io Programmo 9/IOPROG_9.ISO/contrib/iis4/iis4_07.cab/CoolHeadLines.java

Java Source | 1997-09-04 | 13.1 KB | 425 lines

////////////////////////////////////////////////////////////////////////////
// Implementatation of CoolHeadLines class
//
// The main applet.
//
// This is a part of the Internet Information Server SDK Samples
// Copyright (C) 1997 Microsoft Corporation
// All rights reserved.
//
// This source code is only intended as a supplement to the Software
// Development Kit Reference and related electronic documentation provided.
//
////////////////////////////////////////////////////////////////////////////

import java.applet.*;
import java.awt.*;
import java.util.*;
import java.net.*;
import TextJump;
import DoubleBuffer;

public class CoolHeadLines extends Applet implements Runnable
{
    // constants to gather data from <param> tags
    private final String    PARAM_BackColor = "BackColor";
    private final String    PARAM_TextColor = "TextColor";
    private final String    PARAM_HiliteTextColor = "HiliteTextColor";
    private final String    PARAM_ScrollDelay = "ScrollDelay";
    private final String    PARAM_MessageDelay = "MessageDelay";
    private final String    PARAM_NumItems = "NumItems";
    private final String    PARAM_URLPrefix = "URLPrefix";

    // data from <param> tags
    private Color            m_colBackColor;
    private Color            m_colTextColor;
    private Color            m_colHiliteTextColor;
    private int                m_iScrollDelay = 10;
    private int                m_iMessageDelay = 4;
    private int                m_iNumItems;
    private String            m_strURLPrefix;

    private Thread            m_CoolHeadLines = null;                // worker thread
    private Dimension        m_dimAppletSize;                    // size of the containing applet
    private Vector            m_vectData=null;                    // vector of TextJump objects
    private Font            m_font;                                // font to draw text with
    private FontMetrics        m_fm;                                // size of the font
    private int                m_iFontHeight;                        // maximum height of font
    private DoubleBuffer    m_buff=null;                        // off-screen buffer
    private boolean            m_fStoppedScrolling = false;        // has the image stopped scrolling (when true mouse-clicks are active)
    private int                m_iCurrentMessage = -1;                // what's the current message at the bottom of the screen?
    private int                m_iMaxMessage=0;                        // how many messages can the applet display at once?
    private int                m_iOldMessageSelected = -1;            // what was the last message the mouse moved over?
    private int                m_iOldMessageSelectedYOffset = -1;    // what was the last message location on screen?

    ////////////////////////////////////////////////////////////////////////////
    // ctor
    public CoolHeadLines()
    {
        // set some default colors
        m_colBackColor =       new Color(255,255,128);
        m_colTextColor =        new Color(0,0,0);
        m_colHiliteTextColor = new Color(255,0,0);
    }

    ////////////////////////////////////////////////////////////////////////////
    // getAppletInfo
    // info about this applet
    public String getAppletInfo()
    {
        return "Name: CoolHeadLines\r\n" +
               "Author: Michael Howard ([e-mail])\r\n" +
               "Created with Microsoft Visual J++ Version 1.1";
    }

    ////////////////////////////////////////////////////////////////////////////
    // getParameterInfo
    // <param> info
    public String[][] getParameterInfo()
    {
        String[][] info =
        {
            { PARAM_BackColor,            "String",    "Background Color" },
            { PARAM_TextColor,            "String",    "Text Color" },
            { PARAM_HiliteTextColor,    "String",    "Hilited Text Color" },
            { PARAM_ScrollDelay,        "int",        "msec delay between each scroll" },
            { PARAM_MessageDelay,        "int",        "sec delay between each message" },
            { PARAM_NumItems,            "int",        "Number of items" },
            { PARAM_URLPrefix,            "String",    "Prefix for all .htm or .asp files" },
        };

        return info;
    }

    ////////////////////////////////////////////////////////////////////////////
    // init
    // initialize the applet
    public void init()
    {
        String param;

        // background color
        param = getParameter(PARAM_BackColor);
        if (param != null)
            m_colBackColor = getColorFromRGB(param);

        // text color
        param = getParameter(PARAM_TextColor);
        if (param != null)
            m_colTextColor = getColorFromRGB(param);

        // high-lighted text color
        param = getParameter(PARAM_HiliteTextColor);
        if (param != null)
            m_colHiliteTextColor = getColorFromRGB(param);

        // scroll delay in msec
        param = getParameter(PARAM_ScrollDelay);
        if (param != null)
            m_iScrollDelay = Integer.parseInt(param);

        // pause between messages in seconds
        param = getParameter(PARAM_MessageDelay);
        if (param != null)
            m_iMessageDelay = Integer.parseInt(param);

