Hello, i'm attempting to make a simple drawing app similar to the flash one on ratemydrawing.com, but before my app reaches anything near the number of vertices required for a semi-decent drawing, it begins to seriously chug. Is there any way of improving the efficiency of drawing thousands of lines, perhaps by combining each section into a shape? I've attempted to use drawing onto a canvas instead (which meant that the number of lines draw didn't affect the framerate) but to get the canvas size I wanted it had to be huge...and the memory usage was off the charts!

Thanks,
Rob

/*
Buttons:
1 - draw (drag mouse to draw)
2 - move  (drag mouse to move)
*/

PFont font;

int fps=60;
int dX=800;
int dY=800;

ArrayList userPoints=new ArrayList();

boolean mouse=false;
int viewX=0;
int viewY=0;
int dragStartX=0;
int dragStartY=0;
int tool=0;

void setup(){
 size(dX,dY);
 frameRate(fps);
 smooth();
 background(255);
 font=createFont("Arial",12);
 textFont(font,12);
}

void draw(){
 background(255);
 
 if(mousePressed){
   
   //button held
   if(!mouse){
     if(tool==0){
       userPoints.add(new Point(mouseX-viewX,mouseY-viewY));
     }
     if(tool==1){
       dragStartX=mouseX-viewX;
       dragStartY=mouseY-viewY;
     }
   }
     
   
   //add point
   if(tool==0)
   if(!(mouseX==pmouseX && mouseY==pmouseY)|| !mouse){
     userPoints.add(new Point(mouseX-viewX,mouseY-viewY));
   }
    //set drag start pos
   if(tool==1){
     viewX=(mouseX-dragStartX);
     viewY=(mouseY-dragStartY);
   }
   
   mouse=true;
 }
 //released
 else
 if(mouse){
   if(tool==0){
     userPoints.add(new Point());
   }
   mouse=false;
 }
 
 //draw lines
 if(userPoints.size()>0){
   for(int i=0;i<userPoints.size()-1;i++){
     Point p2=(Point)userPoints.get(i+1);
     Point p1=(Point)userPoints.get(i);
     if(!p2.empty && !p1.empty){
       int x2=p2.x+viewX;
       int y2=p2.y+viewY;
       int x1=p1.x+viewX;
       int y1=p1.y+viewY;
       stroke(0);
       strokeWeight(3);
       line(x1,y1,x2,y2);
     }
     noFill();
   }
 }

 fill(0);
 //show view position
 text("("+-viewX+","+-viewY+")",10,20);
 text("Num vertices: "+userPoints.size(),width/2,20);
 text("fps: "+frameRate,width/4,20);
 if(tool==0)text("Drawing",width-50,20);
 if(tool==1)text("Moving",width-50,20);
}

void keyPressed(){
 if(key=='1'){
   tool=0;
 }
 if(key=='2'){
   tool=1;
 }
}

public class Point{
 int x,y;
 boolean empty=false;
 Point(){
   empty=true;
   x=0;
   y=0;
 }
 Point(int x,int y){
   this.x=x;
   this.y=y;
 }
 
 void setPos(int x,int y){
   this.x=x;
   this.y=y;
 }
 
 String toString(){
   if(!empty)return x+" "+y;
   else return "-";
 }
}

Cheers for the swift reply. Sorry, used a bit of welsh lingo there...chug just means to seriously slow down. I've done as you've suggested and seperated the mouse stuff into the callbacks; it looks a lot nicer now.
The canvas size I wanted was infinite! So I was using a set of 4 canvases that scrolled as you moved which eventually looping back to the start and drawing the new content when off screen. So the effect was an infinite canvas. But the there was a serious memory issue because you needed 4 PGraphics each larger than the window size in memory at one time. Any ideas?

Is flash significantly more efficient at drawing than java? Because that ratemydrawings flash applet can handle several times more vertices.

Cheers,
Rob

Well, the Flash applet doesn't handle infinite canvas, does it?
Beside, if you have an infinite canvas, you would need infinite variables to store the coordinates...
This infinite canvas complicates the problem, because it is harder to put in cache the strokes: if you reveal a portion of canvas, you would need to repaint that part with the strokes there...