From: "meinrad.recheis" <my.name.here@...>
Date: 2003-05-12T14:58:53+09:00
Subject: Re: efficiency advice needed

On Mon, 12 May 2003 08:31:58 +0900, Ryan Pavlik <rpav@nwlink.com> wrote:

> On Mon, 12 May 2003 06:56:27 +0900
> "meinrad.recheis" <my.name.here@gmx.at> wrote:
>
> <snip>
>> data = ''
>> (width*height).times{
>> data += rgb.read( 3) + alpha.read( 1)
>> }
>>
>> i think alternately reading some bytes is slowing down alot. but also 
>> loops operating on strings are
>> slow, i think. i know some solutions, but i don t know which one to use.
>> are there any suggestions how to do this most efficiently in ruby?
> <snip>
>
> Read everything into an array or string and go from there... I don't
> thing String operations are particularly slow, but I could be wrong.
> You _might_ read in the entire file as a string (or a given chunk, for
> scaleability's sake), String#unpack it, and go from there, but that
> sounds like a waste of memory for something like this.
>

unpacking makes no sence for me.

i lately thought of inserting the alpha characters into the rgb string 
using String#insert from
back to front, so i don t need to worry about changing indices (due to 
insertion) and i can Striong#chop! off the used alpha bytes.

there are several other ways to do it, but i allways want to keep code 
short and easy.

thanks for comments, mr.

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