[Development] QPrintPreview: access to single pages

[Giovanni Bajo]

Il giorno 01/nov/2011, alle ore 23:36, John Layt ha scritto:

> On Monday 31 Oct 2011 09:37:18 Giovanni Bajo wrote:
>> Hi John,
>> 
>> thank you very much for accepting to be the printer maintainer.
>> 
>> Last year, we (Develer) proposed a patch that was rejected:
>> http://qt.gitorious.org/qt/qt/merge_requests/733
>> 
>> We then opened a bug to discuss an alternative API to implement the features
>> we require: https://bugreports.qt.nokia.com//browse/QTBUG-12168
>> 
>> (the two links above summarize our needs quite well)
>> 
>> If we could agree on the API at least, we could move on and submit a new
>> patch.
>> 
>> Thanks!
> 
> Hi Giovanni,
> 
> Thanks for bringing this to my notice.  I have to confess that QPrintPreview 
> is something I haven't touched and so have little knowledge of and it is on my 
> learning TODO list.  I'll need to get up to speed there before I can comment 
> on the proposal properly, but it does feel somewhat awkward to me.
> 
> The big hurdle is that we don't really want to make any changes to the 
> existing printing code in 5.0 other than the work done to split it into a 
> separate module.  We want to leave any significant changes for the new module 
> in 5.1 or 5.2.  That said, if the implementation is a single new method that 
> doesn't change much of the existing code and doesn't change the existing api 
> or its behaviour then I would consider it.

OK. More to the point, the QPrintPreview::drawPage() method I was thinking of is very simple: it would just draw the specified page's QPicture through the provided painter (so probably a one-liner). Currently, our modified Qt build uses the patch in the merge request (a method to get a copy of the internal QPictures) but since there were concerns with exposing those objects, we would still be set with just being able to draw them.

> The bug report mentions 2 points, 1) to Aquire a separate preview for each 
> page and 2) the ability to print page subsets like 1,8,12.  I can say now that 
> 2) is not supported by Qt currently and will not be supported in QPrintSupport 
> in 5.0 as it would require considerable changes to the existing code and api.  
> It is a feature that will be in the new printing module though in 5.1/5.2 (in 
> fact, it was writing patches to do this that led to my becoming maintainer).  
> 
> Will fixing 1) still be useful to you without 2)?

Yes, in my case fixing 1 is enough because I can emulate 2 through it (once I get the preview of each page as a "paintable", it's easy to draw the subset of pages your want onto a QPainter and call newPage() inbetween). 

Thanks!
-- 
Giovanni Bajo   ::  rasky at develer.com
Develer S.r.l.  ::  http://www.develer.com

My Blog: http://giovanni.bajo.it





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