add print functionality

Author: sguerrini97

app/src/main/java/org/grapheneos/pdfviewer/PdfDocumentAdapter.java

@@ -0,0 +1,77 @@
+package org.grapheneos.pdfviewer;
+
+import android.content.Context;
+import android.net.Uri;
+import android.os.Bundle;
+import android.os.CancellationSignal;
+import android.os.ParcelFileDescriptor;
+import android.print.PageRange;
+import android.print.PrintAttributes;
+import android.print.PrintDocumentAdapter;
+import android.print.PrintDocumentInfo;
+
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+public class PdfDocumentAdapter extends PrintDocumentAdapter {
+
+    private Context mContext;
+    private String mPrintJobName;
+    private Uri mUri;
+
+    public PdfDocumentAdapter(Context ctx, String jobName, Uri uri) {
+        this.mContext = ctx;
+        this.mPrintJobName = jobName;
+        this.mUri = uri;
+    }
+
+    @Override
+    public void onLayout(PrintAttributes oldAttributes, PrintAttributes newAttributes, CancellationSignal cancellationSignal, LayoutResultCallback layoutResultCallback, Bundle bundle) {
+        if (cancellationSignal.isCanceled()) {
+            layoutResultCallback.onLayoutCancelled();
+        } else {
+            PrintDocumentInfo.Builder pdinfoBuilder = new PrintDocumentInfo.Builder(mPrintJobName);
+            pdinfoBuilder.setContentType(PrintDocumentInfo.CONTENT_TYPE_DOCUMENT);
+            pdinfoBuilder.setPageCount(PrintDocumentInfo.PAGE_COUNT_UNKNOWN);
+            PrintDocumentInfo pdInfo = pdinfoBuilder.build();
+            layoutResultCallback.onLayoutFinished(pdInfo, !newAttributes.equals(oldAttributes));
+        }
+    }
+
+    @Override
+    public void onWrite(PageRange[] pageRanges, ParcelFileDescriptor parcelFileDescriptor, CancellationSignal cancellationSignal, WriteResultCallback writeResultCallback) {
+        InputStream inputStream = null;
+        OutputStream outputStream = null;
+
+        try {
+            inputStream = mContext.getContentResolver().openInputStream(mUri);;
+            outputStream = new FileOutputStream(parcelFileDescriptor.getFileDescriptor());
+            byte[] buffer = new byte[mContext.getResources().getInteger(R.integer.print_adapter_buffer_size)];
+
+            int readSize = inputStream.read(buffer);
+            while (readSize >= 0 && !cancellationSignal.isCanceled()) {
+                outputStream.write(buffer, 0, readSize);
+                readSize = inputStream.read(buffer);
+            }
+
+            if (cancellationSignal.isCanceled()) {
+                writeResultCallback.onWriteCancelled();
+            } else {
+                writeResultCallback.onWriteFinished(new PageRange[] { PageRange.ALL_PAGES });
+            }
+        } catch (IOException ex) {
+            writeResultCallback.onWriteFailed(ex.getMessage());
+        } finally {
+            try {
+                if (outputStream != null)
+                    outputStream.close();
+                if (inputStream != null)
+                    inputStream.close();
+            } catch (IOException ignored) {
+
+            }
+        }
+    }
+}

app/src/main/java/org/grapheneos/pdfviewer/PdfViewer.java

@@ -7,6 +7,9 @@
 import android.graphics.Color;
 import android.net.Uri;
 import android.os.Bundle;
+import android.print.PrintAttributes;
+import android.print.PrintDocumentAdapter;
+import android.print.PrintManager;
 import android.util.Log;
 import android.view.Gravity;
 import android.view.Menu;
@@ -22,6 +25,7 @@
 import android.webkit.WebViewClient;
 import android.widget.TextView;
 import android.widget.Toast;
+import android.content.Context;
 
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.loader.app.LoaderManager;
@@ -345,6 +349,14 @@ private void renderPage(final int zoom) {
         mWebView.evaluateJavascript("onRenderPage(" + zoom + ")", null);
     }
 
+    private void printDocument() {
+        PrintManager printManager = (PrintManager)getSystemService(Context.PRINT_SERVICE);
+        String jobName = getString(R.string.print_job_base_name);
+        PrintDocumentAdapter printDocumentAdapter = new PdfDocumentAdapter(this, jobName, mUri);
+        PrintAttributes printAttributes = new PrintAttributes.Builder().build();
+        printManager.print(jobName, printDocumentAdapter, printAttributes);
+    }
+
     private void documentOrientationChanged(final int orientationDegreesOffset) {
         mDocumentOrientationDegrees = (mDocumentOrientationDegrees + orientationDegreesOffset) % 360;
         if (mDocumentOrientationDegrees < 0) {
@@ -465,6 +477,7 @@ public boolean onPrepareOptionsMenu(Menu menu) {
         final int ids[] = { R.id.action_zoom_in, R.id.action_zoom_out, R.id.action_jump_to_page,
                 R.id.action_next, R.id.action_previous, R.id.action_first, R.id.action_last,
                 R.id.action_rotate_clockwise, R.id.action_rotate_counterclockwise,
+                R.id.action_print,
                 R.id.action_view_document_properties };
         if (mDocumentState < STATE_LOADED) {
             for (final int id : ids) {
@@ -541,6 +554,10 @@ public boolean onOptionsItemSelected(MenuItem item) {
                         .show(getSupportFragmentManager(), JumpToPageFragment.TAG);
                 return true;
 
+            case R.id.action_print:
+                printDocument();
+                return true;
+
             default:
                 return super.onOptionsItemSelected(item);
         }

app/src/main/res/menu/pdf_viewer.xml

@@ -67,6 +67,11 @@
         android:title="@string/action_rotate_counterclockwise"
         app:showAsAction="ifRoom" />
 
+    <item
+        android:id="@+id/action_print"
+        android:title="@string/action_print"
+        app:showAsAction="never" />
+
     <item
         android:id="@+id/action_view_document_properties"
         android:title="@string/action_view_document_properties"

app/src/main/res/values/integers.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <integer name="print_adapter_buffer_size">16384</integer>
+</resources>

app/src/main/res/values/strings.xml

@@ -13,6 +13,11 @@
     <string name="action_rotate_counterclockwise">Rotate counterclockwise</string>
     <string name="action_jump_to_page">Jump to page</string>
     <string name="action_view_document_properties">Properties</string>
+    <string name="action_print">Print</string>
+
+    <string name="print_job_base_name">PDF Document</string>
+    <string name="toast_print_completed">Print job completed successfully</string>
+    <string name="toast_print_failed">Print job failed</string>
 
     <string name="document_properties_invalid_date">Invalid date</string>
     <string name="document_properties_retrieval_failed">Failed to obtain document metadata</string>