Java JScrollBar scrollByUnits(JScrollBar scrollbar, int direction, int units, boolean limitToBlock)

Description

scroll By Units

License

Apache License

Declaration

public static void scrollByUnits(JScrollBar scrollbar, int direction, int units, boolean limitToBlock) 

Method Source Code

//package com.java2s;
/*//w w  w . jav  a2s  .c o m
 * Copyright 2014 kohii.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

import javax.swing.JScrollBar;

public class Main {
    public static void scrollByUnits(JScrollBar scrollbar, int direction, int units, boolean limitToBlock) {
        // This method is called from BasicScrollPaneUI to implement wheel
        // scrolling, as well as from scrollByUnit().
        int delta;
        int limit = -1;

        if (limitToBlock) {
            if (direction < 0) {
                limit = scrollbar.getValue() - scrollbar.getBlockIncrement(direction);
            } else {
                limit = scrollbar.getValue() + scrollbar.getBlockIncrement(direction);
            }
        }

        for (int i = 0; i < units; i++) {
            if (direction > 0) {
                delta = scrollbar.getUnitIncrement(direction);
            } else {
                delta = -scrollbar.getUnitIncrement(direction);
            }

            int oldValue = scrollbar.getValue();
            int newValue = oldValue + delta;

            // Check for overflow.
            if (delta > 0 && newValue < oldValue) {
                newValue = scrollbar.getMaximum();
            } else if (delta < 0 && newValue > oldValue) {
                newValue = scrollbar.getMinimum();
            }
            if (oldValue == newValue) {
                break;
            }

            if (limitToBlock && i > 0) {
                assert limit != -1;
                if ((direction < 0 && newValue < limit) || (direction > 0 && newValue > limit)) {
                    break;
                }
            }
            scrollbar.setValue(newValue);
        }
    }
}

Related

1. isPaintRequiredFor(javax.swing.JScrollBar jScrollBar)
2. scrollByBlock(JScrollBar scrollbar, int direction)