How do I specify width and height of Android GridLayout cells in relative measures?

Question

I'm trying to figure out how GridLayout works, but one thing I can't figure out from the documentation is how or if one can control the size of the grid cells.

Say I want a two by two grid where each cell occupy exactly 25% of the screen real estate (half height, half width) - can I do this?

With LinearLayout I would accomplish this by nesting two horizontal LinearLayout's in one vertical and then assigning a weight of 1 to all elements. GridLayout does not support the weight property though.

Answer 1

There's two properties android:layout_columnWeight and layout_rowWeight which works like layout_weight in LinearLayout. This is supported in API 21. For older android devices, use the GridLayout from the v7 support library.

Those properties will allow you to adjust the width/height of column base on the value you assigned to each column. The formula goes like this (column_weight/ sum_of_column_weight) * gridLayout_width = column_width.

Here's an example which is a gridview with 2 rows and 2 columns evenly spread out, each takes 50% of the weight and height of the grid.

<GridLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:columnCount="2"
>

    <TextView
        android:text="SEARCH FEE"
        android:layout_columnWeight="1"
        android:layout_rowWeight="1"
     />

    <TextView
        android:layout_columnWeight="1"
        android:text="SEARCH FEE"
        android:layout_rowWeight="1"
     />

    <TextView
        android:text="SEARCH FEE"
        android:layout_columnWeight="1"
        android:layout_rowWeight="1"
        />

    <TextView
        android:layout_columnWeight="1"
        android:text="SEARCH FEE"
        android:layout_rowWeight="1"
        />
</GridLayout>

Answer 2

it looks like setting it as you'd like should be fairly straightforward according to the documentation:

android:rowCount='2'
android:columnCount='2'

and in the children set

android:layout_columnSpan="1"
android:layout_rowSpan="1"

This reference also mentions stretching:

To prevent a column from stretching, ensure that one of the components in the column does not define a gravity.

Which would seem like a solution to keep the rows and columns in a 50:50 ratio without resizing according to content

Answer 3

It would be something like this:

<?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="1"
        app:layout_columnWeight="1"
        app:layout_rowWeight="1" />

    <TextView
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:gravity="center"
        android:text="2"
        app:layout_columnWeight="1"
        app:layout_rowWeight="1" />

    <TextView
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:gravity="center"
        android:text="3"
        app:layout_columnWeight="1"
        app:layout_rowWeight="1" />

    <TextView
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:gravity="center"
        android:text="4"
        app:layout_columnWeight="1"
        app:layout_rowWeight="1" />

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