Ondraw method not calling in custom view

Question

I am making custom view using custom ViewGroup and custom View in Android.

public class Custom_ViewGroup extends ViewGroup
{
public Custom_ViewGroup(Context context)
{
    super(context);
    addView(new OwnView(context));
}

public Custom_ViewGroup(Context context,AttributeSet attrs) 
{
    super(context, attrs);
    addView(new OwnView(context));
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b)
{
    // TODO Auto-generated method stub
}

class OwnView extends View
{
    public OwnView(Context context)
    {
        super(context);
        System.out.println("on constructor");
    }
    @Override
    protected void onDraw(Canvas canvas)
    {
        super.onDraw(canvas);

        System.out.println("ondraw child");
    }
  }
}

onDraw() method of OwnView class is not calling. constructor of OwnView class called. I have used invalidate() method after adding view, but it did not work.

pathfinderelite · Accepted Answer · 2015-05-09T12:46:58.290

1

This is your problem

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b)
{
    // TODO Auto-generated method stub
}

Your view is never laid-out, so it will not draw. You need to implement the onLayout method properly. Also, if your ViewGroup contains only a single view, consider using FrameLayout instead of ViewGroup.

edited May 09 '15 at 12:46

answered May 09 '15 at 12:39

pathfinderelite

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"Also, if your `ViewGroup` is only a single view" you mean if it has only one child View? – pskink May 09 '15 at 12:46
so if it has only one child view, its better just to remove the "one child" parent – pskink May 09 '15 at 12:51
@pskink Possibly. It depends on how the child view is laid-out. – pathfinderelite May 09 '15 at 12:56
@pathfinderelite thanks, It is working. But I did not understand your point to use FrameLayout. Can you put some more light on use of FrameLayout.... – Akashsingla19 May 09 '15 at 16:38
1

@Akashsingla19 I'm not saying you should use `FrameLayout`. I'm saying you _may_ want to use it if your ViewGroup only contains a single child. You can read more [here](http://developer.android.com/reference/android/widget/FrameLayout.html) – pathfinderelite May 09 '15 at 16:42
@pathfinderelite ok. I made a demo to learn custom view and custom viewgroup. If you have any type of material on custom view, Please give me. – Akashsingla19 May 09 '15 at 16:46
@Akashsingla19 Google is your friend :) – pathfinderelite May 09 '15 at 16:49

Ondraw method not calling in custom view

1 Answers1