        // number of items to be displayed
        param = getParameter(PARAM_NumItems);
        if (param != null)
            m_iNumItems = Integer.parseInt(param);

        // path for .htm and .asp files
        param = getParameter(PARAM_URLPrefix);
        if (param != null)
            m_strURLPrefix = param;

        // various vars
        m_dimAppletSize = size();
        m_font            = new Font("Helvetica",Font.PLAIN,12);
        m_fm            = getFontMetrics(m_font);
        m_iFontHeight    = m_fm.getMaxDescent() + m_fm.getLeading() + m_fm.getMaxAscent();
        Rectangle r        = new Rectangle(0,0,m_dimAppletSize.width,m_dimAppletSize.height + m_iFontHeight);
        m_buff            = new DoubleBuffer(this,r);

        // fill in the background of the off-screen buffer and the applet
        m_buff.getGraphics().setColor(m_colBackColor);
        m_buff.getGraphics().fillRect(r.x, r.y, r.width, r.height);
        setBackground(m_colBackColor);

        // maximum number of messages
        m_iMaxMessage = 1 +( m_dimAppletSize.height / m_iFontHeight);

        // get all the headlines from the <param> tags
        m_vectData = new Vector();
        for (int i=0; i<m_iNumItems; i++)
        {
            String strText = getParameter("Text"+i);
            String strURL = getParameter("URL"+i);
            m_vectData.addElement(new TextJump(strURL,strText));
        }
    }

    ////////////////////////////////////////////////////////////////////////////
    // getColorFromRGB
    // converts an RGB triplet (such as "255 255 255") to a Color object
    public Color getColorFromRGB(String strRGB)
    {
        StringTokenizer st  = new StringTokenizer(strRGB);
        int iRed   = Integer.parseInt(st.nextToken());
        int iGreen = Integer.parseInt(st.nextToken());
        int iBlue  = Integer.parseInt(st.nextToken());
        return new Color(iRed,iGreen,iBlue);
    }

    ////////////////////////////////////////////////////////////////////////////
    // start
    public void start()
    {
        if (m_CoolHeadLines == null)
        {
            m_CoolHeadLines = new Thread(this);
            m_CoolHeadLines.start();
        }
        else
        {
            // This is so we get a quick refresh when we move back to the homepage
            drawHeadlines();
        }
    }

    ////////////////////////////////////////////////////////////////////////////
    // stop
    public void stop()
    {
        if (m_CoolHeadLines != null)
        {
            m_CoolHeadLines.stop();
            m_CoolHeadLines = null;
        }
    }

    ////////////////////////////////////////////////////////////////////////////
    // run
    // most of the work is done here, essentially loops until the applet dies
    public void run()
    {
        while (true)
        {
            try
            {
                // the applet is about to scroll
                m_fStoppedScrolling = false;

                // there is no old message because we are about to
                // scroll which invalidates the last message
                m_iOldMessageSelected=-1;
                m_iOldMessageSelectedYOffset=-1;

                // re-draw the headlines
                drawHeadlines();

                // ok, we've stopped scrolling, we can now accept mouse input
                m_fStoppedScrolling = true;

                // ZZZzzzz...
                Thread.sleep(m_iMessageDelay * 1000);
            }
            catch (InterruptedException e)
            {
                stop();
            }
        }
    }

    ////////////////////////////////////////////////////////////////////////////
    // drawHeadlines
    // draws the headlines on the screen
    private void drawHeadlines()
    {
        // get the next message and loop round to message #0
        // if we reach the last message
        m_iCurrentMessage++;
        m_iCurrentMessage %= m_vectData.size();

        // if we are about to display the first message then clear the screen
        if (m_iCurrentMessage == 0)
            for (int i=0; i<m_iMaxMessage; i++)
                scrollOneLine();

        // write in the text in the off-screen buffer.
        // note the text is drawn BELOW the bottom of the applet so when it
        // gets scrolled it appears to rise from nowhere
        drawString(m_buff.getGraphics(),
                   m_iCurrentMessage,
                   0,
                   m_buff.getSize().height-m_fm.getDescent(),
                   m_colTextColor);

        // scroll one line
        scrollOneLine();
    }

    ////////////////////////////////////////////////////////////////////////////
    // drawString
    // draw a string at a given location and place a 'dot' at the start
    private void drawString(Graphics g,String str, int x, int y, Color col)
    {
        int iFontWidth = m_fm.charWidth('W');
        int iOvalWidth = Math.min(iFontWidth/2,m_iFontHeight/2);
        g.setFont(m_font);
        g.setColor(col);
        g.drawString(str,x + iFontWidth,y);
        g.fillOval(x + iOvalWidth/2,y-iOvalWidth-2,iOvalWidth,iOvalWidth);
    }

