https://github.com/mabe02/lanterna: Java library for creating text-based terminal GUIs
  • Martin Berglund 
/*
 * This file is part of lanterna (https://github.com/mabe02/lanterna).
 * 
 * lanterna is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * Copyright (C) 2010-2020 Martin Berglund
 */
package com.googlecode.lanterna.gui2;

import com.googlecode.lanterna.TerminalSize;

import java.util.List;


Window manager is a class that is plugged in to a WindowBasedTextGUI to manage the position and placement of windows. The window manager doesn't contain the list of windows so it normally does not need to maintain much state but it is passed all required objects as the window model changes. 
Author:Martin
See Also:
/**
 * Window manager is a class that is plugged in to a {@code WindowBasedTextGUI} to manage the position and placement
 * of windows. The window manager doesn't contain the list of windows so it normally does not need to maintain much
 * state but it is passed all required objects as the window model changes.
 * @see DefaultWindowManager
 * @author Martin
 */
public interface WindowManager {

    
Will be polled by the the WindowBasedTextGUI to see if the window manager believes an update is required. For example, it could be that there is no input, no events and none of the components are invalid, but the window manager decides for some other reason that the GUI needs to be updated, in that case you should return true here. Please note that returning false will not prevent updates from happening, it's just stating that the window manager isn't aware of some internal state change that would require an update. 
Returns:true if the window manager believes the GUI needs to be update, false otherwise
/**
     * Will be polled by the the {@link WindowBasedTextGUI} to see if the window manager believes an update is required.
     * For example, it could be that there is no input, no events and none of the components are invalid, but the window
     * manager decides for some other reason that the GUI needs to be updated, in that case you should return
     * {@code true} here. Please note that returning {@code false} will not prevent updates from happening, it's just
     * stating that the window manager isn't aware of some internal state change that would require an update.
     * @return {@code true} if the window manager believes the GUI needs to be update, {@code false} otherwise
     */
    boolean isInvalid();

    
Returns the WindowDecorationRenderer for a particular window 
Params:
  • window – Window to get the decoration renderer for
Returns:WindowDecorationRenderer for the window
/**
     * Returns the {@code WindowDecorationRenderer} for a particular window
     * @param window Window to get the decoration renderer for
     * @return {@code WindowDecorationRenderer} for the window
     */
    WindowDecorationRenderer getWindowDecorationRenderer(Window window);

    
Called whenever a window is added to the WindowBasedTextGUI. This gives the window manager an opportunity to setup internal state, if required, or decide on an initial position of the window 
Params:
  • textGUI – GUI that the window was added too
  • window – Window that was added
  • allWindows – All windows, including the new window, in the GUI
/**
     * Called whenever a window is added to the {@code WindowBasedTextGUI}. This gives the window manager an opportunity
     * to setup internal state, if required, or decide on an initial position of the window
     * @param textGUI GUI that the window was added too
     * @param window Window that was added
     * @param allWindows All windows, including the new window, in the GUI
     */
    void onAdded(WindowBasedTextGUI textGUI, Window window, List<Window> allWindows);

    
Called whenever a window is removed from a WindowBasedTextGUI. This gives the window manager an opportunity to clear internal state if needed. 
Params:
  • textGUI – GUI that the window was removed from
  • window – Window that was removed
  • allWindows – All windows, excluding the removed window, in the GUI
/**
     * Called whenever a window is removed from a {@code WindowBasedTextGUI}. This gives the window manager an
     * opportunity to clear internal state if needed.
     * @param textGUI GUI that the window was removed from
     * @param window Window that was removed
     * @param allWindows All windows, excluding the removed window, in the GUI
     */
    @SuppressWarnings("EmptyMethod")
    void onRemoved(WindowBasedTextGUI textGUI, Window window, List<Window> allWindows);

    
Called by the GUI system before iterating through all windows during the drawing process. The window manager should ensure the position and decorated size of all windows at this point by using Window.setPosition(..) and Window.setDecoratedSize(..). Be sure to inspect the window hints assigned to the window, in case you want to try to honour them. Use the getWindowDecorationRenderer(Window) method to get the currently assigned window decoration rendering class which can tell you the decorated size of a window given it's content size. 
Params:
  • textGUI – Text GUI that is about to draw the windows
  • allWindows – All windows that are going to be drawn, in the order they will be drawn
  • screenSize – Size of the terminal that is available to draw on
/**
     * Called by the GUI system before iterating through all windows during the drawing process. The window manager
     * should ensure the position and decorated size of all windows at this point by using
     * {@code Window.setPosition(..)} and {@code Window.setDecoratedSize(..)}. Be sure to inspect the window hints
     * assigned to the window, in case you want to try to honour them. Use the
     * {@link #getWindowDecorationRenderer(Window)} method to get the currently assigned window decoration rendering
     * class which can tell you the decorated size of a window given it's content size.
     *
     * @param textGUI Text GUI that is about to draw the windows
     * @param allWindows All windows that are going to be drawn, in the order they will be drawn
     * @param screenSize Size of the terminal that is available to draw on
     */
    void prepareWindows(WindowBasedTextGUI textGUI, List<Window> allWindows, TerminalSize screenSize);
}