如何使字体文本可点击？

Question

My game has 3 BitmapFont (later more) on screen. I Want to be able to touch the font and output it's string in the console so I know which one is pressed. I tried to create a rectangle but I was unable to get the string of the touched BitmapFont .

Here is my code to create BitmapFont :

public class simple  implements ApplicationListener {
    private OrthographicCamera camera;
    private SpriteBatch batch;
    BitmapFont font;
    GlyphLayout layout;
    String a1 = "aa";
    String a2 = "bb";
    String a3 = "cc";
    int a = 0;
    @Override
    public void create() {
      camera = new OrthographicCamera();
      camera.setToOrtho(false, 800, 480);
      batch = new SpriteBatch();
      layout = new GlyphLayout();
      font = new BitmapFont(Gdx.files.internal("arial-15.fnt"));
   }
   @Override
   public void render() {
      Gdx.gl.glClearColor(0, 0, 0.2f, 1);
      Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);    
      camera.update();
      batch.setProjectionMatrix(camera.combined);
      batch.begin();
      for (int i =1; i< 4;i++){ 
          layout.setText(font, "a"+i);
          font.draw(batch, layout,200+(15*i),200 );
      }
      batch.end();  
  }

Answer 1

You want to have combined functionality of String, BitmapFont, Layout and positioning. The best way is to create a class for this clickable font that contains all that we need. I did some work for you since I am a nice guy and I actually have plenty of other things to do :D.

public class ClickableFont {

//Declare the fields
private GlyphLayout layout;
private BitmapFont font;

private String text;

private int posX;
private int posY;

/**
 * Constructs clickable text from a font
 * @param text Text to display
 * @param posX X position of the text
 * @param posY Y position of the text
 */
public ClickableFont(String text, int posX, int posY) {
    this.text = text;
    this.posX = posX;
    this.posY = posY;

    font = new BitmapFont(Gdx.files.internal("arial-15.fnt"));
    layout = new GlyphLayout(font, text);

}

/**
 * @param batch Draws the text using the given SpriteBatch.
 * @param camera Requires a camera to calculate touches between screen and world.
 */
public void update(SpriteBatch batch, OrthographicCamera camera)
{
    checkClicked(camera);

    font.draw(batch, layout, posX, posY);
}

/**
 * Checks if this object is clicked and outputs to console
 * @param camera the camera
 */
private void checkClicked(OrthographicCamera camera)
{
    if (Gdx.input.justTouched())
    {
        //Get screen coordinates
        Vector3 touch = new Vector3(Gdx.input.getX(), Gdx.input.getY(), 0);
        //Transform screen touch to world coordinates using the camera you are drawing with
        camera.unproject(touch);

        //System.out.println(getRectangle());
        //System.out.println(touch);

        if (getRectangle().contains(touch.x, touch.y))
        {
            System.out.println(text + " has been clicked.");
        }
    }
}

/**
 * Creates a rectangle for the sprite to perform collision calculations.
 * Since it seems font.draw draws from top to bottom (coordinate system of LibGDX is not consistent)
 * We have to adept the rectangle position Y position
 * @return rectangle of font bounds
 */
private Rectangle getRectangle()
{
    return new Rectangle(posX, posY - (int)layout.height, (int)layout.width, (int)layout.height);
}
}

As you can see it tackles your problem in steps. Tackling problems is all you are doing in programming. A rule of thumb is to never make a method more then 10 lines, excluding comments. Exceptions can be made but any large method can be broken down into much more readable smaller methods.

Now how to use this ClickableFont class?

    public class simple  implements ApplicationListener {
    private OrthographicCamera camera;
    private SpriteBatch batch;
    //folowing are not nececary anymore since it's handled by the new class
    //BitmapFont font; 
    //GlyphLayout layout; 
    //String a1 = "aa";
    //String a2 = "bb";
    //String a3 = "cc";

    int a = 0;

    //Declare a list to hold your clickable fonts
    List<ClickableFont> clickableFonts = new ArrayList<ClickableFont>();

    @Override
    public void create() {
      camera = new OrthographicCamera();
      camera.setToOrtho(false, 800, 480);
      batch = new SpriteBatch();

    //Add clickable fonts to the list
      clickableFonts.add(new ClickableFont("aa", 200, 200));
      clickableFonts.add(new ClickableFont("bb", 200 + 150, 200));
      clickableFonts.add(new ClickableFont("cc", 200 + 150 * 2, 200));
   }

   @Override
   public void render() {
      Gdx.gl.glClearColor(0, 0, 0.2f, 1);
      Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);    
      camera.update();
      batch.setProjectionMatrix(camera.combined);
      batch.begin();
      /* replace your loop
      for (int i =1; i< 4;i++){ 
          layout.setText(font, "a"+i);
          font.draw(batch, layout,200+(15*i),200 );
      }*/
      for (ClickableFont font : clickableFonts)
      {
          font.update(batch, camera);
      }
      batch.end();  
  }