added support for encrypted PDF

based on https://github.com/GrapheneOS/PdfViewer/pull/17

Signed-off-by: Pratyush <codelab@pratyush.dev>
Co-authored-by: Tommy-Geenexus <tomgapplicationsdevelopment@gmail.com>
Co-authored-by: empratyush <codelab@pratyush.dev>

app/src/main/assets/viewer.js

@@ -198,15 +198,27 @@ function isTextSelected() {
     return window.getSelection().toString() !== "";
 }
 
-pdfjsLib.getDocument("https://localhost/placeholder.pdf").promise.then(function(newDoc) {
+function loadDocument() {
-    pdfDoc = newDoc;
+    const pdfPassword = channel.getPassword();
-    channel.setNumPages(pdfDoc.numPages);
+    const loadingTask = pdfjsLib.getDocument({ url: "https://localhost/placeholder.pdf", password: pdfPassword });
-    pdfDoc.getMetadata().then(function(data) {
+    loadingTask.onPassword = (_, error) => {
-        channel.setDocumentProperties(JSON.stringify(data.info));
+        if (error === pdfjsLib.PasswordResponses.NEED_PASSWORD) {
-    }).catch(function(error) {
+            channel.showPasswordPrompt();
-        console.log("getMetadata error: " + error);
+        } else if (error === pdfjsLib.PasswordResponses.INCORRECT_PASSWORD) {
+            channel.invalidPassword();
+        }
+    }
+
+    loadingTask.promise.then(function (newDoc) {
+        pdfDoc = newDoc;
+        channel.setNumPages(pdfDoc.numPages);
+        pdfDoc.getMetadata().then(function (data) {
+            channel.setDocumentProperties(JSON.stringify(data.info));
+        }).catch(function (error) {
+            console.log("getMetadata error: " + error);
+        });
+        renderPage(channel.getPage(), false, false);
+    }, function (reason) {
+        console.error(reason.name + ": " + reason.message);
     });
-    renderPage(channel.getPage(), false, false);
+}
-}).catch(function(error) {
-    console.log("getDocument error: " + error);
-});

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

@@ -32,6 +32,7 @@ import androidx.core.graphics.Insets;
 import androidx.core.view.ViewCompat;
 import androidx.core.view.WindowCompat;
 import androidx.core.view.WindowInsetsCompat;
+import androidx.fragment.app.Fragment;
 import androidx.loader.app.LoaderManager;
 import androidx.loader.content.Loader;
 
@@ -39,11 +40,13 @@ import com.google.android.material.snackbar.Snackbar;
 
 import app.grapheneos.pdfviewer.databinding.PdfviewerBinding;
 import app.grapheneos.pdfviewer.fragment.DocumentPropertiesFragment;
+import app.grapheneos.pdfviewer.fragment.PasswordPromptFragment;
 import app.grapheneos.pdfviewer.fragment.JumpToPageFragment;
 import app.grapheneos.pdfviewer.loader.DocumentPropertiesLoader;
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.FileNotFoundException;
 import java.util.HashMap;
 import java.util.List;
 
@@ -54,6 +57,7 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
     private static final String STATE_PAGE = "page";
     private static final String STATE_ZOOM_RATIO = "zoomRatio";
     private static final String STATE_DOCUMENT_ORIENTATION_DEGREES = "documentOrientationDegrees";
+    private static final String STATE_ENCRYPTED_DOCUMENT_PASSWORD = "encrypted_document_password";
     private static final String KEY_PROPERTIES = "properties";
     private static final int MIN_WEBVIEW_RELEASE = 89;
 
@@ -110,6 +114,7 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
     private float mZoomRatio = 1f;
     private int mDocumentOrientationDegrees;
     private int mDocumentState;
+    private String mEncryptedDocumentPassword;
     private List<CharSequence> mDocumentProperties;
     private InputStream mInputStream;
 
@@ -117,6 +122,7 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
     private TextView mTextView;
     private Toast mToast;
     private Snackbar snackbar;
+    private PasswordPromptFragment mPasswordPromptFragment;
 
