Double buffering circle not round

I am making an applet where some circles are painted to the screen. When not using the double buffering scenario, the shapes appear correctly.
The problem is when i use the double-buffering technique, the circles are still there, but they look like very ugly. I would call that some "squarcles".
What is the bug here and how to get some decent double buffering with thoses circles?

Here is the code so far i have that is used for painting on the screen:
// Declaration
private BufferedImage ecran;
private Graphics2D buffer_ecran;
// Instantiation
this.ecran = new BufferedImage(getSize().width, getSize().height, BufferedImage.TYPE_INT_ARGB);
this.buffer_ecran = ecran.createGraphics();
// In paint() method
Graphics be = buffer_ecran;
// Clean the surface
be.setColor(Color.WHITE);
be.fillRect(0, 0, getSize().width, getSize().height);
// Draw the circles
be.setColor(Color.RED);
be.drawOval(x, y, ra, rb);
// Output the buffer to the screen
g.drawImage(ecran, 0, 0, this);I was previously using Image and changed to BufferedImage with the hope it would resolve the situation. I can't tell a significant change in image display.

Similar Messages

Double buffering circle not round anymore

I am making an applet where some circles are painted to the screen. When not using the double buffering scenario, the shapes appear correctly.
The problem is when i use the double-buffering technique, the circles are still there, but they look like very ugly. I would call that some "squarcles".
What is the bug here and how to get some decent double buffering with thoses circles?

Ok, i had some problem with the running thread when closing the applet viewer, but now this situation is corrected by setting the animation thread to null before calling stop().
Maybe explanation of the problem is not clear, so i made two versions of the same applet with only 2 lines of code different so that there is one applet that is not double buffered.
You can check these by yourself at this place:
Double buffered circles: http://www.geocities.com/xeneve/cooltrail/ demo_cooltrail.htm
No double buffer:
http://www.geocities.com/xeneve/cooltrail/demo_cooltrail_ndb.htm
This is just annoying to get this result. I realise that maybe not many peoples are coding applets so i guess there is few people that may have a workaround for this.

JNI native drawing - Double Buffering issue

Hi,
I use JNI to paint from a C++ DLL onto a canvas, which works fine.
The problem is that double buffering is not working though.
In C++ I create an offscreen HDC, draw something on it and finally i bitblit the offscreen HDC to the parent window HDC.
That is how double buffering is supposed to work. But each time i repaint my Canvas in Java, i see flickering:
the background color is displayed first, then the C++ paintings are drawn.
Since i already do double buffering in my C++ drawings, i don't know why there still is flickering.
Should i do double buffering on my canvas also?
How would this work, since my paint method looks like;
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this is my lucky day :)
the following thread on http://forum.java.sun.com/thread.jspa?threadID=562392&messageID=2767046 suggested to override the update method on the canvas, which works.
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So my Ipod touch hasn't been connecting to computer, or charging for a week or two until i turn it off completely and now i try to reset all content and setting, the circle goes round and round for like hrs(24) and it still does not complete the reset

so my Ipod touch hasn't been connecting to computer, nor charging for a week or two until i turn it off completely and now i try to reset all content and setting,(thinking it may connect to the computer and itunes and also charge) but the circle goes round and round for like hrs(24) and it still does not complete the reset.
pls pls pls pls help .
i have tried alot of solutions, but non of them have worked.

Have you tried walking it into the nearest Apple Store and asking for assistance there...?
I'm guessing you don't have Apple Care on it.

DAQEvent=2 not fired when double buffered operations stop

Hi,
I am using Config_DAQ_Event_Message with DAQEvent==2 to get an event when synchronous DAQ and WFM are finished. This works fine with single buffered operation, but i get no event in double buffered mode ?
Especially I like to get an event in case of Buffer-Underrun etc. errors.
My hardware: PCI6111
Software: NIDAQ6.9.3 with VisualC++
Thanks in advance
Michael

Hi Michael,
One of the possible causes of this error-10608 is a high update rate. The update rate might be high enough that you are not allowing enough time to fill the buffer with new data. This error can also be the result of having the regeneration option, within software, set to OFF. If you turn the regeneration option to ON, the error will go away. You can also reduce the update rate to see at which point you stop getting the error -10608
I found the following links about errorcode -10843:
http://digital.ni.com/public.nsf/websearch/EC38736BBF430DDC8625677C006F395C?OpenDocument
http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RNAME=ViewQuestion&HOID=506500000008000000CA780000&ECategory=Measurement+Hardware.Digital+I%2FO
regards
TN

How to draw a point without double buffering?

Hello all,
I am drawing points as small red circles, but they are a bit ugly without double buffering. Am I able to draw the points to be nice? I mean not to draw them as just circles, but some special circle with light border that will looks much more nicer?
Or what radius and position of the circle must be to be a nice small circle containing only 5 pixels? (upper, lower, right, left, middle)
ps - they are ugly in the way of having a strange dot on the left side

I use this method:
    private static final float POINT_RADIUS = 2f;
    private static final float POINT_DIAMETER = POINT_RADIUS * 2;
private void drawPoint(float x, float y, Color c) {
        Ellipse2D point = new Ellipse2D.Float(x - POINT_RADIUS, -y
                - POINT_RADIUS, POINT_DIAMETER, POINT_DIAMETER);
        graphics.setStroke(new BasicStroke(0.2f));
        graphics.fill(point);
// and points looks like this:
   ***

Can Flash create dashed line with blunt not rounded dashes ?

