如何在不创建数组来生成矩阵UI模式的情况下使用NgFor

Question

我想实现UI矩阵模式，它应该动态生成。通过接收输入参数，它应该决定什么是UI矩阵模式维度：例如9X3元素：模式9X3要素

我使用Angular2.js、typescript和SCSS。

html模板和。ts外观:

import {Component, Input, OnInit} from 'angular2/core';
import {NgFor} from 'angular2/common';

@Component({
  selector   : 'game-pattern',
  moduleId   : module.id,
  templateUrl: 'game-pattern.component.html',
  styleUrls  : ['game-pattern.component.css'],
  directives : [NgFor],
})
export class GamePatternComponent implements OnInit {
  @Input('CardType') public cardType: number;

  public horizontalElementLocation: number;
  public verticalElementLocation: number;
  public rows: number[]     = [];
  public elements: number[] = [];
  public y: number;
  public x: number;

 // public cardType = 3;
 constructor() {
    this.cardType = 3;
  }

  public ngOnInit() {
    console.log('cardType ' + this.cardType);
    this.chooseGamePattern();
  }

  public chooseGamePattern() {
    if (this.cardType === 3) {
      this.horizontalElementLocation = 9;
      this.verticalElementLocation   = 3;
    }

    for (this.y = 0; this.y < this.verticalElementLocation; this.y++) {
      this.rows[this.y] = 0;
      for (this.x = 0; this.x < this.horizontalElementLocation; this.x++) {
        this.elements[this.x] = 0;
      }
    }
  }
}

<div id="game-pattern" >
  <div class="pattern-row" *ngFor="#row of rows">
    <div class="big-circle" *ngFor="#elemnt of elements"> 
      <div class="small-circle"></div>
    </div>
  </div>
</div>

** 此代码无法在此环境中运行:)*

问：如何在不创建数组来生成 UI 的情况下使用 NgFor。我的意思是，如果我收到输入x = 9和y = 3，它应该构建9X3的UI矩阵模式。请告知:)

Answer 1

构建数组只是为了迭代它们似乎很奢侈。创建一个指令来替换ngFor是多余的。

<div *ngFor="let i of 30|times">{{ i }}</div>

Answer 2

创建重复模板 N 次的自定义结构指令。

import {TemplateRef, ViewContainerRef, Directive, Input} from 'angular2/core';

@Directive({
   selector: '[mgRepeat]'
})
export class mgRepeatDirective {
   constructor(
       private _template: TemplateRef,
       private _viewContainer: ViewContainerRef
   ) { }

   @Input('mgRepeat')
   set times(times: number) {
       for (let i = 0; i < times; ++i)
           this._viewContainer.createEmbeddedView(this._template);
   }
}

按如下方式使用

<div id="game-pattern" >
  <div class="pattern-row" *mgRepeat="verticalElementLocation">
     <div class="big-circle" *mgRepeat="horizontalElementLocation"> 
        <div class="small-circle"></div>
     </div>
 </div>
</div>