[Cuis-dev] [FIX] Re: BMP Reader broken

[Vanessa Freudenberg]

Hmm, curious. While the fix does make it work, it doesn't explain why it
worked on SqueakJS without the fix.

I think the root cause might be that the behavior of
"next:into:startingAt:" changed. It has a time stamp of "jmv 1/8/2024" .

Oh yes. Ooops. When I said it works on SqueakJS, I was actually on a 6.2
image. In a 6.3 image I get the same error.

So while my fix works, maybe it would be better to fix the regression in
"next:into:startingAt:" instead.

Vanessa

On Sat, Mar 16, 2024 at 6:39 PM Vanessa Freudenberg <vanessa at codefrau.net>
wrote:

> Attaching a fix. Not entirely sure what the right process to submit fixes
> is, this is my first. Apparently you use git but not pull requests?
>
> Anyways, the error happened because the code used
>     stream nextInto: pixelLine
> which calls "next:into:startingAt:" which does not read across chunk
> boundaries from the file primitive.
>
> My fix changes the code to use
>      stream readInto: pixelLine startingAt: 1 count: pixelLine size
> which uses "nextBytes:into:startingAt:" which reads across chunk
> boundaries by fetching more contents from the file.
>
> In Squeak, "nextInto:" calls "readInto:startingAt:count:" that's why it
> keeps working there.
>
> Vanessa
>
> On Sat, Mar 16, 2024 at 4:30 PM Vanessa Freudenberg <vanessa at codefrau.net>
> wrote:
>
>> FWIW, dropping splash.bmp into Cuis-6.2 running on SqueakJS works just
>> fine (try here: https://tinyurl.com/squeakjs-cuis62)
>>
>> As does Dave's expression.
>>
>> SqueakJS does not have BMPReadWriterPlugin so the primitive fails. The
>> fallback code works fine.
>>
>> Vanessa
>>
>> On Sat, Mar 16, 2024 at 2:28 PM lewis--- via Cuis-dev <
>> cuis-dev at lists.cuis.st> wrote:
>>
>>> Hi Hilaire,
>>>
>>> I compared the behavior in Squeak with both opensmalltalk-vm and with V3
>>> interpreter VM.
>>>
>>> In Squeak:
>>> ImageReadWriter formFromFileNamed: 'splash.bmp'. "==> Form(400x300x32)"
>>>
>>> In Cuis (with the same VM):
>>> ImageReadWriter formFromFileEntry: 'splash.bmp' asFileEntry. "==> Error"
>>>
>>> I see two possible issues here.
>>> 1) The call to #primitiveRead24BmpLine is failing in both Squeak and
>>> Cuis. This may be a problem in the VM plugin (or maybe it is expected in
>>> this case, I am not sure).
>>>
>>> 2) In the primitive fallback code in method
>>> #read24BmpLine:into:startingAt:width: the error happens at the "formBits
>>> at: (bitsIndex := bitsIndex+1) put: rgb". The formBits is a BitMap, so
>>> maybe the some difference between Squeak and Cuis here.
>>>
>>> I also tried Squeak with a V3 image and interpreter VM, and the results
>>> are the same as with opensmalltalk-vm. The form is created successfully,
>>> and the #primitiveRead24BmpLine call fails and goes to the fallback code.
>>>
>>> At this point I cannot say if there primitive failure is a problem in
>>> the VM plugin, or if the primitive failure is normal and expected for this
>>> particular case. But I can say that the actual Error in Cuis must be
>>> something related to the fallback code when it updates the formBits BitMap.
>>>
>>> Dave
>>>
>>>
>>> On 2024-03-16 18:47, Hilaire Fernandes via Cuis-dev wrote:
>>>
>>> Hi folks,
>>>
>>> It looks like the BMP reader is broken.
>>>
>>> ImageReadWriter formFromFileEntry: 'splash.bmp'.
>>>
>>> Could it be a VM issue? Seem to occure in a plugin. I am not forwarding
>>> to VM mailing list for now, waiting for more advices.
>>>
>>> See screen capture and bmp example known to load previously.
>>>
>>> --
>>> GNU Dr. Geohttp://gnu.org/s/dr-geo/http://gnu-drgeo.blogspot.com/
>>>
>>>
>>>
>>>
>>> --
>>> Cuis-dev mailing list
>>> Cuis-dev at lists.cuis.st
>>> https://lists.cuis.st/mailman/listinfo/cuis-dev
>>>
>>
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