[英]The PDF renderer class is not rendering a PDF on Android SDK 21
Here's the code I'm using to render a PDF called "answerkey.pdf" that's stored in "Download/Adobe Reader/answerkey.pdf" 这是我用来呈现称为“ answerkey.pdf”的PDF的代码,该PDF存储在“下载/ Adobe Reader / answerkey.pdf”中
package com.practice.pdftest;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.graphics.Rect;
import android.graphics.pdf.PdfRenderer;
import android.os.Environment;
import android.os.ParcelFileDescriptor;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
public class MainActivity extends Activity {
private ImageView imageView;
private Button next, previous;
private TextView tv;
private int currentPage = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
next = (Button)findViewById(R.id.next);
next.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
currentPage++;
render();
}
});
previous = (Button)findViewById(R.id.previous);
previous.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
currentPage--;
render();
}
});
// tv = (TextView)findViewById(R.id.testText);
// tv.setText(Environment.getExternalStorageDirectory().getAbsolutePath());
//
// Toast toast = Toast.makeText(getApplicationContext(),Environment.getExternalStorageDirectory().getAbsolutePath(),Toast.LENGTH_LONG);
// toast.show();
}
private void render() {
try {
imageView = (ImageView)findViewById(R.id.imageView);
int REQ_WIDTH = 1;
int REQ_HEIGHT = 1;
REQ_WIDTH = imageView.getWidth();
REQ_HEIGHT = imageView.getHeight();
Bitmap bitmap = Bitmap.createBitmap(REQ_WIDTH, REQ_HEIGHT, Bitmap.Config.ARGB_4444);
File file = new File(Environment.getDataDirectory().getPath()+"Adobe Reader/answerkey.pdf");
PdfRenderer pdfRenderer = new PdfRenderer(ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY));
if(currentPage < 0) {
currentPage=0;
}
else if (currentPage > pdfRenderer.getPageCount()) {
currentPage = pdfRenderer.getPageCount()-1;
}
Matrix matrix = imageView.getImageMatrix();
Rect rect = new Rect(0,0,REQ_HEIGHT,REQ_WIDTH);
pdfRenderer.openPage(currentPage).render(bitmap,rect,matrix,PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);
imageView.setImageMatrix(matrix);
imageView.setImageBitmap(bitmap);
imageView.invalidate();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Here's the layout.xml file I've made - 这是我制作的layout.xml文件-
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:orientation="vertical"
tools:context="com.practice.pdftest.MainActivity">
<ImageView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/imageView"
android:layout_weight="4"
android:background="@android:color/white"
android:layout_marginBottom="20dp"
/>
<!--<TextView-->
<!--android:layout_width="wrap_content"-->
<!--android:layout_height="wrap_content"-->
<!--android:id="@+id/testText"-->
<!--android:text="Test"-->
<!--/>-->
<LinearLayout
android:layout_width="match_parent"
android:orientation="horizontal"
android:layout_weight="2"
android:gravity="center"
android:layout_height="wrap_content"
android:layout_marginTop="-100dp">
<Button
android:id="@+id/previous"
android:layout_width="200dp"
android:layout_height="wrap_content"
android:text="Previous"
/>
<Button
android:id="@+id/next"
android:layout_width="200dp"
android:layout_height="wrap_content"
android:text="Next" />
</LinearLayout>
</LinearLayout>
For some reason, the PDF just isn't being displayed on screen, I keep getting a white, blank background. 由于某种原因,PDF并未在屏幕上显示,我一直得到白色空白背景。 What am I doing wrong?
我究竟做错了什么? Is the path incorrect?
路径不正确吗? I have no SD card on my device.
我的设备上没有SD卡。 Or am I doing something wrong with the bitmap?
还是我对位图做错了?
Is the path incorrect?
路径不正确吗?
Yes. 是。
I have no SD card on my device
我的设备上没有SD卡
That is fine. 那也行。 That would be removable storage .
那将是可移动存储 。 I am interpreting "Download/Adobe Reader/answerkey.pdf" as referring to something on external storage .
我将“ Download / Adobe Reader / answerkey.pdf”解释为是指外部存储上的某些内容。
The recommended way to get this location would be to replace: 推荐的获取该位置的方法是替换:
File file = new File(Environment.getDataDirectory().getPath()+"Adobe Reader/answerkey.pdf");
with: 与:
File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), "Adobe Reader/answerkey.pdf");
Note that your app will need to request the READ_EXTERNAL_STORAGE
or WRITE_EXTERNAL_STORAGE
permission, and that will involve runtime permissions on Android 6.0+ (if your targetSdkVersion
is 23 or higher). 请注意,您的应用将需要请求
READ_EXTERNAL_STORAGE
或WRITE_EXTERNAL_STORAGE
权限,而这将涉及Android 6.0+上的运行时权限 (如果targetSdkVersion
为23或更高)。
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