I've been browsing the entire internet, but I could not find any answer to this question. I want to create a background, some image buttons, along with a bunch of moving graphics (circles). Since I do not know how to overwrite a xml layout with moving graphics, I chose to customly create my view, draw the background, the imageButtons and the circles (2D graphics).
public class GameView extends View implements UtilConstants
since I extended the View class, I had to call the super class constructor in my constructor
GameView(Context context) {
super(context);
this.context = context;
this.paint = new Paint();
}
and to implement the onDraw method, which acts like the java paintComponent
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas); // necessary for some reason
setGridBackground(); // sets the background
paint.setColor(Color.parseColor("#FF0000"));
canvas.drawCircle(this.x += 10, 300, 20, paint); //moves my graphics (ball) within the screen
drawScoreInLeftUpperCorner(canvas, 20); // paints a string text on the screen
setAbilitiesImages(); // places some imageButtons
try {
Thread.sleep(THREAD_REFRESH_RATE_MS);
} catch (InterruptedException ex) {
System.out.println(ex);
}
invalidate();
}
Now, to get to my problem: I do not know how to set those ImageButtons !!! I am trying
private void setAbilititesImages() {
ImageButton imageButton = new ImageButton(this.context); // is this ok to put the argument this.context??
imageButton.setLayoutParams(new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));
imageButton.setImageResource(R.drawable.monster); // set my resource
RelativeLayout relativeLayout = findViewById(R.id.in_game_layout); // what is the purpose of this???
if (relativeLayout != null) { // it never enters this if, relativeLayout is always null
relativeLayout.addView(imageButton);
}
}
Aaaaand the image button never shows up...why is it necessary to use Relative/Linear layouts? That R.id.in_game_layout I created is just an empty RelativeLayout xml. Can't I just use something like
imageButton.setImageResource(R.drawable.monster); // set my resource
imageButton.setBounds(.....);
(View)this.add(imageButton); ???
ImageButton requires a parent view to be hosted in it. The parent View can be a RelativeLayout, a linearlayout or a ConstraintLayout.
In your case, the instance relativeLayout is always null because you not specify the view parent in which you do findViewById.
You should make something like :
RelativeLayout relativeLayout = view.findViewById(R.id.in_game_layout);
You need to add layout param to your parent Relative layout also to display your Image button appropriately.
Example
RelativeLayout relativeLayout = findViewById(R.id.relativeLayout);
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
ImageButton imageButton = new ImageButton(this);
imageButton.setImageDrawable(getResources().getDrawable(R.drawable.ic_launcher_background,null));
relativeLayout.addView(imageButton,params);
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