[java] Best double buffer scheme in 1.1 applets

Absolution · 2002-12-05T16:42:28+00:00

I'm still using 1.1 for applet support. I was wondering what people think the best (i.e. fastest, least flicker) double buffer scheme is? Currently I'm creating an image with MemoryImageSource, manipulating the pixels in run(), and copying that image to the Graphics object using drawImage every time paint is called. I still seem to get a bit of flicker now and then then, especially during input handling. [edited by - Absolution on December 5, 2002 5:48:44 PM]


import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;
public class spiralColor extends Applet
                         implements MouseListener, MouseMotionListener
{
  Graphics bufferg;  // Sets bufferg for graphic use
  Image buffer;  // Image to be used to draw next frame
  double[] xSpiral = new double[129];
  double[] ySpiral = new double[xSpiral.length];
  int[] imageXPostion = { 316, 354, 394};
  int imageYPosition =248;
  int[] green = new int[xSpiral.length]; int[] red = new int[xSpiral.length]; int[] blue = new int[xSpiral.length];
  int xMouse, yMouse, R, G, B, incRed , incGreen , incBlue, xPosition = 2;
  int spiralXCenter = 147, spiralYCenter = 142;
  boolean redColor, blueColor = true, greenColor, start;

  public void init()
  {
    setBackground(Color.white); // sets the background color
    buffer  = createImage(getSize().width , getSize().height);//Createsthe next frame to be displayed
    bufferg = buffer.getGraphics();//Calls the back frame
    addMouseListener(this);
    addMouseMotionListener(this);
  }

  public void update(Graphics gr)
  {
    paint(bufferg);  // Updates paint
    gr.drawImage(buffer , 0, 0, this);// Draws the next frame
  }

  public void paint(Graphics gr)
  {
    double Pi = 3.1415926535897932384626433832795;
    int spiralRadius = 20, colorTouched =0;
    if(redColor  ){ R = 254; G = 0; B = 0; incRed = 0; incGreen = 2; incBlue =2;}
    if(blueColor ){ R = 0; G = 0; B = 254; incRed = 2; incGreen = 2; incBlue =0;}
    if(greenColor){ R = 0; G = 254; B = 0; incRed = 2; incGreen = 0; incBlue =2;}
    gr.setColor(getBackground());// Sets up the color for the erasing frame
    gr.fillRect(0 , 0,getSize().width, getSize().height);//Erases the old frames
    gr.setColor(Color.black);
    gr.drawString("V", imageXPostion[xPosition], imageYPosition);
    gr.drawRect(0,0,20,20);
    gr.drawRect(0,0, getSize().width - 1, getSize().height-1);
    gr.drawLine(getSize().width - 120,249,getSize().width,249);
    gr.drawRect(getSize().width -81,249,40,39);
    gr.drawRect(getSize().width - 121, 0, getSize().width - 121, getSize().height);
    gr.drawString("Green:",getSize().width - 115, 30);
    gr.drawString("Red  :",getSize().width - 115, 45);
    gr.drawString("Blue :",getSize().width - 115, 60);
    gr.setColor(Color.red); gr.fillRect(getSize().width - 120,250, 39, 39);
    gr.setColor(Color.green); gr.fillRect(getSize().width - 80,250, 39,39);
    gr.setColor(Color.blue); gr.fillRect(getSize().width - 40,250, 39, 39);

    for(int i = xSpiral.length -1; i>0 ; i--)
    {
      green = G; blue[i]  = B; red[i]   = R;
      xSpiral[i] = spiralXCenter - (spiralRadius)*Math.sin(Pi);
      ySpiral[i] = spiralYCenter + (spiralRadius)*Math.cos(Pi);
      spiralRadius +=1;  Pi -= (3.1415926535897932384626433832795/10);
      gr.setColor(new Color(red[i],green[i],blue[i]));
      gr.fillRect((int)xSpiral[i],(int)ySpiral[i],15,15);
      if( xMouse>= (int)xSpiral[i] && xMouse <= (int)xSpiral[i] + 15)
        if( yMouse>= (int)ySpiral[i] && yMouse <= (int)ySpiral[i] +15 && colorTouched !=1)
        {
          gr.fillRect(0,0,20,20);
          gr.setColor(Color.black);
          gr.drawString("" + G ,getSize().width - 75, 30);
          gr.drawString("" + R ,getSize().width - 75, 45);
          gr.drawString("" + B ,getSize().width - 75, 60);
          colorTouched =1;
        }
      R += incRed;  B +=incBlue;  G +=incGreen;
      gr.setColor(Color.black);
      gr.drawRect((int)xSpiral[i],(int)ySpiral[i],15,15);
    }
    if(colorTouched ==0) setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
    else setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
    // CROSSHAIR_CURSOR, DEFAULT_CURSOR,
    // E_RESIZE_CURSOR, HAND_CURSOR
    // MOVE_CURSOR, N_RESIZE_CURSOR,
    // NE_RESIZE_CURSOR, NW_RESIZE_CURSOR;
    // S_RESIZE_CURSOR,SE_RESIZE_CURSOR,
    // SW_RESIZE_CURSOR, TEXT_CURSOR,
    // W_RESIZE_CURSOR, WAIT_CURSOR
  }

  public void mouseDragged(MouseEvent evt){}
  public void mouseExited(MouseEvent evt){}
  public void mouseEntered(MouseEvent evt){}
  public void mousePressed(MouseEvent evt)
  {
    int x = evt.getX();  int y = evt.getY();
    if(x>=getSize().width - 120 && x<=getSize().width - 81)
    if(y>=250 && y <= 290){ redColor = true; blueColor = false; greenColor = false; xPosition =0; repaint();}
    if(x>=getSize().width - 80 && x<=getSize().width - 41)
    if(y>=250 && y <= 290){ redColor = false; blueColor = false; greenColor = true; xPosition =1; repaint();}
    if(x>=getSize().width - 40 && x<=getSize().width - 1)
    if(y>=250 && y <= 290){ redColor = false; blueColor = true; greenColor = false; xPosition =2; repaint();}
  }
  public void mouseClicked(MouseEvent evt){}
  public void mouseReleased(MouseEvent evt){ repaint();}
  public void mouseMoved(MouseEvent evt)
  {
    int x = evt.getX(); int y = evt.getY();
    xMouse = x; yMouse = y;
    repaint();
  }

} // end class spiralColor

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