libgdx background Image change

android, libgdx, scene2d

Solution

`Image` is a subclass of `Actor`. The main difference is, that `Image` has a `Drawable` inside. This `Drawable` gets drawn if you call `stage.draw()`, which calls the `draw()` of `Image`. Instead of changing `Image` you can change the `Drawable` by using `setDrawable(Drawable param);`. What is a `Drawable`? It is any class, which implements the `Drawable` interface, for example the `TextureRegionDrawable`. If you are using `TextureRegion`s you can use this constructor: `TextureRegionDrawable(TextureRegion region);`. Maybe it would be better to store your background images in a `Drawable` Array so you don't have to call a construcor each time you set a new `Drawable`. Example code:

TextureRegionDrawable[] images = new TextureRegionDrawable[12];
for (int i = 0; i<12; i++) {
    images[i] = new TextureRegionDrawable(Assets.instance.textureRegions[i]);
}

Then in your render:

if(changeBackground) {
   counter -= delta;
   if (counter < 0) {
       counter = refreshtime
       background.setDrawable(images[(int)(Math.random()*12)]);
   }
}

This should work

Problem

I want to change background image of a menu every x-amount of seconds. I'm using libGDX scene2D.ui for making the menu. The TestScreen class extends the AbstractScreen which is a abstract class that implements libGDX's Screen class. Problem: After I load the Image to the stage through a Table object on a stack, changing the image reference to a different image does nothing. Stage.draw() gives no cares as if it made a copy of my original image. I would like to keep the background as Image class and render through stage.draw(). To further complicate things, if I do change the image to another in render() method, then image.setVisible(false) also stops working. ``` public class TestScreen extends AbstractScreen { private Stage stage; private Image background; private boolean ChangeBackground = true; private final float refreshTime = 2.0f; // refresh to new image every 2 seconds. private float counter = refreshTime; public TestScreen(Game game) { super(game); } @Override public void render(float deltaTime) { Gdx.gl.glClearColor(0.0f, 0.0f, 0.0f, 1.0f); Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT); if(ChangeBackground){ counter -= deltaTime; if(counter < 0){ counter = refreshTime; // Assets class has the 12 images loaded as "Image" objects already. // I simple want to change the reference to other (already loaded in memory images) ... // and make stage render the new image. background = Assets.instance.wallpapers[(int) (Math.random()*12)]; // The image should change. //background.setVisible(false); } } stage.act(deltaTime); stage.draw(); } @Override public void resize(int width, int height) { stage.setViewport(Constants.VIEWPORT_GUI_WIDTH, Constants.VIEWPORT_GUI_HEIGHT, false); } @Override public void show() { stage = new Stage(); Gdx.input.setInputProcessor(stage); makeStage(); } @Override public void hide() { stage.dispose(); } @Override public void pause() { } // Builds the Background later and adds it to a stage through a stack. // This is how it's done in my game. I made this test bench to demonstrate. private void makeStage() { Table BackGroundLayer = new Table(); background = Assets.instance.wallpapers[(int) (Math.random()*12)]; BackGroundLayer.add(background); Stack layers = new Stack(); layers.setSize(800, 480); layers.add(BackGroundLayer); stage.clear(); stage.addActor(layers); } ``` }

Original source