如何将图像转换为 PDF？
How to convert Image to PDF?
我正在开发一个需要将图像转换为 PDF 的应用程序。我尝试了一些方法，但问题是，该 PDF 中的图像尺寸非常非常小。我需要解决方案来解决这个问题。此外，我正在寻找将多个图像转换为单个 PDF 文档的方法。
我将 post 我试过的代码。
public void convertPDF(byte[] path)
{
String FILE = "mnt/sdcard/FirstPdf.pdf";
Document document=new Document();
try {
PdfWriter.getInstance(document, new FileOutputStream(FILE));
document.open();
try {
image=Image.getInstance(path);
document.add(new Paragraph("My Heading"));
document.add(image);
document.close();
} catch (IOException e) {
e.printStackTrace();
}
} catch (DocumentException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
当我将位图转换为字节数组时，我正在压缩图像，我想这就是原因。不压缩图像，我无法将位图转换为字节数组。
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bmp.compress(Bitmap.CompressFormat.PNG,100,stream);
byte[] byteArray=stream.toByteArray();
convertPDF(byteArray);
有什么解决办法吗？
已更新
这里我实现了@Burak Cakir 在答案中建议的答案。但现在我在 PDF 中获得了更大的图像。为了更好地理解，请找到下面的图片。
实际图片是
我建议您使用 iText pdf 库。这是 gradle 依赖项：
implementation 'com.itextpdf:itextg:5.5.10'
Document document = new Document();
String directoryPath = android.os.Environment.getExternalStorageDirectory().toString();
PdfWriter.getInstance(document, new FileOutputStream(directoryPath + "/example.pdf")); // Change pdf's name.
document.open();
Image image = Image.getInstance(directoryPath + "/" + "example.jpg"); // Change image's name and extension.
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(Image.ALIGN_CENTER | Image.ALIGN_TOP);
document.add(image);
document.close();
从这里下载源代码 (Convert Image to pdf in android programmatically)
MainActivity.java:
package com.deepshikha.convertbitmap;
import android.Manifest;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.pdf.PdfDocument;
import android.net.Uri;
import android.provider.MediaStore;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.Display;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
public static final int GALLERY_PICTURE = 1;
Button btn_select, btn_convert;
ImageView iv_image;
boolean boolean_permission;
boolean boolean_save;
Bitmap bitmap;
public static final int REQUEST_PERMISSIONS = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
init();
listener();
fn_permission();
}
private void init() {
btn_select = (Button) findViewById(R.id.btn_select);
btn_convert = (Button) findViewById(R.id.btn_convert);
iv_image = (ImageView) findViewById(R.id.iv_image);
}
private void listener() {
btn_select.setOnClickListener(this);
btn_convert.setOnClickListener(this);
}
@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.btn_select:
Intent intent = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(intent, GALLERY_PICTURE);
break;
case R.id.btn_convert:
if (boolean_save){
Intent intent1=new Intent(getApplicationContext(),PDFViewActivity.class);
startActivity(intent1);
}else {
createPdf();
}
break;
}
}
private void createPdf(){
WindowManager wm = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay();
DisplayMetrics displaymetrics = new DisplayMetrics();
this.getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
float hight = displaymetrics.heightPixels ;
float width = displaymetrics.widthPixels ;
int convertHighet = (int) hight, convertWidth = (int) width;
// Resources mResources = getResources();
// Bitmap bitmap = BitmapFactory.decodeResource(mResources, R.drawable.screenshot);
PdfDocument document = new PdfDocument();
PdfDocument.PageInfo pageInfo = new PdfDocument.PageInfo.Builder(bitmap.getWidth(), bitmap.getHeight(), 1).create();
PdfDocument.Page page = document.startPage(pageInfo);
Canvas canvas = page.getCanvas();
Paint paint = new Paint();
paint.setColor(Color.parseColor("#ffffff"));
canvas.drawPaint(paint);
