PGraphic not updated in JAVA2D (while in P2D it works as expected)

Programming Questions

amnon.owed

PGraphic not updated in JAVA2D (while in P2D it works as expected)

in Programming Questions • 3 years ago

Hey everyone,

I ran into something weird. When using one pgraphic in another I noticed that in JAVA2D it wasn't working as expected, while in P2D it was working fine. Here is a small code example which reproduces this issue. Try saving the image multiple times. With JAVA2D the first image is saved every time, instead of the updated image. Not a big thing, but still I was wondering why this could be happening?

PGraphics pg;
PGraphics pgSave;
void setup() {
size(500,500);
pg = createGraphics(500,500,JAVA2D);
pgSave = createGraphics(500,500,JAVA2D); // saves correctly only once, then stops updating the image
// pgSave = createGraphics(500,500,P2D); // continues to update the image and thus saves correctly
pg.beginDraw();
pg.background(255);
pg.endDraw();
}
void draw() {
image(pg,0,0);
}
void mouseMoved() {
pg.beginDraw();
pg.ellipse(mouseX,mouseY,25,25);
pg.endDraw();
}
void keyPressed() {
if (key == 's') {
pgSave.beginDraw();
pgSave.image(pg,0,0);
pgSave.endDraw();
pgSave.save(year() + "-" + month() + "-" + day() + " " + hour() + "." + minute() + "." + second());
}
}

Replies(6)

blindfish

Re: PGraphic not updated in JAVA2D (while in P2D it works as expected)

3 years ago

Odd... The Reference would seem to suggest that the P2D option shouldn't work at all. Look at the createGraphics entry and you'll see that P2D is "not yet implemented"; which might explain why that's not consistent with JAVA2D... Unless of course it's not up-to-date.

Also I don't see any support for the image() method in the PImage reference; though admittedly that doesn't mean it doesn't support it ;)

Just in case you might want to try copy()...

mariuswatz

Re: PGraphic not updated in JAVA2D (while in P2D it works as expected)

3 years ago

Try throwing a pgSave.loadPixels() in there for good measure, not sure if it would work but I've had luck with that in the past.

PhiLho

Re: PGraphic not updated in JAVA2D (while in P2D it works as expected)

3 years ago

blindfish, he doesn't use a PImage but a PGraphics... And indeed, the createGraphics page is obsolete (like some others), I already reported this.

And indeed, it is quite strange... I don't see where the problem is.

blindfish

Re: PGraphic not updated in JAVA2D (while in P2D it works as expected)

3 years ago

Still my suggestion does work: replace the image() call in the save routine with copy() and it saves in both P2D and JAVA2D mode:

pgSave.copy(pg,0,0,width,height,0,0,width,height);

adamcsmit..

Re: PGraphic not updated in JAVA2D (while in P2D it works as expected)

3 years ago

I've wrestled with this issue while developing the napplet library, and found basically the same behavior: using the image() method to write data into a PGraphicsJava2D object doesn't work reliably. I've tried liberally sprinkling loadPixels() and updatePixels() around without success. (What's maddening about it is that I'm positive it worked just fine in the earliest incarnations of napplet, but for some reason it doesn't work now, and I can't figure out what I added that broke it.)

I've looked at the source code for PGraphicsJava2D, but I don't think I have the expertise to fully understand how it implelments pixel operations like image(). It looks to me like PGraphicsJava2D tries to access screen memory directly somehow in order to run faster.

Anyway, for now I think the best options are either to make sure you use P2D for any PGraphics you'll be using as a target for image(), or to use the copy() method instead as blindfish suggests (which means you can't use alpha in your pasted image, but as long as you're doing "opaque" stuff you should be fine.)

amnon.owed

Re: PGraphic not updated in JAVA2D (while in P2D it works as expected)

3 years ago

Thanks for the useful suggestions guys. Using copy() works fine, but in my sketch it wasn't handy because of some other code later on. So I ended up switching partly to P3D, since P2D was giving me coloring issues. So for me the workaround is working. But still it could be fruitful for future updates if someone could look into adam's suggestions or this issue in general...

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