Question

I’m writing a texture loader, attempting to use libpng with it. I am currently stumped on one tiny part, which makes no sense. I’m trying to get the image width and height, and am finding that the returned values are not saving.

unsigned int width;
unsigned int height;

...

width = png_get_image_width(png_ptr, info_ptr);
height = png_get_image_height(png_ptr, info_ptr);

printf("Width: %d\nHeight: %d\n\n", width, height);
printf("Width: %d\nHeight: %d\n\n", png_get_image_width(png_ptr, info_ptr), png_get_image_height(png_ptr, info_ptr));

This returns the following:

Width: 0
Height: 0

Width: 1024
Height: 2048

So what’s the deal? This should work, but it is very clearly not.

Pastbin of all relevent code: http://pastebin.com/9RP1iqqU

Answer 1

It looks like you’re using the wrong type. width and height should be png_uint_32 not unsigned int

UPDATE:

After seeing your pastebin, it looks like you’re passing in width and height to the function as unsigned char which are effectively hiding the class members width and height and is probably not what you want, specifically since unsigned char can only hold values up to 255 and the width and height are 1024 and 2048.

Just rename the function parameters.