     private final ActivityResultLauncher<Intent> openDocumentLauncher = registerForActivityResult(
             new ActivityResultContracts.StartActivityForResult(), result -> {
@@ -127,6 +133,7 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
                     mUri = result.getData().getData();
                     mPage = 1;
                     mDocumentProperties = null;
+                    mEncryptedDocumentPassword = "";
                     loadPdf();
                     invalidateOptionsMenu();
                 }
@@ -177,6 +184,29 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
             args.putString(KEY_PROPERTIES, properties);
             runOnUiThread(() -> LoaderManager.getInstance(PdfViewer.this).restartLoader(DocumentPropertiesLoader.ID, args, PdfViewer.this));
         }
+
+        @JavascriptInterface
+        public void showPasswordPrompt() {
+            if (getPasswordPromptFragment().isAdded()) {
+                getPasswordPromptFragment().dismiss();
+            }
+            getPasswordPromptFragment().show(getSupportFragmentManager(), PasswordPromptFragment.class.getName());
+        }
+
+        @JavascriptInterface
+        public void invalidPassword() {
+            runOnUiThread(PdfViewer.this::notifyInvalidPassword);
+            showPasswordPrompt();
+        }
+
+        @JavascriptInterface
+        public String getPassword() {
+            return mEncryptedDocumentPassword != null ? mEncryptedDocumentPassword : "";
+        }
+    }
+
+    private void notifyInvalidPassword() {
+        snackbar.setText(R.string.password_prompt_invalid_password).show();
     }
 
     @Override
@@ -241,6 +271,12 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
                 Log.d(TAG, "path " + path);
 
                 if ("/placeholder.pdf".equals(path)) {
+                    maybeCloseInputStream();
+                    try {
+                        mInputStream = getContentResolver().openInputStream(mUri);
+                    } catch (FileNotFoundException ignored) {
+                        snackbar.setText(R.string.io_error).show();
+                    }
                     return new WebResourceResponse("application/pdf", null, mInputStream);
                 }
 
@@ -274,6 +310,7 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
             public void onPageFinished(WebView view, String url) {
                 mDocumentState = STATE_LOADED;
                 invalidateOptionsMenu();
+                loadPdfWithPassword(mEncryptedDocumentPassword);
             }
         });
 
@@ -341,6 +378,7 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
             mPage = savedInstanceState.getInt(STATE_PAGE);
             mZoomRatio = savedInstanceState.getFloat(STATE_ZOOM_RATIO);
             mDocumentOrientationDegrees = savedInstanceState.getInt(STATE_DOCUMENT_ORIENTATION_DEGREES);
+            mEncryptedDocumentPassword = savedInstanceState.getString(STATE_ENCRYPTED_DOCUMENT_PASSWORD);
         }
 
         if (mUri != null) {
@@ -353,6 +391,38 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
         }
     }
 
+    @Override
+    protected void onDestroy() {
+        super.onDestroy();
+        binding.webview.removeJavascriptInterface("channel");
+        binding.getRoot().removeView(binding.webview);
+        binding.webview.destroy();
+        maybeCloseInputStream();
+    }
+
+    void maybeCloseInputStream() {
+        InputStream stream = mInputStream;
+        if (stream == null) {
+            return;
+        }
+        mInputStream = null;
+        try {
+            stream.close();
+        } catch (IOException ignored) {}
+    }
+
+    private PasswordPromptFragment getPasswordPromptFragment() {
+        if (mPasswordPromptFragment == null) {
+            final Fragment fragment = getSupportFragmentManager().findFragmentByTag(PasswordPromptFragment.class.getName());
+            if (fragment != null) {
+                mPasswordPromptFragment = (PasswordPromptFragment) fragment;
+            } else {
+                mPasswordPromptFragment = new PasswordPromptFragment();
+            }
+        }
+        return mPasswordPromptFragment;
+    }
+
     @Override
     protected void onResume() {
         super.onResume();
@@ -403,10 +473,17 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
             return;
         }
 
+        mDocumentState = 0;
         showSystemUi();
+        invalidateOptionsMenu();
         binding.webview.loadUrl("https://localhost/viewer.html");
     }
 
+    public void loadPdfWithPassword(final String password) {
+        mEncryptedDocumentPassword = password;
+        binding.webview.evaluateJavascript("loadDocument()", null);
+    }
+
     private void renderPage(final int zoom) {
         binding.webview.evaluateJavascript("onRenderPage(" + zoom + ")", null);
     }
@@ -503,6 +580,7 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
         savedInstanceState.putInt(STATE_PAGE, mPage);
         savedInstanceState.putFloat(STATE_ZOOM_RATIO, mZoomRatio);
         savedInstanceState.putInt(STATE_DOCUMENT_ORIENTATION_DEGREES, mDocumentOrientationDegrees);
+        savedInstanceState.putString(STATE_ENCRYPTED_DOCUMENT_PASSWORD, mEncryptedDocumentPassword);
     }
 