bitmap = Bitmap.createScaledBitmap(bitmap, bitmap.getWidth(), bitmap.getHeight(), true);
paint.setColor(Color.BLUE);
canvas.drawBitmap(bitmap, 0, 0 , null);
document.finishPage(page);
// write the document content
String targetPdf = "/sdcard/test.pdf";
File filePath = new File(targetPdf);
try {
document.writeTo(new FileOutputStream(filePath));
btn_convert.setText("Check PDF");
boolean_save=true;
} catch (IOException e) {
e.printStackTrace();
Toast.makeText(this, "Something wrong: " + e.toString(), Toast.LENGTH_LONG).show();
}
// close the document
document.close();
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == GALLERY_PICTURE && resultCode == RESULT_OK) {
if (resultCode == RESULT_OK) {
Uri selectedImage = data.getData();
String[] filePathColumn = {MediaStore.Images.Media.DATA};
Cursor cursor = getContentResolver().query(
selectedImage, filePathColumn, null, null, null);
cursor.moveToFirst();
int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
String filePath = cursor.getString(columnIndex);
cursor.close();
bitmap = BitmapFactory.decodeFile(filePath);
iv_image.setImageBitmap(bitmap);
btn_convert.setClickable(true);
}
}
}
private void fn_permission() {
if ((ContextCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED)||
(ContextCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED)) {
if ((ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this, android.Manifest.permission.READ_EXTERNAL_STORAGE))) {
} else {
ActivityCompat.requestPermissions(MainActivity.this, new String[]{android.Manifest.permission.READ_EXTERNAL_STORAGE},
REQUEST_PERMISSIONS);
}
if ((ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE))) {
} else {
ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
REQUEST_PERMISSIONS);
}
} else {
boolean_permission = true;
}
}
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == REQUEST_PERMISSIONS) {
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
boolean_permission = true;
} else {
Toast.makeText(getApplicationContext(), "Please allow the permission", Toast.LENGTH_LONG).show();
}
}
}
}
谢谢！
您可以通过将最低 SDK 设置为 19 (KitKat 4.4) 并使用 Google 的 PdfDocument API ( https://developer.android.com/reference/android/graphics/pdf/PdfDocument ) 将 JPG 转换为 PDF，如下所示在 Kotlin 中：
// Load JPG file into bitmap
val f: File = myJPGFile
val bitmap: Bitmap = BitmapFactory.decodeFile(f.absolutePath)
// Create a PdfDocument with a page of the same size as the image
val document: PdfDocument = PdfDocument()
val pageInfo: PdfDocument.PageInfo = PdfDocument.PageInfo.Builder(bitmap.width, bitmap.height, 1).create()
val page: PdfDocument.Page = document.startPage(pageInfo)
// Draw the bitmap onto the page
val canvas: Canvas = page.canvas
canvas.drawBitmap(bitmap, 0f, 0f, null)
document.finishPage(page)
// Write the PDF file to a file
val directoryPath: String = android.os.Environment.getExternalStorageDirectory().toString()
document.writeTo( FileOutputStream(directoryPath + "/example.pdf"))
document.close()
在gradle
中添加库
implementation 'com.itextpdf:itextg:5.5.10'
创建文件夹路径 - 它将从文件夹的所有图像创建 pdf
File folderPath = new File(Environment.getExternalStorageDirectory() + "/YourImagesFolder");
File[] imageList = folderPath .listFiles();
ArrayList<File> imagesArrayList = new ArrayList<>();
for (File absolutePath : imageList) {
imagesArrayList.add(absolutePath);
}
new CreatePdfTask(context, imagesArrayList).execute();
异步任务
public class CreatePdfTask extends AsyncTask<String, Integer, File> {
Context context;
ArrayList<File> files;
ProgressDialog progressDialog;
public CreatePdfTask(Context context2, ArrayList<File> arrayList) {
context = context2;
