Question

I am trying to load images so I can use them as textures. I have libpng, but how do find a path to an image? Is it a bad idea to put it into .apk? Is there a better way?

Answer 1

It appears there are two ways of doing it. I can either do what Simon N. has suggested or I can convert the images into a C Array and compile them into the source. I choose to do the latter as I can do it easily on the native side. I have even created a python (v3.2) for converting a png file to a c array header and source file. It requires PyPNG

#!/usr/bin/env python

import png
import re
import itertools

def grouper(n, iterable, fillvalue=None):
    args = [iter(iterable)] * n
    return itertools.zip_longest(fillvalue=fillvalue, *args)

def expand(array):
    new_array = [];
    for row in array:
        for v in row:
            new_array.append(v)
    return new_array

def c_array_name(filename):
    '''converts the filename to the c array name'''
    return re.sub(r'\W', '_', filename)

def c_array_header_filename(filename):
    '''converts the filename to the c array header filename'''
    return "{0}.h".format(filename)

def c_array_source_filename(filename):
    '''converts the filename to the c array source filename'''
    return "{0}.cpp".format(filename)

def c_array_header(filename):
    '''returns a string that is the c array header,
    where
        filename is the png file'''
    name = c_array_name(filename)
    return """
#ifndef __{0}__
#define __{0}__

#include <stdint.h>

extern uint_least32_t const {1}[];

#endif /* __{0}__ */
""".format(name.upper(), name)

def c_array_source(filename, header_filename, array_string):
    '''returns a string that is the c array source,
    where
        name is the value from c_array_name
        array_string'''
    name = c_array_name(filename)
    return """
#include "{0}"

uint_least32_t const {1}[] = {{
{2}
}};
""".format(header_filename, name, array_string)

def convert_data_array_string(data):
    '''returns a string of hexes of bytes, 
    where
        data is a map of bytes'''
    return ", ".join(["0x{:02x}{:02x}{:02x}{:02x}".format(a, b, g, r)
        for r, g, b, a in grouper(4, expand(data), 0)])

def png_data_from_file(path):
    '''returns a map of bytes of the png file'''
    with open(path, 'rb') as file:
        reader = png.Reader(file = file)
        data = reader.read();
        return list(data[2]);

if __name__ == '__main__':
    import sys
    import os
    if len(sys.argv) != 2:
        sys.stdout.write("{0} image_path".format(sys.argv[0]))
        exit()
    path = sys.argv[1]
    filename = os.path.split(path)[1]
    header_filename = c_array_header_filename(filename)
    sys.stdout.write("Creating header file '{}'... ".format(header_filename))
    with open(header_filename, 'w') as header_file:
        header_file.write(c_array_header(filename))
    sys.stdout.write("done\n")
    source_filename = c_array_source_filename(filename)
    sys.stdout.write("Creating source file '{}'... ".format(source_filename))
    data = png_data_from_file(path)
    with open(source_filename, 'w') as source_file:
        source_file.write(c_array_source(filename, header_filename, convert_data_array_string(data)))
    del data
    sys.stdout.write("done\n")