     private void showPageNumber() {

app/src/main/java/app/grapheneos/pdfviewer/fragment/PasswordPromptFragment.kt

@@ -0,0 +1,67 @@
+package app.grapheneos.pdfviewer.fragment
+
+import android.app.Dialog
+import android.content.DialogInterface
+import android.os.Bundle
+import android.text.Editable
+import android.text.TextUtils
+import android.text.TextWatcher
+import android.view.LayoutInflater
+import android.view.WindowManager
+import android.view.inputmethod.EditorInfo.IME_ACTION_DONE
+import androidx.appcompat.app.AlertDialog
+import androidx.fragment.app.DialogFragment
+import app.grapheneos.pdfviewer.PdfViewer
+import app.grapheneos.pdfviewer.R
+import app.grapheneos.pdfviewer.databinding.PasswordDialogFragmentBinding
+import com.google.android.material.textfield.TextInputEditText
+
+class PasswordPromptFragment : DialogFragment() {
+
+    private lateinit var passwordEditText : TextInputEditText
+
+    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
+        val passwordPrompt = AlertDialog.Builder(requireContext())
+        val passwordDialogFragmentBinding =
+            PasswordDialogFragmentBinding.inflate(LayoutInflater.from(requireContext()))
+        passwordEditText = passwordDialogFragmentBinding.pdfPasswordEditText
+        passwordPrompt.setView(passwordDialogFragmentBinding.root)
+        passwordEditText.addTextChangedListener(object : TextWatcher {
+            override fun beforeTextChanged(charSequence: CharSequence, i: Int, i1: Int, i2: Int) {}
+            override fun onTextChanged(input: CharSequence, i: Int, i1: Int, i2: Int) {
+                updatePositiveButton()
+            }
+            override fun afterTextChanged(editable: Editable) {}
+        })
+        passwordEditText.setOnEditorActionListener { _, actionId, _ ->
+            if (actionId != IME_ACTION_DONE) return@setOnEditorActionListener false
+            sendPassword()
+            true
+        }
+        passwordPrompt.setPositiveButton(R.string.open) { _, _ -> sendPassword() }
+        passwordPrompt.setNegativeButton(R.string.cancel, null)
+        val dialog = passwordPrompt.create()
+        dialog.setCanceledOnTouchOutside(false)
+        dialog.window?.setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_VISIBLE)
+        return dialog
+    }
+
+    private fun updatePositiveButton() {
+        val btn = (dialog as AlertDialog).getButton(DialogInterface.BUTTON_POSITIVE)
+        btn.isEnabled = passwordEditText.text?.isNotEmpty() ?: false
+    }
+
+    private fun sendPassword() {
+        val password = passwordEditText.text.toString()
+        if (!TextUtils.isEmpty(password)) {
+            (activity as PdfViewer).loadPdfWithPassword(password)
+            dialog?.dismiss()
+        }
+    }
+
+    override fun onStart() {
+        super.onStart()
+        updatePositiveButton()
+        passwordEditText.requestFocus()
+    }
+}

app/src/main/res/layout/password_dialog_fragment.xml

@@ -0,0 +1,38 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    android:orientation="vertical">
+
+    <TextView
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="24dp"
+        android:layout_marginTop="24dp"
+        android:layout_marginEnd="24dp"
+        android:layout_marginBottom="20dp"
+        android:text="@string/password_prompt_description"
+        android:textColor="?android:attr/colorAccent"
+        android:textSize="20sp" />
+
+    <com.google.android.material.textfield.TextInputLayout
+        style="@style/Widget.Material3.TextInputLayout.OutlinedBox"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        app:hintEnabled="false"
+        app:passwordToggleEnabled="true"
+        app:passwordToggleTint="?android:attr/colorAccent">
+
+        <com.google.android.material.textfield.TextInputEditText
+            android:id="@+id/pdf_password_edit_text"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="24dp"
+            android:layout_marginEnd="24dp"
+            android:layout_marginBottom="24dp"
+            android:hint="@string/password_prompt_hint"
+            android:inputType="textPassword" />
+
+    </com.google.android.material.textfield.TextInputLayout>
+</LinearLayout>

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

@@ -24,4 +24,10 @@
 
     <string name="webview_out_of_date_title">WebView out-of-date</string>
     <string name="webview_out_of_date_message">Your current WebView version is %1$d. The WebView should be at least version %2$d for the PDF Viewer to work.</string>
+
+    <string name="password_prompt_hint">Password</string>
+    <string name="password_prompt_description">Enter the password to decrypt this PDF file</string>
+    <string name="password_prompt_invalid_password">Invalid password</string>
+    <string name="open">Open</string>
+    <string name="cancel">Cancel</string>
 </resources>