Question

How can you ensure a good GPS signal is found before allowing a button click which starts logging GPS locations?

Answer 1

Well, if you use the LocationManager-class and act upon the onLocationChanged(), it won’t actually trigger until it’s gotten a position.

Edit: Here’s something you can try out.
Edit#2: D’oh, I actually misread the question. I’ll leave my response though.

.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
>
  <Button android:id="@+id/mybutton1"
      android:visibility="INVISIBLE"
      android:layout_width="200dp"
      android:layout_height="100dp"
      android:text="MyButton1"
  />
</LinearLayout>

.java:

//Get the LocationManager & Button
final LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
final Button button = (Button) findViewById(R.id.mybutton1);

//Add the listener
LocationListener locationListener = new LocationListener() {

    public void onLocationChanged(Location location) {

        //Remove the listener and make the button visible        
        locManager.removeUpdates(locationListener);
        button.setVisibility(1);
    }

    public void onStatusChanged(String provider, int status, Bundle extras) {}
    public void onProviderEnabled(String provider) {}
    public void onProviderDisabled(String provider) {}
};

locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);

Let me know if this works out for you!