//每頁顯示條目，默認(rèn)0
@Input() rows: number = 0;
//顯示分頁按鈕數(shù)量，默認(rèn)5
@Input() pageLinkSize: number = 5;
//點(diǎn)擊按鈕后向父組件發(fā)送事件
@Output() onPageChange: EventEmitter<any> = new EventEmitter();
//調(diào)整每頁顯示條目數(shù)量的下拉菜單
@Input() rowsPerPageOptions: number[];
//定義分頁按鈕
pageLinks: number[];
_totalRecords: number = 0;
_first: number = 0;
//數(shù)據(jù)總數(shù)
@Input() get totalRecords(): number {
 return this._totalRecords;
}
set totalRecords(val: number) {
 this._totalRecords = val;
 this.updatePageLinks();
}
//高亮按鈕位置
@Input() get first(): number {
 return this._first;
}
set first(val: number) {
 this._first = val;
 this.updatePageLinks();
}

 //獲取一共多少頁
getPageCount() {
 return Math.ceil(this.totalRecords / this.rows) || 1;
}

//獲取當(dāng)前頁,0為第一頁
getPage(): number {
 return Math.floor(this.first / this.rows);
}

//是否為第一頁
isFirstPage(): boolean {
 return this.getPage() === 0;
}

//是否為最后一頁
isLastPage(): boolean {
 return this.getPage() === this.getPageCount() - 1;
}

//確定當(dāng)先需要顯示的起始分頁和結(jié)束分頁
calculatePageLinkBoundaries() {
 let numberOfPages = this.getPageCount();
 let visiblePages = Math.min(this.pageLinkSize, numberOfPages);
 let start = Math.max(0, Math.ceil(this.getPage() - (visiblePages / 2)));
 let end = Math.min(numberOfPages - 1, start + visiblePages - 1);

 const delta = this.pageLinkSize - (end - start + 1);
 start = Math.max(0, start - delta);
 return [start, end];
}

//更新需要顯示的分頁條目
updatePageLinks(): void {
 this.pageLinks = [];
 let boundaries = this.calculatePageLinkBoundaries;
 const start = boundaries[0];
 const end = boundaries[1];
 for (let i = start; i <= end; i++) {
  this.pageLinks.push(i + 1);
 }
}

//點(diǎn)擊分頁
changePage(p: number, event) {
 var pageCount = this.getPageCount();
 if (p > 0 && p < pageCount) {
  this.first = this.rows * p;
  const state = {
   page: p,
   first: this.first,
   rows: this.rows,
   pageCount: pageCount
  };
  this.updatePageLinks();

  this.onPageChange.emit(state);
 }
 if (event) {
  event.preventDefault();
 }
}

//第一頁
changePageToFirst(event){
 this.changePage(0,event);
}

//上一頁
changePageToPrev(event){
 this.changePage(this.getPage() - 1,event);
}

//下一頁
changePageToNext(event){
 this.changePage(this.getPage() + 1,event);
}

//最后一頁
changePageToLast(event){
 this.changePage(this.getPageCount() - 1,event);
}

//通過下拉菜單更改每頁顯示數(shù)量
onRppChange(event){
 this.rows = this.rowsPerPageOptions[event.target.selectedIndex];
 this.changePageToFirst(event);
}