在 Android Java 中将 Pdf 页面转换为 Bitmap [英] Convert a Pdf page into Bitmap in Android Java

问题描述

我需要在 Android 中将 PDFfile(PDF 页面)转换为位图(或图像文件).

I need to convert PDFfile(PDF page) into a Bitmap(or Image file) in Android.

1. 使用 Apache 的 Pdfbox jar.但它使用了一些 android 不支持的 java 类.2.尝试将图像转换为pdf的Itext jar(我需要它的反向操作)像那样，我试过很多罐子.但没有积极的结果.

1.Used Pdfbox jar from Apache. But it uses some java classes that is not supported in android. 2. Tried Itext jar which converts image to pdf(I need its reverse operation) Like that I have tried many jars. But no positive result.

byte[] bytes;
    try {

        File file = new File(this.getFilesDir().getAbsolutePath()+"/2010Q2_SDK_Overview.pdf");
        FileInputStream is = new FileInputStream(file);

        // Get the size of the file
        long length = file.length();
        bytes = new byte[(int) length];
        int offset = 0;
        int numRead = 0;
        while (offset < bytes.length && (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {
            offset += numRead;
        }


        ByteBuffer buffer = ByteBuffer.NEW(bytes);
        String data = Base64.encodeToString(bytes, Base64.DEFAULT);
        PDFFile pdf_file = new PDFFile(buffer);
        PDFPage page = pdf_file.getPage(2);

        RectF rect = new RectF(0, 0, (int) page.getBBox().width(),
                (int) page.getBBox().height());
      //  Bitmap bufferedImage = Bitmap.createBitmap((int)rect.width(), (int)rect.height(),
         //        Bitmap.Config.ARGB_8888);

        Bitmap image = page.getImage((int)rect.width(), (int)rect.height(), rect);
        FileOutputStream os = new FileOutputStream(this.getFilesDir().getAbsolutePath()+"/pdf.jpg");
        image.compress(Bitmap.CompressFormat.JPEG, 80, os);

       // ((ImageView) findViewById(R.id.testView)).setImageBitmap(image);

我正在获取图像文件，

取而代之的是

package com.test123;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;

import com.sun.pdfview.PDFFile;
import com.sun.pdfview.PDFPage;
import net.sf.andpdf.nio.ByteBuffer;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.RectF;
import android.os.Bundle;
import android.util.Base64;

public class Test123Activity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        byte[] bytes;
        try {

            File file = new File(this.getFilesDir().getAbsolutePath()+"/2010Q2_SDK_Overview.pdf");
            FileInputStream is = new FileInputStream(file);

            // Get the size of the file
            long length = file.length();
            bytes = new byte[(int) length];
            int offset = 0;
            int numRead = 0;
            while (offset < bytes.length && (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {
                offset += numRead;
            }


            ByteBuffer buffer = ByteBuffer.NEW(bytes);
            String data = Base64.encodeToString(bytes, Base64.DEFAULT);
            PDFFile pdf_file = new PDFFile(buffer);
            PDFPage page = pdf_file.getPage(2);

            RectF rect = new RectF(0, 0, (int) page.getBBox().width(),
                    (int) page.getBBox().height());
          //  Bitmap bufferedImage = Bitmap.createBitmap((int)rect.width(), (int)rect.height(),
             //        Bitmap.Config.ARGB_8888);

            Bitmap image = page.getImage((int)rect.width(), (int)rect.height(), rect);
            FileOutputStream os = new FileOutputStream(this.getFilesDir().getAbsolutePath()+"/pdf.jpg");
            image.compress(Bitmap.CompressFormat.JPEG, 80, os);

            //((ImageView) findViewById(R.id.testView)).setImageBitmap(image);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

另外，还有什么其他方法可以使用应用程序内置的函数在 android 中显示 pdf 文件?

Else, any other way to display pdf file in android using function inbuilt within application?

推荐答案

我解决了这个问题.就像让设备有时间渲染每个页面一样简单.

I solved this issue. it's as simple as letting the device have time to render each page.

要解决这个问题，你所要做的就是改变

To fix this all you have to do is change

PDFPage page = pdf_file.getPage(2);

到

PDFPage page = pdf_file.getPage(2, true);

首先要在 Android 中查看 PDF，您必须将 PDF 转换为图像，然后将它们显示给用户.(我将使用 webview)

Firstly to view a PDF in Android you have to convert the PDF into images then display them to the user. (I am going to use a webview)

为此，我们需要这个图书馆.这是我对该 git 的编辑版本.

So to do this we need this library. It is my edited version of this git.

将库导入项目后，您需要创建活动.

After you have imported the library into your project you need to create your activity.

