How can I move a created Image in Slick2D?

Question

I want a image to follow the mouse, and I use Image class of Slick 2D:

public void init(GameContainer gameContainer, StateBasedGame stateBasedGame) throws SlickException {
    mouseImage = new Image("res/mouse.png");
}
public void render(GameContainer gameContainer, StateBasedGame stateBasedGame, Graphics  graphics) throws SlickException {
    mouseImage.draw(0,0,0.1f);
}

But it seems that it does not have method for re-positioning a Image object. So how can I implement it (in update method)? Thanks.

Answer 1

You need to create variables that determine the position of your image, make your render function use those variables as the position, and change those variables when you want to move your object.

Here's how you can do it:

private float x = 0;
private float y = 0;

public void init(GameContainer gameContainer, StateBasedGame stateBasedGame) throws SlickException {
    mouseImage = new Image("res/mouse.png");
}

public void render(GameContainer gameContainer, StateBasedGame stateBasedGame, Graphics  graphics) throws SlickException {
    mouseImage.draw(x,y,0.1f);
}

public void moveDown(float amount) {
    y += amount;
}

public void moveRight(float amount) {
    x += amount;
}

Answer 2

Haven't used Slick2D, but I guess you should just change the coordinates, maybe when rendering?

Answer 3

If you want it to be in update, you can use the setCenterX and setCenterY methods.

mouseImage.setCenterX(Mouse.getX());
mouseImage.setCenterY(Mouse.getY());

However Y coordinates are going to be reversed. If you want them to correspond to proper ones you can do:

mouseImage.setCenter(container.getInput().getMouseY());