Change game from portrait to landscape dynamically

问题:

I have multiple classes that implement Screen.

I want to, say, have the Main Menu screen portrait, then the Play Screen landscape. Is there anyway of changing the orientation dynamically?

I thought I could just start another Activity and have the Play Screen extend Game. And the new Activity would intialize the Play Screen. But it appears that you can't call startActivity or the like, obviously, as LibGDX is platform independent.

I use Gdx.graphics.getWidth() and Gdx.graphics.getHeight() to align Sprites and Actors, so it looks "right" on different devices.

I've also tried swapping the Gdx.graphics.getWidth() and Gdx.graphics.getHeight(), respectively, but can't seem to get the position of sprites and actors correct.

Also, in my manifest I have orientation="landscape".

Here are some images that should make more sense.

So this is my Main Menu in landscape:

And this is my Main Menu in portrait:

The position and size of Actors and Sprites are all based on Gdx.graphics.getWidth() and Gdx.graphics.getHeight(). The only thing that changes between the two images is orientation="landscape" and orientation="portrait" in my manifest.

Now I want my Main Menu in portrait but the Play Screen, where the game is on, should be in landscape.

I initially started working on the Play Screen and the sizes and positions where set based on orientation="landscape", and now that I am working on the Main Menu it is based on orientation="portrait". Hence why I want to change the orientation dynamically.

回答1:

You should not have multiple Activities. To learn how to switch the orientation programmatically you can have a look at this link.

As you said, LibGDX is platform-independent. That's why you cannot access your Android-Activity from your "core" code. To learn how to workaround that, have a look at Interfacing with platform specific code.

When you call your interface to change the orientation from your game when doing a Screen transition, LibGDX will automatically call resize(width, height) with the new values and you can align your Stage and so on according to the new values.

回答2:

This is a good question :) I develop noone's answer (which is correct)

How to set lanscape screen with Android sdk specific classes ?

And how to import android classes in a libgdx project ?

First of all note that Android classes can only be imported in the android project and not in the core. So there we save the Activity in a platform dependant object. Here is my AndroidLauncher:

import android.os.Bundle;

import com.badlogic.gdx.backends.android.AndroidApplication;
import com.badlogic.gdx.backends.android.AndroidApplicationConfiguration;
import com.mygdx.game.MyGdxGame;
import com.mygdx.game.util.Platform;

public class AndroidLauncher extends AndroidApplication {
    @Override
    protected void onCreate (Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        AndroidApplicationConfiguration cfg = new AndroidApplicationConfiguration();
        PlatformAndroid platform = new PlatformAndroid();
        platform.setActivity(this);
        initialize(new MyGdxGame((Platform) platform ), cfg);
}

}

PlatformAndroid implements Platform. These two classes are made to access platform specific objects. Let's look at them :

public interface Platform {
   public void SetOrientation(String string);
}

and

package com.mygdx.game.android;
import android.app.Activity;
import android.content.pm.ActivityInfo;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.backends.android.AndroidApplication;
import com.mygdx.game.util.Platform;

public class PlatformAndroid extends AndroidApplication implements Platform {
    private Activity activity;
    @Override
    public void SetOrientation(String string) {
       if (string == "landscape"){
       activity.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
       }
    }
    public void setActivity(Activity activity){ this.activity = activity;   }
}  

You can also create a PLatformDesktop called by the desktop launcher. Anyway, keep the platform variable in your classes and when you want to set the screen to landscape just call:

 platform.SetOrientation("landscape");

回答3:

I had the same problem and this solved it:

@Override
public void resize(int width, int height) {
    stage.getViewport().setScreenSize(width, height);
}

For some reason, even though the screen resolution changed, the stage didn't know that. So I've told it to the stage.

回答4:

Just create a interface in core project and and declare a method with any name than implement that interface in your AndroidLauncher class. Give definition of your method.

For me GameOrien.java is interface having method declaration

public interface GameOrien {

    public static final int PORTRAIT=1;

    public static final int LANDSCAPE=2;

    void setOrientation(int orientation);
}

In AndroidLauncher.java class which is in Android project.

public class AndroidLauncher extends AndroidApplication implements GameOrien {

**...**

    @Override
    public void setOrientation(int orientation) {

        if(orientation==PORTRAIT)
            setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        else if(orientation==LANDSCAPE)
            setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
    }

}

When you want to change orientation for GamePlay just call setOrientaion() method of interface. Your orientation changed.