XML:

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

    <WebView
            android:id="@+id/webView1"
            android:layout_width="match_parent"
            android:layout_height="match_parent"/>

</LinearLayout>

Java:

//Imports:
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.graphics.Bitmap;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.util.Base64;
import android.util.Log;
import android.view.View;
import android.view.ViewTreeObserver;
import android.webkit.WebView;
import com.sun.pdfview.PDFFile;
import com.sun.pdfview.PDFImage;
import com.sun.pdfview.PDFPage;
import com.sun.pdfview.PDFPaint;
import net.sf.andpdf.nio.ByteBuffer;
import net.sf.andpdf.refs.HardReference;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.RandomAccessFile;
import java.nio.channels.FileChannel;

//Globals:
private WebView wv;
private int ViewSize = 0;

//OnCreate Method:
@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    //Settings
    PDFImage.sShowImages = true; // show images
    PDFPaint.s_doAntiAlias = true; // make text smooth
    HardReference.sKeepCaches = true; // save images in cache

    //Setup webview
    wv = (WebView)findViewById(R.id.webView1);
    wv.getSettings().setBuiltInZoomControls(true);//show zoom buttons
    wv.getSettings().setSupportZoom(true);//allow zoom
    //get the width of the webview
    wv.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener()
    {
        @Override
        public void onGlobalLayout()
        {
            ViewSize = wv.getWidth();
            wv.getViewTreeObserver().removeGlobalOnLayoutListener(this);
        }
    });

    try
    {
        File file = new File(Environment.getExternalStorageDirectory().getPath() + "/randompdf.pdf");
        RandomAccessFile f = new RandomAccessFile(file, "r");
        byte[] data = new byte[(int)f.length()];
        f.readFully(data);
        pdfLoadImages(data);
    }
    catch(Exception ignored)
    {
    }
}

//Load Images:
private void pdfLoadImages(final byte[] data)
{
    try
    {
        // run async
        new AsyncTask<Void, Void, String>()
        {
            // create and show a progress dialog
            ProgressDialog progressDialog = ProgressDialog.show(MainActivity.this, "", "Opening...");

            @Override
            protected void onPostExecute(String html)
            {
                //after async close progress dialog
                progressDialog.dismiss();
                //load the html in the webview
                wv.loadDataWithBaseURL("", html, "text/html","UTF-8", "");
            }

            @Override
            protected String doInBackground(Void... params)
            {
                try
                {
                    //create pdf document object from bytes
                    ByteBuffer bb = ByteBuffer.NEW(data);
                    PDFFile pdf = new PDFFile(bb);
                    //Get the first page from the pdf doc
                    PDFPage PDFpage = pdf.getPage(1, true);
                    //create a scaling value according to the WebView Width
                    final float scale = ViewSize / PDFpage.getWidth() * 0.95f;
                    //convert the page into a bitmap with a scaling value
                    Bitmap page = PDFpage.getImage((int)(PDFpage.getWidth() * scale), (int)(PDFpage.getHeight() * scale), null, true, true);
                    //save the bitmap to a byte array
                    ByteArrayOutputStream stream = new ByteArrayOutputStream();
                    page.compress(Bitmap.CompressFormat.PNG, 100, stream);
                    byte[] byteArray = stream.toByteArray();
                    stream.reset();
                    //convert the byte array to a base64 string
                    String base64 = Base64.encodeToString(byteArray, Base64.NO_WRAP);
                    //create the html + add the first image to the html
                    String html = "<!DOCTYPE html><html><body bgcolor="#b4b4b4"><img src="data:image/png;base64,"+base64+"" hspace=10 vspace=10><br>";
                    //loop though the rest of the pages and repeat the above
                    for(int i = 2; i <= pdf.getNumPages(); i++)
                    {
                        PDFpage = pdf.getPage(i, true);
                        page = PDFpage.getImage((int)(PDFpage.getWidth() * scale), (int)(PDFpage.getHeight() * scale), null, true, true);
                        page.compress(Bitmap.CompressFormat.PNG, 100, stream);
                        byteArray = stream.toByteArray();
                        stream.reset();
                        base64 = Base64.encodeToString(byteArray, Base64.NO_WRAP);
                        html += "<img src="data:image/png;base64,"+base64+"" hspace=10 vspace=10><br>";
                    }
                    stream.close();
                    html += "</body></html>";
                    return html;
                }
                catch (Exception e)
                {
                    Log.d("error", e.toString());
                }
                return null;
            }
        }.execute();
        System.gc();// run GC
    }
    catch (Exception e)
    {
        Log.d("error", e.toString());
    }
}

这篇关于在 Android Java 中将 Pdf 页面转换为 Bitmap的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！