NextPage.java

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/*
 * InputHandler.java - Manages key bindings and executes actions
 * Copyright (C) 1999 Slava Pestov
 * Copyright (C) 2000-2023 The Gridarta Developers.
 *
 * You may use and modify this package for any purpose. Redistribution is
 * permitted, in both source and binary form, provided that this notice
 * remains intact in all source distributions of this package.
 */
 
package net.sf.gridarta.textedit.textarea.actions;
 
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import net.sf.gridarta.textedit.textarea.InputHandler;
import net.sf.gridarta.textedit.textarea.JEditTextArea;
 
public class NextPage implements ActionListener {
 
    private final boolean select;
 
    public NextPage(final boolean select) {
        this.select = select;
    }
 
    @Override
    public void actionPerformed(final ActionEvent e) {
        final JEditTextArea textArea = InputHandler.getTextArea(e);
        final int lineCount = textArea.getLineCount();
        int firstLine = textArea.getFirstLine();
        final int visibleLines = textArea.getVisibleLines();
        final int line = textArea.getCaretLine();
 
        firstLine += visibleLines;
 
        if (firstLine + visibleLines >= lineCount - 1) {
            firstLine = lineCount - visibleLines;
        }
 
        textArea.setFirstLine(firstLine);
 
        final int caret = textArea.getLineStartOffset(Math.min(textArea.getLineCount() - 1, line + visibleLines));
        if (select) {
            textArea.select(textArea.getMarkPosition(), caret);
        } else {
            textArea.setCaretPosition(caret);
        }
    }
 
}