files = arrayList;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
progressDialog = new ProgressDialog(context);
progressDialog.setTitle("Please wait...");
progressDialog.setMessage("Creating pdf...");
progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
progressDialog.setIndeterminate(false);
progressDialog.setMax(100);
progressDialog.setCancelable(true);
progressDialog.show();
}
@Override
protected File doInBackground(String... strings) {
File outputMediaFile = Constant.getPdfPath();//path in which you want to save pdf
Document document = new Document(PageSize.A4, 38.0f, 38.0f, 50.0f, 38.0f);
try {
PdfWriter.getInstance(document, new FileOutputStream(outputMediaFile));
} catch (DocumentException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
return null;
}
document.open();
int i = 0;
while (true) {
if (i < this.files.size()) {
try {
Image image = Image.getInstance(files.get(i).getAbsolutePath());
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(Image.ALIGN_CENTER | Image.ALIGN_TOP);
image.setAbsolutePosition((document.getPageSize().getWidth() - image.getScaledWidth()) / 2.0f,
(document.getPageSize().getHeight() - image.getScaledHeight()) / 2.0f);
document.add(image);
document.newPage();
publishProgress(i);
i++;
} catch (BadElementException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (DocumentException e) {
e.printStackTrace();
}
} else {
document.close();
return outputMediaFile;
}
}
}
@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
this.progressDialog.setProgress(((values[0] + 1) * 100) / this.files.size());
StringBuilder sb = new StringBuilder();
sb.append("Processing images (");
sb.append(values[0] + 1);
sb.append("/");
sb.append(this.files.size());
sb.append(")");
progressDialog.setTitle(sb.toString());
}
@Override
protected void onPostExecute(File file) {
super.onPostExecute(file);
progressDialog.dismiss();
Toast.makeText(context, "Pdf store at " + file.getAbsolutePath(), Toast.LENGTH_SHORT).show();
}
}
只需传递上下文和文件列表
它将在缓存目录中创建一个 PDF 文件
将您自己的逻辑添加到 share/open PDF
工作快速可靠的方法
- No library needed (Uses android internal android.graphics.pdf.PdfDocument classes)
- Works in background, Doesn''t freeze UI
- No need to declare and grant storage permission :)
private static void createPdf(Context context,ArrayList<File> data){
File pdfFile = new File(context.getExternalCacheDir().getAbsolutePath() + File.separator + "TemperoryPDF_"+System.currentTimeMillis()+".pdf");
Toast.makeText(context, "Creating PDF,Please wait..", Toast.LENGTH_SHORT).show();
new AsyncTask<Void, Void, Void>() {
@Override
protected Void doInBackground(Void... voids) {
PdfDocument document = new PdfDocument();
try {
for(File item:data) {
Bitmap bitmap = BitmapFactory.decodeFile(item.getAbsolutePath());
PdfDocument.PageInfo pageInfo = new PdfDocument.PageInfo.Builder(bitmap.getWidth(), bitmap.getHeight(), 1).create();
PdfDocument.Page page = document.startPage(pageInfo);
Canvas canvas = page.getCanvas();
Paint paint = new Paint();
paint.setColor(Color.parseColor("#ffffff"));
canvas.drawPaint(paint);
canvas.drawBitmap(bitmap, 0, 0, null);
document.finishPage(page);
}
document.writeTo(new FileOutputStream(pdfFile));
} catch (IOException e) {
e.printStackTrace();
}finally {
document.close();
}
return null;
}
@Override
protected void onPostExecute(Void unused) {
super.onPostExecute(unused);
if(pdfFile.exists() && pdfFile.length()>0) {
FileUtil.openFile(context, pdfFile.getAbsolutePath()); // See: https://gist.github.com/omkar-tenkale/34d3aa1966653e6949d1ddaee1ba3355
}else {
Toast.makeText(context, "Something went wrong creating the PDF :(", Toast.LENGTH_SHORT).show();
}
}
}.execute();
