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feat: add vertical scrolling mode for PDF viewer #511

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e8afb2e
feat: add vertical scrolling mode for PDF viewer
cameronaaron Jun 28, 2025
89970a4
Delete VERTICAL_SCROLL_FEATURE.md
cameronaaron Jun 28, 2025
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46 changes: 42 additions & 4 deletions app/src/main/java/app/grapheneos/pdfviewer/PdfViewer.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -65,6 +65,7 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
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 STATE_VERTICAL_SCROLL_MODE = "vertical_scroll_mode";
private static final String KEY_PROPERTIES = "properties";
private static final int MIN_WEBVIEW_RELEASE = 133;

Expand Down Expand Up @@ -130,6 +131,7 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
private String mEncryptedDocumentPassword;
private List<CharSequence> mDocumentProperties;
private InputStream mInputStream;
private boolean isVerticalScrollMode = false;

private PdfviewerBinding binding;
private TextView mTextView;
Expand Down Expand Up @@ -265,6 +267,22 @@ public void onLoaded() {
public String getPassword() {
return mEncryptedDocumentPassword != null ? mEncryptedDocumentPassword : "";
}

@JavascriptInterface
public boolean isVerticalScrollMode() {
return isVerticalScrollMode;
}

@JavascriptInterface
public void onPageChanged(final int pageNumber) {
if (isVerticalScrollMode) {
mPage = pageNumber;
runOnUiThread(() -> {
invalidateOptionsMenu();
showPageNumber();
});
}
}
}

private void showWebViewCrashed() {
Expand Down Expand Up @@ -502,6 +520,7 @@ public void onZoomEnd() {
mZoomRatio = savedInstanceState.getFloat(STATE_ZOOM_RATIO);
mDocumentOrientationDegrees = savedInstanceState.getInt(STATE_DOCUMENT_ORIENTATION_DEGREES);
mEncryptedDocumentPassword = savedInstanceState.getString(STATE_ENCRYPTED_DOCUMENT_PASSWORD);
isVerticalScrollMode = savedInstanceState.getBoolean(STATE_VERTICAL_SCROLL_MODE, false);
}

binding.webviewAlertReload.setOnClickListener(v -> {
Expand Down Expand Up @@ -675,12 +694,22 @@ private static void enableDisableMenuItem(MenuItem item, boolean enable) {
public void onJumpToPageInDocument(final int selected_page) {
if (selected_page >= 1 && selected_page <= mNumPages && mPage != selected_page) {
mPage = selected_page;
renderPage(0);
if (isVerticalScrollMode) {
binding.webview.evaluateJavascript("scrollToPageInDocument(" + selected_page + ")", null);
} else {
renderPage(0);
}
showPageNumber();
invalidateOptionsMenu();
}
}

private void toggleVerticalScrollMode() {
isVerticalScrollMode = !isVerticalScrollMode;
binding.webview.evaluateJavascript("setVerticalScrollMode(" + isVerticalScrollMode + ")", null);
invalidateOptionsMenu();
}

private void showSystemUi() {
ViewKt.showSystemUi(binding.getRoot(), getWindow());
getSupportActionBar().show();
Expand All @@ -700,6 +729,7 @@ public void onSaveInstanceState(@NonNull Bundle savedInstanceState) {
savedInstanceState.putFloat(STATE_ZOOM_RATIO, mZoomRatio);
savedInstanceState.putInt(STATE_DOCUMENT_ORIENTATION_DEGREES, mDocumentOrientationDegrees);
savedInstanceState.putString(STATE_ENCRYPTED_DOCUMENT_PASSWORD, mEncryptedDocumentPassword);
savedInstanceState.putBoolean(STATE_VERTICAL_SCROLL_MODE, isVerticalScrollMode);
}

