ts-universal-attributes-layout-constraints.md

# 布局约束

> ![icon-note.gif](public_sys-resources/icon-note.gif) **说明：**
> 从API Version 7开始支持。后续版本如有新增内容，则采用上角标单独标记该内容的起始版本。


## 权限列表

无


## 属性


| 名称 | 参数说明 | 默认值 | 描述 | 
| -------- | -------- | -------- | -------- |
| aspectRatio | number | - | 指定当前组件的宽高比。 | 
| displayPriority | number | - | 设置当前组件在布局容器中显示的优先级，当父容器空间不足时，低优先级的组件会被隐藏。<br/>>&nbsp;![icon-note.gif](public_sys-resources/icon-note.gif)&nbsp;**说明：**<br/>>&nbsp;仅在Row/Column/Flex(单行)容器组件中生效。 | 


## 示例

```
@Entry
@Component
struct AspectRatioExample {
  private children : string[] = ['1', '2', '3', '4', '5', '6']

  build() {
    Column({space: 20}) {
      Text('using container: row').fontSize(14).fontColor(0xCCCCCC).width('100%')
      Row({space: 10}) {
        ForEach(this.children, (item) => {
          Text(item)
            .backgroundColor(0xbbb2cb)
            .fontSize(20)
            .aspectRatio(1.5)
            .height(60)
          Text(item)
            .backgroundColor(0xbbb2cb)
            .fontSize(20)
            .aspectRatio(1.5)
            .width(60)
        }, item=>item)
      }
      .size({width: "100%", height: 100})
      .backgroundColor(0xd2cab3)
      .clip(true)

      Text('using container: grid').fontSize(14).fontColor(0xCCCCCC).width('100%')
      Grid() {
        ForEach(this.children, (item) => {
          GridItem() {
            Text(item)
              .backgroundColor(0xbbb2cb)
              .fontSize(40)
              .aspectRatio(1.5)
          }
        }, item=>item)
      }
      .columnsTemplate('1fr 1fr 1fr')
      .columnsGap(10)
      .rowsGap(10)
      .size({width: "100%", height: 165})
      .backgroundColor(0xd2cab3)
    }.padding(10)
  }
}
```

**图1** 竖屏显示<br>
![zh-cn_image_0000001219744205](figures/zh-cn_image_0000001219744205.gif)

**图2** 横屏显示<br>
![zh-cn_image_0000001174264382](figures/zh-cn_image_0000001174264382.gif)

```
class ContainerInfo {
  label : string = ''
  size : string = ''
}

class ChildInfo {
  text : string = ''
  priority : number = 0
}

@Entry
@Component
struct DisplayPriorityExample {
  private container : ContainerInfo[] = [
    {label: 'Big container', size: '90%'},
    {label: 'Middle container', size: '50%'},
    {label: 'Small container', size: '30%'}]
  private children : ChildInfo[] = [
    {text: '1\n(priority:2)', priority: 2},
    {text: '2\n(priority:1)', priority: 1},
    {text: '3\n(priority:3)', priority: 3},
    {text: '4\n(priority:1)', priority: 1},
    {text: '5\n(priority:2)', priority: 2}]
  @State currentIndex : number = 0

  build() {
    Column({space: 10}) {
      Button(this.container[this.currentIndex].label).backgroundColor(0x317aff)
        .onClick((event: ClickEvent) => {
          this.currentIndex = (this.currentIndex + 1) % this.container.length
        })
      Flex({justifyContent: FlexAlign.SpaceBetween}) {
        ForEach(this.children, (item)=>{
          Text(item.text)
            .width(120)
            .height(60)
            .fontSize(24)
            .textAlign(TextAlign.Center)
            .backgroundColor(0xbbb2cb)
            .displayPriority(item.priority)
        }, item=>item.text)
      }
      .width(this.container[this.currentIndex].size)
      .backgroundColor(0xd2cab3)
    }.width("100%").margin({top:50})
  }
}

```

![zh-cn_image_0000001219662667](figures/zh-cn_image_0000001219662667.gif)