Flickering when using the Java frame.resize() method

Programming Questions

thebigboo

Flickering when using the Java frame.resize() method

in Programming Questions • 1 year ago

Hello,

I'm quite familiar to Processing but I'm still starting to learn how to use other Java methods in my sketches.

Whenever I continuously use any method that resizes the Java frame, such as setSize(), the application window starts flashing white.

This is an example of what I'm talking about:

int windowHeight=200;

void setup() {

size (200, 200);

smooth();

stroke(0);

fill(255);

ellipseMode(CORNER);

}

void draw() {

background(128);

for (int i=0;i<100;i++){

ellipse((i/10)*20,(i%10)*20,20,20);

}

windowHeight++;

frame.setSize(200,windowHeight);

}

Curiously, the flickering happens more frequently in some computers than others, and apparently in some computers it doesn't happen at all. If you don't see the flickering, try dragging the window while it grows, it should get more intense.

Also, I found out you can change the color of the flash by using this line in the setup() method:

setBackground(new java.awt.Color(255,0,0));

I've searched through the web and found other people who had the same problem in Java forums, but apparently no one found a solution.

Does anyone know a way to prevent this from happening? Thanks in advance.

Replies(2)

PhiLho

Re: Flickering when using the Java frame.resize() method

1 year ago

GUI applications aren't designed to be continually resized... Only recently, on Windows at least, one is able to resize a window while still seeing what is inside. Before that, the window was blanked until the user released the mouse. Some window systems only shows a skeleton to show the current frame size, keeping the original size unchanged until the end of the action.
On Windows 7, if I resize the side of my text editor (written in C++ with native Windows calls), the content is relatively stable but I see the scrollbar and the status bar to flicker a lot.

In your sketch, there might be a conflict between the normal Processing cycle (redrawing the content at the end of draw()) and the redrawing asked by the resize operation, at a variable rate.
If I delay the latter, it flickers a little less, although still a bit:

javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
frame.setSize(200,windowHeight);
}
});

As you saw, I doubt there is a good solution, as we cannot control the system's redrawing. And that probably won't be fixed by the designers of the system as, again, GUI are not designed for such behavior: a little flickering isn't important when resizing manually, and continuous, programmed resizing is quite uncommon...

thebigboo

Re: Re: Flickering when using the Java frame.resize() method

1 year ago

Thanks for the suggestion and the enlightenment on that issue.

It sucks to learn that probably there's no complete solution to this =/

I noticed that dropping the Processing framerate to 20fps makes the flashing much better (though it's not completely eliminated), perhaps it's closer to Java's refresh rate for the window resizing. Unfortunately, my program (which is far more complex than the example I posted here) was made with 30fps in mind and changing the framerate would mess up with a lot of animations and behaviors.

If anyone else can find a solution for synchronizing the Processing cycle and the Java resize refresh rate, I'd be very grateful.

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