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[mechacrash]

I am looking at implementing a PNG loader into my program but I don't know how to. I have searched google a lot and everything uses a png library. I really dont want to use one so I was wondering if someone could link me somewhere where I could get the code for loading pngs.

I realise it's not going to be easy or a short method to decompress but I don't want to use a library or any extra .dlls if possible.

[brog]

read the PNG spec and code it yourself.
or, you know, just use a library.

[Saint]

You could use stb_image; http://www.ohloh.net/p/7147 or http://nothings.org/

It's not a library, just a c file that you can jam directly into your project with the rest of your code. It's also public domain so you can use it however you want.

Or if you desperately want to write your own, download stb_image and read the code. Also, there is probably documentation on any other formats you might like over at Wotsit ( http://www.wotsit.org/ ), but this means you will have to write your own zlib unpacker as well.

[LemonScented]

I use PicoPNG: http://members.gamedev.net/lode/projects/LodePNG/picopng.cpp although you might also consider the slightly less cryptic LodePNG by the same author: http://members.gamedev.net/lode/projects/LodePNG/

No extra libraries or DLLs to link to, just a couple of files you should be able to drop straight into a project and get working right away. Best not to spend too much time trying to work out HOW that code works, mind - just trust that it does! 

[mcc]

I haven't used the PicoPNG version, but LodePNG is fantastic, can also create PNGs, is easy to use and easy to integrate. Like LemonScented says t's not exactly a library, LodePNG like PicoPNG is a single source code file + header so you can just add it to your project. You can use it like this:

Code:

	LodePNG_Decoder decoder;
	LodePNG_Decoder_init(&decoder);
	unsigned char* buffer;
	unsigned char* image;
	size_t buffersize, imagesize;
	
	LodePNG_loadFile(&buffer, &buffersize, filename); /*load the image file with given filename*/
	
	if ( !buffer || buffersize <= 0 ){
		printf("Couldn't open file: %s\n", filename);
		return;
	}
	
	LodePNG_decode(&decoder, &image, &imagesize, buffer, buffersize); /*decode the png*/
	
	int width = decoder.infoPng.width; height = decoder.infoPng.height;
	
	init(width, height);
	uint32_t *image2 = (uint32_t *)image;
	for(int x = 0; x < decoder.infoPng.width; x++) {
		for(int y = 0; y < decoder.infoPng.height; y++) {
			uint32_t pixel = htonl(image2[y * decoder.infoPng.width + x]);
			// DO WHATEVER HERE
		}
	}	
	
	free(buffer); free(image);

[Ivan]

Just use libpng itself, its like 10 lines of code to read in RBGA pixel data.

Here's some really old code of mine to read it, so you can use that as a start:
http://code.google.com/p/owlcountry/source/browse/trunk/pngLoad.c

[slembcke]

http://files.slembcke.net/misc/PNGTexture.tar.gz

Shows how to load a PNG as an RGBA texture using the official library (supports every format of PNG file), set up a GLUT window and load the texture. All in 150 lines of code. You can statically link against libPNG without any licensing issues, so I don't see why you wouldn't want to do that really...

[Sos]

i see you need some fresh SOIL for your opengl game

try here: http://www.lonesock.net/soil.html

simple opengl image loader, it's the simplest ever.