[android] GridLayout and Row/Column Span Woe

The Android Developers Blog post introducing GridLayout shows this diagram of how spans impact automatic index allocation:

I am attempting to actually implement that using a GridLayout. Here is what I have so far:

<android.support.v7.widget.GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res/com.commonsware.android.gridlayout"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    app:orientation="horizontal"
    app:columnCount="8">

    <Button
        app:layout_columnSpan="2"
        app:layout_rowSpan="2"
        android:layout_gravity="fill_horizontal"
        android:text="@string/string_1"/>

  <Button
    app:layout_columnSpan="2"
    android:layout_gravity="fill_horizontal"
    android:text="@string/string_2"/>

  <Button
    app:layout_rowSpan="4"
    android:text="@string/string_3"/>

  <Button
    app:layout_columnSpan="3"
    app:layout_rowSpan="2"
    android:layout_gravity="fill_horizontal"
    android:text="@string/string_4"/>

  <Button
    app:layout_columnSpan="3"
    android:layout_gravity="fill_horizontal"
    android:text="@string/string_5"/>

  <Button
    app:layout_columnSpan="2"
    android:layout_gravity="fill_horizontal"
    android:text="@string/string_6"/>

  <android.support.v7.widget.Space
    app:layout_column="0"
    android:layout_width="36dp"
    />

  <android.support.v7.widget.Space
    android:layout_width="36dp"
    />

  <android.support.v7.widget.Space
    android:layout_width="36dp"
    />

  <android.support.v7.widget.Space
    android:layout_width="36dp"
    />

  <android.support.v7.widget.Space
    android:layout_width="36dp"
    />

  <android.support.v7.widget.Space
    android:layout_width="36dp"
    />

  <android.support.v7.widget.Space
    android:layout_width="36dp"
    />

  <android.support.v7.widget.Space
    android:layout_width="36dp"
    />

</android.support.v7.widget.GridLayout>

I had to introduce the <Space> elements to ensure each column had a minimum width, otherwise, I would have a bunch of zero-width columns.

However, even with them, I get this:

Notably:

• Despite android:layout_gravity="fill_horizontal", my widgets with column spans do not fill the spanned columns

• Despite the android:layout_rowSpan values, nothing spans rows

Can anyone reproduce the diagram from the blog post using a GridLayout?

Thanks!

You have to set both layout_gravity and layout_columntWeight on your columns

<android.support.v7.widget.GridLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <TextView android:text="??? ???"
        app:layout_gravity="fill_horizontal"
        app:layout_columnWeight="1"
        />

    <TextView android:text="??? ???"
        app:layout_gravity="fill_horizontal"
        app:layout_columnWeight="1"
        />

    <TextView android:text="??? ???"
        app:layout_gravity="fill_horizontal"
        app:layout_columnWeight="1"
        />
 </android.support.v7.widget.GridLayout>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <GridLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:columnCount="8"
        android:rowCount="7" >

        <TextView
            android:layout_width="50dip"
            android:layout_height="50dip"
            android:layout_columnSpan="2"
            android:layout_rowSpan="2"
            android:background="#a30000"
            android:gravity="center"
            android:text="1"
            android:textColor="@android:color/white"
            android:textSize="20dip" />

        <TextView
            android:layout_width="50dip"
            android:layout_height="25dip"
            android:layout_columnSpan="2"
            android:layout_rowSpan="1"
            android:background="#0c00a3"
            android:gravity="center"
            android:text="2"
            android:textColor="@android:color/white"
            android:textSize="20dip" />

        <TextView
            android:layout_width="25dip"
            android:layout_height="100dip"
            android:layout_columnSpan="1"
            android:layout_rowSpan="4"
            android:background="#00a313"
            android:gravity="center"
            android:text="3"
            android:textColor="@android:color/white"
            android:textSize="20dip" />

        <TextView
            android:layout_width="75dip"
            android:layout_height="50dip"
            android:layout_columnSpan="3"
            android:layout_rowSpan="2"
            android:background="#a29100"
            android:gravity="center"
            android:text="4"
            android:textColor="@android:color/white"
            android:textSize="20dip" />

        <TextView
            android:layout_width="75dip"
            android:layout_height="25dip"
            android:layout_columnSpan="3"
            android:layout_rowSpan="1"
            android:background="#a500ab"
            android:gravity="center"
            android:text="5"
            android:textColor="@android:color/white"
            android:textSize="20dip" />

        <TextView
            android:layout_width="50dip"
            android:layout_height="25dip"
            android:layout_columnSpan="2"
            android:layout_rowSpan="1"
            android:background="#00a9ab"
            android:gravity="center"
            android:text="6"
            android:textColor="@android:color/white"
            android:textSize="20dip" />
    </GridLayout>

</RelativeLayout>

Starting from API 21, the GridLayout now supports the weight like LinearLayout. For details please see the link below:

https://stackoverflow.com/a/31089200/1296944

Android Support V7 GridLayout library makes excess space distribution easy by accommodating the principle of weight. To make a column stretch, make sure the components inside it define a weight or a gravity. To prevent a column from stretching, ensure that one of the components in the column does not define a weight or a gravity. Remember to add dependency for this library. Add com.android.support:gridlayout-v7:25.0.1 in build.gradle.

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:columnCount="2"
app:rowCount="2">

<TextView
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:gravity="center"
    android:text="First"
    app:layout_columnWeight="1"
    app:layout_rowWeight="1" />

<TextView
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:gravity="center"
    android:text="Second"
    app:layout_columnWeight="1"
    app:layout_rowWeight="1" />

<TextView
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:gravity="center"
    android:text="Third"
    app:layout_columnWeight="1"
    app:layout_rowWeight="1" />

<TextView
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:gravity="center"        
    app:layout_columnWeight="1"
    app:layout_rowWeight="1"
    android:text="fourth"/>

</android.support.v7.widget.GridLayout>