/*
* 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 on which is drawn the images
* of the object and handle pools on the compact heap
* canvas. All of this drawing is done by the paint()
* method of this class.
*
* @author  Bill Venners
*/
public class CompactHeapCanvas extends Canvas {

    private GCHeap gcHeap;
    private final int poolImageInsets = 5;

    CompactHeapCanvas(GCHeap heap) {
        gcHeap = heap;
    }

    public void paint(Graphics g) {

        // First calculate the positions of the goodies on the canvas based on the width
        // and height of the canvas.
        Dimension dim = size();

        // Divide width into three equal portions. The left portion will hold the handle pool.
        // The right portion will hold the object pool. The middle portion will have arrows
        // that go from valid handles to their respective objects.
        int xHandlePoolPortion = 0;
        int xArrowPortion = dim.width / 3;
        int xObjectPoolPortion = 2 * xArrowPortion;

        Font font = getFont();
        FontMetrics fm = getFontMetrics(font);

        int labelHeight = fm.getAscent() + fm.getDescent() + (2 * poolImageInsets);

        int heightAvailableForPools = dim.height - labelHeight - poolImageInsets;
        int objectPoolIntsCount = gcHeap.getObjectPoolSize();
        int handlePoolIntsCount = gcHeap.getHandlePoolSize() * 2;

        int maxIntsCount = objectPoolIntsCount;
        if (maxIntsCount < handlePoolIntsCount) {
            maxIntsCount = handlePoolIntsCount;
        }

        int yPixelsPerInt = heightAvailableForPools / maxIntsCount;

        int handlePoolHeight = handlePoolIntsCount * yPixelsPerInt;
        int objectPoolHeight = objectPoolIntsCount * yPixelsPerInt;

        int poolsWidth = xArrowPortion - poolImageInsets;

        int xTextStart = poolsWidth - fm.stringWidth(HeapOfFishStrings.handlePool);
        if (xTextStart < 0) {
            xTextStart = 0;
        }
        xTextStart /= 2;

        int yStart = (dim.height - handlePoolHeight - labelHeight - (2 * poolImageInsets)) / 2;
        if (yStart < 0) {
            yStart = 0;
        }
        g.setColor(Color.white);
        g.drawString(HeapOfFishStrings.handlePool, poolImageInsets + xTextStart, poolImageInsets + yStart + fm.getAscent());
        int yHandlePoolRect = yStart + labelHeight;
        g.fillRect(xHandlePoolPortion + poolImageInsets, yHandlePoolRect, poolsWidth, handlePoolHeight);

        xTextStart = poolsWidth - fm.stringWidth(HeapOfFishStrings.objectPool);
        if (xTextStart < 0) {
            xTextStart = 0;
        }
        xTextStart /= 2;

        yStart = (dim.height - objectPoolHeight - labelHeight - (2 * poolImageInsets)) / 2;
        if (yStart < 0) {
            yStart = 0;
        }

        //g.setColor(Color.white);
        g.drawString(HeapOfFishStrings.objectPool, xObjectPoolPortion + xTextStart, poolImageInsets + yStart + fm.getAscent());
        int yObjectPoolRect = yStart + labelHeight;
        //g.setColor(Color.white);
        g.fillRect(xObjectPoolPortion, yObjectPoolRect, poolsWidth, objectPoolHeight);

        // Draw the headers in the object pool
        g.setColor(Color.black);
        int i = 0;
        while (i < objectPoolIntsCount) {

            for (int j = 0; j < yPixelsPerInt; ++j) {
                int yLinePos = yObjectPoolRect + (i * yPixelsPerInt) + j;
                g.drawLine(xObjectPoolPortion, yLinePos, xObjectPoolPortion + poolsWidth - 1, yLinePos);
            }
            int header = gcHeap.getObjectPool(i);
            int length = gcHeap.getMemBlockLength(header);
            if (length <= 0) { // In case object pool gets corrupted, don't hang up.
                break;
            }
            i += length;
        }

        for (i = 0; i < gcHeap.getHandlePoolSize(); ++i) {
            ObjectHandle oh = gcHeap.getObjectHandle(i + 1);
            if (!oh.free) {

                Color color = Color.red;
                int objectSizeInInts = 3;
                if (oh.fish.getFishColor() == Color.cyan) {
                    color = Color.cyan;
                    objectSizeInInts = 2;
                }
                else if (oh.fish.getFishColor() == Color.yellow) {
                    color = Color.yellow;
                    objectSizeInInts = 1;
                }
                g.setColor(color);

                // Draw bar across handle pool
                for (int j = 0; j < yPixelsPerInt * 2; ++j) {
                    int yLinePos = yHandlePoolRect + (i * yPixelsPerInt * 2) + j;
                    g.drawLine(xHandlePoolPortion + poolImageInsets, yLinePos, xHandlePoolPortion + poolImageInsets + poolsWidth - 1, yLinePos);
                }

                // Draw colored bars to represent object in the object pool
                for (int j = 0; j < yPixelsPerInt * objectSizeInInts; ++j) {
                    int yLinePos = yObjectPoolRect + (oh.objectPos * yPixelsPerInt) + j;
                    g.drawLine(xObjectPoolPortion, yLinePos, xObjectPoolPortion + poolsWidth - 1, yLinePos);
                }

                // Draw a line from the handle to the object to show that the handle
                // points to the object.
                int yArrowStart = yHandlePoolRect + (i * yPixelsPerInt * 2) + yPixelsPerInt;
                int yArrowEnd = yObjectPoolRect + (oh.objectPos * yPixelsPerInt) + ((yPixelsPerInt * objectSizeInInts) / 2);
                g.drawLine(xHandlePoolPortion + poolImageInsets + poolsWidth + 2, yArrowStart,
                    xObjectPoolPortion - 3, yArrowEnd);
            }
        }
    }
}