什么是DirectionalLayout

DirectionalLayout又称方向布局,是鸿蒙开发中几个常用的布局之一,使用频率较高,而且非常简单.布局内的控件依次排列,支持横向或纵向排列.

基础样例

1. 纵向排列

效果图

代码

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:orientation="vertical">

    <Text
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="花生皮编程1"/>

    <Text
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="花生皮编程2"/>

    <Text
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="花生皮编程3"/>
</DirectionalLayout>

代码说明:

1. 设置ohos:orientation为vertical,展示方向变成纵向
2. DirectionalLayout里面包括了三个显示文本的Text.

2. 横向排列

效果图

代码

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:orientation="horizontal">

    <Text
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="花生皮编程1"/>

    <Text
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="花生皮编程2"/>

    <Text
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="花生皮编程3"/>
</DirectionalLayout>

代码说明:

1. 设置ohos:orientation为horizontal,展示方向变成横向.

3. 调整子控件摆放位置(gravity属性)

通过DirectionalLayout的ohos:alignment属性控制其子控件相对于自己的对齐方式.

3.1 水平居中

效果图

代码

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:alignment="horizontal_center">

    <Text
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="花生皮编程-水平居中"/>
</DirectionalLayout>

3.2 垂直居中

效果图

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代码

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:alignment="vertical_center">

    <Text
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="花生皮编程-垂直居中"/>
</DirectionalLayout>

3.3 水平+垂直居中

效果图

代码

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:alignment="center">

    <Text
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:text="花生皮编程-居中"/>
</DirectionalLayout>

4. 按比例分空间(layout_weight)

DirectionalLayout里的子控件可以通过weight属性按比例分空间大小(横向或纵向).按照DirectionalLayout里所有直属子控件(不算子控件的子控件)设置的weight作为总和,各个控件按照自己的weight所占总和比例来分空闲空间(有些控件未设置weight,则按照固定值).

4.1 等分空间

效果图

代码

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:orientation="horizontal">

    <Text
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:background_element="#f2eada"
        ohos:text="Text1"
        ohos:text_alignment="center"
        ohos:weight="1"/>

    <Text
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:background_element="#9b95c9"
        ohos:text="Text2"
        ohos:text_alignment="center"
        ohos:weight="1"/>
</DirectionalLayout>

代码说明:
1.两个按钮都设置ohos:weight属性,且值相同,故平分空间.

4.2 按比例分

一个控件保持固定大小,一个占据剩余可用空间.

效果图

代码

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:orientation="horizontal">

    <Text
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:background_element="#f2eada"
        ohos:text="Text1"
        ohos:text_alignment="center"/>

    <Text
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:background_element="#9b95c9"
        ohos:text="Text2"
        ohos:text_alignment="center"
        ohos:weight="1"/>
</DirectionalLayout>

代码说明:

1. 第一个按钮不设置ohos:weight属性,保持本身大小.
2. 第二个按钮设置ohos:weight属性,占据所有剩余可用空间.

完整源代码

https://gitee.com/hspbc/harmonyos_demos/tree/master/directionalLayoutDemo

常用属性说明