# The screen is updating after while loop is completed ? need help
**URL:** https://discourse.processing.org/t/the-screen-is-updating-after-while-loop-is-completed-need-help/7119
**Category:** Beginners
**Created:** [January 2, 2019, 9:52pm UTC](https://discourse.processing.org/t/the-screen-is-updating-after-while-loop-is-completed-need-help/7119 "2019-01-02T21:52:07Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@liceroy](https://discourse.processing.org/u/liceroy)
#### Post date: [January 2, 2019, 9:52pm UTC](https://discourse.processing.org/t/the-screen-is-updating-after-while-loop-is-completed-need-help/7119/1 "2019-01-02T21:52:07Z")
I am using " delay() " inside while loop and making some changes in the screen. I was hoping the changes will be visiable since I am using delay(1000) in every while loop but only the final result is printed on screen . I am not doing anything inside draw function. I am trying to make a event based system where user can interact with just mouse and keyboard.
I want to run while loop such that it will show me the changes I made on screen after every iteration for 1sec then proceed forward.
my code is something like this
```auto
while(){
…
…
delay(1000);
..
..
}
```
---
### Author:  [@Sky](https://discourse.processing.org/u/Sky)
#### Post date: [January 2, 2019, 10:08pm UTC](https://discourse.processing.org/t/the-screen-is-updating-after-while-loop-is-completed-need-help/7119/2 "2019-01-02T22:08:05Z")
The rects(),and every shape,text… is displayed everytime draw() is called, this means everything u change in your while, cant be seen until your while terminates and draw() is called once again.
" **draw()** is called automatically and should never be called explicitly. All Processing programs update the screen at the end of draw(), never earlier. "
[https://processing.org/reference/draw\_.html](https://processing.org/reference/draw_.html)
“The screen only updates when the end of **draw()** is reached, so **delay()** cannot be used to slow down drawing. For instance, you cannot use **delay()** to control the timing of an animation.”
[https://processing.org/reference/delay\_.html](https://processing.org/reference/delay_.html)
If you want to “slow” the draw() function, you can use frameRate(num\_of\_frame\_per\_sec)
(Default is 60fps)
[https://processing.org/reference/frameRate\_.html](https://processing.org/reference/frameRate_.html)
(I hope I didnt misunderstood your problem)
---
### Author:  [@kll](https://discourse.processing.org/u/kll)
#### Post date: [January 3, 2019, 1:08am UTC](https://discourse.processing.org/t/the-screen-is-updating-after-while-loop-is-completed-need-help/7119/3 "2019-01-03T01:08:06Z")
here a example using a millis timer:
```auto
long startT, stopT=1000;
float ang = 0;
float colc;
color rf;
void setup() {
size(500, 500);
colc=random(255);
rf=color(colc, 0, 255-colc);
}
void myTimer() {
if ( millis() > startT + stopT ) {
startT = millis();
println("_next loop_");
// what else you need to be done now?
ang++;
colc=random(255);
rf=color(colc, 0, 255-colc);
}
}
void draw() {
background(255, 244, 206);
myTimer();
translate(width/2, height/2);
rotate(ang *TWO_PI/60.0);
draw_object();
}
void draw_object() {
stroke(0, 0, 200);
line(0, 0, 50, 50);
fill(rf);
rect( 50, 50, 20, 20);
}
```
---
### Author:  [@liceroy](https://discourse.processing.org/u/liceroy)
#### Post date: [January 20, 2019, 6:37pm UTC](https://discourse.processing.org/t/the-screen-is-updating-after-while-loop-is-completed-need-help/7119/4 "2019-01-20T18:37:50Z")
@Sky
Sorry for replying late , I was busy implementing max heap and some other stuff in processing. I didn’t knew that screen was updated after draw() xD .
The problem is now solved, thanks you.
---
### Author:  [@Sky](https://discourse.processing.org/u/Sky)
#### Post date: [January 20, 2019, 7:36pm UTC](https://discourse.processing.org/t/the-screen-is-updating-after-while-loop-is-completed-need-help/7119/5 "2019-01-20T19:36:28Z")
No problem, I’m glad you solved the problem