www.pudn.com > src.rar > MoveFishCanvas.java
/*
* Copyright (c) 1996, 1997 Bill Venners. All Rights Reserved.
*
* This Java source file is part of the Interactive Illustrations Web
* Site, which is delivered in the applets directory of the CD-ROM
* that accompanies the book "Inside the Java Virtual Machine" by Bill
* Venners, published by McGraw-Hill, 1997,ISBN: 0-07-913248-0. This
* source file is provided for evaluation purposes only, but you can
* redistribute it under certain conditions, described in the full
* copyright notice below.
*
* Full Copyright Notice:
*
* All the web pages and Java applets delivered in the applets
* directory of the CD-ROM, consisting of ".html," ".gif," ".class,"
* and ".java" files, are copyrighted (c) 1996, 1997 by Bill
* Venners, and all rights are reserved. This material may be copied
* and placed on any commercial or non-commercial web server on any
* network (including the internet) provided that the following
* guidelines are followed:
*
* a. All the web pages and Java Applets (".html," ".gif," ".class,"
* and ".java" files), including the source code, that are delivered
* in the applets directory of the CD-ROM that
* accompanies the book must be published together on the same web
* site.
*
* b. All the web pages and Java Applets (".html," ".gif," ".class,"
* and ".java" files) must be published "as is" and may not be altered
* in any way.
*
* c. All use and access to this web site must be free, and no fees
* can be charged to view these materials, unless express written
* permission is obtained from Bill Venners.
*
* d. The web pages and Java Applets may not be distributed on any
* media, other than a web server on a network, and may not accompany
* any book or publication.
*
* BILL VENNERS MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE
* SUITABILITY OF THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING
* BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR PARTICULAR PURPOSE, OR NON-INFRINGEMENT. BILL VENNERS
* SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY A LICENSEE AS A
* RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES.
*/
import java.awt.*;
/**
* This class is the canvas that displays the user interface
* during the move fish sub-mode of the assign references mode.
* This class contains the code that handles the clicking and
* dragging that moves fish from one place to another.
*
* @author Bill Venners
*/
public class MoveFishCanvas extends AssignReferencesCanvas {
private boolean iconClicked = false;
private Point posOfMouseInsideIconWhenFirstPressed = new Point(0, 0);
private int objectIndexOfFishIconThatWasClicked;
private boolean dragging = false;
private Point currentMouseDragPosition = new Point(0, 0);
MoveFishCanvas(GCHeap heap, LocalVariables locVars, HeapOfFishTextArea ta) {
gcHeap = heap;
localVars = locVars;
controlPanelTextArea = ta;
}
public Dimension minimumSize() {
return new Dimension(500, 240);
}
public Dimension preferredSize() {
return new Dimension(500, 240);
}
public boolean mouseDown(Event evt, int x, int y) {
// Find out if the mouse went down inside an icon's hot area. Count down from the
// top of the heap list so that fish that are drawn later will be found first. This
// is because if two fish are overlapping, the one later in the array will be
// drawn second and appear to be on top. The top fish will be found first by this
// for loop.
for (int i = gcHeap.getHandlePoolSize() - 1; i >= 0; --i) {
ObjectHandle oh = gcHeap.getObjectHandle(i + 1);
if (!oh.free) {
Point o = oh.fish.getFishPosition();
if (x >= o.x && x < o.x + oh.fish.getFishWidth() && y >= o.y
&& y < o.y + oh.fish.getFishHeight()) {
iconClicked = true;
objectIndexOfFishIconThatWasClicked = i + 1;
posOfMouseInsideIconWhenFirstPressed.x = x - o.x;
posOfMouseInsideIconWhenFirstPressed.y = y - o.y;
//fishObjectThatWasClicked = oh;
break;
}
}
}
return true;
}
public boolean mouseUp(Event evt, int x, int y) {
if (iconClicked == false) {
return true;
}
iconClicked = false;
FishIcon fishIconThatWasClicked = gcHeap.getObjectHandle(objectIndexOfFishIconThatWasClicked).fish;
Color colorOfClickedFish = gcHeap.getObjectHandle(objectIndexOfFishIconThatWasClicked).fish.getFishColor();
if (dragging) {
dragging = false;
// Clear old drag icon.
Graphics g = getGraphics();
g.setColor(Color.blue);
g.setXORMode(colorOfClickedFish);
fishIconThatWasClicked.drawFishOutline(g, currentMouseDragPosition.x,
currentMouseDragPosition.y);
fishIconThatWasClicked.moveFish(currentMouseDragPosition.x,
currentMouseDragPosition.y);
repaint();
}
return true;
}
public boolean mouseDrag(Event evt, int x, int y) {
if (!iconClicked) {
return true;
}
FishIcon fishIconThatWasClicked = gcHeap.getObjectHandle(objectIndexOfFishIconThatWasClicked).fish;
Color colorOfClickedFish = gcHeap.getObjectHandle(objectIndexOfFishIconThatWasClicked).fish.getFishColor();
// Don't start dragging unless the mouse has moved a threshold number of
// pixels in x or y.
if (!dragging) {
int thresholdPixels = 5;
Point iconOrigin = fishIconThatWasClicked.getFishPosition();
int xOriginalClick = iconOrigin.x + posOfMouseInsideIconWhenFirstPressed.x;
int yOriginalClick = iconOrigin.y + posOfMouseInsideIconWhenFirstPressed.y;
int xDifference = x - xOriginalClick;
if (xDifference < 0) {
xDifference = 0 - xDifference;
}
int yDifference = y - yOriginalClick;
if (yDifference < 0) {
yDifference = 0 - yDifference;
}
if (xDifference < thresholdPixels && yDifference < thresholdPixels) {
return true;
}
}
Graphics g = getGraphics();
g.setColor(Color.blue);
g.setXORMode(colorOfClickedFish);
if (!dragging) {
dragging = true;
}
else {
// Clear old drag icon.
fishIconThatWasClicked.drawFishOutline(g, currentMouseDragPosition.x,
currentMouseDragPosition.y);
}
int xNew = x - posOfMouseInsideIconWhenFirstPressed.x;
int yNew = y - posOfMouseInsideIconWhenFirstPressed.y;
// Don't let any of the icon go off of either the left
// or the right side of the Component.
if (xNew < xFishAreaStart) {
xNew = xFishAreaStart;
}
else if (xNew + fishIconThatWasClicked.getFishWidth() - 1 > size().width) {
xNew = size().width - fishIconThatWasClicked.getFishWidth() - 1;
}
// Don't let any of the icon go off of either the top
// or the bottom side of the Component.
if (yNew < 0) {
yNew = 0;
}
else if (yNew + fishIconThatWasClicked.getFishHeight() - 1 > size().height) {
yNew = size().height - fishIconThatWasClicked.getFishHeight() - 1;
}
// Then draw the new outline around the icon
fishIconThatWasClicked.drawFishOutline(g, xNew, yNew);
currentMouseDragPosition.x = xNew;
currentMouseDragPosition.y = yNew;
g.setPaintMode();
return true;
}
}