Slick2D-检测图像上的鼠标悬停

Question

I'm trying to detect when a mouse is hovering an image (Play Image) and when I'm clicking the mouse something happens.

I draw an image on the center of the screen and I don't know how to implement this on my own code:

    @Override
        public void init(GameContainer arg0, StateBasedGame arg1) throws SlickException {
            f = (float) (0.1 * Main_Activity.apg.getHeight() / 180);
            play = new Image("res/play_image.png");
            play_Original_Width = play.getWidth();
            play_Original_Height = play.getHeight();
            Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
            width = screenSize.getWidth();
            height = screenSize.getHeight();
        }

        @Override
        public void render(GameContainer arg0, StateBasedGame arg1, Graphics g) throws SlickException {

            play.draw(Main_Activity.apg.getWidth() / 2 - ((play_Original_Width * f) / 2),
                    Main_Activity.apg.getHeight() / 2 - ((play_Original_Height * f) / 2), f);

        }

@Override
    public void update(GameContainer gc, StateBasedGame sbg, int arg2) throws SlickException {
        int x = Mouse.getX();
        int y = Mouse.getY();

    }

apg:

apg = new AppGameContainer(new Main_Activity(game_Name));
            apg.setDisplayMode((int) width, (int) height, false);
            apg.setShowFPS(false);
            apg.start();

How can I manage to detect when the mouse is hovering the image (Play Image)?

Thanks in advanace.

Answer 1

You just have to test if your x value is between your Image X and Image X + image width, and same for your y value.

In your update method :

int x = Mouse.getX();
int y = Mouse.getY();
int playX = Main_Activity.apg.getWidth() / 2 - ((play_Original_Width * f) / 2);
int playY = Main_Activity.apg.getHeight() / 2 - ((play_Original_Height * f) / 2);

if (x > playX && x < playX+play_Original_Width && y > playY && y < playY + play_Original_Height) {
    // then your mouse coordinates are over your image.
}

Additional (use if useful to you):

In some personal code, I used to implement a ImageRectangle that inherits from Rectangle and contains an Image. With this behaviour I could use the method intersects to detect this over. And I prefer using a mouseListener to manage these mouse event.

public ImageRectangle extends Rectangle {
    Image play;
    public ImageRectangle(Image,x,y,f){...}
    public void init(...){...}
    public void render(...){this.image.draw();}
    public void update(...){...}
}

In your mouseMoved method :

Rectangle mousePosition = new Rectangle(x,y,1,1);
if(mousePosition.intersects(playImageRectangle)) {//do whatever you need}