Flutter PDF Library - Create, Read, and Edit PDF Files

///Package imports
import 'package:flutter/material.dart';
import 'package:intl/intl.dart';

///PDF import
import 'package:syncfusion_flutter_pdf/pdf.dart';

///Local imports
import '../../model/sample_view.dart';
import 'helper/save_file_mobile.dart'
    if (dart.library.html) 'helper/save_file_web.dart';

/// Render PDF of invoice
class InvoicePdf extends SampleView {
  /// Render pdf of invoice
  const InvoicePdf(Key key) : super(key: key);
  @override
  _InvoicePdfState createState() => _InvoicePdfState();
}

class _InvoicePdfState extends SampleViewState {
  _InvoicePdfState();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: model.cardThemeColor,
      body: Padding(
        padding: const EdgeInsets.fromLTRB(10, 10, 10, 10),
        child: Container(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.start,
            crossAxisAlignment: CrossAxisAlignment.start,
            children: <Widget>[
              Text(
                  'The PDF package is a non-UI and reusable flutter library to create PDF reports programmatically with formatted text, images, tables, links, list, header and footer, and more.\r\n\r\nThis sample showcase how to create a simple invoice report using PDF grid with built-in styles.',
                  style: TextStyle(fontSize: 16, color: model.textColor)),
              const SizedBox(height: 20, width: 30),
              Align(
                  alignment: Alignment.center,
                  child: TextButton(
                    style: ButtonStyle(
                      backgroundColor: MaterialStateProperty.all<Color>(
                          model.backgroundColor),
                      padding: model.isMobile
                          ? null
                          : MaterialStateProperty.all(
                              const EdgeInsets.symmetric(
                                  vertical: 15, horizontal: 15)),
                    ),
                    onPressed: _generatePDF,
                    child: const Text('Generate PDF',
                        style: TextStyle(color: Colors.white)),
                  ))
            ],
          ),
        ),
      ),
    );
  }

  Future<void> _generatePDF() async {
    //Create a PDF document.
    final PdfDocument document = PdfDocument();
    //Add page to the PDF
    final PdfPage page = document.pages.add();
    //Get page client size
    final Size pageSize = page.getClientSize();
    //Draw rectangle
    page.graphics.drawRectangle(
        bounds: Rect.fromLTWH(0, 0, pageSize.width, pageSize.height),
        pen: PdfPen(PdfColor(142, 170, 219, 255)));
    //Generate PDF grid.
    final PdfGrid grid = _getGrid();
    //Draw the header section by creating text element
    final PdfLayoutResult result = _drawHeader(page, pageSize, grid);
    //Draw grid
    _drawGrid(page, grid, result);
    //Add invoice footer
    _drawFooter(page, pageSize);
    //Save and dispose the document.
    final List<int> bytes = document.save();
    document.dispose();
    //Launch file.
    await FileSaveHelper.saveAndLaunchFile(bytes, 'Invoice.pdf');
  }

  //Draw the invoice header
  PdfLayoutResult _drawHeader(PdfPage page, Size pageSize, PdfGrid grid) {
    //Draw rectangle
    page.graphics.drawRectangle(
        brush: PdfSolidBrush(PdfColor(91, 126, 215, 255)),
        bounds: Rect.fromLTWH(0, 0, pageSize.width - 115, 90));
    //Draw string
    page.graphics.drawString(
        'INVOICE', PdfStandardFont(PdfFontFamily.helvetica, 30),
        brush: PdfBrushes.white,
        bounds: Rect.fromLTWH(25, 0, pageSize.width - 115, 90),
        format: PdfStringFormat(lineAlignment: PdfVerticalAlignment.middle));
    page.graphics.drawRectangle(
        bounds: Rect.fromLTWH(400, 0, pageSize.width - 400, 90),
        brush: PdfSolidBrush(PdfColor(65, 104, 205)));
    page.graphics.drawString(r'$' + _getTotalAmount(grid).toString(),
        PdfStandardFont(PdfFontFamily.helvetica, 18),
        bounds: Rect.fromLTWH(400, 0, pageSize.width - 400, 100),
        brush: PdfBrushes.white,
        format: PdfStringFormat(
            alignment: PdfTextAlignment.center,
            lineAlignment: PdfVerticalAlignment.middle));
    final PdfFont contentFont = PdfStandardFont(PdfFontFamily.helvetica, 9);
    //Draw string
    page.graphics.drawString('Amount', contentFont,
        brush: PdfBrushes.white,
        bounds: Rect.fromLTWH(400, 0, pageSize.width - 400, 33),
        format: PdfStringFormat(
            alignment: PdfTextAlignment.center,
            lineAlignment: PdfVerticalAlignment.bottom));
    //Create data format and convert it to text.
    final DateFormat format = DateFormat.yMMMMd('en_US');
    final String invoiceNumber = 'Invoice Number: 2058557939\r\n\r\nDate: ' +
        format.format(DateTime.now());
    final Size contentSize = contentFont.measureString(invoiceNumber);
    const String address =
        'Bill To: \r\n\r\nAbraham Swearegin, \r\n\r\nUnited States, California, San Mateo, \r\n\r\n9920 BridgePointe Parkway, \r\n\r\n9365550136';
    PdfTextElement(text: invoiceNumber, font: contentFont).draw(
        page: page,
        bounds: Rect.fromLTWH(pageSize.width - (contentSize.width + 30), 120,
            contentSize.width + 30, pageSize.height - 120));
    return PdfTextElement(text: address, font: contentFont).draw(
        page: page,
        bounds: Rect.fromLTWH(30, 120,
            pageSize.width - (contentSize.width + 30), pageSize.height - 120))!;
  }