    ////////////////////////////////////////////////////////////////////////////
    // drawString
    // draw a string at a given location and place a 'dot' at the start
    // this version takes an index into the vector to get the string
    private void drawString(Graphics g,int iMsg, int x, int y, Color col)
    {
        drawString(g,getStringFromVector(iMsg),x,y,col);
    }

    ////////////////////////////////////////////////////////////////////////////
    // getStringFromVector
    // returns a string from the vector of TextJumps.
    private String getStringFromVector(int iIndex)
    {
        TextJump t = (TextJump)m_vectData.elementAt(iIndex);
        return (String)t.getString();
    }

    ////////////////////////////////////////////////////////////////////////////
    // scrollOneLine
    //
    private void scrollOneLine()
    {
        // smoothly draw the off-screen buffer
        for (int j=0; j < m_iFontHeight; j++)
        {
            getGraphics().drawImage(m_buff.getImage(),0,-j,this);
            try { Thread.sleep(m_iScrollDelay);}
            catch (InterruptedException e) { }
        }

        Graphics g = m_buff.getGraphics();

        // move image up one-line inside the off-screen buffer
        g.drawImage(m_buff.getImage(),0,-m_iFontHeight,this);

        // erase old text at bottom of image
        g.setColor(m_colBackColor);
        g.fillRect(0,
                   m_dimAppletSize.height,
                   m_dimAppletSize.width,
                   m_dimAppletSize.height+m_iFontHeight);
    }

    ////////////////////////////////////////////////////////////////////////////
    // getYOffset
    // based on a mouse y-location determine which text row we are on
    private int getYOffset(int y)
    {
        int iY = (m_dimAppletSize.height - y) / m_iFontHeight;
        return iY;
    }

    ////////////////////////////////////////////////////////////////////////////
    // mouseMove
    // highlights a row of text as we move over it
    public boolean mouseMove(Event evt, int x, int y)
    {
        // if the image is still scrolling then bail
        if (!m_fStoppedScrolling)
            return true;

        // get the message we must be over
        int iYOffset = getYOffset(y);
        int iWhichMsg = m_iCurrentMessage - iYOffset;

        // if we are still over the same message then don't do anything
        if (m_iOldMessageSelected == iWhichMsg)
            return true;

        // if there was an old message we were over then re-draw it in it's non-highlighted color
        if (m_iOldMessageSelected >= 0)
        {
            drawString(getGraphics(),
                       m_iOldMessageSelected,
                       0,
                       m_dimAppletSize.height - (m_iOldMessageSelectedYOffset * m_iFontHeight) - m_fm.getDescent() + 1,
                       m_colTextColor);

            if (iWhichMsg < 0)
                m_iOldMessageSelected=-1;
        }

        // if we are over a valid message then draw it in a highlighted color
        if (iWhichMsg >= 0)
        {
            // set the old message to be this message
            m_iOldMessageSelected = iWhichMsg;
            m_iOldMessageSelectedYOffset = iYOffset;

            drawString(getGraphics(),
                       iWhichMsg,
                       0,
                       m_dimAppletSize.height - (iYOffset * m_iFontHeight) - m_fm.getDescent() + 1,
                       m_colHiliteTextColor);
        }

        return true;
    }

    ////////////////////////////////////////////////////////////////////////////
    // mouseExit
    // if we move the mouse out of the applet and there was an old message
    // highlighted then redraw it as a non-highlighted message
    public boolean mouseExit(Event evt, int x, int y)
    {
        if (!m_fStoppedScrolling)
            return true;

        if (m_iOldMessageSelected >= 0)
        {
            drawString(getGraphics(),
                       m_iOldMessageSelected,
                       0,
                       m_dimAppletSize.height - (m_iOldMessageSelectedYOffset * m_iFontHeight) - m_fm.getDescent() + 1,
                       m_colTextColor);

            m_iOldMessageSelected=-1;
        }

        return true;
    }

    ////////////////////////////////////////////////////////////////////////////
    // mouseDown
    // user is interested in a message
    public boolean mouseDown(Event evt, int x, int y)
    {
        // if the image is still scrolling then bail
        if (!m_fStoppedScrolling)
            return true;

        // get the message we must be over
        int iYOffset = getYOffset(y);
        int iWhichMsg = m_iCurrentMessage - iYOffset;

        try
        {
            m_CoolHeadLines.suspend();

             // Build the url for the sample
            String strSampleURL = m_strURLPrefix + "/" + (((TextJump)m_vectData.elementAt(iWhichMsg)).getURL());
            showStatus(strSampleURL);
            getAppletContext().showDocument(new URL(strSampleURL));

        } catch(MalformedURLException e) { }

        return true;
    }
}