Hi,
using Flash8
I can select line tool and dashed line in properties and draw a dashed line and get a line of sausages. How do I get a line of dashes without rounded ends to each dash ?
Line option has end caps option with None (gives straight or blunt tip to line, round gives rounded tip .
Draw a line with None and its got blunt ends, select it and choose dashed line option and it gets round ends to the dashes, the end cap option is greyed out !
Are dashed lines with blunt dashes now possible again with CS4, a forum poster also found that CS3 no longer gave blunt dashes ?
Why do I ask:-
I am trying to bring a map into Flash8 from Illustrator (Illus version 10 as it allows blunt tip lines to remain blunt it was said on the forum)... which has blunt ends to roads and has blunt type dashed lines. The roads remain blunt..GOOD !..but the dashed lines become what looks like a solid line. BAD !
I do a right click - break apart, then double click one of those now solid lines that should be dashed, and I am able to select a portion of the line, it is no longer a continual line as drawn in Illustrator. Properties shows it as solid line. Flash8 obviously having a problem with supporting Illustrator 10 dashed line then !
Select dashed in properties box and I get a portion of the line as sausage dashes, but working my way along the line doing each bit sees a far from correct dashed line result as sausages dont start stop evenly as each line is a separate entity and ignores the previous line.
Looks like I shall have to try and draw the line as one long line again in flash but unless I can give it blunt dashes when done, there is no point even trying that method, hence my question.
Would the latest Illustrator and Flash versions (CS4) allow blunt type dashed lines to appear in Flash ?
This is crucial for bringing maps into Flash.
Envirographics

I noticed one problem with my solution.
If you look, very carefully, at the end of the stream, it's flat. Not rounded like it should be. After a bit of trial and error, I tried a different brush:
Note that, in addition to the rounded rectangle (done with the new corner controls in the latest version of Illustrator CC that just came out) and the three circles, there is also a rectangle, with no stroke and no fill, to provide a space at the end of the three dots. Here is the result:

Double buffering && repaint

Hi there,
I have a frame F that contains two panels P1 and P2.
P1 uses double buffering for drawing circles and lines.
P2 has buttons and a JList.
When i click on a JList to have popup menu
or when i move the frame F on the screen
the panel P2 lost some of JList drawing.
Actually i iconify the frame in order to oblige
JVM to do repaint.
How can i resolve this problem please.

Do not ever mix heavyweight and lightweight, or else
you won't be able to set up the correct zorder.But when i iconfiy and desiconify my frame Java
repaint correctly.
I need a nice tip article of how to simulate
desiconify repainting process.
Thabk u

"Class Circle not found in TryBouncingBalls" error message. Help !