}
这就是我把图片转成pdf的方法，非常简单，你需要先在清单中声明用户权限
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
然后在你的主 activity 中，你必须检查权限是否被授予，如果你不知道该怎么做，只需在 youtube 上搜索你会发现很多关于该主题的视频，之后那，我用这个方法从图库中拍摄我想转换成 pdf 的图像。
public void pickImage() {
Intent intent = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(intent,120);
}
之后，我覆盖了 onActivityResult() 方法来检索所选图像。
@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == 120 && resultCode == RESULT_OK && data != null) {
Uri selectedImageUri = data.getData();
String[] filePath = {MediaStore.Images.Media.DATA};
Cursor cursor =getContentResolver().query(selectedImageUri,filePath,null,null,null);
cursor.moveToFirst();
int columnIndex = cursor.getColumnIndex(filePath[0]);
String myPath = cursor.getString(columnIndex);
cursor.close();
Bitmap bitmap = BitmapFactory.decodeFile(myPath);
imageView.setImageBitmap(bitmap);
PdfDocument pdfDocument = new PdfDocument();
PdfDocument.PageInfo pageInfo = new PdfDocument.PageInfo.Builder(bitmap.getWidth(),
bitmap.getHeight(),1).create();
PdfDocument.Page page = pdfDocument.startPage(pageInfo);
Canvas canvas = page.getCanvas();
Paint paint = new Paint();
paint.setColor(Color.parseColor("#FFFFFF"));
canvas.drawPaint(paint);
bitmap=Bitmap.createScaledBitmap(bitmap,bitmap.getWidth(),bitmap.getHeight(),true);
paint.setColor(Color.BLUE);
canvas.drawBitmap(bitmap,0,0,null);
pdfDocument.finishPage(page);
//save the bitmap image
File root = new File(Environment.getExternalStorageDirectory(),"PDF folder 12");
if (!root.exists()){
root.mkdir();
}
File file = new File(root,"picture.pdf");
try {
FileOutputStream fileOutputStream = new FileOutputStream(file);
pdfDocument.writeTo(fileOutputStream);
}catch (Exception e){
e.getStackTrace();
}
pdfDocument.close();
}
}
不要忘记权限，请用户授予权限
如果要自动打开 pdf 文件，请在给出正确的文件夹路径和 pdf 文件名后使用此方法
String path ="/sdcard/PDF folder 12/picture.pdf";
public void openPDF (){
File pdfFile = new File(path);//File path
if (pdfFile.exists()) //Checking if the file exists or not
{
Uri path = Uri.fromFile(pdfFile);
Intent objIntent = new Intent(Intent.ACTION_VIEW);
objIntent.setDataAndType(path, "application/pdf");
objIntent.setFlags(Intent. FLAG_ACTIVITY_CLEAR_TOP);
startActivity(objIntent);//Starting the pdf viewer
} else {
Toast.makeText(GenerateQRActivity.this, "The file not exists! ", Toast.LENGTH_SHORT).show();
}
}
我正在开发一个需要将图像转换为 PDF 的应用程序。我尝试了一些方法，但问题是，该 PDF 中的图像尺寸非常非常小。我需要解决方案来解决这个问题。此外，我正在寻找将多个图像转换为单个 PDF 文档的方法。 我将 post 我试过的代码。
public void convertPDF(byte[] path)
{
String FILE = "mnt/sdcard/FirstPdf.pdf";
Document document=new Document();
try {
PdfWriter.getInstance(document, new FileOutputStream(FILE));
document.open();
try {
image=Image.getInstance(path);
document.add(new Paragraph("My Heading"));
document.add(image);
document.close();
} catch (IOException e) {
e.printStackTrace();
}
} catch (DocumentException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
当我将位图转换为字节数组时，我正在压缩图像，我想这就是原因。不压缩图像，我无法将位图转换为字节数组。
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bmp.compress(Bitmap.CompressFormat.PNG,100,stream);
byte[] byteArray=stream.toByteArray();
convertPDF(byteArray);
有什么解决办法吗？
已更新
这里我实现了@Burak Cakir 在答案中建议的答案。但现在我在 PDF 中获得了更大的图像。为了更好地理解，请找到下面的图片。
实际图片是
我建议您使用 iText pdf 库。这是 gradle 依赖项：
implementation 'com.itextpdf:itextg:5.5.10'
Document document = new Document();
String directoryPath = android.os.Environment.getExternalStorageDirectory().toString();
PdfWriter.getInstance(document, new FileOutputStream(directoryPath + "/example.pdf")); // Change pdf's name.
document.open();
Image image = Image.getInstance(directoryPath + "/" + "example.jpg"); // Change image's name and extension.
