Guides

Reader State and Interface Callbacks

The ComPDF Flutter SDK provides reader-level callbacks through CPDFReaderWidget. Use these callbacks for viewer lifecycle and UI events.

Available Callbacks

Callback	Trigger Timing	Payload
onCreated	Reader and controller are ready	CPDFReaderWidgetController controller
onPageChanged	Current page changes	int pageIndex
onSaveCallback	The Reader completes a save. For an application-initiated save, use the relevant Future<bool> result	No payload
onFillScreenChanged	Fullscreen state changes	bool isFillScreen
onTapMainDocAreaCallback	User taps the main PDF page area	No payload
onPageEditDialogBackPress	User taps the back button in the page edit dialog	No payload
onIOSClickBackPressed	iOS top-left reader back button is tapped	No payload
onSearchBackButtonTappedCallback	User taps the back button in the search view	No payload
onAddWatermarkDialogDismissedCallback	Add watermark dialog is dismissed	No payload

Example Usage

CPDFReaderWidget(
  document: documentPath,
  configuration: configuration,
  onCreated: (controller) {
    // Store the controller if listener events are needed later.
  },
  onPageChanged: (int pageIndex) {
    debugPrint('Current page: $pageIndex');
  },
  onSaveCallback: () {
    debugPrint('The native Reader reported a successful save');
  },
  onFillScreenChanged: (bool isFillScreen) {
    debugPrint('Fill screen: $isFillScreen');
  },
  onTapMainDocAreaCallback: () {
    debugPrint('Main document area tapped');
  },
  onPageEditDialogBackPress: () {
    debugPrint('Back button pressed in page edit dialog');
  },
  onIOSClickBackPressed: () {
    debugPrint('iOS back button pressed');
  },
  onSearchBackButtonTappedCallback: () {
    debugPrint('Search back button tapped');
  },
  onAddWatermarkDialogDismissedCallback: () {
    debugPrint('Add watermark dialog dismissed');
  },
);

Note

• Widget callbacks follow the CPDFReaderWidget lifecycle and are not removed with removeEventListener().
• onSearchBackButtonTappedCallback is useful when you manage search state on the Flutter side.
• onAddWatermarkDialogDismissedCallback fires after the add watermark panel closes. Use it to restore custom UI state or refresh watermark-related controls.