Dear People,
I have an error message :
"TryBouncingBalls.java": Error : class Circle not found in class stan_bluej_ch5_p135.TryBouncingBalls at line 67, "
Circle circle = new Circle(xPos + 130, 30);
below are the classes TryBouncingBalls, BouncingBall, BallDemo, Canvas
Thank you in advance
Stan
package stan_bluej_ch5_p135;
import java.awt.*;
import java.awt.geom.*;
public class TryBouncingBalls
public static void main(String[] args)
Canvas myCanvas = new Canvas("Creativity at its best");
myCanvas.setVisible(true);
BouncingBall ball = new BouncingBall(50,50,16, Color.red, 500, myCanvas);
BouncingBall ball2 = new BouncingBall(70,80,20, Color.green, 500, myCanvas);
BouncingBall ball3 = new BouncingBall(90,100,16, Color.red, 500, myCanvas);
BouncingBall ball4 = new BouncingBall(30,30,20, Color.green, 500, myCanvas);
ball.draw();
ball2.draw();
ball.draw();
ball2.draw();
// make them bounce
boolean finished = false;
while(!finished) {
myCanvas.wait(50); // small delay
ball.move();
ball2.move();
ball3.move();
ball4.move();
// stop once ball has travelled a certain distance on x axis
if(ball.getXPosition() >= 550 && ball2.getXPosition() >= 550)
finished = true;
myCanvas.setFont(new Font("helvetica", Font.BOLD, 14));
myCanvas.setForegroundColor(Color.red);
myCanvas.drawString("We are having fun, ...\n\n", 20, 30);
myCanvas.wait(1000);
myCanvas.setForegroundColor(Color.black);
myCanvas.drawString("...drawing lines...", 60, 60);
myCanvas.wait(500);
myCanvas.setForegroundColor(Color.gray);
myCanvas.drawLine(200, 20, 300, 50);
myCanvas.wait(500);
myCanvas.setForegroundColor(Color.blue);
myCanvas.drawLine(220, 100, 370, 40);
myCanvas.wait(500);
myCanvas.setForegroundColor(Color.green);
myCanvas.drawLine(290, 10, 320, 120);
myCanvas.wait(1000);
myCanvas.setForegroundColor(Color.gray);
myCanvas.drawString("...and shapes!", 110, 90);
myCanvas.setForegroundColor(Color.red);
myCanvas.drawString("to bring to focus creative ideas !", 310, 290);
// the shape to draw and move
int xPos = 10;
Rectangle rect = new Rectangle(xPos + 40, 150, 30, 20);
Rectangle rect2 = new Rectangle(xPos + 80, 120, 50, 25);
Rectangle rect3 = new Rectangle(xPos+ 1200, 180, 30, 30);
Rectangle rect4 = new Rectangle(xPos + 150, 220, 40, 15);
myCanvas.fill(rect);
myCanvas.fill(rect2);
myCanvas.fill(rect3);
myCanvas.fill(rect4);
Circle circle = new Circle(xPos + 130, 30);
// Circle circle2 = new Circle(xPos + 150, 50);
// Circle circle3 = new Circle(xPos + 170, 30);
// Circle circle4 = new Circle(xPos + 200, 40);
// myCanvas.fill(circle);
// myCanvas.fill(circle2);
// myCanvas.fill(circle3);
// myCanvas.fill(circle4);
// move the rectangle and circles across the screen
for(int i = 0; i < 200; i ++) {
myCanvas.fill(rect);
myCanvas.fill(rect2);
myCanvas.fill(rect3);
myCanvas.fill(rect4);
myCanvas.wait(10);
myCanvas.erase(rect);
myCanvas.erase(rect2);
myCanvas.erase(rect3);
myCanvas.erase(rect4);
xPos++;
rect.setLocation(xPos, 150);
rect2.setLocation(xPos, 120);
rect3.setLocation(xPos, 180);
rect4.setLocation(xPos, 220);
// at the end of the move, draw once more so that it remains visible
myCanvas.fill(rect);
myCanvas.fill(rect2);
myCanvas.fill(rect3);
myCanvas.fill(rect4);
package stan_bluej_ch5_p135;
import java.awt.*;
import java.awt.geom.*;
* Class BouncingBall - a graphical ball that observes the effect of gravity. The ball
* has the ability to move. Details of movement are determined by the ball itself. It
* will fall downwards, accelerating with time due to the effect of gravity, and bounce
* upward again when hitting the ground.
* This movement can be initiated by repeated calls to the "move" method.
* @author Bruce Quig
* @author Michael Kolling (mik)
* @author David J. Barnes
* @version 1.1 (23-Jan-2002)
public class BouncingBall
private static final int gravity = 3; // effect of gravity
private int ballDegradation = 2;
private Ellipse2D.Double circle;
private Color color;
private int diameter;
private int xPosition;
private int yPosition;
private final int groundPosition; // y position of ground
private Canvas canvas;
private int ySpeed = 1; // initial downward speed
* Constructor for objects of class BouncingBall
* @param xPos the horizontal coordinate of the ball
* @param yPos the vertical coordinate of the ball
* @param ballDiameter the diameter (in pixels) of the ball
* @param ballColor the color of the ball
* @param groundPos the position of the ground (where the wall will bounce)
* @param drawingCanvas the canvas to draw this ball on
public BouncingBall(int xPos, int yPos, int ballDiameter, Color ballColor,
int groundPos, Canvas drawingCanvas)
xPosition = xPos;
yPosition = yPos;
color = ballColor;
diameter = ballDiameter;
groundPosition = groundPos;
canvas = drawingCanvas;
* Draw this ball at its current position onto the canvas.
public void draw()
canvas.setForegroundColor(color);
canvas.fillCircle(xPosition, yPosition, diameter);
* Erase this ball at its current position.
public void erase()
canvas.eraseCircle(xPosition, yPosition, diameter);
* Move this ball according to its position and speed and redraw.
public void move()
// remove from canvas at the current position
erase();
// compute new position
ySpeed += gravity;
yPosition += ySpeed;
xPosition +=2;
// check if it has hit the ground
if(yPosition >= (groundPosition - diameter) && ySpeed > 0) {
yPosition = (int)(groundPosition - diameter);
ySpeed = -ySpeed + ballDegradation;
// draw again at new position
draw();
* return the horizontal position of this ball
public int getXPosition()
return xPosition;
* return the vertical position of this ball
public int getYPosition()
return yPosition;
package stan_bluej_ch5_p135;
import java.awt.*;
import java.awt.geom.*;
* Class BallDemo - provides two short demonstrations showing how to use the
* Canvas class.
* @author Michael Kolling and David J. Barnes
* @version 1.0 (23-Jan-2002)
public class BallDemo
private Canvas myCanvas;
* Create a BallDemo object. Creates a fresh canvas and makes it visible.
public BallDemo()
myCanvas = new Canvas("Ball Demo", 600, 500);
myCanvas.setVisible(true);
* This method demonstrates some of the drawing operations that are
* available on a Canvas object.
public void drawDemo()
myCanvas.setFont(new Font("helvetica", Font.BOLD, 14));
myCanvas.setForegroundColor(Color.red);
myCanvas.drawString("We can draw text, ...", 20, 30);
myCanvas.wait(1000);
myCanvas.setForegroundColor(Color.black);
myCanvas.drawString("...draw lines...", 60, 60);
myCanvas.wait(500);
myCanvas.setForegroundColor(Color.gray);
myCanvas.drawLine(200, 20, 300, 50);
myCanvas.wait(500);
myCanvas.setForegroundColor(Color.blue);
myCanvas.drawLine(220, 100, 370, 40);
myCanvas.wait(500);
myCanvas.setForegroundColor(Color.green);
myCanvas.drawLine(290, 10, 320, 120);
myCanvas.wait(1000);
myCanvas.setForegroundColor(Color.gray);
myCanvas.drawString("...and shapes!", 110, 90);
myCanvas.setForegroundColor(Color.red);
// the shape to draw and move
int xPos = 10;
Rectangle rect = new Rectangle(xPos, 150, 30, 20);
// move the rectangle across the screen
for(int i = 0; i < 200; i ++) {
myCanvas.fill(rect);
myCanvas.wait(10);
myCanvas.erase(rect);
xPos++;
rect.setLocation(xPos, 150);
// at the end of the move, draw once more so that it remains visible
myCanvas.fill(rect);
* Simulates two bouncing balls
public void bounce()
int ground = 400; // position of the ground line
myCanvas.setVisible(true);
// draw the ground
myCanvas.drawLine(50, ground, 550, ground);
// crate and show the balls
BouncingBall ball = new BouncingBall(50, 50, 16, Color.blue, ground, myCanvas);
ball.draw();
BouncingBall ball2 = new BouncingBall(70, 80, 20, Color.red, ground, myCanvas);
ball2.draw();
// make them bounce
boolean finished = false;
while(!finished) {
myCanvas.wait(50); // small delay
ball.move();
ball2.move();
// stop once ball has travelled a certain distance on x axis
if(ball.getXPosition() >= 550 && ball2.getXPosition() >= 550)
finished = true;
ball.erase();
ball2.erase();
package stan_bluej_ch5_p135;
import javax.swing.*;
import java.awt.*;
