Java tutorial
/* * Copyright (c) 1995, 2008, Oracle and/or its affiliates. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * - Neither the name of Oracle or the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ package misc; import java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.border.*; /* ScrollablePicture.java is used by AccessibleScrollDemo.java. */ public class ScrollablePicture extends JLabel implements Scrollable { private int maxUnitIncrement = 1; private boolean missingPicture = false; public ScrollablePicture(ImageIcon i, int m) { super(i); if (i == null) { missingPicture = true; setText("No picture found."); setHorizontalAlignment(CENTER); setOpaque(true); setBackground(Color.white); } maxUnitIncrement = m; } public Dimension getPreferredSize() { if (missingPicture) { return new Dimension(320, 480); } else { return super.getPreferredSize(); } } public Dimension getPreferredScrollableViewportSize() { return getPreferredSize(); } public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) { //Get the current position. int currentPosition = 0; if (orientation == SwingConstants.HORIZONTAL) { currentPosition = visibleRect.x; } else { currentPosition = visibleRect.y; } //Return the number of pixels between currentPosition //and the nearest tick mark in the indicated direction. if (direction < 0) { int newPosition = currentPosition - (currentPosition / maxUnitIncrement) * maxUnitIncrement; return (newPosition == 0) ? maxUnitIncrement : newPosition; } else { return ((currentPosition / maxUnitIncrement) + 1) * maxUnitIncrement - currentPosition; } } public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) { if (orientation == SwingConstants.HORIZONTAL) { return visibleRect.width - maxUnitIncrement; } else { return visibleRect.height - maxUnitIncrement; } } public boolean getScrollableTracksViewportWidth() { return false; } public boolean getScrollableTracksViewportHeight() { return false; } public void setMaxUnitIncrement(int pixels) { maxUnitIncrement = pixels; } }