public class ColorPicker 
{
  int  x, y, w, h, c;
  
  PImage cpImage;
  
  public ColorPicker ( int x, int y, int w, int h, int c )
  {
    this.x = x;
    this.y = y;
    this.w = w;
    this.h = h;
    this.c = c;
    
    cpImage = new PImage( w, h );
    
    init();
  }
  
  private void init ()
  {
    x = 250;
    y = 50;
    // draw color.
    int cw = w - 60;
    for( int i=0; i<cw; i++ ) 
    {
  float nColorPercent = i / (float)cw;
  float rad = (-360 * nColorPercent) * (PI / 180);
  int nR = (int)(cos(rad) * 127 + 128) << 16;
  int nG = (int)(cos(rad + 2 * PI / 3) * 127 + 128) << 8;
  int nB = (int)(Math.cos(rad + 4 * PI / 3) * 127 + 128);
  int nColor = nR | nG | nB;
      
  setGradient( i, 0, 1, h/2, 0xFFFFFF, nColor );
  setGradient( i, (h/2), 1, h/2, nColor, 0x000000 );
    }
    
    
  }

  private void setGradient(int x, int y, float w, float h, int c1, int c2 )
  {
    float deltaR = red(c2) - red(c1);
    float deltaG = green(c2) - green(c1);
    float deltaB = blue(c2) - blue(c1);

    for (int j = y; j<(y+h); j++)
    {
  int c = color( red(c1)+(j-y)*(deltaR/h), green(c1)+(j-y)*(deltaG/h), blue(c1)+(j-y)*(deltaB/h) );
  cpImage.set( x, j, c );
  
    }
  }
  
  private void drawRect( int rx, int ry, int rw, int rh, int rc )
  {
    for(int i=rx; i<rx+rw; i++) 
    {
  for(int j=ry; j<ry+rh; j++) 
  {
    cpImage.set( i, j, rc );
  }
    }
  }
  
  public void render ()
  {
    image( cpImage, x, y );
    if( mousePressed && mouseX >= x && mouseX < x + w && mouseY >= y && mouseY < y + h )
    {
  c = get( mouseX, mouseY );
    }
    fill( c );

    rect( x, y+h+10, 20, 20 ); //rectangle affichant la couleur;
  }
}