lvandeve
commented
3 years ago This is for the following reason: there are potential scenarios where one may want to append, e.g. encode a png image into some stream that embeds a PNG image. For decoding it's in case one wants to decode raw pixels at the end of some existing stream.
It's easy to clear the array before calling encode/decode, and in most cases one would use a freshly initialized array anyway.
On the other hand if the encoder/decoder would overwrite an existing array, the user has to append which is slightly harder.
So since it's easier to clear, than to append, the behavior chosen is to append, not to clear and overwrite
alecazam
There are a couple spots where lodepng inserts onto the end of the out buffer passed in. Callers more likely expect a resize instead of a constantly growing buffer. This would happen if the out buffer was reused to load another image.
Alternately, clearing the out array before the insert would also work.
unsigned decode(std::vector& out, unsigned& w, unsigned& h, const unsigned char in,
size_t insize, LodePNGColorType colortype, unsigned bitdepth)
{
unsigned char buffer;
unsigned error = lodepng_decode_memory(&buffer, &w, &h, in, insize, colortype, bitdepth);
if(buffer && !error)
{
State state;
state.info_raw.colortype = colortype;
state.info_raw.bitdepth = bitdepth;
size_t buffersize = lodepng_get_raw_size(w, h, &state.info_raw);
out.insert(out.end(), &buffer[0], &buffer[buffersize]); <- should this use reize
lodepng_free(buffer);
}
return error;
}