- **virtualized**: `boolean` 启用虚拟加载

## 模板
```html
<farris-datagrid
    [fit]="true"
    [virtualized]="true"
    [pagination]="false"
    [fitColumns]="true"
    [columns]="columns"
    [data]="items">
</farris-datagrid>
```

## ts

```javascript
import { Component, OnInit } from '@angular/core';
import { CalculationType } from '@farris/ui-datagrid';
import { DemoDataService } from '../../demo-data.service';
import { DemoDataSeed } from '../../demo-data-seed';


@Component({
    selector: 'demo-large-data',
    templateUrl: './demo-big-data.component.html',
    providers: [
        DemoDataService
    ]
})
export class DemoLargeDataComponent implements OnInit {
    columns = [];
    items;

    fitColumns = true;
    recordCount = 500;
    html = '';
    ts = '';
    constructor(private dds: DemoDataService) { }

    ngOnInit(): void {

        const enumData = DemoDataSeed.enumData();
        const enumOpts = { valueField: 'value', textField: 'label', data: enumData };

        this.columns = [
            { field: 'id', width: 100, title: 'ID', footer: {
                options: { text: '合计'},
                formatter: (v, d, i) => {
                    return `<b>${v}</b>`;
                }
            }},
            { field: 'name', width: 130, title: '姓名'},
            { field: 'sex', width: 70, title: '性别' },
            { field: 'birthday', width: 120, title: '出生日期'},
            { field: 'maray', width: 70, title: '婚否', formatter: { type: 'boolean', options: { trueText: '已婚', falseText: '未婚' }}},
            { field: 'addr', width: 170, title: '地址' },
            { field: 'company', width: 100, title: '公司'},
            { field: 'nianxin', width: 70, title: '年薪', footer: {
                options: { calculationType: CalculationType.sum},
                formatter: { type: 'number', options: { prefix: '￥', suffix: '元', precision: 2 }}
            }},
            { field: 'zhiwei', width: 100, title: '职位', formatter: {type: 'enum', options: enumOpts} }
        ];

        this.loadData();
    }

    loadData(count?: number) {
        count = count || this.recordCount;
        this.items = this.dds.createData(count);
    }
}

```