How to create custom attributes for a custom component that can be assigned from XML in HarmonyOS?

Question

I am implementing a custom component and trying to take input from XML for an attribute. In Android, it looks something like this

<it.beppi.arcpageindicator.ArcPageIndicator
   android:layout_width="100dp"
   android:layout_height="20dp"
   android:layout_alignParentTop="true"
   android:layout_centerHorizontal="true"
   app:apiViewPager="@id/view_pager"
   app:apiArcOrientation="toDown"
   app:apiAnimationType="cover"
   />

How can I do this in HarmonyOS?

Answer 1

Step 1: You need to customize the label app (the name can be customized) in the root layout of the XML file. The format is: xmlns:app="http://schemas.huawei.com/res/ohos-auto",and the code is as follows:

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    xmlns:app="http://schemas.huawei.com/res/ohos-auto"
    ......
    >
</DirectionalLayout>

Step 2: When ArcPageIndicator is used in the XML file, define the line custom attribute apiArcOrientation. The code is as follows:

<!--com.huawei.flowlayout.library is the package path of the FlowLayout class ---->
<com.huawei.flowlayout.library.FlowLayout
    ......
    app:apiArcOrientation="toDown"
    />

Step 3: Obtain the attribute value through AttrSet in the Java code. The code is as follows:

public ArcPageIndicator(Context context, AttrSet attrSet) {
    ......
    String apiArcOrientation = attrSet.getAttr("apiArcOrientation").get().getStringValue();
}