DETECT THE SCREEN SIZE

This recipe will show how to detect the screen size of a device, in density-

independent pixels.

Sample Code:Sample Code:Sample Code:Sample Code:

[DetectScreenSize.zip]

Related Xamarin Documentation:Related Xamarin Documentation:Related Xamarin Documentation:Related Xamarin Documentation:

Creating Resources for Varying Screens

Related Related Related Related GoogleGoogleGoogleGoogle Documentation:Documentation:Documentation:Documentation:

Supporting Multiple Screens

DisplayMetrics

Recipe

1. Create a new Mono for Android application named ScreenSize.

2. Edit Main.axml so that it contains two TextViews:

<?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">

<TextView

android:text="Screen Width:"

android:textAppearance="?android:attr/textAppearanceLarge"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:id="@+id/screenWidthDp" />

<TextView

android:text="Screen Height:"

android:textAppearance="?android:attr/textAppearanceLarge"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:id="@+id/screenHeightDp" />

</LinearLayout>

3. Edit Activity1.cs, change the code in OnCreate to the following:

protected override void OnCreate(Bundle bundle)

{

base.OnCreate(bundle);

SetContentView(Resource.Layout.Main);

var metrics = Resources.DisplayMetrics;

var widthInDp = ConvertPixelsToDp(metrics.WidthPixels);

var heightInDp = ConvertPixelsToDp(metrics.HeightPixels);

FindViewById<TextView>(Resource.Id.screenWidthDp).Text = "Screen

Width: " + widthInDp + " dp.";

FindViewById<TextView>(Resource.Id.screenHeightDp).Text = "Screen

Height: " + heightInDp + " dp.";

}

4. After OnCreate, add the following helper to:

private int ConvertPixelsToDp(float pixelValue)

{

var dp = (int) ((pixelValue)/Resources.DisplayMetrics.Density);

return dp;

}

5. Run the application. Depending on the device, it will display the screen height and width. The following screen shot is from a Galaxy Nexus:

Additional Information

The structure DisplayMetrics contains general information about a device’s

display. DisplayMetrics.Width and DisplayMetrics.Height will return the width

and height of a screen in pixels. The appearance of a user interface is influenced

by not only by the resolution in pixels, but the physical screen size and the density

of the pixels. To help deal with this complexity, Android has a virtual unit of

measurement called density-independent pixels (dp). Using density-independent pixels allows an Android application to render elements of the UI so that they

appear the same on all screens.

DisplayMetrics.Density is a scaling factor that can be used to convert from

pixels to density-independent pixels.