public splitSelf(currentPage: PageClass) {
  const nextQuestion = this;
  return {
    currentPage,
    nextQuestion,
  }
}

public splitSelf(currentPage: PageClass) {
  const delta = this.requiredHeight - currentPage.availableHeight;
  this.requiredHeight = currentPage.availableHeight;
  let nextQuestion = null;

  if (delta >= 10) { // 下页不足10mm时，省略掉
    nextQuestion = new AnswerQuestionClass(this.question, delta);
    nextQuestion.partNo = this.partNo + 1;
  }
  currentPage.components.push(this);
  return {
    currentPage,
    nextQuestion,
  }
}

public splitSelf(currentPage: PageClass) {
  this.rows = Math.floor((currentPage.availableHeight - 10) / (8 + 2.5));
  const restLength = this.restLength - this.rows * this.lenPerRow;
  const nextQuestion = new EssayQuestionClass(this.question, this.paperType, restLength);
  nextQuestion.partNo = this.partNo + 1;
  nextQuestion.prevRows = this.prevRows + this.rows;
  currentPage.components.push(this);
  return {
    currentPage,
    nextQuestion,
  }
}

public splitSelf(currentPage: PageClass) {
  const { contentHeight, availableHeight } = currentPage;
  let splitIdx = 0;
  let totalHeight = 0;

  for(let i = 0; i < this.groupRows.length; i++) {
    totalHeight += this.groupRows[i].height;
    if (totalHeight > availableHeight) {
      splitIdx = i;
      break;
    }
  }

  const currentGroupRows = this.groupRows.slice(0, splitIdx);
  const nextGroupRows = this.groupRows.slice(splitIdx);
  this.groupRows = currentGroupRows;
  this.offsetY = contentHeight - availableHeight;
  currentPage.addComponents(this);
  const nextQuestion = new ChoiceQuestionCLass(this.question, this.paperType, nextGroupRows);
  return {
    currentPage,
    nextQuestion,
  }
}