树叶云鸿蒙OS教程：鸿蒙OS Button

鸿蒙OS Button

按钮（Button）是一种常见的组件，点击可以触发对应的操作，通常由文本或图标组成，也可以由图标和文本共同组成。

图1 文本按钮

图2 图标按钮

图3 图标和文本共同组成的按钮

创建Button

使用 Button 组件，可以生成形状、颜色丰富的按钮。

<Button    
    ohos:id="$+id:button_sample"
    ohos:width="match_content"
    ohos:height="match_content"
    ohos:text_size="27fp"
    ohos:text="button"
    ohos:background_element="$graphic:button_element"
    ohos:left_margin="15vp"
    ohos:bottom_margin="15vp"
    ohos:right_padding="8vp"
    ohos:left_padding="8vp"
    ohos:element_left="$graphic:ic_btn_reload"

button_element.xml：

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:shape="rectangle">
    <corners
        ohos:radius="10"/>
    <solid
        ohos:color="#FF007DFF"/>
</shape>

响应点击事件

按钮的重要作用是当用户单击按钮时，会执行相应的操作或者界面出现相应的变化。实际上用户点击按钮时，Button 对象将收到一个点击事件。开发者可以自定义响应点击事件的方法。例如，通过创建一个 Component.ClickedListener 对象，然后通过调用 setClickedListener 将其分配给按钮。

//从定义的xml中获取Button对象
Button button = (Button) rootLayout.findComponentById(ResourceTable.Id_button_sample); 
// 为按钮设置点击事件回调
button.setClickedListener(new Component.ClickedListener() {
    public void onClick(Component v) {
        // 此处添加点击按钮后的事件处理逻辑
    }
});

不同类型的按钮

按照按钮的形状，按钮可以分为：普通按钮，椭圆按钮，胶囊按钮，圆形按钮等。

普通按钮

普通按钮和其他按钮的区别在于不需要设置任何形状，只设置文本和背景颜色即可，例如：

  <Button
    ohos:width="150vp"
    ohos:height="50vp"
    ohos:text_size="27fp"
    ohos:text="button"
    ohos:background_element="$graphic:color_blue_element"
    ohos:left_margin="15vp"
    ohos:bottom_margin="15vp"
    ohos:right_padding="8vp"
    ohos:left_padding="8vp"
  />

color_blue_element.xml：

  <?xml version="1.0" encoding="utf-8"?>
  <shape xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:shape="rectangle">
    <solid
        ohos:color="#FF007DFF"/>
  </shape>

椭圆按钮

椭圆按钮是通过设置 background_element 的来实现的，background_element 的shape 设置为椭圆（oval），例如：

  <Button
    ohos:width="150vp"
    ohos:height="50vp"
    ohos:text_size="27fp"
    ohos:text="button"
    ohos:background_element="$graphic:oval_button_element"
    ohos:left_margin="15vp"
    ohos:bottom_margin="15vp"
    ohos:right_padding="8vp"
    ohos:left_padding="8vp"
    ohos:element_left="$graphic:ic_btn_reload"
  />

oval_button_element.xml:

  <?xml version="1.0" encoding="utf-8"?>
  <shape xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:shape="oval">
    <solid
        ohos:color="#FF007DFF"/>
  </shape>

胶囊按钮

胶囊按钮是一种常见的按钮，设置按钮背景时将背景设置为矩形形状，并且设置 ShapeElement 的 radius 的半径，例如：

  <Button
    ohos:id="$+id:button"
    ohos:width="match_content"
    ohos:height="match_content"
    ohos:text_size="27fp"
    ohos:text="button"
    ohos:background_element="$graphic:capsule_button_element"
    ohos:left_margin="15vp"
    ohos:bottom_margin="15vp"
    ohos:right_padding="15vp"
    ohos:left_padding="15vp"
  />

capsule_button_element.xml:

  <?xml version="1.0" encoding="utf-8"?>
  <shape xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:shape="rectangle">
    <corners
        ohos:radius="100"/>
    <solid
        ohos:color="#FF007DFF"/>
  </shape>

圆形按钮

圆形按钮和椭圆按钮的区别在于组件本身的宽度和高度需要相同，例如：

  <Button
    ohos:id="$+id:button4"
    ohos:width="50vp"
    ohos:height="50vp"
    ohos:text_size="27fp"
    ohos:background_element="$graphic:circle_button_element"
    ohos:text="+"
    ohos:left_margin="15vp"
    ohos:bottom_margin="15vp"
    ohos:right_padding="15vp"
    ohos:left_padding="15vp"
  />

circle_button_element.xml:

  <?xml version="1.0" encoding="utf-8"?>
  <shape xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:shape="oval">
    <solid
        ohos:color="#FF007DFF"/>
  </shape>

