paint method

void paint(Canvas canvas, Offset offset, TextPosition position, bool lineHasEmbed,)

Paints cursor on canvas at specified position. offset is global top left (x, y) of text line position is relative (x) in text line

Implementation

void paint(
    Canvas canvas, Offset offset, TextPosition position, bool lineHasEmbed) {
  // relative (x, y) to global offset
  var relativeCaretOffset = editable!.getOffsetForCaret(position, prototype);
  if (lineHasEmbed && relativeCaretOffset == Offset.zero) {
    relativeCaretOffset = editable!.getOffsetForCaret(
        TextPosition(
            offset: position.offset - 1, affinity: position.affinity),
        prototype);
    // Hardcoded 6 as estimate of the width of a character
    relativeCaretOffset =
        Offset(relativeCaretOffset.dx + 6, relativeCaretOffset.dy);
  }

  final caretOffset = relativeCaretOffset + offset;
  var caretRect = prototype.shift(caretOffset);
  if (style.offset != null) {
    caretRect = caretRect.shift(style.offset!);
  }

  if (caretRect.left < 0.0) {
    // For iOS the cursor may get clipped by the scroll view when
    // it's located at a beginning of a line. We ensure that this
    // does not happen here. This may result in the cursor being painted
    // closer to the character on the right, but it's arguably better
    // then painting clipped cursor (or even cursor completely hidden).
    caretRect = caretRect.shift(Offset(-caretRect.left, 0));
  }

  final caretHeight = editable!.getFullHeightForCaret(position);
  if (caretHeight != null) {
    switch (defaultTargetPlatform) {
      case TargetPlatform.android:
      case TargetPlatform.fuchsia:
      case TargetPlatform.linux:
      case TargetPlatform.windows:
        // Override the height to take the full height of the glyph at the
        // TextPosition when not on iOS. iOS has special handling that
        // creates a taller caret.
        caretRect = Rect.fromLTWH(
          caretRect.left,
          caretRect.top - 2.0,
          caretRect.width,
          caretHeight,
        );
        break;
      case TargetPlatform.iOS:
      case TargetPlatform.macOS:
        // Center the caret vertically along the text.
        caretRect = Rect.fromLTWH(
          caretRect.left,
          caretRect.top + (caretHeight - caretRect.height) / 2,
          caretRect.width,
          caretRect.height,
        );
        break;
      default:
        throw UnimplementedError();
    }
  }

  final pixelPerfectOffset = _getPixelPerfectCursorOffset(caretRect);
  if (!pixelPerfectOffset.isFinite) {
    return;
  }
  caretRect = caretRect.shift(pixelPerfectOffset);

  final paint = Paint()..color = color;
  if (style.radius == null) {
    canvas.drawRect(caretRect, paint);
  } else {
    final caretRRect = RRect.fromRectAndRadius(caretRect, style.radius!);
    canvas.drawRRect(caretRRect, paint);
  }
}