On 4-Jun-06, at 11:16 AM, Bert Freudenberg wrote:
>>
>> Ah, Squeak bitmaps are BIG endian, not little. The first
>> implementation was 68k mac based and the PPC. Us little endian
>> guys (ARM, x86 etc) had all sorts of fun developing efficient
>> Squeak 'Display' to actual glass transfer routines. You would most
>> likely benefit most from looking at the Mac code for this stuff.
>> You might need to convert the *pixel* format though since not
>> every platform is RGB. RISC OS is little-endian BGR for example,
>> some thing that took a lot of attention to resolve in the early
>> days of Squeak.
>
> Note, though, that the recent bitblt code can deal with both,
> little *and* big endian RGB. While big endian is standard, little
> endian is indicated by negative depth values. However, I guess a
> 2.3 image might not have the in-image support for negative bit
> depths, yet, and also, it might not call the hasDisplayDepth
> primitive. Implementing bit shuffling for big endian still is the
> most compatible way.
I never did manage to get that stuff to work on RISC OS,
unfortunately. It certainly doesn't cope with pixel format
conversions, for one thing. 2.3 doesn't have image support for it and
I don't think VM support went in until about 3.4 or so; could be wrong.
tim
--
tim Rowledge;
tim@...;
http://www.rowledge.org/timDisclaimer: Any errors in spelling, tact, or fact are transmission
errors.