  //Draws the grid
  void _drawGrid(PdfPage page, PdfGrid grid, PdfLayoutResult result) {
    Rect? totalPriceCellBounds;
    Rect? quantityCellBounds;
    //Invoke the beginCellLayout event.
    grid.beginCellLayout = (Object sender, PdfGridBeginCellLayoutArgs args) {
      final PdfGrid grid = sender as PdfGrid;
      if (args.cellIndex == grid.columns.count - 1) {
        totalPriceCellBounds = args.bounds;
      } else if (args.cellIndex == grid.columns.count - 2) {
        quantityCellBounds = args.bounds;
      }
    };
    //Draw the PDF grid and get the result.
    result = grid.draw(
        page: page, bounds: Rect.fromLTWH(0, result.bounds.bottom + 40, 0, 0))!;
    //Draw grand total.
    page.graphics.drawString('Grand Total',
        PdfStandardFont(PdfFontFamily.helvetica, 9, style: PdfFontStyle.bold),
        bounds: Rect.fromLTWH(
            quantityCellBounds!.left,
            result.bounds.bottom + 10,
            quantityCellBounds!.width,
            quantityCellBounds!.height));
    page.graphics.drawString(_getTotalAmount(grid).toString(),
        PdfStandardFont(PdfFontFamily.helvetica, 9, style: PdfFontStyle.bold),
        bounds: Rect.fromLTWH(
            totalPriceCellBounds!.left,
            result.bounds.bottom + 10,
            totalPriceCellBounds!.width,
            totalPriceCellBounds!.height));
  }

  //Draw the invoice footer data.
  void _drawFooter(PdfPage page, Size pageSize) {
    final PdfPen linePen =
        PdfPen(PdfColor(142, 170, 219, 255), dashStyle: PdfDashStyle.custom);
    linePen.dashPattern = <double>[3, 3];
    //Draw line
    page.graphics.drawLine(linePen, Offset(0, pageSize.height - 100),
        Offset(pageSize.width, pageSize.height - 100));
    const String footerContent =
        '800 Interchange Blvd.\r\n\r\nSuite 2501, Austin, TX 78721\r\n\r\nAny Questions? support@adventure-works.com';
    //Added 30 as a margin for the layout
    page.graphics.drawString(
        footerContent, PdfStandardFont(PdfFontFamily.helvetica, 9),
        format: PdfStringFormat(alignment: PdfTextAlignment.right),
        bounds: Rect.fromLTWH(pageSize.width - 30, pageSize.height - 70, 0, 0));
  }

  //Create PDF grid and return
  PdfGrid _getGrid() {
    //Create a PDF grid
    final PdfGrid grid = PdfGrid();
    //Set the columns count to the grid.
    grid.columns.add(count: 5);
    //Create the header row of the grid.
    final PdfGridRow headerRow = grid.headers.add(1)[0];
    //Set style
    headerRow.style.backgroundBrush = PdfSolidBrush(PdfColor(68, 114, 196));
    headerRow.style.textBrush = PdfBrushes.white;
    headerRow.cells[0].value = 'Product Id';
    headerRow.cells[0].stringFormat.alignment = PdfTextAlignment.center;
    headerRow.cells[1].value = 'Product Name';
    headerRow.cells[2].value = 'Price';
    headerRow.cells[3].value = 'Quantity';
    headerRow.cells[4].value = 'Total';
    _addProducts('CA-1098', 'AWC Logo Cap', 8.99, 2, 17.98, grid);
    _addProducts(
        'LJ-0192', 'Long-Sleeve Logo Jersey,M', 49.99, 3, 149.97, grid);
    _addProducts('So-B909-M', 'Mountain Bike Socks,M', 9.5, 2, 19, grid);
    _addProducts(
        'LJ-0192', 'Long-Sleeve Logo Jersey,M', 49.99, 4, 199.96, grid);
    _addProducts('FK-5136', 'ML Fork', 175.49, 6, 1052.94, grid);
    _addProducts('HL-U509', 'Sports-100 Helmet,Black', 34.99, 1, 34.99, grid);
    grid.applyBuiltInStyle(PdfGridBuiltInStyle.listTable4Accent5);
    grid.columns[1].width = 200;
    for (int i = 0; i < headerRow.cells.count; i++) {
      headerRow.cells[i].style.cellPadding =
          PdfPaddings(bottom: 5, left: 5, right: 5, top: 5);
    }
    for (int i = 0; i < grid.rows.count; i++) {
      final PdfGridRow row = grid.rows[i];
      for (int j = 0; j < row.cells.count; j++) {
        final PdfGridCell cell = row.cells[j];
        if (j == 0) {
          cell.stringFormat.alignment = PdfTextAlignment.center;
        }
        cell.style.cellPadding =
            PdfPaddings(bottom: 5, left: 5, right: 5, top: 5);
      }
    }
    return grid;
  }

  //Create row for the grid.
  void _addProducts(String productId, String productName, double price,
      int quantity, double total, PdfGrid grid) {
    final PdfGridRow row = grid.rows.add();
    row.cells[0].value = productId;
    row.cells[1].value = productName;
    row.cells[2].value = price.toString();
    row.cells[3].value = quantity.toString();
    row.cells[4].value = total.toString();
  }

  //Get the total amount.
  double _getTotalAmount(PdfGrid grid) {
    double total = 0;
    for (int i = 0; i < grid.rows.count; i++) {
      final String value =
          grid.rows[i].cells[grid.columns.count - 1].value as String;
      total += double.parse(value);
    }
    return total;
  }
}