I did an app that sets the wallpaper using several png images on timed intervals. The wallpaper size that is displayed on the screen is not correct an all devices. On a 9.7" tablet, the size is perfect which includes enough room to scroll it left and right. On a phone however, only a small portion of each image can be seen. It looks like it's zoomed in.
What coding do I need to tell Android to display the images in the correct size on all devices?
I was assuming the WallpaperManager did this but it seems I don't know how to use it yet.
Here is how I'm changing the wallpaper:
myWallpaperManager.setResource(R.drawable.muzdalifah);
Edit showing all code used for changing the wallpapers:
public class AlarmReceiverChangeImage extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
    /*
     * Make the settings available from the settings xml file.
     */
    SharedPreferences mySettings = PreferenceManager
            .getDefaultSharedPreferences(context);
    /*
     * Allow editing.
     */
    SharedPreferences.Editor editor = mySettings.edit();
    /*
     * Get the settings into variables.
     */
    boolean bln_checkbox_changing_is_activated = mySettings.getBoolean(
            "checkbox_changing_is_activated", false);
    String myCurrentImageName = mySettings.getString("current_image",
            "kabanight1");
    WallpaperManager myWallpaperManager = WallpaperManager
            .getInstance(context.getApplicationContext());
    if (bln_checkbox_changing_is_activated == true) {
        if (myCurrentImageName.equals("tentcity")) {
            try {
                myWallpaperManager.setResource(R.drawable.kabacloseup);
                myCurrentImageName = "kabacloseup";
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else if (myCurrentImageName.equals("kabacloseup")) {
            try {
                myWallpaperManager.setResource(R.drawable.kabanight1);
                myCurrentImageName = "kabanight1";
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else if (myCurrentImageName.equals("kabanight1")) {
            try {
                myWallpaperManager.setResource(R.drawable.madina1);
                myCurrentImageName = "madina1";
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else if (myCurrentImageName.equals("madina1")) {
            try {
                myWallpaperManager.setResource(R.drawable.madina2);
                myCurrentImageName = "madina2";
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else if (myCurrentImageName.equals("madina2")) {
            try {
                myWallpaperManager.setResource(R.drawable.kabaday1);
                myCurrentImageName = "kabaday1";
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else if (myCurrentImageName.equals("kabaday1")) {
            try {
                myWallpaperManager.setResource(R.drawable.uhud1);
                myCurrentImageName = "uhud1";
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else if (myCurrentImageName.equals("uhud1")) {
            try {
                myWallpaperManager.setResource(R.drawable.bus);
                myCurrentImageName = "bus";
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else if (myCurrentImageName.equals("bus")) {
            try {
                myWallpaperManager.setResource(R.drawable.muzdalifah);
                myCurrentImageName = "muzdalifah";
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else if (myCurrentImageName.equals("muzdalifah")) {
            try {
                myWallpaperManager.setResource(R.drawable.tentcity);
                myCurrentImageName = "tentcity";
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else {
            try {
                myWallpaperManager.setResource(R.drawable.madina1);
                myCurrentImageName = "madina1";
            } catch (IOException e) {
                e.printStackTrace();
            }
        } // End if myCurrentImageName.equals("kabaday1").
    } // End if bln_checkbox_changing_is_activated == true.
    editor.putString("current_image", myCurrentImageName); // value to store
    editor.commit();
} // End method onReceive.
				
                        
The rendering of your image depends on following:
Screen size
Screen density
Resolution
You should better read the below document completely to understand how you handle this situation: Supporting Multiple Screens