import java.awt.geom.*;
* Class Canvas - a class to allow for simple graphical
* drawing on a canvas.
* @author Michael Kolling (mik)
* @author Bruce Quig
* @version 1.8 (23.01.2002)
public class Canvas
private JFrame frame;
private CanvasPane canvas;
private Graphics2D graphic;
private Color backgroundColor;
private Image canvasImage;
* Create a Canvas with default height, width and background color
* (300, 300, white).
* @param title title to appear in Canvas Frame
public Canvas(String title)
this(title, 600, 600, Color.white);
* Create a Canvas with default background color (white).
* @param title title to appear in Canvas Frame
* @param width the desired width for the canvas
* @param height the desired height for the canvas
public Canvas(String title, int width, int height)
this(title, width, height, Color.white);
* Create a Canvas.
* @param title title to appear in Canvas Frame
* @param width the desired width for the canvas
* @param height the desired height for the canvas
* @param bgClour the desired background color of the canvas
public Canvas(String title, int width, int height, Color bgColor)
frame = new JFrame();
canvas = new CanvasPane();
frame.setContentPane(canvas);
frame.setTitle(title);
canvas.setPreferredSize(new Dimension(width, height));
backgroundColor = bgColor;
frame.pack();
* Set the canvas visibility and brings canvas to the front of screen
* when made visible. This method can also be used to bring an already
* visible canvas to the front of other windows.
* @param visible boolean value representing the desired visibility of
* the canvas (true or false)
public void setVisible(boolean visible)
if(graphic == null) {
// first time: instantiate the offscreen image and fill it with
// the background color
Dimension size = canvas.getSize();
canvasImage = canvas.createImage(size.width, size.height);
graphic = (Graphics2D)canvasImage.getGraphics();
graphic.setColor(backgroundColor);
graphic.fillRect(0, 0, size.width, size.height);
graphic.setColor(Color.black);
frame.show();
* Provide information on visibility of the Canvas.
* @return true if canvas is visible, false otherwise
public boolean isVisible()
return frame.isVisible();
* Draw the outline of a given shape onto the canvas.
* @param shape the shape object to be drawn on the canvas
public void draw(Shape shape)
graphic.draw(shape);
canvas.repaint();
* Fill the internal dimensions of a given shape with the current
* foreground color of the canvas.
* @param shape the shape object to be filled
public void fill(Shape shape)
graphic.fill(shape);
canvas.repaint();
* Fill the internal dimensions of the given circle with the current
* foreground color of the canvas.
public void fillCircle(int xPos, int yPos, int diameter)
Ellipse2D.Double circle = new Ellipse2D.Double(xPos, yPos, diameter, diameter);
fill(circle);
* Fill the internal dimensions of the given rectangle with the current
* foreground color of the canvas. This is a convenience method. A similar
* effect can be achieved with the "fill" method.
public void fillRectangle(int xPos, int yPos, int width, int height)
fill(new Rectangle(xPos, yPos, width, height));
* Erase the whole canvas.
public void erase()
Color original = graphic.getColor();
graphic.setColor(backgroundColor);
Dimension size = canvas.getSize();
graphic.fill(new Rectangle(0, 0, size.width, size.height));
graphic.setColor(original);
canvas.repaint();
* Erase the internal dimensions of the given circle. This is a
* convenience method. A similar effect can be achieved with
* the "erase" method.
public void eraseCircle(int xPos, int yPos, int diameter)
Ellipse2D.Double circle = new Ellipse2D.Double(xPos, yPos, diameter, diameter);
erase(circle);
* Erase the internal dimensions of the given rectangle. This is a
* convenience method. A similar effect can be achieved with
* the "erase" method.
public void eraseRectangle(int xPos, int yPos, int width, int height)
erase(new Rectangle(xPos, yPos, width, height));
* Erase a given shape's interior on the screen.
* @param shape the shape object to be erased
public void erase(Shape shape)
Color original = graphic.getColor();
graphic.setColor(backgroundColor);
graphic.fill(shape); // erase by filling background color
graphic.setColor(original);
canvas.repaint();
* Erases a given shape's outline on the screen.
* @param shape the shape object to be erased
public void eraseOutline(Shape shape)
Color original = graphic.getColor();
graphic.setColor(backgroundColor);
graphic.draw(shape); // erase by drawing background color
graphic.setColor(original);
canvas.repaint();
* Draws an image onto the canvas.
* @param image the Image object to be displayed
* @param x x co-ordinate for Image placement
* @param y y co-ordinate for Image placement
* @return returns boolean value representing whether the image was
* completely loaded
public boolean drawImage(Image image, int x, int y)
boolean result = graphic.drawImage(image, x, y, null);
canvas.repaint();
return result;
* Draws a String on the Canvas.
* @param text the String to be displayed
* @param x x co-ordinate for text placement
* @param y y co-ordinate for text placement
public void drawString(String text, int x, int y)
graphic.drawString(text, x, y);
canvas.repaint();
* Erases a String on the Canvas.
* @param text the String to be displayed
* @param x x co-ordinate for text placement
* @param y y co-ordinate for text placement
public void eraseString(String text, int x, int y)
Color original = graphic.getColor();
graphic.setColor(backgroundColor);
graphic.drawString(text, x, y);
graphic.setColor(original);
canvas.repaint();
* Draws a line on the Canvas.
* @param x1 x co-ordinate of start of line
* @param y1 y co-ordinate of start of line
* @param x2 x co-ordinate of end of line
* @param y2 y co-ordinate of end of line
public void drawLine(int x1, int y1, int x2, int y2)
graphic.drawLine(x1, y1, x2, y2);
canvas.repaint();
* Sets the foreground color of the Canvas.
* @param newColor the new color for the foreground of the Canvas
public void setForegroundColor(Color blue)
graphic.setColor(Color.blue);
* Returns the current color of the foreground.
* @return the color of the foreground of the Canvas
public Color getForegroundColor()
return graphic.getColor();
* Sets the background color of the Canvas.
* @param newColor the new color for the background of the Canvas
public void setBackgroundColor(Color newColor)
backgroundColor = newColor;
graphic.setBackground(newColor);
* Returns the current color of the background
* @return the color of the background of the Canvas
public Color getBackgroundColor()
return backgroundColor;
* changes the current Font used on the Canvas
* @param newFont new font to be used for String output
public void setFont(Font newFont)
graphic.setFont(newFont);
* Returns the current font of the canvas.
* @return the font currently in use
public Font getFont()
return graphic.getFont();
* Sets the size of the canvas.
* @param width new width
* @param height new height
public void setSize(int width, int height)
canvas.setPreferredSize(new Dimension(width, height));
Image oldImage = canvasImage;
canvasImage = canvas.createImage(width, height);
graphic = (Graphics2D)canvasImage.getGraphics();
graphic.drawImage(oldImage, 0, 0, null);
frame.pack();
* Returns the size of the canvas.
* @return The current dimension of the canvas
public Dimension getSize()
return canvas.getSize();
* Waits for a specified number of milliseconds before finishing.
* This provides an easy way to specify a small delay which can be
* used when producing animations.
* @param milliseconds the number
public void wait(int milliseconds)
try
Thread.sleep(milliseconds);
catch (InterruptedException e)
// ignoring exception at the moment
* Nested class CanvasPane - the actual canvas component contained in the
* Canvas frame. This is essentially a JPanel with added capability to
* refresh the image drawn on it.
private class CanvasPane extends JPanel
public void paint(Graphics g)
g.drawImage(canvasImage, 0, 0, null);

