Nested Weights Vs Nested Layouts with weights. Which is better?

Question

Android Lint gives us warning when we do nested weights saying that nested weights are bad for performance so i was wondering what will happen if i add an extra layout which encloses the nested weigh layouts. Will it make any difference in performance?

The guy here said that Layout weights require a widget to be measured twice. When a LinearLayout with non-zero weights is nested inside another LinearLayout with non-zero weights, then the number of measurements increase exponentially.

So i was wondering is

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dip"
        android:layout_weight="1" >

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:baselineAligned="false"
            android:gravity="center"
            android:orientation="horizontal" >

            <FrameLayout
                android:id="@+id/fl_topleft"
                android:layout_width="0dip"
                android:layout_height="match_parent"
                android:layout_margin="5dp"
                android:layout_weight="1"
                android:background="@drawable/shape" />

            <FrameLayout
                android:id="@+id/fl_topright"
                android:layout_width="0dip"
                android:layout_height="match_parent"
                android:layout_margin="5dp"
                android:layout_weight="1"
                android:background="@drawable/shape" />
        </LinearLayout>
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dip"
        android:layout_weight="1" >

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:baselineAligned="false"
            android:gravity="center"
            android:orientation="horizontal" >

            <FrameLayout
                android:id="@+id/fl_bottomleft"
                android:layout_width="0dip"
                android:layout_height="match_parent"
                android:layout_margin="5dp"
                android:layout_weight="1"
                android:background="@drawable/shape" />

            <FrameLayout
                android:id="@+id/fl_bottomright"
                android:layout_width="0dip"
                android:layout_height="match_parent"
                android:layout_margin="5dp"
                android:layout_weight="1"
                android:background="@drawable/shape" />
        </LinearLayout>
    </LinearLayout>

</LinearLayout>

Better than

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dip"
         android:orientation="horizontal"
        android:layout_weight="1" >



            <FrameLayout
                android:id="@+id/fl_topleft"
                android:layout_width="0dip"
                android:layout_height="match_parent"
                android:layout_margin="5dp"
                android:layout_weight="1"
                android:background="@drawable/shape" />

            <FrameLayout
                android:id="@+id/fl_topright"
                android:layout_width="0dip"
                android:layout_height="match_parent"
                android:layout_margin="5dp"
                android:layout_weight="1"
                android:background="@drawable/shape" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dip"
         android:orientation="horizontal"
        android:layout_weight="1" >



            <FrameLayout
                android:id="@+id/fl_bottomleft"
                android:layout_width="0dip"
                android:layout_height="match_parent"
                android:layout_margin="5dp"
                android:layout_weight="1"
                android:background="@drawable/shape" />

            <FrameLayout
                android:id="@+id/fl_bottomright"
                android:layout_width="0dip"
                android:layout_height="match_parent"
                android:layout_margin="5dp"
                android:layout_weight="1"
                android:background="@drawable/shape" />

    </LinearLayout>

</LinearLayout>

http://developer.android.com/training/improving-layouts/optimizing-layout.html — Muhammad Babar, Dec 04 '13 at 07:35

Pork 'n' Bunny · Accepted Answer · 2013-09-15T03:52:14.053

1

The second layer of layouts doesn't prevent the extra processing from occurring/propagating.

My understanding is that linearlayout actually ALWAYS does the two passes but that could be simply what happens in practice because if you aren't using weights, you could do the same layout using relativelayout.

Just to elaborate. the onMeasure propogation occurs twice from the root moving down. In both cases, the framelayouts are measured 4 times.

edited Sep 15 '13 at 03:52

answered Sep 14 '13 at 11:40

Pork 'n' Bunny

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I hope this answer was useful to you, I'd appreciate marking it correct if it is. – Pork 'n' Bunny Sep 15 '13 at 03:52
You said your understanding is that linearlayout actually ALWAYS does the two passes . Does Android docs say the same. Can you provide any reference ? – Sheraz Ahmad Khilji Sep 16 '13 at 07:23
Well as I said, it should not matter either way because you can use a relativelayout if you are not using weights in a linearlayout. That being said, onMeasure in LinearLayout.java doesn't use the totalWeight as a paramater to avoid pre-measuring children. So even if you leave out weights, the measurement takes place twice for child of a linearlayout. I hope that makes this clear on a couple levels. – Pork 'n' Bunny Sep 16 '13 at 10:28
If you found my answer and follow-up helpful, I'd appreciate if you marked it as correct. Cheers. – Pork 'n' Bunny Sep 16 '13 at 22:52

Nested Weights Vs Nested Layouts with weights. Which is better?

1 Answers1