Canon LBP3010 + Armbian 22.04 on OrangePi PC: Incorrect Indents/Margins

[awkitsune]

This couple working fine with LAN CUPS setup, printed couple of pictures and docs from my mac completely fine. Only Issue is top and bottom margins displaced by around 2.5 mm while printing from Word

[mounaiban]

This issue may be related to #21: please check my comment there for a little more detail.

Long story short, we don't have precise control over the rasterisation process for accurate printing. I believe we need to have our own GhostScript output device for this to happen, but it's going to take some time before we figure out how to do this...

[ValdikSS]

@mounaiban
That's because Margins value in CUPS headers is not what the printer expects — it's a margin from the bottom and left of raster document.

captdriver/src/paper.c

Lines 36 to 37 in 6271924

	dims->margin_height = header->Margins[0];
	dims->margin_width = header->Margins[1];

You need to get the margin by reading cups raster header cupsPageSize and cupsImagingBBox values.
https://www.cups.org/doc/spec-raster.html#:~:text=Single%20Precision%20(4)-,cupsimagingbbox,-Four%20floating%20point

cupsPageSize is a (physical) page size in (float) points, cupsImagingBBox is where the raster data positioned on this page, also in (float) points.

uint16_t marginLeft = header.cupsImagingBBox[0] / 72.0f * header.HWResolution[0];
uint16_t marginTop = (header.cupsPageSize[1] - header.cupsImagingBBox[3]) / 72.0f * header.HWResolution[0];

Also I guess PaperWidth and Height should NOT be read from the raster data pixels, as the raster data come without any padding (that's why Margins are [0 0] on the screenshot below). cupsPageSize (converted from pt to px) should be used instead.

captdriver/src/paper.c

Lines 28 to 29 in 6271924

	dims->paper_width = header->cupsWidth; //header->PageSize[0] * header->HWResolution[0] / 72;
	dims->paper_height = header->cupsHeight; //header->PageSize[1] * header->HWResolution[1] / 72;