CODEWITHSUNDEEP
javaandroid
ronash
ronash

Reputation: 866

Using View components in XML files (Android)

First of all, I would like to apologise if my question is very basic - I don't know which keywords are useful to find the answer.

I know how to programme two "types" of application - ones which are run by .xml files (for instance, a converter from Celsius to Fahrenheit, some options menu and so on), and ones which are run with a class which extends View (for applications with graphical components). My question is, how to combine them? More precisely, how to add a View component into an XML file? Practical example: drawing a circle in an options menu, which moves once touched.

Thank you in advance.

Upvotes: 0

Views: 343

Answers (2)

Alex Gitelman
Alex Gitelman

Reputation: 24722

To use custom view in XML you will need to

  • Code your view in such a way that it accepts AttributeSet. Example:

    public ActivityTitleView(Context context, AttributeSet attrs)

  • Define styleable attributes. They go into res/values/attr.xml 

<resources>
    <declare-styleable name="ActivityTitleView">   
        <attr name="text" format="string"/>
        <attr name="helpContext" format="string"/>   
    </declare-styleable>
</resources
  • Include your view in XML with your own namespace. Own namespace is important if you want your attributes:

< LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:yournamespace="http://schemas.android.com/apk/res/com.yourpackage" >

<com.yourpackage.ActivityTitleView yournamespace:text="Bla Bla"  
           android:layout_width="fill_parent"
           android:layout_height="wrap_content"/>
  • Extract attributes in code
     TypedArray array = context.obtainStyledAttributes(attrs,
          R.styleable.ActivityTitleView, 0, 0);
     String text = array.getString(R.styleable.ActivityTitleView_text);
     helpContext = array.getString(R.styleable.ActivityTitleView_helpContext);

Sorry StackOverflow does not seem to format my snippets well. Feel free to edit formatting.

Upvotes: 1

harism
harism

Reputation: 6073

I don't know about drawing a circle in options menu, but in general you can use your custom View classes in layout xmls like this;

<com.testing.MyCustomView
  id="@+id/my_view"
  ... />

Making them very much alike compared to using TextViews, ImageViews etc.

Upvotes: 1

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