columnSpan property Null safety

int columnSpan

Gets or sets a value that indicates the total number of columns that cell spans within a PdfGrid.

//Create a new PDF document
PdfDocument document = PdfDocument();
//Create a PdfGrid
PdfGrid grid = PdfGrid();
//Add columns to grid
grid.columns.add(count: 3);
//Add headers to grid
PdfGridRow header = grid.headers.add(1)[0];
header.cells[0].value = 'Employee ID';
header.cells[1].value = 'Employee Name';
header.cells[2].value = 'Salary';
//Add the styles to specific cell
header.cells[0].style.stringFormat = PdfStringFormat(
    lineAlignment: PdfVerticalAlignment.bottom,
    wordSpacing: 10);
header.cells[1].style.textPen = PdfPens.mediumVioletRed;
header.cells[2].style.backgroundBrush = PdfBrushes.yellow;
header.cells[2].style.textBrush = PdfBrushes.darkOrange;
//Add rows to grid
PdfGridRow row1 = grid.rows.add();
row1.cells[0].value = 'E01';
row1.cells[1].value = 'Clay';
row1.cells[2].value = '\$10000';
//Sets the rowSpan
row1.cells[1].rowSpan = 1;
//Sets the colSpan
row1.cells[1].columnSpan = 2;
//Apply the cell style to specific row cells
row1.cells[0].style = PdfGridCellStyle(
  backgroundBrush: PdfBrushes.lightYellow,
  cellPadding: PdfPaddings(left: 2, right: 3, top: 4, bottom: 5),
  font: PdfStandardFont(PdfFontFamily.timesRoman, 17),
  textBrush: PdfBrushes.white,
PdfGridRow row2 = grid.rows.add();
row2.cells[0].value = 'E02';
row2.cells[1].value = 'Simon';
row2.cells[2].value = '\$12,000';
//Gets the width of the PDF grid cell
double width = row2.cells[2].width;
//Gets the height of the PDF grid cell
double height = row2.cells[2].height;
//Draw the grid in PDF document page
    page: document.pages.add(), bounds:;
//Save the document.
List<int> bytes = await;
//Dispose the document.


int get columnSpan => _columnSpan;
void columnSpan=(int value)


set columnSpan(int value) {
  if (value < 1) {
    throw ArgumentError.value('value', 'column span',
        'Invalid span specified, must be greater than or equal to 1');
  if (value > 1) {
    _columnSpan = value;
        .hasColumnSpan = true;