Dear Miciuli,
I found the definition for the circle in the canvas class and used it to creates circles ! Thank you for jaring my brain into thinking !
Stan
Ellipse2D.Double circle = new Ellipse2D.Double(xPos, 70, 30 , 30);

Problem with Double Buffering and Swing

Hi
I made a game and basically it works pretty well, my only problem is it flickers really badly right now. I read up on a whole lot of forums about double buffering and none of those methods seemed to work. Then I noticed that Swing has double buffering built in so I tried that but then I get compilation errors and I'm really not sure why. My original code was a console application and worked perfectly, then I ported it into a JApplet and it still works but it flickers and thats what I'm tryign to fix now.
The code below is in my main class under the constructor.
Heres the double buffering code I'm trying to use, I'm sure you all seen it before lol
public void update(Graphics g)
          // initialize buffer
          if (dbImage == null)
               dbImage = createImage(this.getSize().width, this.getSize().height);
               dbg = dbImage.getGraphics();
          // clear screen in background
          dbg.setColor(getBackground());
          dbg.fillRect(0, 0, this.getSize().width, this.getSize().height);
          // draw elements in background
          dbg.setColor(getForeground());
          paint(dbg);
          // draw image on the screen
          g.drawImage(dbImage, 0, 0, this);
     }My paint is right under neath and heres how it looks
This snipet of code works but when I change the method to
public paintComponent(Graphics g){
super.paintComponent(g)...
everythign stops working and get a compilation error and says that it can't find paintComponent in javax.swing.JFrame.
public void paint(Graphics g)
          super.paint(g);
          //if game starting display menue
          if (show_menue)
               //to restart lives if player dies
               lives = 3;
               menue.draw_menue(g);
               menue_ufo1.draw_shape(g);
               menue_ufo2.shape_color = Color.DARK_GRAY;
               menue_ufo2.draw_shape(g);
               menue_ufo3.shape_color = Color.BLUE;
               menue_ufo3.draw_shape(g);
               menue_ufo4.shape_color = new Color(82, 157, 22);
               menue_ufo4.draw_shape(g);
               menue_ufo5.draw_shape(g);
               menue_ufo6.shape_color = new Color(130, 3, 3); ;
               menue_ufo6.draw_shape(g);
               menue_turret.draw_ship(g);
               menue_ammo.draw_ammo(g);
          else
               //otherwise redraw game objects
               gunner.draw_ship(g);
               y_ammo.draw_ammo(g);
               grass.draw_bar(g);
               o_ufo.draw_shape(g);
               b_ufo.draw_shape(g);
               m_ufo.draw_shape(g);
               s_ufo.draw_shape(g);
               z_ufo.draw_shape(g);
               xx_ufo.draw_shape(g);
               info.draw_bar(g);
               live_painter.draw_lives(g, lives);
               score_painter.draw_score(g, score);
               level_display.draw_level(g, level);
               explosion.draw_boom(g);
     }I just want to get rid of the flickering for now so any help will be greatly appreciated. Depending which will be simpler I can either try to double buffer this program or port it all to swing but I'm not sure which elements are effected by AWT and which by Swing. Also I read some of the Java documentation but couldn't really understand how to implement it to fix my program.
Thanks in advance
Sebastian

This is a simple animation example quickly thrown together. I have two classes, an animation panel which is a JPanel subclass that overrides paintComponent and draws the animation, and a JApplet subclass that simply holds the animation panel in the applet's contentpane:
SimpleAnimationPanel.java
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.JPanel;
import javax.swing.Timer;
class SimpleAnimationPanel extends JPanel
    private static final int DELAY = 20;
    public static final int X_TRANSLATION = 2;
    public static final int Y_TRANSLATION = 2;
    private Point point = new Point(5, 32);
    private BufferedImage duke = null;
    private Timer timer = new Timer(DELAY, new TimerAction());
    public SimpleAnimationPanel()
        try
            // borrow an image from sun.com
            duke = ImageIO.read(new URL(
                    "http://java.sun.com/products/plugin/images/duke.wave.med.gif"));
        catch (MalformedURLException e)
            e.printStackTrace();
        catch (IOException e)
            e.printStackTrace();
        setPreferredSize(new Dimension(600, 400));
        timer.start();
    // do our drawing here in the paintComponent override
    @Override
    protected void paintComponent(Graphics g)
        super.paintComponent(g);
        if (duke != null)
            g.drawImage(duke, point.x, point.y, this);
    private class TimerAction implements ActionListener
        @Override
        public void actionPerformed(ActionEvent e)
            int x = point.x;
            int y = point.y;
            Dimension size = SimpleAnimationPanel.this.getSize();
            if (x > size.width)
                x = 0;
            else
                x += X_TRANSLATION;
            if (y > size.height)
                y = 0;
            else
                y += Y_TRANSLATION;
            point.setLocation(new Point(x, y)); // update the point
            SimpleAnimationPanel.this.repaint();
}AnimationApplet.java
import java.lang.reflect.InvocationTargetException;
import javax.swing.JApplet;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class AnimationApplet extends JApplet
    public void init()
        try
            SwingUtilities.invokeAndWait(new Runnable()
                public void run()
                    // construct the panel
                    JPanel simpleAnimation = new SimpleAnimationPanel();
                    // put it in the contentPane of the JApplet
                    getContentPane().add(simpleAnimation);
                    setSize(simpleAnimation.getPreferredSize());
        catch (InterruptedException e)
            e.printStackTrace();
        catch (InvocationTargetException e)
            e.printStackTrace();
}Here's a 3rd bonus class that shows how to put the JPanel into a stand-alone program, a JFrame. It's very similar to doing it in the JApplet:
AnimationFrame.java
import javax.swing.JFrame;
public class AnimationFrame
    private static void createAndShowUI()
        JFrame frame = new JFrame("SimpleAnimationPanel");
        frame.getContentPane().add(new SimpleAnimationPanel());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    public static void main(String[] args)
        java.awt.EventQueue.invokeLater(new Runnable()
            public void run()
                createAndShowUI();
}Edited by: Encephalopathic on Mar 15, 2008 11:01 PM

