| [ java ] in KIDS 글 쓴 이(By): cesung ( 사 기 ) 날 짜 (Date): 1997년11월09일(일) 19시24분31초 ROK 제 목(Title): Re: [질문] repaint()....... doublu buffering과 thread를 같이 써야 하는것 같은데요... 예제 소스 하나를 올립니다... 얼마전 SDS에서 java교육받을때 사용한 예제 입니다.. "TickerTape"...... /* * @(#)TickerTape.java 1.0 96/05/07 Tom McGinn * * Copyright (c) 1996 Sun Microsystems, Inc. All Rights Reserved. * * SUN 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 A * PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES. * * THIS SOFTWARE IS NOT DESIGNED OR INTENDED FOR USE OR RESALE AS ON-LINE * CONTROL EQUIPMENT IN HAZARDOUS ENVIRONMENTS REQUIRING FAIL-SAFE * PERFORMANCE, SUCH AS IN THE OPERATION OF NUCLEAR FACILITIES, AIRCRAFT * NAVIGATION OR COMMUNICATION SYSTEMS, AIR TRAFFIC CONTROL, DIRECT LIFE * SUPPORT MACHINES, OR WEAPONS SYSTEMS, IN WHICH THE FAILURE OF THE * SOFTWARE COULD LEAD DIRECTLY TO DEATH, PERSONAL INJURY, OR SEVERE * PHYSICAL OR ENVIRONMENTAL DAMAGE ("HIGH RISK ACTIVITIES"). SUN * SPECIFICALLY DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR * HIGH RISK ACTIVITIES. */ // package something; import java.awt.*; import java.applet.*; import java.io.*; import java.net.*; import TickerReader; // TickerTape class // This class borrows heavily from Ticker class applet in // "Java by example", Jackson & McClellan, SunSoft Press, 1996. // public class TickerTape extends Canvas implements Runnable { char currChar; int strIndex = 0; String tape; // Keep arrays of the current symbols and their current price String symbols[]; float currPrices[]; // Constants. private static final int TEXTMARGIN = 3; private static final int RECTMARGIN = 1; private static final int SCROLLPAUSE = 15; private static final int TICKERHOSTPORT = 5432; private Thread scrollThread; // Thread that scrolls the text. private Image offscreenImage = null; // The offscreen image we write // text into before displaying it. private Font textFont; // The displayed font. private int tapeIndex; // The current index into the text. private int totalTapeSteps; // The number of steps required to // to traverse a complete scroll. private int textWidth; // The width of the text in pixels. private int textHeight; // The height of the text in pixels. private int textDescent; // How far the text goes below the // font's baseline in pixels. private int previousWidth = -1; // How wide the Ticker was the last // time we drew it. FontMetrics metrics; // The ticker object, which manages the connection to the ticker // port and the display of the information TickerReader tickerHost; // Constructor public TickerTape (String hostname, int width) { // Create an instance of TickerReader with the hostname and // port number we expect the host to be on tickerHost = new TickerReader (hostname, TICKERHOSTPORT); // Read from the Ticker host regardless of whether or not // there actually is a connection tape = getNextString(); // Use a 12 point Helvetica font textFont = new Font("Helvetica", Font.PLAIN, 12); // We use the font height and font descent to draw the text // centered in the scrolling area. The width is used to // determine how far to scroll before starting over. //FontMetrics metrics = getFontMetrics(textFont); metrics = getFontMetrics(textFont); textHeight = metrics.getHeight(); textDescent = metrics.getDescent(); // Get the next char and its width //currChar = getNextChar(); textWidth = metrics.stringWidth(tape); // Create the canvas size resize (width, 50); // Create a thread and start it scrollThread = new Thread(this); scrollThread.start(); } // end TickerTape constructor // Read the next available string from the host public String getNextString () { String tickerStr; // Attempt to read the current ticker port tickerStr = tickerHost.readData(); // If the string returned was null, use some kind of default if (tickerStr == null) { tickerStr = "Data connection to ticker tape host is down....Attempting reconnection...."; System.out.println ("Ticker Reader readData failed."); } return (tickerStr); } // The paint() method first checks if the Ticker has grown wider or // taller. If it has grown taller, it is resized back to the right // height for the font. If it has grown wider, setupTape() will // create a new wider offscreen image and reset the number of steps // required to scroll all the way across. // // After checking for resize, paint() draws the string into the // offscreen image at the current scroll position then draws the // image on the display. public void paint(Graphics g) { // Adjust for resize if necessary. setupTape(); // Draw the string into the offscreen image. Graphics offg = offscreenImage.getGraphics(); offg.setColor(getBackground()); offg.fillRect(0, 0, size().width - (RECTMARGIN * 2), textHeight); offg.setColor(getForeground()); offg.setFont(textFont); // previousWidth is the width of the displayed area in pixels. // The text starts at the right edge of the Ticker at a position // previousWidth pixels from the left. Each time it is repainted // it is drawn one pixel farther to the left. offg.drawString(tape, previousWidth - tapeIndex, textHeight - textDescent); // totalTapeSteps is set to the width of the display area + // the width of the text. After the text has scrolled the // width of the display area it is at the left end of the // display and it must scroll its own width to complete // one traversal. tapeIndex = (tapeIndex + 1) % totalTapeSteps; // When tapeIndex has reached 0, get a new string if (tapeIndex == 0) { tape = getNextString (); return; } // Draw a 3D rectangle just within the display area for a border. g.draw3DRect(RECTMARGIN, RECTMARGIN, size().width - RECTMARGIN, size().height - RECTMARGIN, false); // Draw the offscreen image within the rectangle. g.drawImage(offscreenImage, RECTMARGIN + 1, RECTMARGIN + TEXTMARGIN + 1, this); } // end paint public void close() { tickerHost.closePort(); } // The stop() method stops the scrolling thread. public void stop() { scrollThread.stop(); } // The Ticker update() method just calls paint() since we are covering the // background with our offscreen image. public void update(Graphics g) { paint(g); } // The run() method just pauses briefly between repaints. public void run() { while (true) { try { scrollThread.sleep(SCROLLPAUSE); } catch (InterruptedException e) { } repaint(); } } // The setupTape() method adjusts the state of the Ticker after a resize. // If the height has changed, it is reset to the appropriate height for // the selected font. If the width has changed, the number of steps // required for a complete scroll traversal is reset and a new offscreen // image is created to draw into. private void setupTape() { Dimension dim = size(); // resize() does nothing if the size hasn't changed. resize(dim.width, textHeight + (TEXTMARGIN * 2) + (RECTMARGIN * 2)); // If the width hasn't changed, we're done. if (dim.width == previousWidth) { return; } // Save the width to compare against next time. previousWidth = dim.width; // Reset the tape to the beginning. tapeIndex = 0; // The total steps required for a scroll traversal is the width // of the display area + the width of the text. totalTapeSteps = dim.width + textWidth; // If there is already an existing offscreen image, destroy it. if (offscreenImage != null) { offscreenImage.flush(); } offscreenImage = createImage(dim.width - (RECTMARGIN * 2), textHeight); } // end setupTape } // end class TickerTape |