Scrolls the given JComponent by its unit or block increment in the given direction (actually a scale factor, so use +1 or -1). - Java Swing

Java examples for Swing:JComponent

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Description

Scrolls the given JComponent by its unit or block increment in the given direction (actually a scale factor, so use +1 or -1).

Demo Code


//package com.java2s;

import javax.swing.*;

public class Main {
    /**//from  w w w.j a v  a  2 s.  c o m
     * Scrolls the given component by its unit or block increment in the given direction (actually a scale factor, so use +1 or -1).
     * Useful for implementing behavior like in Apple's Mail where page up/page down in the list cause scrolling in the text.
     */
    public static void scroll(JComponent c, boolean byBlock, int direction) {
        JScrollPane scrollPane = (JScrollPane) SwingUtilities
                .getAncestorOfClass(JScrollPane.class, c);
        JScrollBar scrollBar = scrollPane.getVerticalScrollBar();
        int increment = byBlock ? scrollBar.getBlockIncrement(direction)
                : scrollBar.getUnitIncrement(direction);
        int newValue = scrollBar.getValue() + direction * increment;
        newValue = Math.min(newValue, scrollBar.getMaximum());
        newValue = Math.max(newValue, scrollBar.getMinimum());
        scrollBar.setValue(newValue);
    }
}

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