[TYPO3-core] RFC: Bug #6261: Crop-Scaling the same image with different dimensions might produce wrong files

[Ernesto Baschny [cron IT]]

REMINDER... easy to test, just follow the "how to reproduce" steps! :)

Ernesto Baschny [cron IT] wrote: on 04.09.2007 16:33:
> Hi,
> 
> this is a SVN patch request.
> 
> Branch: trunk, TYPO3_4-1
> 
> Problem:
> If the same image needs to be generated more than once by an "IMAGE"
> with different crop-scale configurations (width=XXc or height=YYc), it
> might occur that the same hash will be generated for both versions, so
> that the second crop-scaling will render the same image which was
> produced with the first crop-scaling.
> 
> How to reproduce:
> Test with an 800x600 image (the proportions are important!):
> 
> page = PAGE
> page {
>   10 = IMAGE
>   10 {
>     file = fileadmin/Blaue_Berge.jpg
>     file.width = 80c
>     file.height = 80c
>     wrap = <div>Image 80x80:<br/>|</div>
>   }
>   20 < .10
>   20.file.width = 100c
>   20.file.height = 80c
>   20.wrap = <div>Image 100x80:<br/>|</div>
> }
> 
> Expected is two different files (and hashes), but we get the same hash
> twice (thus the same 80x80 file).
> 
> Why this happens:
> The problem is that in both situations the same scaled-down version of
> the file will be generated (107x80) before they are cropped down later
> by imagemagick. Since only the scale-down + "crop-percentage" will be
> used to generate the hash, it will render both files twice.
> 
> Solution:
> We need to add the information about the destination crop width/height
> in the hash so that we end up with two different files. The patch does
> that. This will only happen for crop-scaled images, all other hashes
> will be left untouchted. Cleaning up the typo3temp/pics/ might be
> recommended after upgrading.
> 
> Reference:
> http://bugs.typo3.org/view.php?id=6261
> 
> Cheers,
> Ernesto