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(Image.ALIGN_CENTER | Image.ALIGN_TOP);
document.add(image);
document.close();
从这里下载源代码 (Convert Image to pdf in android programmatically)
MainActivity.java:
package com.deepshikha.convertbitmap;
import android.Manifest;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.pdf.PdfDocument;
import android.net.Uri;
import android.provider.MediaStore;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.Display;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
public static final int GALLERY_PICTURE = 1;
Button btn_select, btn_convert;
ImageView iv_image;
boolean boolean_permission;
boolean boolean_save;
Bitmap bitmap;
public static final int REQUEST_PERMISSIONS = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
init();
listener();
fn_permission();
}
private void init() {
btn_select = (Button) findViewById(R.id.btn_select);
btn_convert = (Button) findViewById(R.id.btn_convert);
iv_image = (ImageView) findViewById(R.id.iv_image);
}
private void listener() {
btn_select.setOnClickListener(this);
btn_convert.setOnClickListener(this);
}
@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.btn_select:
Intent intent = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(intent, GALLERY_PICTURE);
break;
case R.id.btn_convert:
if (boolean_save){
Intent intent1=new Intent(getApplicationContext(),PDFViewActivity.class);
startActivity(intent1);
}else {
createPdf();
}
break;
}
}
private void createPdf(){
WindowManager wm = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay();
DisplayMetrics displaymetrics = new DisplayMetrics();
this.getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
float hight = displaymetrics.heightPixels ;
float width = displaymetrics.widthPixels ;
int convertHighet = (int) hight, convertWidth = (int) width;
// Resources mResources = getResources();
// Bitmap bitmap = BitmapFactory.decodeResource(mResources, R.drawable.screenshot);
PdfDocument document = new PdfDocument();
PdfDocument.PageInfo pageInfo = new PdfDocument.PageInfo.Builder(bitmap.getWidth(), bitmap.getHeight(), 1).create();
PdfDocument.Page page = document.startPage(pageInfo);
Canvas canvas = page.getCanvas();
Paint paint = new Paint();
paint.setColor(Color.parseColor("#ffffff"));
canvas.drawPaint(paint);
bitmap = Bitmap.createScaledBitmap(bitmap, bitmap.getWidth(), bitmap.getHeight(), true);
paint.setColor(Color.BLUE);
canvas.drawBitmap(bitmap, 0, 0 , null);
document.finishPage(page);
// write the document content
String targetPdf = "/sdcard/test.pdf";
File filePath = new File(targetPdf);
try {
document.writeTo(new FileOutputStream(filePath));
btn_convert.setText("Check PDF");
boolean_save=true;
} catch (IOException e) {
e.printStackTrace();
Toast.makeText(this, "Something wrong: " + e.toString(), Toast.LENGTH_LONG).show();
}
// close the document
document.close();
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == GALLERY_PICTURE && resultCode == RESULT_OK) {
if (resultCode == RESULT_OK) {
Uri selectedImage = data.getData();
String[] filePathColumn = {MediaStore.Images.Media.DATA};
Cursor cursor = getContentResolver().query(
selectedImage, filePathColumn, null, null, null);
cursor.moveToFirst();
int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
String filePath = cursor.getString(columnIndex);
cursor.close();
bitmap = BitmapFactory.decodeFile(filePath);
iv_image.setImageBitmap(bitmap);
btn_convert.setClickable(true);
}
}
}
private void fn_permission() {
if ((ContextCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED)||
(ContextCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED)) {
if ((ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this, android.Manifest.permission.READ_EXTERNAL_STORAGE))) {
} else {
ActivityCompat.requestPermissions(MainActivity.this, new String[]{android.Manifest.permission.READ_EXTERNAL_STORAGE},
REQUEST_PERMISSIONS);
}
if ((ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE))) {
