[Cuis-dev] BMP Reader broken

[Juan Vuletich]

Hi Dave,

On 3/18/2024 12:35 PM, lewis--- via Cuis-dev wrote:
>
>  Hi Juan,
>
> On 2024-03-17 18:17, Juan Vuletich via Cuis-dev wrote:
>
>> Hi Dave,
>>
>> On 3/16/2024 6:22 PM, lewis--- via Cuis-dev wrote:As I said in a 
>> separate email, Vanessa found the origin of the problem, and the fix 
>> is now at GitHub.
>>
>> Still, as you say, the primitive fails, both in Cuis and Squeak, but 
>> only the first time it is called. The lines are read in reverse 
>> order, so the line that is first copied is actually the last one.
>>
>> In #read24BmpLine:into:startingAt:width:, at the start of the 
>> fallback code, I added this line: `{formBitsIndex+width. formBits 
>> size} print.`. Then tried to load Hilaire's BMP. In the Transcript I 
>> got #(63601 63600). So, in BMPReadWriterPlugin.c, the lines that read:
>>
>>     if (!(((formBitsIndex + width) <= formBitsSize)
>> && ((width * 3) <= pixelLineSize))) {
>>         return primitiveFail();
>>
>> should actually read
>>
>>     if (!(((formBitsIndex + width - 1) <= formBitsSize)
>> && ((width * 3) <= pixelLineSize))) {
>>         return primitiveFail();
>>
>> and the primitive will not fail.
>>
>> It is a minor bug, with no practical consequences, so this is not 
>> really important. But I found this while investigating the BMP read 
>> failure, and I thought it was worth commenting.
>>
>> Thanks,
>
>
> The expression appears in both 
> BMPReadWriterPlugin>>primitiveRead24BmpLine and 
> BMPReadWriterPlugin>>primitiveWrite24BmpLine. Can you please confirm 
> my assumption that the same fix should be applied to both methods? 
> Sorry if this is obvious but I just want to be sure.
>
> Thanks!
>
> Dave
>

Yep. Checking the code in both methods it is pretty clear that they are 
analogous. In any case, I did some quick testing, and in both cases the 
primitive fails exactly once and for the same value of the parameters. 
The tweak should be same in both cases.

Thanks!

-- 
Juan Vuletich
cuis.st
github.com/jvuletich
researchgate.net/profile/Juan-Vuletich
independent.academia.edu/JuanVuletich
patents.justia.com/inventor/juan-manuel-vuletich
linkedin.com/in/juan-vuletich-75611b3
twitter.com/JuanVuletich

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