drawText method

double drawText(Canvas canvas, TextPainter? paint, double offsetY, [ LyricsLineModel? element, ])

绘制文本并返回行高度 when element not null,then draw gradient

Implementation

double drawText(Canvas canvas, TextPainter? paint, double offsetY,
    [LyricsLineModel? element]) {
  //paint 理论上不可能为空，预期报错
  var lineHeight = paint!.height;
  if (offsetY < 0 - lineHeight || offsetY > mSize.height) {
    return lineHeight;
  }
  var isEnableLight = element != null && lyricUI.enableHighlight();
  var offset = Offset(getLineOffsetX(paint), offsetY);
  if (isEnableLight) {
    canvas.saveLayer(
        Rect.fromLTWH(0, 0, mSize.width, mSize.height), layerPaint);
  }
  paint.paint(canvas, offset);
  if (isEnableLight) {
    drawHighlight(element!, canvas, paint, offset);
    canvas.restore();
  }
  return lineHeight;
}