View Inflation and custom views

Question

I have a custom view in my app that I draw using the onDraw() function in the View. Also it needs some data from the ACtivity to draw the graphic. So instead of using the standard setContentView(R.layout.myview) I am using the following -

MyView mv = new MyView(this, userData);
setContentView(mv);

This seemed to work until I added a textview above the customview. Then I realized that the above code does not show the textview at all. Also the onFinishInflate() is never called. Do I have to inflate the layout myself in this case? If so do I have to call the onDraw() function myself too?

Thanks, - P

score 6 · Answer 1 · edited Jan 04 '13 at 08:49

onFinishInflate ()

Finalize inflating a view from XML. This is called as the last phase of inflation, after all child views have been added.

When you create your view by code (new ...) you are not inflating it... on the other hand, if you declare it in the XML or you use something like getLayoutInflater().inflate(R.layout.your_view,null,null); then you are inflating it (and onFinishInflate) will be called.

It does not matter how you are doing it, onDraw method will always be called; so you don't have to invoke it manually.

By the way... it's always a good idea to keep your custom view on the XML, even if it needs data. So you have at least two options:

setContentView(R.layout.your_layout);
YourCustom custom = (YourCustom)findViewById(R.id.custom);
custom.setUserData(userData);

or... you can fetch that data from the custom view (not recommended):

// inside your custom view...
UserData userData = Someclass.getUserData(getContext());
// etc... so that you don't have to pass it from the activity

score 4 · Accepted Answer · answered Jun 10 '11 at 15:12

What you should have here is a layout that contains the TextView and your MyView and then inside your activity, find your custom view and pass in your user data. Your MyView can then use this during its onDraw(). Perhaps something like this:

res/layout/main.xml:

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="veritcal">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Hello World" />
    <my.package.MyView
        android:id="@+id/myview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
</LinearLayout>

src/my/package/MyView.java:

public class MyView extends View {
    UserData mUserData = null;
    public void setUserData(userData) {
        mUserData = userData;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        performCustomDrawingWithUserData(mUserData);
        super.onDraw(canvas);
    }

}

src/my/package/MyActivity.java:

public class MyActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // pass the user data into myview here.
        MyView myView = (MyView) findViewById(R.id.myview);
        myView.setUserData(userData);
    }

}

View Inflation and custom views

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