Why is Android lint showing “nested weights are bad for performance” when none are nested?

Question

The layout_weight attribute in the last TextView in this layout is being highlighted by lint as causing bad performance. I suspect the name of the lint warning is erroneous as there are no nested weights. There are several stretching views, and I suspect what it means is dependent weighted views.

What's the solution, to build this layout, and avoid this lint warning, and improve performance?

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:orientation="vertical"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent"
          android:gravity="center_horizontal"
          android:background="@drawable/background_gradient"
    >
<ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/image4"
        android:layout_margin="6dp"
        android:contentDescription="@string/PLACEHOLDER_TEXT"
        />
<LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:orientation="horizontal"
        >
    <Button
            style="@style/dashboard_button"
            android:id="@+id/home_management"
            android:text="@string/ICON_MANAGEMENT"
            />
    <Button
            style="@style/dashboard_button"
            android:id="@+id/home_calculators"
            android:text="@string/ICON_CALCULATORS"
            />
</LinearLayout>
<LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:orientation="horizontal"
        >
    <Button
            style="@style/dashboard_button"
            android:id="@+id/home_guidelines"
            android:text="@string/ICON_GUIDELINES"
            />
    <Button
            style="@style/dashboard_button"
            android:id="@+id/home_faq"
            android:text="@string/ICON_FAQ"
            />
</LinearLayout>
<LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:orientation="horizontal"
        >
    <Button
            style="@style/dashboard_button"
            android:id="@+id/home_refs"
            android:text="@string/ICON_REFERENCES"
            />
    <Button
            style="@style/dashboard_button"
            android:text=""
            android:visibility="invisible"
            />
</LinearLayout>
<LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:gravity="center_vertical"
        android:layout_margin="6dp"
        >
    <TextView
            android:text="@string/HOMEPAGE_CONTENT"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:textStyle="bold"
            android:textColor="#FFFFFF"
            />
    <View
            android:layout_width="8dp"
            android:layout_height="1dp"
            />
    <ImageView
            android:id="@+id/home_logo"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:src="@drawable/image7"
            android:contentDescription="@string/PLACEHOLDER_TEXT"
            />
</LinearLayout>
<Button
        android:id="@+id/home_web_site"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/HOMEPAGE_FOOTER"
        android:paddingLeft="4dp"
        android:paddingRight="4dp"
        android:paddingTop="8dp"
        android:paddingBottom="8dp"
        android:textSize="12sp"
        android:background="@drawable/button_red"
        android:layout_margin="6dp"
        android:textColor="#FFFFFF"
        />
</LinearLayout>

Answer 1

The TextView and ImageView in your @string/HOMEPAGE_CONTENT area are nested in their parent LinearLayout and have weights assigned. I suspect those are your problem, especially since the parent is wrap_content, so theoretically there shouldn't be any space for the child elements to stretch into.

Answer 2

You don't need to worry about this, however, especially if you really need the weights, and if that's the only way to declare your layout properly.

Answer 3

Concerning this part of code.

<LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1"
    android:orientation="horizontal"

<Button
        style="@style/dashboard_button"
        android:id="@+id/home_management"
        android:text="@string/ICON_MANAGEMENT"
        />
<Button
        style="@style/dashboard_button"
        android:id="@+id/home_calculators"
        android:text="@string/ICON_CALCULATORS"
        />

Your LinearLayout contains "layout_weight" attribute, and if the style "dashboard_button" contains the attribute "layout_weight" too, then you got couple of nested views with the "layout_weight" attribute, though the lint doesn't warn me now concerning "layout_weight" inside the styles. My solution is to substitue one(or both) of the LinearLayouts with RelativLayout and adjust the sizes and places programmatically.