) throws IOException {
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        // In this sample, we read a PDF from the assets directory.
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        File file = new File(context.getCacheDir(), FILENAME);
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        if (!file.exists()) {
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            // Since PdfRenderer cannot handle the compressed asset file directly, we copy it into
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            // the cache directory.
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            InputStream asset = context.getAssets().open(FILENAME);
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            FileOutputStream output = new FileOutputStream(file);
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            final byte[] buffer = new byte[1024];
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            int size;
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            while ((size = asset.read(buffer)) != -1) {
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                output.write(buffer, 0, size);
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            }
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            asset.close();
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            output.close();
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        }
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        mFileDescriptor = ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY);
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        // This is the PdfRenderer we use to render the PDF.
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        mPdfRenderer = new PdfRenderer(mFileDescriptor);
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    }
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    /**
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     * Closes the {@link android.graphics.pdf.PdfRenderer} and related resources.
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     *
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     * @throws java.io.IOException When the PDF file cannot be closed.
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     */
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    private void closeRenderer() throws IOException {
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        if (null != mCurrentPage) {
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            mCurrentPage.close();
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        }
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        mPdfRenderer.close();
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        mFileDescriptor.close();
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    }
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    /**
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     * Shows the specified page of PDF to the screen.
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     *
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     * @param index The page index.
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     */
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    private void showPage(int index) {
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        if (mPdfRenderer.getPageCount() <= index) {
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            return;
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        }
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        // Make sure to close the current page before opening another one.
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        if (null != mCurrentPage) {
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            mCurrentPage.close();
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        }
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        // Use `openPage` to open a specific page in PDF.
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        mCurrentPage = mPdfRenderer.openPage(index);
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        // Important: the destination bitmap must be ARGB (not RGB).
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        Bitmap bitmap = Bitmap.createBitmap(mCurrentPage.getWidth(), mCurrentPage.getHeight(),
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                Bitmap.Config.ARGB_8888);
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        // Here, we render the page onto the Bitmap.
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        // To render a portion of the page, use the second and third parameter. Pass nulls to get
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        // the default result.
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        // Pass either RENDER_MODE_FOR_DISPLAY or RENDER_MODE_FOR_PRINT for the last parameter.
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        mCurrentPage.render(bitmap, null, null, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);
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        // We are ready to show the Bitmap to user.
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        mImageView.setImageBitmap(bitmap);
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        updateUi();
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    }
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    /**
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     * Updates the state of 2 control buttons in response to the current page index.
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     */
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    private void updateUi() {
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        int index = mCurrentPage.getIndex();
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        int pageCount = mPdfRenderer.getPageCount();
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        mButtonPrevious.setEnabled(0 != index);
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        mButtonNext.setEnabled(index + 1 < pageCount);
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        getActivity().setTitle(getString(R.string.app_name_with_index, index + 1, pageCount));
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    }
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    /**
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     * Gets the number of pages in the PDF. This method is marked as public for testing.
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     *
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     * @return The number of pages.
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     */
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    public int getPageCount() {
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        return mPdfRenderer.getPageCount();
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    }
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    @Override
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    public void onClick(View view) {
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        switch (view.getId()) {
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            case R.id.previous: {
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                // Move to the previous page
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                showPage(mCurrentPage.getIndex() - 1);
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                break;
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            }
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            case R.id.next: {
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                // Move to the next page
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                showPage(mCurrentPage.getIndex() + 1);
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                break;
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            }
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        }
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    }
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}