Question

In the camera app layout it has:

camera.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/app_root"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
<include layout="@layout/preview_frame"/>
<include layout="@layout/camera_control"/>
</LinearLayout>

and preview_frame.xml is

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/frame_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_weight="1">
    .....
</RelativeLayout> 

and camera_control.xml is:

<ControlPanelLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/control_panel"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:minHeight="76dp"
    android:background="@drawable/bg_camera_pattern">
    .....
 </ControlPanelLayout>

My question is what is the ‘layout_weight=”1″ ‘ in preview_frame.xml for?
I have read about layout_weight but most of the time it used with layout_width=”0px”
And in camera_control, it does not have any layout_weight specified.

But in this case, it is not.

Thank you.

Answer 1

Layout weight decides how any remaining space in the parent is filled after all the added views have taken up their basic area.

The weights of the views in a viewgroup are added up and the leftover space is divided proportionally. So two views with width 0 and weights 1 and 2 will sum to a weight of 3 and one view will expand to 1/3 of the view size and the other to 2/3.

However if views have width, they will take up that space before handing out the extra space. So a view with a width and no weight will take up the allotted space and a weighted view beside it will fill the remainder, so in our previous example of weights 1 and 2 if the weight 1 view has a width, it will expand to additionally include 1/3 of the REMAINING space which could put it at being larger than the weight 2 view.

A little unfocused, haven’t had me coffee,but I hope it helps you out 😛