Scaling up viewport - libgdx

Question

My game is 200 x 320 pixels and I want to scale this up to fit any screen. The problem is I need to scale this up in integer multiples of these dimensions so the upscaled pixels don't look uneven.
What should I put in my constructor, render() and resize() methods to achieve this?
In the constructor I now have:
camera = new OrthographicCamera();
camera.setToOrtho(false,200,320);
stage = new Stage(new ScalingViewport(Scaling.fill,200,320, camera));
In render():
camera.update();
game.batch.setProjectionMatrix(camera.combined);
And in resize():
int widthScale = width/200;
int heightScale = height/320;
int newScale = Math.max(widthScale, heightScale);
int multiplesWidth = newScale*200;
int multiplesHeight = newScale*320;
stage.getViewport().update(multiplesWidth, multiplesHeight, true);
camera.setToOrtho(false, 200, 320);
My problem is that the content isn't centered. How and where can I center whatever is on the screen? I tried with:
camera.position.set(Gdx.graphics.getWidth()/2f, Gdx.graphics.getHeight()/2f, 0);
but the screen is blank!

Answer 1

I think the problem is that you are trying to center the screen using the screen dimensions and not the world dimensions.
Try replacing
camera.position.set(Gdx.graphics.getWidth()/2f, Gdx.graphics.getHeight()/2f, 0);
with
camera.position.set(stage.getViewport().getWorldWidth()/2f, stage.getViewport().getWorldHeight()/2f, 0);
EDIT:
Okay, so here is an explanation why I proposed you set the camera to (width/2, height/2). (I will leave out the third z-Coordinate from now on as it will always be 0.)
camera.position.set() sets the center point of the camera. At (0,0) the camera is positioned right at the center of the screen, depicted by the red rectangle below. What libgdx does by default, and what I proposed offsets the camera by width/2(the blue line) and height/2(the green line) which translates to the magenta rectangle.
Side note: the reason camera.position.set(Gdx.graphics.getWidth()/2f, Gdx.graphics.getHeight()/2f, 0); didn't work is because Gdx.graphics.getX() returns the width and height of the window in pixels, not in the measurement system the Viewport uses. This offsets the camera about a meter up and to the right, where you obviously didn't draw anything.
If you want the red rectangle as camera, you can change the last argument of
stage.getViewport().update(multiplesWidth, multiplesHeight, true);
to false. Or use camera.position.set(0,0,0);