createMissingBitmap method

Future<TileBitmap> createMissingBitmap(
  1. int tileSize
)

creates a tile bitmap with the information that the rendering of the given tile is not yet finished. This tile will normally be replaced when the rendering finishes.

Implementation

Future<TileBitmap> createMissingBitmap(int tileSize) async {
  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: paint.color))
    ..addText("Waiting for rendering...");
  canvas.drawParagraph(
      builder.build()
        ..layout(ui.ParagraphConstraints(width: tileSize.toDouble())),
      Offset(0, tileSize / 2));

  var pic = pictureRecorder.endRecording();
  ui.Image img = await pic.toImage(tileSize.toInt(), tileSize.toInt());
//    var byteData = await img.toByteData(format: ui.ImageByteFormat.png);
//    var buffer = byteData.buffer.asUint8List();
  return FlutterTileBitmap(img);
}