performPaint method

@override void performPaint(Buffer buffer, Offset offset)

Hook for subclasses to implement actual painting.

Implementation

@override
void performPaint(Buffer buffer, Offset offset) {
  final table = widget as LazyTable;
  final w = size.width;
  final h = size.height;
  if (w <= 0 || h <= 0) return;

  final hasHeaders = table.headers.isNotEmpty;
  final headerRowsCount = hasHeaders ? 2 : 0;
  final usableHeight = h - headerRowsCount;

  if (usableHeight <= 0) return;

  // Cache total column layout width (columns + single space separators)
  final int columnsTotalWidth =
      resolvedColumnWidths.fold<int>(0, (prev, val) => prev + val) +
      (table.headers.isNotEmpty ? table.headers.length - 1 : 0);

  // 1. Render Headers
  if (hasHeaders) {
    final headerSb = StringBuffer();
    for (var i = 0; i < table.headers.length; i++) {
      final width = resolvedColumnWidths[i];
      final text = table.headers[i];
      final padded = padOrTruncate(text, width);
      headerSb.write(padded);
      if (i < table.headers.length - 1) headerSb.write(' ');
    }

    String headerStr;
    if (columnsTotalWidth <= w) {
      if (columnsTotalWidth < w) {
        headerSb.write(' ' * (w - columnsTotalWidth));
      }
      headerStr = headerSb.toString();
    } else {
      headerStr = padOrTruncate(headerSb.toString(), w);
    }
    buffer.writeString(offset.dx, offset.dy, headerStr, table.headerStyle);

    // Render Divider Line
    final dividerChar = '─';
    final divider = dividerChar * w;
    buffer.writeString(offset.dx, offset.dy + 1, divider, table.borderStyle);
  }

  // 2. Render Visible Rows
  for (var r = 0; r < usableHeight; r++) {
    final rowIdx = table.scrollOffset + r;
    if (rowIdx >= table.itemCount) break;

    final rowData = table.itemBuilder(rowIdx);
    final isSelected = rowIdx == table.selectedRowIndex;
    final currentStyle = isSelected ? table.selectedRowStyle : table.rowStyle;

    final rowSb = StringBuffer();
    for (var c = 0; c < table.headers.length; c++) {
      final width = resolvedColumnWidths[c];
      final cellText = c < rowData.length ? rowData[c] : '';
      final padded = padOrTruncate(cellText, width);
      rowSb.write(padded);
      if (c < table.headers.length - 1) rowSb.write(' ');
    }

    String rowStr;
    if (columnsTotalWidth <= w) {
      if (columnsTotalWidth < w) {
        rowSb.write(' ' * (w - columnsTotalWidth));
      }
      rowStr = rowSb.toString();
    } else {
      rowStr = padOrTruncate(rowSb.toString(), w);
    }
    final targetY = offset.dy + headerRowsCount + r;

    buffer.writeString(offset.dx, targetY, rowStr, currentStyle);
  }
}