createErrorBitmap method
Creates a tile bitmap to display an error message.
Implementation
Future<TilePicture> createErrorBitmap(dynamic error) async {
double tileSize = MapsforgeSettingsMgr().tileSize;
var pictureRecorder = ui.PictureRecorder();
var canvas = ui.Canvas(pictureRecorder);
var paint = ui.Paint();
paint.strokeWidth = 1;
paint.color = const ui.Color(0xffaaaaaa);
paint.isAntiAlias = true;
canvas.drawLine(ui.Offset(_margin, _margin), ui.Offset(tileSize - _margin, _margin), paint);
canvas.drawLine(ui.Offset(_margin, _margin), ui.Offset(_margin, tileSize - _margin), paint);
canvas.drawLine(ui.Offset(tileSize - _margin, _margin), ui.Offset(tileSize - _margin, tileSize - _margin), paint);
canvas.drawLine(ui.Offset(_margin, tileSize - _margin), ui.Offset(tileSize - _margin, tileSize - _margin), paint);
ui.ParagraphBuilder builder = ui.ParagraphBuilder(ui.ParagraphStyle(fontSize: 10.0, textAlign: TextAlign.center))
..pushStyle(ui.TextStyle(color: Colors.black87))
..addText(error?.toString() ?? "Error");
canvas.drawParagraph(builder.build()..layout(ui.ParagraphConstraints(width: tileSize - _margin * 2)), Offset(_margin, _margin));
var pic = pictureRecorder.endRecording();
return TilePicture.fromPicture(pic);
}