[cups.general] cupsrasterreadpixels fails

[Michael R Sweet]

shermin wrote:
> Hi,
> I am writing backend using libusb and in print_device function i am using
> ras = cupsRasterOpen(print_fd, CUPS_RASTER_READ);
> cupsRasterReadPixels(ras, rasterData, ((header.cupsHeight) * (header.cupsBytesPerLine)) and this rasterData contains NO data.
> What could be the reason?

What is the value of print_fd?

What is cupsRasterOpen returning?

What is cupsRasterReadPixels returning?

What does errno contain after the cupsRasterReadPixels call?

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Michael R Sweet                        Senior Printing System Engineer