Image larger then canvas, save-able to PNG

General Discussion Other

grouchysm..

Image larger then canvas, save-able to PNG

in General Discussion • Other • 11 months ago

Hi there,

Let me first introduce myself as it's the very first post on the forum -- my name is Lukasz, 33, Warsaw in Poland. It's been few months I've been tinkering with Processing; it's a great piece of software. Each day I catch myself thinking that human creativity has literally no boundaries.

The question follows.

There is a generated image, a noise map, for example, of size X vs Y. The size of the canvas is x vs y, where y<Y and x=X (the more generic question would be when x<X but it's not the case here).

The image is generated, row by row, from the very top, downwards, successively filling the canvas. What I would like to achieve is to scroll the image, moving up the top rows, so that the rows which are about to be created at the bottom of the canvas, would fill in the empty space. On a keypress, however, the system should save the *whole* image to the disk -- the image, mind you, would be of height greater that the height of the canvas.

What is the generic way to achieve that?

Cheers,

Ł.

Replies(9)

quarks

Re: Image larger then canvas, save-able to PNG

11 months ago

One answer would be to use

createGraphics - to create an off screen buffer large enough for the biggest image
draw the lines to the buffer
get to get the part of the buffer to display

then when you hit the appropriate key

use get to get an image of the part of the buffer drawn to
then save the image

grouchysm..

Re: Image larger then canvas, save-able to PNG

11 months ago

Not very convoluted, is it? I will try to incorporate this into the code later this day. Thanks for a swift reply, quarks.

grouchysm..

Re: Image larger then canvas, save-able to PNG

11 months ago

Right, so is it a standard behaviour of PGraphics that its rendering is much worse than the rendering of the original canvas? Lines are jaggy and not smooth at all. And I do use the same render in the canvas and in PGraphics.

quarks

Re: Image larger then canvas, save-able to PNG

11 months ago

Which renderer are you using?

Try an alternative e.g. JAVA2D instead of P2D

grouchysm..

Re: Image larger then canvas, save-able to PNG

11 months ago

In terms of quality, JAVA2D > P2D, right?

I am giving it a try; processing seems to have some sort of hiccups with either JAVA2D or P2D -- it slows down beyond being usable.

grouchysm..

Re: Image larger then canvas, save-able to PNG

11 months ago

It works now but it's very very slow. What I cam up with so far is that:

if (p.draw) p.draw(pg);
PImage pi=pg.get(0,0,width,height);
image(pi,0,0,width,height);

"p" is the instance of the object that draw the image. p.draw(pg) draws to the buffer which is then copied to pi, object of PImage type which is then pasted onto canvas by the "image" function. It works, but it is slow; moreover, after a while I get a out of memory error. Yikes!

EDIT: width=1200, height=500, FWIW.

PhiLho

Re: Image larger then canvas, save-able to PNG

11 months ago

Instead of:

if (p.draw) p.draw(pg);
PImage pi=pg.get(0,0,width,height);
image(pi,0,0,width,height);

you can just do:

if (p.draw) p.draw(pg);
image(pg, 0, 0);

(if pg has dimensions width x height).
That's one image copy less to do... And it might solve your OOME problem...

grouchysm..

Re: Image larger then canvas, save-able to PNG

11 months ago

pg is larger than the image as per quarks recommendation.

I solved the problem: I write to the canvas instead of writing to pg -- once the canvas is filled, its content is copied to pg and then it's cleared.

Not exactly what had in mind when asking the question but it works.

PhiLho

Re: Image larger then canvas, save-able to PNG

11 months ago

Ah, OK, I skimmed the topic too fast... That's another opportunity to regret that image() isn't able to take a part of an image, the get() intermediary step is memory intensive.

Top Reply