avl42
commented
6 years ago My observation is that for an Interactable to get initially focused it must already have been added to the structure of (maybe nested) Panels before the main Panel is set as the Component for the Window. Later adding of further components will not automatically set focus.
I have rearranged and modified your code:
package com.googlecode.lanterna.issue;
import com.googlecode.lanterna.gui2.*;
import com.googlecode.lanterna.screen.*;
import com.googlecode.lanterna.terminal.*;
public class Issue360 {
public static void main(String[] args) {
try {
Terminal terminal = new DefaultTerminalFactory().createTerminal();
Screen screen = new TerminalScreen(terminal);
screen.startScreen();
MultiWindowTextGUI gui = new MultiWindowTextGUI(screen);
Window window = new BasicWindow();
Button button1 = new Button("Button 1");
Panel panel = new Panel(new GridLayout(2));
panel.addComponent(button1);
window.setComponent(panel);
gui.addWindow(window);
gui.updateScreen(); // shows focused Button 1
Thread.sleep(1000);
panel.removeComponent(button1);
gui.updateScreen(); // shows empty Window
Thread.sleep(1000);
Button button2 = new Button("Button 2");
panel.addComponent(button2);
gui.updateScreen(); // shows non-focused Button 2
Thread.sleep(1000);
// mainly for demonstration purpose:
window.setComponent(null); // don't let a draw() happen while null ...
window.setComponent(panel);
// alternatively, you can ask the Panel for any focusable child components:
//window.setFocusedInteractable(panel.nextFocus(null));
// (that's what window.setComponent() does, when called with a Container like a Panel.)
gui.updateScreen(); // now shows focused Button 2
Thread.sleep(1000);
System.exit(0);
} catch (Exception e) {
e.printStackTrace();
}
}
}
mabe02
xazap
Hi,
I ran into an issue where I am unable to get focus or keyboard navigation when adding buttons to a Panel after calling removeAllComponents on that same Panel. The code below reproduces this with Lanterna 3.0.0.
The use-case for this is where my (MVC) controller updates a view implemented with Lanterna. I remove all components from a panel and then initialize all components again with updated model values.
Experimenting a bit, I found that calling setFocusedInteractable on the Window that contains the panel sets focus. This is a very expensive workaround as it would require me to keep track of which interactable component had focus before calling removeAllComponents. The component having focus is usually some other panel that may even be in some other window.
I observed this: When I add buttons to a panel the first time, the first button automatically gets focus. When you clear all components and add another set of buttons, none of them get focus. Even worse: interactable components on other panels also have no focus, resulting in a stuck GUI. Is this a bug?