场景示例

利用圆形按钮，胶囊按钮，文本组件可以绘制出如下拨号盘的UI界面。

图4 界面效果

源码示例：

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:width="match_parent"
    ohos:height="match_parent"
    ohos:background_element="$graphic:color_light_gray_element"
    ohos:orientation="vertical">
    <Text
        ohos:width="match_content"
        ohos:height="match_content"
        ohos:text_size="20fp"
        ohos:text="0123456789"
        ohos:background_element="$graphic:green_text_element"
        ohos:text_alignment="center"
        ohos:layout_alignment="horizontal_center"
    />
    <DirectionalLayout
        ohos:width="match_parent"
        ohos:height="match_content"
        ohos:alignment="horizontal_center"
        ohos:orientation="horizontal"
        ohos:top_margin="5vp"
        ohos:bottom_margin="5vp">
        <Button
            ohos:width="40vp"
            ohos:height="40vp"
            ohos:text_size="15fp"
            ohos:background_element="$graphic:green_circle_button_element"
            ohos:text="1"
            ohos:text_alignment="center"
        />
        <Button
            ohos:width="40vp"
            ohos:height="40vp"
            ohos:text_size="15fp"
            ohos:background_element="$graphic:green_circle_button_element"
            ohos:text="2"
            ohos:left_margin="5vp"
            ohos:right_margin="5vp"
            ohos:text_alignment="center"
        />
        <Button
            ohos:width="40vp"
            ohos:height="40vp"
            ohos:text_size="15fp"
            ohos:background_element="$graphic:green_circle_button_element"
            ohos:text="3"
            ohos:text_alignment="center"
        />
    </DirectionalLayout>
    <DirectionalLayout
        ohos:width="match_parent"
        ohos:height="match_content"
        ohos:alignment="horizontal_center"
        ohos:orientation="horizontal"
        ohos:bottom_margin="5vp">
        <Button
            ohos:width="40vp"
            ohos:height="40vp"
            ohos:text_size="15fp"
            ohos:background_element="$graphic:green_circle_button_element"
            ohos:text="4"
            ohos:text_alignment="center"
        />
        <Button
            ohos:width="40vp"
            ohos:height="40vp"
            ohos:text_size="15fp"
            ohos:left_margin="5vp"
            ohos:right_margin="5vp"
            ohos:background_element="$graphic:green_circle_button_element"
            ohos:text="5"
            ohos:text_alignment="center"
        />
        <Button
            ohos:width="40vp"
            ohos:height="40vp"
            ohos:text_size="15fp"
            ohos:background_element="$graphic:green_circle_button_element"
            ohos:text="6"
            ohos:text_alignment="center"
        />
    </DirectionalLayout>
    <DirectionalLayout
        ohos:width="match_parent"
        ohos:height="match_content"
        ohos:alignment="horizontal_center"
        ohos:orientation="horizontal"
        ohos:bottom_margin="5vp">
        <Button
            ohos:width="40vp"
            ohos:height="40vp"
            ohos:text_size="15fp"
            ohos:background_element="$graphic:green_circle_button_element"
            ohos:text="7"
            ohos:text_alignment="center"
        />
        <Button
            ohos:width="40vp"
            ohos:height="40vp"
            ohos:text_size="15fp"
            ohos:left_margin="5vp"
            ohos:right_margin="5vp"
            ohos:background_element="$graphic:green_circle_button_element"
            ohos:text="8"
            ohos:text_alignment="center"
        />
        <Button
            ohos:width="40vp"
            ohos:height="40vp"
            ohos:text_size="15fp"
            ohos:background_element="$graphic:green_circle_button_element"
            ohos:text="9"
            ohos:text_alignment="center"
        />
    </DirectionalLayout>
    <DirectionalLayout
        ohos:width="match_parent"
        ohos:height="match_content"
        ohos:alignment="horizontal_center"
        ohos:orientation="horizontal"
        ohos:bottom_margin="5vp">
        <Button
            ohos:width="40vp"
            ohos:height="40vp"
            ohos:text_size="15fp"
            ohos:background_element="$graphic:green_circle_button_element"
            ohos:text="*"
            ohos:text_alignment="center"
        />
        <Button
            ohos:width="40vp"
            ohos:height="40vp"
            ohos:text_size="15fp"
            ohos:left_margin="5vp"
            ohos:right_margin="5vp"
            ohos:background_element="$graphic:green_circle_button_element"
            ohos:text="0"
            ohos:text_alignment="center"
        />
        <Button
            ohos:width="40vp"
            ohos:height="40vp"
            ohos:text_size="15fp"
            ohos:background_element="$graphic:green_circle_button_element"
            ohos:text="#"
            ohos:text_alignment="center"
        />
    </DirectionalLayout>
    <Button
        ohos:width="match_content"
        ohos:height="match_content"
        ohos:text_size="15fp"
        ohos:text="CALL"
        ohos:background_element="$graphic:green_capsule_button_element"
        ohos:bottom_margin="5vp"
        ohos:text_alignment="center"
        ohos:layout_alignment="horizontal_center"
        ohos:left_padding="10vp"
        ohos:right_padding="10vp"
        ohos:top_padding="2vp"
        ohos:bottom_padding="2vp"
    />
</DirectionalLayout>

color_light_gray_element.xml：

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:shape="rectangle">
    <solid
        ohos:color="#ffeeeeee"/>
</shape>

green_text_element.xml：

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:shape="rectangle">
    <corners
        ohos:radius="20"/>
    <stroke
        ohos:width="2"
        ohos:color="#ff008B00"/>
    <solid
        ohos:color="#ffeeeeee"/>
</shape>

green_circle_button_element.xml：

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:shape="oval">
    <stroke
        ohos:width="5"
        ohos:color="#ff008B00"/>
    <solid
        ohos:color="#ffeeeeee"/>
</shape>

green_capsule_button_element.xml：

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:shape="rectangle">
    <corners
        ohos:radius="100"/>
    <solid
        ohos:color="#ff008B00"/>
</shape>

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