Downloading & Displaying An Image

Hey folks! I'm taking a dive into some new APIs today, and I'm having a little bit of trouble. Here is my goal in the program:

1. Download an image from a URL (in this example, cobblestone: http://i.imgur.com/hNFQzKp.png)
2. Load the image using paintutils
3. Display the image using paintutils

And here's my code..

downloadImage = http.get("http://i.imgur.com/hNFQzKp.png")
loadImage = paintutils.loadImage("downloadImage")
paintutils.drawImage(loadImage, 1, 1)

Currently that's returning the following error:

paintutils:92: attempt to get length of nil

Which I assume means it's not downloading the image correctly, but I have no way of testing. I'm on a multiplayer server and don't have access to the file system. Any help is appreciated :)/>

because you cant display images -_-/>
your doing it all wrong

http.get returns a handle(?) but you have to do

 downloadImage.readAll() --# to get actual data
downloadImage.close() --# dont forget to close 

jay5476, on 25 September 2013 - 07:28 PM said:

http.get returns a handle(?) but you have to do

 downloadImage.readAll() --# to get actual data
downloadImage.close() --# dont forget to close 

Okay, so should my code look like this?

downloadImage = http.get("http://i.imgur.com/hNFQzKp.png")
downloadImage.readAll()
loadImage = paintutils.loadImage("downloadImage")
paintutils.drawImage(loadImage, 1, 1)
downloadImage.close()

Or do I need to assign downloadImage.readAll() to a variable, like this:

downloadImage = http.get("http://i.imgur.com/hNFQzKp.png")
readImage = downloadImage.readAll()
loadImage = paintutils.loadImage("readImage")
paintutils.drawImage(loadImage, 1, 1)
downloadImage.close()

You can't directly display a PNG with the paintutils API. It will only work with the text-based image format ComputerCraft uses. You would need to write a program to convert and palettize the image data from the PNG into the ComputerCraft format.

Lyqyd, on 25 September 2013 - 08:00 PM said:

You can't directly display a PNG with the paintutils API. It will only work with the text-based image format ComputerCraft uses. You would need to write a program to convert and palettize the image data from the PNG into the ComputerCraft format.

Oh… darn… Has anyone written a program that does that? That is WAAAAAY out of my league.

EDIT: Also, I should add, I'm using OpenPerihperal Terminal Glasses, which can display more than 16bit.

Sigh. ComputerCraft displays aren't "16 bit". I've no idea where that nonsense comes from. Paintutils couldn't draw to the terminal glasses anyway, without a terminal redirect of some sort.

There is a program somewhere on the forums that does this, though I'm not sure whether it is for .jpg or .png. Search for "image converter" and you should be able to find it.

Lyqyd, on 25 September 2013 - 08:31 PM said:

Sigh. ComputerCraft displays aren't "16 bit". I've no idea where that nonsense comes from.

There is a program somewhere on the forums that does this, though I'm not sure whether it is for .jpg or .png. Search for "image converter" and you should be able to find it.

Haha sorry. I found an applet that let me convert, and the quality looked like 16bit, so I just assumed… Should I be converting to NFP?

Yeah, nfp is the correct format.

Okay, cool, I'll work on that. Thanks!

EDIT: I found this program, but.. I'm not sure, it's giving me trouble. I don't know what the best way to go about this is: I was hoping to be able to automatically create sprites for blocks in the game, but I'm not sure that's possible.

Also another problem, you do not need speech/quotation marks to load the image, as the image you have downloaded is in the variable 'download'. You just do:

paintutils.loadImage(download)

instead of

paintutils.loadImage("download")

paintutils.loadImage loads an image from a file. You then pass the file name to it - not the actual image data. You have to save the downloaded image to a file before you load it.