postToWeb cannot save PNG

arranger

in Contributed Library Questions • 2 years ago

Hi,
I'm trying to use the postToWeb library to upload to a server an image I'm creating in my program. When I specify the selected file type through a

setType()

I see that only with the JPEG and TIFF format the file gets saved on the software, not with the PNG one. The error it reports on the console is an exception:

java.lang.IllegalArgumentException: im == null!
at javax.imageio.ImageIO.write(ImageIO.java:1457)
at javax.imageio.ImageIO.write(ImageIO.java:1571)
at org.seltar.Bytes2Web.ImageToWeb.getBytes(ImageToWeb.java:142)
at hackatar.keyPressed(hackatar.java:304)
at processing.core.PApplet.handleKeyEvent(PApplet.java:1996)
at processing.core.PApplet.dequeueKeyEvents(PApplet.java:1979)
at processing.core.PApplet.handleDraw(PApplet.java:1643)
at processing.core.PApplet.run(PApplet.java:1530)
at java.lang.Thread.run(Thread.java:680)
<p><b>Error:</b> File is empty!</p>

am I missing something?

This is when I save it:

PImage img = get(0, controlOffset, width, wHeight); // I get a portion of the screen
img.save(path +".png"); // I save it locally
PGraphics pg = createGraphics(width, wHeight, P2D); // I create a PGraphics from it
pg.loadPixels();
img.loadPixels();
for (int i = 0; i < img.pixels.length; i++)
{
pg.pixels[i] = img.pixels[i];
}
ImageToWeb imgTW = new ImageToWeb(this); //Creating imageToWeb
imgTW.setType(ImageToWeb.PNG); //Setting Type
imgTW.post("test", url, "hacktion", true, imgTW.getBytes(pg)); //posting to wesite

Looking at the code of the library it seems that PNG and GIF are treated the same and maybe the solution can lie in how I built the PGraphics (am I doing it right?)

Replies(3)

arranger

Re: postToWeb cannot save PNG

2 years ago

I solved this problem: it was necessary to set the renderer to JAVA2D in createGraphics since postToWeb assumes that you are using that

corpuscal..

Re: postToWeb cannot save PNG

1 year ago

Hi! I am trying to do the same thing, but when I post the image, it comes up as all black. Any idea why?

Here is my code:

void takePicture() {
PGraphics pg = createGraphics(grabImage.width, grabImage.height, JAVA2D); // I create a PGraphics from it
pg.loadPixels();
grabImage.loadPixels();
for (int i = 0; i < grabImage.pixels.length; i++)
{
pg.pixels = grabImage.pixels;
}
// "this" references the processing PApplet itself and is mandatory here
img = new ImageToWeb(this);
img.setType(ImageToWeb.PNG);
// load the raw bytes from the thing
imgBytes = img.getBytes(pg);
// upload the picture
uploadPicture();
}
void uploadPicture() {
img.post("test", uploadURL, getTimestamp() + ".png", false, imgBytes);
}

http://www.jackkalish.com

PhiLho

Re: postToWeb cannot save PNG

1 year ago

for (int i = 0; i < grabImage.pixels.length; i++)
{
pg.pixels = grabImage.pixels;
}

This code is doubly useless: there are better ways to do it, and it does nothing useful lot of times...
You copy a reference of the grabImage.pixels array onto pg.pixels, ie. you replace one array by the other, as many times as there are pixels...

The code above by arranger shows an inefficient way to do it, another way is to use arrayCopy, or perhaps even get(), although I see that getBytes() wants a PGraphics instead of a PImage, which would have been more flexible. Well, an alternative to get() is image() to draw grabImage onto pg.
But, arrayCopy might be the most efficient, if you really need to make a copy, ie. if grabImage isn't in JAVA2D format (although I don't see why this format is needed). Otherwise, you can use getBytes() directly on grabImage.

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