private void showPageNumber() {
Expand Down Expand Up @@ -731,7 +761,7 @@ public boolean onPrepareOptionsMenu(@NonNull Menu menu) {
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_view_document_properties, R.id.action_share, R.id.action_save_as,
R.id.action_outline));
R.id.action_outline, R.id.action_toggle_vertical_scroll));
if (BuildConfig.DEBUG) {
ids.add(R.id.debug_action_toggle_text_layer_visibility);
ids.add(R.id.debug_action_crash_webview);
Expand All @@ -757,8 +787,13 @@ public boolean onPrepareOptionsMenu(@NonNull Menu menu) {
enableDisableMenuItem(menu.findItem(R.id.action_open),
!webViewCrashed && getWebViewRelease() >= MIN_WEBVIEW_RELEASE);
enableDisableMenuItem(menu.findItem(R.id.action_share), mUri != null);
enableDisableMenuItem(menu.findItem(R.id.action_next), mPage < mNumPages);
enableDisableMenuItem(menu.findItem(R.id.action_previous), mPage > 1);

// In vertical scroll mode, disable page navigation buttons
enableDisableMenuItem(menu.findItem(R.id.action_next), !isVerticalScrollMode && mPage < mNumPages);
enableDisableMenuItem(menu.findItem(R.id.action_previous), !isVerticalScrollMode && mPage > 1);
enableDisableMenuItem(menu.findItem(R.id.action_first), !isVerticalScrollMode);
enableDisableMenuItem(menu.findItem(R.id.action_last), !isVerticalScrollMode);

enableDisableMenuItem(menu.findItem(R.id.action_save_as), mUri != null);
enableDisableMenuItem(menu.findItem(R.id.action_view_document_properties),
mDocumentProperties != null);
Expand Down Expand Up @@ -822,6 +857,9 @@ public boolean onOptionsItemSelected(MenuItem item) {
return true;
} else if (itemId == R.id.action_save_as) {
saveDocument();
} else if (itemId == R.id.action_toggle_vertical_scroll) {
toggleVerticalScrollMode();
return true;
} else if (itemId == R.id.debug_action_toggle_text_layer_visibility) {
binding.webview.evaluateJavascript("toggleTextLayerVisibility()", null);
return true;
Expand Down
10 changes: 10 additions & 0 deletions app/src/main/res/drawable/ic_view_agenda_24dp.xml
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Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:width="24dp"
android:height="24dp"
android:viewportWidth="24"
android:viewportHeight="24"
android:tint="?attr/colorOnSurface">
<path
android:fillColor="@android:color/white"
android:pathData="M20,13H3c-0.55,0 -1,0.45 -1,1v6c0,0.55 0.45,1 1,1h17c0.55,0 1,-0.45 1,-1v-6c0,-0.55 -0.45,-1 -1,-1zM20,3H3c-0.55,0 -1,0.45 -1,1v6c0,0.55 0.45,1 1,1h17c0.55,0 1,-0.45 1,-1V4c0,-0.55 -0.45,-1 -1,-1z"/>
</vector>
6 changes: 6 additions & 0 deletions app/src/main/res/menu/pdf_viewer.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,12 @@
android:title="@string/action_jump_to_page"
app:showAsAction="ifRoom" />

<item
android:id="@+id/action_toggle_vertical_scroll"
android:icon="@drawable/ic_view_agenda_24dp"
android:title="@string/action_toggle_vertical_scroll"
app:showAsAction="ifRoom" />

<item
android:id="@+id/action_rotate_clockwise"
android:icon="@drawable/ic_rotate_right_24dp"
Expand Down
1 change: 1 addition & 0 deletions app/src/main/res/values/strings.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@
<string name="action_outline">Outline</string>
<string name="action_view_document_properties">Properties</string>
<string name="action_close">Close</string>
<string name="action_toggle_vertical_scroll">Vertical scroll</string>

<string name="outline_child_button_description">View nested outline entries</string>
<string name="outline_not_available">No outline available</string>
Expand Down
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