[WinPrnDev] DrvQueryPerBandInfo question
- From: "Terry Cl." <cl.terry@xxxxxxxxx>
- To: "winprndev@xxxxxxxxxxxxx" <winprndev@xxxxxxxxxxxxx>
- Date: Thu, 15 Mar 2012 13:14:44 -0700 (PDT)
Hi,
I am writing a wrapper dll for an existing printer driver. Basically what I
want to do is to make some changes to the final output of the page in either
DrvNextBand or DrvSendPage functions. I am having an interesting case regarding
calling of DrvQueryPerBandInfo function by the GDI and drivers returned values.
When this function is first called, driver returns the full width and height of
the surface in PERBANDINFO structure instead of the band size and also sets the
bRepeatThisBand to 1 which tells the GDI to repeat this band. GDI then calls
the rendering function (DrvBitBlt, DrvTextOut etc.) and then calls
DrvQueryPerBandInfo again. In this second call the DrvQueryPerBandInfo, driver
returns the band size as normal and bRepeatThisBand is set to 0. After that,
usual banding calls occurs.
What I don't understand is that why driver wants GDI to repeat the band (in
this case band size is equal to whole page) without sending it to the printer?
What's the possible use case of setting bRepeatThisBand to 1?
By the way, for the same driver, if I don't return function pointer to
DrvQueryPerBandInfo (everything else is same), driver works as expected and
produces correct output, but with DrvqueryPerBandInfo implemented, some
internal exception occurs in the driver.
Thank you all.
---
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