PDF background Image not show

[MakSinroja]

Describe the bug
I am trying to add background image for pdf. As per the PDFImage widget requirement, I am convert background image into UInt8List and its converted, but didn't show expected background image and its gave the white background and its doesn't give any error.

Background Image

My Code
Code snippet to reproduce the behavior:

import 'dart:async';
import 'dart:io';
import 'dart:typed_data';
import 'dart:ui' as ui;

import 'package:pdf/pdf.dart';
import 'package:pdf/widgets.dart';
import 'package:example/main.dart';
import 'package:flutter/material.dart' as prefix0;
import 'package:flutter/services.dart';

class PDFCreatorWidget {
  String fileName = 'background_demo.pdf';

  PdfDocument _generateDocument() {
    final pdf = new PdfDocument(deflate: zlib.encode);
    final page = new PdfPage(pdf, pageFormat: PdfPageFormat.a4);
    final g = page.getGraphics();
    g.setColor(new PdfColor(0.0, 1.0, 1.0));
    g.setColor(new PdfColor(0.3, 0.3, 0.3));
    return pdf;
  }

  Future<PdfImage> pdfImageFromImage({PdfDocument pdf, ui.Image image}) async {
    final ByteData bytes =
    await image.toByteData(format: ui.ImageByteFormat.rawRgba);

    return PdfImage(
      pdf,
      image: bytes.buffer.asUint8List(),
      width: PdfPageFormat.a4.width.toInt(),
      height: PdfPageFormat.a4.height.toInt(),
    );
  }

  Future<PdfImage> pdfImageFromImageProvider(
      {PdfDocument pdf,
        prefix0.ImageProvider image,
        prefix0.ImageConfiguration configuration,
        prefix0.ImageErrorListener onError}) async {
    final Completer<PdfImage> completer = Completer<PdfImage>();
    final prefix0.ImageStream stream =
    image.resolve(configuration ?? prefix0.ImageConfiguration.empty);

    prefix0.ImageStreamListener listener;
    listener =
        prefix0.ImageStreamListener((prefix0.ImageInfo image, bool sync) async {
          final PdfImage result =
          await pdfImageFromImage(pdf: pdf, image: image.image);
          if (!completer.isCompleted) {
            completer.complete(result);
          }
          stream.removeListener(listener);
        }, onError: (dynamic exception, StackTrace stackTrace) {
          if (!completer.isCompleted) {
            completer.complete(null);
          }
          if (onError != null) {
            onError(exception, stackTrace);
          } else {
            // https://groups.google.com/forum/#!topic/flutter-announce/hp1RNIgej38
            assert(false, 'image failed to load');
          }
        });

    stream.addListener(listener);
    return completer.future;
  }

  Future<String> createPDF() async {
    final Document pdf = Document();
    final PdfDocument pdfDocument = _generateDocument();

    const imageProvider = const prefix0.AssetImage('assets/ic_background_view.png');
    final PdfImage pdfImage =
    await pdfImageFromImageProvider(pdf: pdfDocument, image: imageProvider);

    pdf.addPage(
      MultiPage(
        crossAxisAlignment: CrossAxisAlignment.start,
        pageTheme: PageTheme(
          buildBackground: (context) {
            return Container(
              decoration: BoxDecoration(
                image: DecorationImage(
                  image: pdfImage,
                  fit: BoxFit.cover,
                ),
              ),
              child: Container(),
            );
          },
          pageFormat: PdfPageFormat.a4,
        ),
        header: (Context context) {
          return null;
        },
        footer: (Context context) {
          return Container(
            alignment: Alignment.centerRight,
            child: Text(
              '${context.pageNumber} / ${context.pagesCount}',
              textAlign: TextAlign.right,
              style: TextStyle(
                color: PdfColors.grey,
              ),
            ),
          );
        },
        build: (Context context) => <Widget>[
          Container(child: Text('Background Image Demo')),
        ],
      ),
    );

    String filePath;

    await getApplicationDocumentsDirectory().then((directory) async {
      filePath = directory.path;
    });

    Directory pdfDirectory;

    await Directory('$filePath/PDFs')
        .exists()
        .then((isExistsDirectory) async {
      if (isExistsDirectory) {
        pdfDirectory = Directory('$filePath/PDFs');
      } else {
        await Directory('$filePath/PDFs')
            .create()
            .then((createdDirectory) {
          pdfDirectory = createdDirectory;
        });
      }
    });

    final File file = File('${pdfDirectory.path}/$fileName');
    file.writeAsBytesSync(pdf.save());
    return file.path;
  }
}

Expected behavior
I want to add background image into pdf background.(i.e. same as like watermark)

Flutter Doctor

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel master, v1.10.6-pre.59, on Linux, locale en_GB.UTF-8)
[✓] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
[✓] Chrome - develop for the web
[✓] Android Studio (version 3.5)
[✓] Android Studio (version 3.4)
[✓] Connected device (3 available)

Desktop (please complete the following information):

• iOS
• Android
• Browser

[DavBfr]

You cannot use width: PdfPageFormat.a4.width.toInt() and height: PdfPageFormat.a4.height.toInt(), for the size. It must be the exact pixel dimentions of the RGBA buffer you pass. Please use the provided functions pdfImageFromImage and pdfImageFromImageProvider They work as expected.

Your code:

DecorationImage(
                  image: pdfImage,
                  fit: BoxFit.cover,
                ),

will take care to stretch the image to fill the page, keeping the aspect ratio.

[MakSinroja]

Sir, I have already used pdfImageFromImage and pdfImageFromImageProvider functions into the code but still couldn't show the background image.

And as per your suggestion, I have changed the width and height (414x815) which is exact pixel dimensions of the RGBA buffer I am passing, but it wan't work.

[DavBfr]

ok, replace the line

final PdfDocument pdfDocument = _generateDocument();

with

final PdfDocument pdfDocument = pdf.document;

and Buy Me A Coffee.

[MakSinroja]

Thank you for helping me and its worked.