Question

Loading class (View):

public class Loading extends View {

    private long movieStart;
    private Movie movie;

    public Loading(Context context, InputStream inputStream) {
            super(context);
        movie = Movie.decodeStream(inputStream);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawColor(Color.WHITE);
        super.onDraw(canvas);
        final long now = SystemClock.uptimeMillis();
        if(movieStart == 0)
            movieStart = now;
        final int relTime = (int)((now - movieStart) % movie.duration());
        movie.setTime(relTime);
        movie.draw(canvas, 100, 100);
        this.invalidate();
    }

}

Activity onCreate method:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    InputStream inputStream = null;
    try {
       inputStream = getAssets().open("loading.gif");
    } catch(IOException e) {
      e.printStackTrace();
    }
    Loading loading = new Loading(this, inputStream);
    setContentView(loading);
}

I want to set the view in center of the device layout. Like in XML layout, that we can set android:layout_centerHorizontal=”true”. How can I do it?

Answer 1

You need to set LayoutParams for the View. What I would do is put your custom view in a container, for example a FrameLayout. Then, create your view and set the FrameLayout.LayoutParams for your View with gravity set to CENTER_HORIZONTAL. It’ll look something like this

FrameLayout frame = new FrameLayout(context);

FrameLayout.LayoutParams flParams = new FrameLayout.LayoutParams(
    ViewGroup.LayoutParams.WRAP_CONTENT, 
    ViewGroup.LayoutParams.WRAP_CONTENT, 
    Gravity.CENTER_HORIZONTAL
);

Loading loading = new Loading(this, inputStream);
loading.setLayoutParams(flParams);
frame.addView(loading);
setContentView(frame);

You may want to configure the FrameLayout to get it to display how you want.

Here’s the documentation for the LayoutParams constructor I’d use: http://developer.android.com/reference/android/widget/FrameLayout.LayoutParams.html#FrameLayout.LayoutParams%28int,%20int,%20int%29

It’s important to remember that each of the Views that extend ViewParent have their own LayoutParams class, so, for example, if you wanted to use a LinearLayout instead of a FrameLayout, you’d use LinearLayout.LayoutParams. Different types of Params have different constructor options, so you can play around with it and find which is best for you. Good luck.