[gdal-dev] RasterIO vs progress bar

Frank Warmerdam warmerdam at pobox.com
Thu Feb 5 19:26:58 EST 2009

Oliver Eichler wrote:
> Hi,
> Is there a way to get a progress when using RasterIO? Guess not ;) But it 
> would be quite nice to have. Usually RatserIO is really fast, so you don't 
> need it, but if you play with WMS access a feedback would be _really_ nice.
> I know API changes suck. But is there any chance in future to pass a callback 
> function pointer and a void pointer to RasterIO. The callback function will 
> receive the progress and the void pointer. That should make C and C++ lads 
> happy. A way to abort transaction would be nice, too.
> I would really like to press on this topic, because I thing RasterIO is pretty 
> neat and fast. I can get WMS access with just a few lines and it's quite the 
> same as handling a file. I really appreciate that, however  without visual 
> feedback on the download progress the normal user will get frustrated. And 
> that would force me to re-implement all the magic. 
> How is the chance to get this into GDAL?


I'm generally not too keen on this due to the disruption and the complexity
of doing a decent job of progress reporting through the RasterIO process.

For the case of WMS it might make sense to just make modest sized requests
so the user sees progress after each chunk is completed.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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