自学鸿蒙应用开发（15）- ScrollView-技术圈

本文介绍在鸿蒙应用中ScrollView组件的基本用法。

增加ScrollView组件

如下代码中第2行~第10行和第137行所示，可以很简单地在布局中增加ScrollView组件。

<ScrollView    xmlns:ohos="http://schemas.huawei.com/res/ohos"    ohos:id="$+id:scrollview"    ohos:height="match_parent"    ohos:width="match_parent"    ohos:background_element="#FFFFFF"    ohos:top_margin="32vp"    ohos:bottom_padding="16vp"    ohos:layout_alignment="horizontal_center">    <DirectionalLayout        ohos:height="match_content"        ohos:width="match_parent"        ohos:left_margin="40vp"        ohos:right_margin="40vp"        ohos:orientation="vertical">        <Component            ohos:height="40vp"            ohos:weight="3"            ohos:width="match_parent"            />        <DirectionalLayout            xmlns:ohos="http://schemas.huawei.com/res/ohos"            ohos:height="match_content"            ohos:width="match_parent"            ohos:layout_alignment="center"            ohos:orientation="vertical">            <Image                ohos:id="$+id:image"                ohos:width="match_content"                ohos:height="match_content"                ohos:layout_alignment="center"                ohos:image_src="$media:DevEco"            />            <TextField                ohos:id="$+id:text_field"                ohos:width="match_parent"                ohos:height="30vp"                ohos:text_size="20fp"                ohos:text_alignment="center"                ohos:hint="Please input text and press [Click me!] button."                ohos:background_element="$graphic:background_text_field"                />            <Button                ohos:id="$+id:hello_button"                ohos:width="match_content"                ohos:height="match_content"                ohos:text_size="27fp"                ohos:text="Click me!"                ohos:layout_alignment="center"                ohos:background_element="$graphic:background_button"                ohos:margin="15vp"                ohos:right_padding="8vp"                ohos:left_padding="8vp"                />            <DirectionalLayout                ohos:height="match_content"                ohos:width="match_content"                ohos:layout_alignment="center"                ohos:orientation="horizontal">                <Text                    ohos:id="$+id:text_pick_type"                    ohos:height="match_content"                    ohos:width="match_content"                    ohos:text="时间类型："                    ohos:text_size="20fp"/>                <Switch                    ohos:id="$+id:btn_switch"                    ohos:text_state_off="12H"                    ohos:text_color="#FFFFFF"                    ohos:text_state_on="24H"                    ohos:text_size="20fp"                    ohos:height="match_content"                    ohos:width="match_content"                    />            DirectionalLayout>            <TimePicker                ohos:id="$+id:time_picker"                ohos:24_hour_mode="false"                ohos:height="match_content"                ohos:width="match_parent"                ohos:layout_alignment="horizontal_center"                ohos:text_am="AM"                ohos:text_pm="PM"                ohos:normal_text_size="20fp"                ohos:selected_text_size="25fp"/>            <ProgressBar                ohos:id="$+id:hour_progress"                ohos:progress_width="10vp"                ohos:height="60vp"                ohos:width="match_parent"                ohos:left_margin="40vp"                ohos:right_margin="40vp"                ohos:progress_color="#FF0000"                ohos:max="100"                ohos:min="0"                ohos:progress="60"/>            <ProgressBar                ohos:id="$+id:minute_progress"                ohos:progress_width="10vp"                ohos:height="60vp"                ohos:width="match_parent"                ohos:left_margin="40vp"                ohos:right_margin="40vp"                ohos:progress_color="#00FF00"                ohos:max="100"                ohos:min="0"                ohos:progress="60"/>            <ProgressBar                ohos:id="$+id:second_progress"                ohos:progress_width="10vp"                ohos:height="60vp"                ohos:width="match_parent"                ohos:left_margin="40vp"                ohos:right_margin="40vp"                ohos:progress_color="#0000FF"                ohos:max="100"                ohos:min="0"                ohos:progress="60"/>            <RoundProgressBar                ohos:id="$+id:round_progress"                ohos:height="200vp"                ohos:width="200vp"                ohos:layout_alignment="horizontal_center"                ohos:progress_width="20vp"                ohos:start_angle="45"                ohos:max_angle="270"                ohos:progress="20"                ohos:progress_color="#FF00FF"/>        DirectionalLayout>        <Component            ohos:height="0vp"            ohos:weight="5"            ohos:width="match_parent"            />    DirectionalLayout>ScrollView>

代码中组件id被指定为scrollview，如果有需要可以在代码中使用它获取ScrollView组件。

展示ScrollView的效果

本文只是简单展示ScrollView的效果，因此没有对它进行任何操作。如果有需要可以参照本文后面的文档链接。

下面代码中的第29行~第51行，根据TimePicker状态分别更新3个ProgressBar和RoundProgressBar的内容，通过视频可以看到，无论画面滚动到哪个位置，用户的操作体验都是一样的。

package com.example.helloharmony.slice;import com.example.helloharmony.ResourceTable;import ohos.aafwk.ability.AbilitySlice;import ohos.aafwk.content.Intent;import ohos.agp.components.*;import ohos.agp.window.dialog.ToastDialog;import java.time.LocalTime;import java.time.temporal.ChronoUnit;
public class ComponentAbilitySlice extends AbilitySlice {    @Override    public void onStart(Intent intent) {        super.onStart(intent);        super.setUIContent(ResourceTable.Layout_ability_component);        //获取TimePicker组件        TimePicker picker = (TimePicker) findComponentById(ResourceTable.Id_time_picker);        //获取ProgressBar组件        updateProgressValue(picker);        //为TimePicker设定事件响应        ComponentAbilitySlice this_slice = this;        picker.setTimeChangedListener(            new TimePicker.TimeChangedListener() {                @Override                public void onTimeChanged(TimePicker timePicker, int hour, int minute, int second) {                    this_slice.updateProgressValue(timePicker);                }            }        );    }    @Override    public void onActive() {        super.onActive();    }    @Override    public void onForeground(Intent intent) {        super.onForeground(intent);    }
    private void updateProgressValue(TimePicker picker){        int seconds = (picker.getHour() * 60 + picker.getMinute()) * 60 + picker.getSecond();        setProgressValue(ResourceTable.Id_hour_progress, picker.getHour(), 24);        setProgressValue(ResourceTable.Id_minute_progress, picker.getMinute(), 60);        setProgressValue(ResourceTable.Id_second_progress, picker.getSecond(), 60);        setProgressValue(ResourceTable.Id_round_progress, seconds, 86400);    }
    private void setProgressValue(int id, int value, int span){        ProgressBar progress = (ProgressBar)findComponentById(id);        progress.setProgressValue(progress.getMin() + value * (progress.getMax() - progress.getMin()) / span);    }}

画面显示如下：

参考文档

ScrollView组件

https://developer.harmonyos.com/cn/docs/documentation/doc-guides/ui-java-component-scrollview-0000001060965602

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