To double buffer or not double buffer..that is the question

i am not very familiar with double buffering but am reading examples
of it now. Im not doing animaiton and i dont think im doing alot of
drawing to the screen but im arookie so its hard to tell. Can you tell
me if i should implement double buffering by looking at my code. Im
wondering cuz my webpage is a mess.(http://ktowndrivewaysealing.tripod.com).
i have trailing components and flickering and i dont know how to fix it.
thanx
trin
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.util.*;
public class MyProg extends Applet implements ActionListener
     Button btnOne = new Button("Home");
     Button btnTwo = new Button("Asphalt Sealing");
     Button btnThree = new Button("Crack Repairs");
     Button btnFour = new Button("Pressure Washing");
     Button btnFive = new Button("Free Estimates");
     Button btnSix = new Button("Contact Us");
     Font font1= new Font ( "TimesNewRoman",Font.BOLD,12);
     Font font2=new Font("TimesNewRoman", Font.BOLD, 35);
     Font font3=new Font("TimesNewRoman", Font.BOLD, 25);
     Font font4=new Font("TimesNewRoman",Font.BOLD,20);
     Font font5=new Font("Dialog", Font.BOLD+Font.ITALIC, 16);
     Label title1=new Label("KINGSTON", Label.CENTER);
     Label title2 = new Label("Driveway Sealing", Label.CENTER);
     Label title3=new Label("613-531-3369", Label.CENTER);
     Label caption1=new Label("Your driveway is the first impression your home makes...", Label.CENTER);
     Label caption2=new Label("Make it a Good one.", Label.CENTER);
     Image drivewaypic1;
     Image drivewaypic2;
     URL homeUrl;
     URL asphaltUrl;
     URL crackUrl;
     URL pressureUrl;
     URL freeUrl;
     URL contactUrl;
     public void init()
          setLayout(null);
           try
               homeUrl = new URL(getCodeBase(),"Home.html");
               asphaltUrl=new URL(getCodeBase(),"AsphaltHtml.html");
               crackUrl= new URL(getCodeBase(),"CrackHtml.html");
               pressureUrl=new URL(getCodeBase(),"PressureHtml.html");
               freeUrl= new URL(getCodeBase(),"FreeHtml.html");
               contactUrl= new URL(getCodeBase(),"ContactUsHtml.html");
          catch (MalformedURLException e)
                return;//maybe i should leave blank..will test later
          drivewaypic1=getImage(getCodeBase(),"drivewaypic1.jpg");
          drivewaypic2=getImage(getCodeBase(),"drivewaypic2.jpg");
          add(btnOne);
          add(btnTwo);
          add(btnThree);
          add(btnFour);
          add(btnFive);
          add(btnSix);
          add(title1);
          add(title2);
          add(title3);
          add(caption1);
          add(caption2);
          btnOne.setFont(font1);
          btnOne.setBounds(15,159,120,40);
          btnOne.setBackground(Color.black);
          btnOne.setForeground(Color.white);
          btnTwo.setFont(font1);
          btnTwo.setBounds(15,199,120,40);
          btnTwo.setBackground(Color.black);
          btnTwo.setForeground(Color.white);
          btnThree.setFont(font1);
          btnThree.setBounds(15,239,120,40);
          btnThree.setBackground(Color.black);
          btnThree.setForeground(Color.white);
          btnFour.setFont(font1);
          btnFour.setBounds(15,279,120,40);
          btnFour.setBackground(Color.black);
          btnFour.setForeground(Color.white);
          btnFive.setFont(font1);
          btnFive.setBounds(15,319,120,40);
          btnFive.setBackground(Color.black);
          btnFive.setForeground(Color.white);
          btnSix.setFont(font1);
          btnSix.setBounds(15,359,120,40);
          btnSix.setBackground(Color.black);
          btnSix.setForeground(Color.white);
          title1.setBounds(5,5,585,33);
          title1.setBackground(Color.lightGray);
          title1.setForeground(Color.black);
          title1.setFont(font3);
          title2.setBounds(5,39,590,36);
          title2.setBackground(Color.black);
          title2.setForeground(Color.white);
          title2.setFont(font2);
          title3.setBounds(5,75,590,30);
          title3.setBackground(Color.lightGray);
          title3.setForeground(Color.black);
          title3.setFont(font4);
          caption1.setBounds(163,113,450,23);
          caption1.setFont(font5);
          caption1.setBackground(Color.lightGray);
          caption1.setForeground(Color.blue);
          caption2.setBounds(163,134,446,23);
          caption2.setFont(font5);
          caption2.setBackground(Color.lightGray);
          caption2.setForeground(Color.blue);
          btnOne.addActionListener(this);
          btnTwo.addActionListener(this);
          btnThree.addActionListener(this);
          btnFour.addActionListener(this);
          btnFive.addActionListener(this);
          btnSix.addActionListener(this);
          btnOne.setActionCommand("Home");
          btnTwo.setActionCommand("Asphalt Sealing");
          btnThree.setActionCommand("Crack Repairs");
          btnFour.setActionCommand("Pressure Washing");
          btnFive.setActionCommand("Free Estimates");
          btnSix.setActionCommand("Contact Us");
     public void actionPerformed (ActionEvent e)
          String s=e.getActionCommand();
          if (s.equals("Home"))
               getAppletContext().showDocument(homeUrl);
          if (s.equals("Asphalt Sealing"))
               getAppletContext().showDocument(asphaltUrl);
          if (s.equals("Crack Repairs"))
               getAppletContext().showDocument(crackUrl);
          if (s.equals("Pressure Washing"))
               getAppletContext().showDocument(pressureUrl);
          if (s.equals("Free Estimates"))
               getAppletContext().showDocument(freeUrl);
          if (s.equals("Contact Us"))
               getAppletContext().showDocument(contactUrl);
     public void paint(Graphics g)
          super.paint(g);
          g.setColor(Color.lightGray);
          g.fillRect(1,1,600,600);
          //g.fillRect(1,1,147,650);
          g.setColor(Color.black);
          g.drawRoundRect(1,1,595,105,10,10);
          g.drawRoundRect(2,2,593,103,10,10);
          g.drawRoundRect(3,3,591,101,10,10);
          g.drawRoundRect(4,4,589,99,10,10);
          g.drawImage(drivewaypic1,170,159,375,225,this);
          g.drawImage(drivewaypic2,170,386,375,225,this);
          g.drawRoundRect(1,110,150,495,10,10);
          g.drawRoundRect(2,111,148,493,10,10);
          g.drawRoundRect(3,112,146,491,10,10);
          g.drawRoundRect(4,113,144,489,10,10);


