99 lines
3.4 KiB
Dart
99 lines
3.4 KiB
Dart
import 'dart:ui' as ui;
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import 'dart:io';
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import 'package:flutter/rendering.dart';
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import 'package:flutter/widgets.dart';
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import 'package:pdf/widgets.dart' as pw;
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// NOTE:
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// - This exporter uses a raster snapshot of the UI (RepaintBoundary) and embeds it into a new PDF.
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// - It does NOT perform vector-accurate stamping into the source PDF.
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// - Vector stamping remains unimplemented with FOSS-only constraints because the `pdf` package
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// cannot import/modify existing PDF pages. If/when a suitable FOSS library exists, wire it here.
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class ExportService {
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Future<bool> exportSignedPdfFromBoundary({
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required GlobalKey boundaryKey,
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required String outputPath,
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}) async {
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try {
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final boundary =
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boundaryKey.currentContext?.findRenderObject()
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as RenderRepaintBoundary?;
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if (boundary == null) return false;
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// Render current view to image
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final ui.Image image = await boundary.toImage(pixelRatio: 2.0);
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final byteData = await image.toByteData(format: ui.ImageByteFormat.png);
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if (byteData == null) return false;
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final pngBytes = byteData.buffer.asUint8List();
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// Compose single-page PDF with the image
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final doc = pw.Document();
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final img = pw.MemoryImage(pngBytes);
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doc.addPage(
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pw.Page(
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build:
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(context) =>
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pw.Center(child: pw.Image(img, fit: pw.BoxFit.contain)),
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),
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);
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final bytes = await doc.save();
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final file = File(outputPath);
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await file.writeAsBytes(bytes, flush: true);
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return true;
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} catch (e) {
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return false;
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}
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}
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/// Multi-page export by navigating the viewer and capturing each page.
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/// onGotoPage must navigate the UI to the requested page and return when the
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/// page is ready to render. We'll still wait for a frame for safety.
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Future<bool> exportMultiPageFromBoundary({
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required GlobalKey boundaryKey,
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required String outputPath,
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required int pageCount,
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required Future<void> Function(int page) onGotoPage,
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double pixelRatio = 3.0,
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}) async {
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try {
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final doc = pw.Document();
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for (int i = 1; i <= pageCount; i++) {
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await onGotoPage(i);
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// Give Flutter and the PDF viewer time to render the page
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await Future<void>.delayed(const Duration(milliseconds: 120));
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for (int f = 0; f < 2; f++) {
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try {
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await WidgetsBinding.instance.endOfFrame;
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} catch (_) {
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// Best-effort if not in a frame-driven context
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await Future<void>.delayed(const Duration(milliseconds: 16));
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}
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}
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final boundary =
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boundaryKey.currentContext?.findRenderObject()
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as RenderRepaintBoundary?;
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if (boundary == null) return false;
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final ui.Image image = await boundary.toImage(pixelRatio: pixelRatio);
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final byteData = await image.toByteData(format: ui.ImageByteFormat.png);
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if (byteData == null) return false;
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final pngBytes = byteData.buffer.asUint8List();
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final img = pw.MemoryImage(pngBytes);
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doc.addPage(
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pw.Page(
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build:
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(context) =>
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pw.Center(child: pw.Image(img, fit: pw.BoxFit.contain)),
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),
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);
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}
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final bytes = await doc.save();
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final file = File(outputPath);
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await file.writeAsBytes(bytes, flush: true);
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return true;
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} catch (e) {
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return false;
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}
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}
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}
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