} else {
ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
REQUEST_PERMISSIONS);
}
} else {
boolean_permission = true;
}
}
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == REQUEST_PERMISSIONS) {
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
boolean_permission = true;
} else {
Toast.makeText(getApplicationContext(), "Please allow the permission", Toast.LENGTH_LONG).show();
}
}
}
}
谢谢！
您可以通过将最低 SDK 设置为 19 (KitKat 4.4) 并使用 Google 的 PdfDocument API ( https://developer.android.com/reference/android/graphics/pdf/PdfDocument ) 将 JPG 转换为 PDF，如下所示在 Kotlin 中：
// Load JPG file into bitmap
val f: File = myJPGFile
val bitmap: Bitmap = BitmapFactory.decodeFile(f.absolutePath)
// Create a PdfDocument with a page of the same size as the image
val document: PdfDocument = PdfDocument()
val pageInfo: PdfDocument.PageInfo = PdfDocument.PageInfo.Builder(bitmap.width, bitmap.height, 1).create()
val page: PdfDocument.Page = document.startPage(pageInfo)
// Draw the bitmap onto the page
val canvas: Canvas = page.canvas
canvas.drawBitmap(bitmap, 0f, 0f, null)
document.finishPage(page)
// Write the PDF file to a file
val directoryPath: String = android.os.Environment.getExternalStorageDirectory().toString()
document.writeTo( FileOutputStream(directoryPath + "/example.pdf"))
document.close()
在gradle
中添加库implementation 'com.itextpdf:itextg:5.5.10'
创建文件夹路径 - 它将从文件夹的所有图像创建 pdf
File folderPath = new File(Environment.getExternalStorageDirectory() + "/YourImagesFolder");
File[] imageList = folderPath .listFiles();
ArrayList<File> imagesArrayList = new ArrayList<>();
for (File absolutePath : imageList) {
imagesArrayList.add(absolutePath);
}
new CreatePdfTask(context, imagesArrayList).execute();
异步任务
public class CreatePdfTask extends AsyncTask<String, Integer, File> {
Context context;
ArrayList<File> files;
ProgressDialog progressDialog;
public CreatePdfTask(Context context2, ArrayList<File> arrayList) {
context = context2;
files = arrayList;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
progressDialog = new ProgressDialog(context);
progressDialog.setTitle("Please wait...");
progressDialog.setMessage("Creating pdf...");
progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
progressDialog.setIndeterminate(false);
progressDialog.setMax(100);
progressDialog.setCancelable(true);
progressDialog.show();
}
@Override
protected File doInBackground(String... strings) {
File outputMediaFile = Constant.getPdfPath();//path in which you want to save pdf
Document document = new Document(PageSize.A4, 38.0f, 38.0f, 50.0f, 38.0f);
try {
PdfWriter.getInstance(document, new FileOutputStream(outputMediaFile));
} catch (DocumentException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
return null;
}
document.open();
int i = 0;
while (true) {
if (i < this.files.size()) {
try {
Image image = Image.getInstance(files.get(i).getAbsolutePath());
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(Image.ALIGN_CENTER | Image.ALIGN_TOP);
image.setAbsolutePosition((document.getPageSize().getWidth() - image.getScaledWidth()) / 2.0f,
(document.getPageSize().getHeight() - image.getScaledHeight()) / 2.0f);
document.add(image);
document.newPage();
publishProgress(i);
i++;
} catch (BadElementException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (DocumentException e) {
e.printStackTrace();
}
} else {
document.close();
return outputMediaFile;
}
}
}
@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
this.progressDialog.setProgress(((values[0] + 1) * 100) / this.files.size());
StringBuilder sb = new StringBuilder();
sb.append("Processing images (");
sb.append(values[0] + 1);
sb.append("/");
sb.append(this.files.size());
sb.append(")");
progressDialog.setTitle(sb.toString());
}
@Override
protected void onPostExecute(File file) {
super.onPostExecute(file);
progressDialog.dismiss();
Toast.makeText(context, "Pdf store at " + file.getAbsolutePath(), Toast.LENGTH_SHORT).show();
}
}