It seems you aren't using any animation in this applet, so you won't have to use double buffering... :)

Double buffering

I was searching through posts to find an answer to my problem of getting double buffering working without flickering when I came across this response:
Upgrade your SDK, early 1.4 implementations had this problem on Windows2k (It's a bug). Pretty much the second buffer will point to an empty portion of video memory always, the solution to this without updating is to fill the entire backbuffer completely, flip it, fill it again, and then flip it again. You should then be able to use it normaly.
-Jason Thomas.
Since I am on dialup I can't really download the SDK, so could someone give me some code to do what Jason has suggested?
Jonathan O'Brien

No I am not recreating the bufferstrategy every frame. Overriding update didn't work either. Here is my code for main:
          GraphicsEnvironment env = GraphicsEnvironment.getLocalGraphicsEnvironment();
          GraphicsDevice device = env.getDefaultScreenDevice();
          GraphicsConfiguration gc = device.getDefaultConfiguration();
          Frame myFrame = new Frame(gc);
BufferCapabilities bufferCaps = gc.getBufferCapabilities();
          boolean multiBuffer = bufferCaps.isMultiBufferAvailable();
          boolean fullScreen = device.isFullScreenSupported();
          System.out.println("Full screen supported = " + fullScreen);
          System.out.println("Multi buffer available = " + multiBuffer);
          System.out.println("Page flipping = " + bufferCaps.isPageFlipping());
          myFrame.setUndecorated(true);
          myFrame.setIgnoreRepaint(true);
          if ((fullScreen) && (multiBuffer))
               device.setFullScreenWindow(myFrame);
               device.setDisplayMode(new DisplayMode(800, 600, 16, 0));
               rectBounds = myFrame.getBounds();
               myFrame.createBufferStrategy(2);
               bufferStrategy = myFrame.getBufferStrategy();
               bufferReady = true;
          Game thisGame = new Game(args[0]);
          myFrame.add(thisGame);
//          myFrame.getContentPane().add(thisGame);
          myFrame.show();
And here is the relevant code for my run method:
          if (bufferReady)
               Graphics g = bufferStrategy.getDrawGraphics();
               if (!bufferStrategy.contentsLost()) {
                    g.fillRect(0,0,getWidth(),getHeight());
                    g.dispose();
                    bufferStrategy.show();

Double buffering still gives flickering graphics.

I copied code from a tutorail which is supposed to illustrate double buffering.
After I run it, it still flickers though.
I use applet viewer, which is part of netbeans to run my applet.
Link to tutorial: http://www.javacooperation.gmxhome.de/TutorialStartEng.html
My questions are:
Is the strategy used for double buffering correct?
Why does it flicker?
Why does the program change the priority a couple of times?
Can you make fast games in JApplets or is there a better way to make games? (I think C++ is too hard)
Here is the code:
package ballspel;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import javax.swing.JApplet;
//import java.applet.*;
* @author Somelauw
public class BallApplet extends /*Applet*/ JApplet implements Runnable {
private Image dbImage;
private Graphics dbg;
private int radius = 20;
private int xPos = 10;
private int yPos = 100;
* Initialization method that will be called after the applet is loaded
* into the browser.
@Override
public void init() {
//System.out.println(this.isDoubleBuffered()); //returns false
// Isn't there a builtin way to force double buffering?
// TODO start asynchronous download of heavy resources
@Override
public void start() {
Thread th = new Thread(this);
th.start();
public void run() {
Thread.currentThread().setPriority(Thread.MIN_PRIORITY);
while (true) {
xPos++;
repaint();
try {
Thread.sleep(20);
} catch (InterruptedException ex) {
ex.printStackTrace();
Thread.currentThread().setPriority(Thread.MAX_PRIORITY);
@Override
public void paint(Graphics g) {
super.paint(g);
//g.clear();//, yPos, WIDTH, WIDTH)
g.setColor(Color.red);
g.fillOval(xPos - radius, yPos - radius, 2 * radius, 2 * radius);
@Override
public void update(Graphics g) {
super.update(g);
// initialize buffer
if (dbImage == null) {
dbImage = createImage(this.getSize().width, this.getSize().height);
dbg = dbImage.getGraphics();
// clear screen in background
dbg.setColor(getBackground());
dbg.fillRect(0, 0, this.getSize().width, this.getSize().height);
// draw elements in background
dbg.setColor(getForeground());
paint(dbg);
// draw image on the screen
g.drawImage(dbImage, 0, 0, this);
// TODO overwrite start(), stop() and destroy() methods
}

