Well, for the round rectangle part, you can let Java do much of the work for you. There's a convenient "RoundRectangle2D" class, with documentation here:

http://java.sun.com/j2se/1.4.2/docs/api/java/awt/geom/RoundRectangle2D.html

That, by itself, won't help you much, but notice that any object that implements Java's Shape interface must contain a "getPathIterator" method:

http://java.sun.com/j2se/1.4.2/docs/api/java/awt/Shape.html

If you dig a little more into the documentation, you'll find that you can combine this PathIterator with Processing's beginShape and endShape methods

(http://processing.org/reference/vertex_.html)

to draw a "java"-style shape using Processing. However, the gradient issue is where things get a little tricky.

If you're willing to stick with the Java2D renderer, you can pretty easily grab the Graphics2D object from Processing and then use Java2D directly to do the gradient fills. This will likely be much easier (and faster) then using Processing to approximate a gradient, although you lose the flexibility (and comfort!) of working strictly within the Processing API.

http://java.sun.com/j2se/1.4.2/docs/api/java/awt/Graphics2D.html

Cheers
greg

Here's a good place to get started:

http://java.sun.com/j2se/1.4.2/docs/api/java/awt/GradientPaint.html

And to get the Graphics2D object from Processing, use this (I'm not sure if it's strictly correct, but this is the general idea):

PGraphicsJava2D pgj = (PGraphicsJava2D)p.g;
Graphics2D g2 = pgj.g2;

Then, you can call various methods on the Graphics2D object to do some further drawing. This includes the draw, fill, and setPaint methods. See this documentation for more info:

http://java.sun.com/j2se/1.4.2/docs/api/java/awt/Graphics2D.html

I think the solution you gave me isn't going to work for me because i also need to make multiple gradients :)
for example: color1 to color2 to color3... :) and in the gradientpaint API it says i can only specify 2.

now i'm having something like this:
- first drawing the gradient
- then hiding the gradient with some rounded corners (but i need to drag and drop this so the backcolor can change, while the color of the rounded corners stays the same)


int h = this.getHeight()+STROKEWEIGHT;
int nboflines= (h/criterias.size())*2;
app.strokeWeight(0);

for(int i = 0; i< criterias.size()-1;i=i+1){
int rd = criterias.get(i).getParentCollection().getColor().getRed()/nboflines;
int gd = criterias.get(i).getParentCollection().getColor().getGreen()/nboflines;
int bd = criterias.get(i).getParentCollection().getColor().getBlue()/nboflines;
int ru = criterias.get(i+1).getParentCollection().getColor().getRed()/nboflines;
int gu = criterias.get(i+1).getParentCollection().getColor().getGreen()/nboflines;
int bu = criterias.get(i+1).getParentCollection().getColor().getBlue()/nboflines;
for(int j = 0; j<nboflines;j++){

int r = (criterias.get(i).getParentCollection().getColor().getRed()-(rd*j))+(j*ru);
int g = (criterias.get(i).getParentCollection().getColor().getGreen()-(gd*j))+(j*gu);
int b = (criterias.get(i).getParentCollection().getColor().getBlue()-(bd*j))+(j*bu);
app.stroke(r,g,b);
app.fill(r,g,b);
//app.line(getX()-(STROKEWEIGHT/2), (getY()+(i*nboflines)+j)+2, getX()+getWidth()+STROKEWEIGHT/2, (getY()+(i*nboflines)+j)+2);
app.rect(getX()-(STROKEWEIGHT/2), (getY()+(i*nboflines)+j)-STROKEWEIGHT/2, this.getWidth()+STROKEWEIGHT, 1);
}



}


app.fill(0);
app.stroke(0);
//upper left
app.beginShape();
app.vertex(getX()-STROKEWEIGHT/2, getY());
app.bezierVertex(getX()-STROKEWEIGHT/2,getY()-STROKEWEIGHT/4,getX()-STROKEWEIGHT
/4,getY()-STROKEWEIGHT/2,getX(),getY()-STROKEWEIGHT/2);
app.vertex(getX()-STROKEWEIGHT/2, getY()-STROKEWEIGHT/2);
app.vertex(getX()-STROKEWEIGHT/2, getY());
app.endShape();
//upper right
app.beginShape();
app.vertex(getX()+getWidth()+STROKEWEIGHT/2,getY());
app.bezierVertex(getX()+getWidth()+STROKEWEIGHT/2,getY()-STROKEWEIGHT/4,getX()+g
etWidth()+STROKEWEIGHT/4,getY()-STROKEWEIGHT/2,getX()+getWidth(),getY()-STROKEWE
IGHT/2);
app.vertex(1+getX()+getWidth()+STROKEWEIGHT/2,getY()-STROKEWEIGHT/2);
app.vertex(1+getX()+getWidth()+STROKEWEIGHT/2, getY());
app.endShape();

//under left
app.beginShape();
app.vertex(getX()-STROKEWEIGHT/2, getY()+getHeight());
app.bezierVertex(getX()-STROKEWEIGHT/2,getY()+getHeight()+STROKEWEIGHT/4,getX()-
STROKEWEIGHT/4,getY()+getHeight()+STROKEWEIGHT/2,getX(),getY()+getHeight()+STROK
EWEIGHT/2);
app.vertex(getX()-STROKEWEIGHT/2, 2+getY()+getHeight()+STROKEWEIGHT/2);
app.vertex(getX()-STROKEWEIGHT/2, 2+getY()+getHeight());
app.endShape();
//under right
app.beginShape();
app.vertex(getX()+getWidth()+STROKEWEIGHT/2,getY()+getHeight());
app.bezierVertex(getX()+getWidth()+STROKEWEIGHT/2,getY()+getHeight()+STROKEWEIGH
T/4,getX()+getWidth()+STROKEWEIGHT/4,getY()+getHeight()+STROKEWEIGHT/2,getX()+ge
tWidth(),getY()+getHeight()+STROKEWEIGHT/2);
app.vertex(1+getX()+getWidth()+STROKEWEIGHT/2,2+getY()+getHeight()+STROKEWEIGHT/
2);
app.vertex(1+getX()+getWidth()+STROKEWEIGHT/2, 2+getY()+getHeight());
app.endShape();