只需传递上下文和文件列表 它将在缓存目录中创建一个 PDF 文件 将您自己的逻辑添加到 share/open PDF 工作快速可靠的方法
- No library needed (Uses android internal android.graphics.pdf.PdfDocument classes)
- Works in background, Doesn''t freeze UI
- No need to declare and grant storage permission :)
private static void createPdf(Context context,ArrayList<File> data){
File pdfFile = new File(context.getExternalCacheDir().getAbsolutePath() + File.separator + "TemperoryPDF_"+System.currentTimeMillis()+".pdf");
Toast.makeText(context, "Creating PDF,Please wait..", Toast.LENGTH_SHORT).show();
new AsyncTask<Void, Void, Void>() {
@Override
protected Void doInBackground(Void... voids) {
PdfDocument document = new PdfDocument();
try {
for(File item:data) {
Bitmap bitmap = BitmapFactory.decodeFile(item.getAbsolutePath());
PdfDocument.PageInfo pageInfo = new PdfDocument.PageInfo.Builder(bitmap.getWidth(), bitmap.getHeight(), 1).create();
PdfDocument.Page page = document.startPage(pageInfo);
Canvas canvas = page.getCanvas();
Paint paint = new Paint();
paint.setColor(Color.parseColor("#ffffff"));
canvas.drawPaint(paint);
canvas.drawBitmap(bitmap, 0, 0, null);
document.finishPage(page);
}
document.writeTo(new FileOutputStream(pdfFile));
} catch (IOException e) {
e.printStackTrace();
}finally {
document.close();
}
return null;
}
@Override
protected void onPostExecute(Void unused) {
super.onPostExecute(unused);
if(pdfFile.exists() && pdfFile.length()>0) {
FileUtil.openFile(context, pdfFile.getAbsolutePath()); // See: https://gist.github.com/omkar-tenkale/34d3aa1966653e6949d1ddaee1ba3355
}else {
Toast.makeText(context, "Something went wrong creating the PDF :(", Toast.LENGTH_SHORT).show();
}
}
}.execute();
}
这就是我把图片转成pdf的方法，非常简单，你需要先在清单中声明用户权限
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
然后在你的主 activity 中，你必须检查权限是否被授予，如果你不知道该怎么做，只需在 youtube 上搜索你会发现很多关于该主题的视频，之后那，我用这个方法从图库中拍摄我想转换成 pdf 的图像。
public void pickImage() {
Intent intent = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(intent,120);
}
之后，我覆盖了 onActivityResult() 方法来检索所选图像。
@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == 120 && resultCode == RESULT_OK && data != null) {
Uri selectedImageUri = data.getData();
String[] filePath = {MediaStore.Images.Media.DATA};
Cursor cursor =getContentResolver().query(selectedImageUri,filePath,null,null,null);
cursor.moveToFirst();
int columnIndex = cursor.getColumnIndex(filePath[0]);
String myPath = cursor.getString(columnIndex);
cursor.close();
Bitmap bitmap = BitmapFactory.decodeFile(myPath);
imageView.setImageBitmap(bitmap);
PdfDocument pdfDocument = new PdfDocument();
PdfDocument.PageInfo pageInfo = new PdfDocument.PageInfo.Builder(bitmap.getWidth(),
bitmap.getHeight(),1).create();
PdfDocument.Page page = pdfDocument.startPage(pageInfo);
Canvas canvas = page.getCanvas();
Paint paint = new Paint();
paint.setColor(Color.parseColor("#FFFFFF"));
canvas.drawPaint(paint);
bitmap=Bitmap.createScaledBitmap(bitmap,bitmap.getWidth(),bitmap.getHeight(),true);
paint.setColor(Color.BLUE);
canvas.drawBitmap(bitmap,0,0,null);
pdfDocument.finishPage(page);
//save the bitmap image
File root = new File(Environment.getExternalStorageDirectory(),"PDF folder 12");
if (!root.exists()){
root.mkdir();
}
File file = new File(root,"picture.pdf");
try {
FileOutputStream fileOutputStream = new FileOutputStream(file);
pdfDocument.writeTo(fileOutputStream);
}catch (Exception e){
e.getStackTrace();
}
pdfDocument.close();
}
}
不要忘记权限，请用户授予权限
如果要自动打开 pdf 文件，请在给出正确的文件夹路径和 pdf 文件名后使用此方法
String path ="/sdcard/PDF folder 12/picture.pdf";
public void openPDF (){
File pdfFile = new File(path);//File path
if (pdfFile.exists()) //Checking if the file exists or not
{
Uri path = Uri.fromFile(pdfFile);
Intent objIntent = new Intent(Intent.ACTION_VIEW);
objIntent.setDataAndType(path, "application/pdf");
objIntent.setFlags(Intent. FLAG_ACTIVITY_CLEAR_TOP);
startActivity(objIntent);//Starting the pdf viewer
} else {
Toast.makeText(GenerateQRActivity.this, "The file not exists! ", Toast.LENGTH_SHORT).show();
}
}