Somelauw wrote:
I copied code from a tutorail which is supposed to illustrate double buffering.
After I run it, it still flickers though.
I use applet viewer, which is part of netbeans.. AppletViewer is part of the JDK, not NetBeans.
..to run my applet.
Link to tutorial: http://www.javacooperation.gmxhome.de/TutorialStartEng.html
Did you specifically mean the code mentioned on this page?
[http://www.javacooperation.gmxhome.de/BildschirmflackernEng.html]
Don't expect people to go hunting around the site, looking for the code you happen to be referring to.
As an aside, please use the code tags when posting code, code snippets, XML/HTML or input/output. The code tags help retain the formatting and indentation of the sample. To use the code tags, select the sample and click the CODE button.
Here is the code you posted, as it appears in code tags.
package ballspel;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import javax.swing.JApplet;
//import java.applet.*;
* @author Somelauw
public class BallApplet extends /*Applet*/ JApplet implements Runnable {
    private Image dbImage;
    private Graphics dbg;
    private int radius = 20;
    private int xPos = 10;
    private int yPos = 100;
     * Initialization method that will be called after the applet is loaded
     * into the browser.
    @Override
    public void init() {
        //System.out.println(this.isDoubleBuffered()); //returns false
        // Isn't there a builtin way to force double buffering?
        // TODO start asynchronous download of heavy resources
    @Override
    public void start() {
        Thread th = new Thread(this);
        th.start();
    public void run() {
        Thread.currentThread().setPriority(Thread.MIN_PRIORITY);
        while (true) {
            xPos++;
            repaint();
            try {
                Thread.sleep(20);
            } catch (InterruptedException ex) {
                ex.printStackTrace();
            Thread.currentThread().setPriority(Thread.MAX_PRIORITY);
    @Override
    public void paint(Graphics g) {
        super.paint(g);
        //g.clear();//, yPos, WIDTH, WIDTH)
        g.setColor(Color.red);
        g.fillOval(xPos - radius, yPos - radius, 2 * radius, 2 * radius);
    @Override
    public void update(Graphics g) {
        super.update(g);
        // initialize buffer
        if (dbImage == null) {
            dbImage = createImage(this.getSize().width, this.getSize().height);
            dbg = dbImage.getGraphics();
        // clear screen in background
        dbg.setColor(getBackground());
        dbg.fillRect(0, 0, this.getSize().width, this.getSize().height);
        // draw elements in background
        dbg.setColor(getForeground());
        paint(dbg);
        // draw image on the screen
        g.drawImage(dbImage, 0, 0, this);
    // TODO overwrite start(), stop() and destroy() methods
}Edit 1:
- For animation code, it would be typical to use a javax.swing.Timer for triggering updates, rather than implementing Runnable (etc.)
- Attempting to set the thread priority will throw a SecurityException, though oddly it occurs when attempting to set the Thread priority to maximum, whereas the earlier call to set the Thread priority to minimum passed without comment (exception).
- The paint() method of that applet is not double buffered.
- It is generally advisable to override paintComponent(Graphics) in a JPanel that is added to the top-level applet (or JFrame, or JWindow, or JDialog..) rather than the paint(Graphics) method of the top-level container itself.
Edited by: AndrewThompson64 on Jan 22, 2010 12:47 PM

Double buffering images

HELP!!! lol i'm trying to figure out how to get the whole double buffering thing to work with a picture like a gif image i drew in paint. i can't quite understand anything aobut how to do it. lol i've read some things and looked at some code samples but they all do it with a polygon. i just can't seem to get it right. i learn best from code snipets if that helps. don't give me a whole program i just want some lines that will help me learn it like what i have to import. and other things. i know a little about using images but not a whole lot. if anyone can help it will be appreciated.
andy

Psst... Tell you teacher that one can read an image with ImageIO, often in one line:
BufferedImage image = ImageIO.read(file_or_url_or_inputstream);(No need for a MediaTracker!) And the resulting BufferedImage (a subclass of Image)
is easier to work with than Image and has more useful features.
Welcome to Java 2D.

Double buffering daqmx

I understand that DAQmx is supposed to do double buffering automatically. When I run the example below in continuous mode, It will run continuously without error. when I hit stop, it will give me a "Not enough memory to complete this operation." error. This error occurs only when i've acquired greater than about 70M samples. If I don't hit stop it will run to about 300M samples, give the above error and also an unspecified Labview error. The rate does not appear to affect this. Am I actually double buffering?
Does it only do double buffering with the "Continuous Samples" mode? I've been using the example below with both continuous and finite samples and in both cases it seems to acquire more samples the 64MB.
Does this have anything to do with what i'm seeing?
http://digital.ni.com/public.nsf/allkb/7DF86CA91D739AD386256DF900785211
Equipment:
Labview 8.2
NI-8350 Controller
MXI-4
PXI-6534

You are creating the second buffer in your application. DAQmx is not at fault here. You are wiring the output from the DAQmx Read VI to an auto-index tunnel on the While Loop. As your program runs this auto-index tunnel builds an array of every value that was sent to it in every iteration of the loop. So as time goes on, this array gets bigger and bigger. Eventually you will run out of available memory.
You should look into other ways of streaming data out of a loop, such as using Queues. You could then have a background loop to handle any data analysis or display.
Jarrod S.
National Instruments

Double buffering circle not round

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