[reportlab-users] Float flowable to bottom of page

[James Lance]

Robin,

Thank you!  

I found that on some calcluations  aH-H was returning a spacer that caused the rest of the flowables to spread across another page break.  I got around that by just doing aH-H-1, that seemed to get around the inaccuracies in the float calculations.

Thank you again.

-James
On Feb 4, 2010, at 7:30 AM, Robin Becker wrote:


> On 03/02/2010 21:59, James Lance wrote:

>> Is there a way to make a flowable element float to the bottom of the page?

>> 

>> I'm working on a invoice document, at the bottom of the page is a tear off segment that can be returned with payment.  I can draw directly on the canvas, but I don't want to include the segment on every page, just the last.

>> 

>> What I've done is put all the elements that make up my tear off segment into a KeepTogether flowable. I've tried messing around with putting a spacer before it what attempts to fill all remaining space with out pushing it to the next page.  I can't seem to work out the correct height of the spacer, and still be flexible concerning the previous flowable content.  Of course if there are enough line items or other data then naturally the tear off segment will go to the next page.

>> 

>> So, how can I pin the tear off to the bottom of the page while still keeping it a flowable?  Is that even possible?

>> 

>> Thanks,

>> 

>> James

> 

> OK this code appears a bit better in that you don't need to work out the height of the flowables before doing stuff

> 

> #############################################

> from reportlab.platypus.flowables import KeepTogether, Spacer, _listWrapOn, _flowableSublist, PageBreak

> from reportlab.platypus.doctemplate import FrameBreak

> class FloatToEnd(KeepTogether):

>    '''

>    Float some flowables to the end of the current frame

>    '''

>    def __init__(self,flowables,maxHeight=None,brk='frame'):

>        self._content = _flowableSublist(flowables)

>        self._maxHeight = maxHeight

>        self._state = 0

>        self._brk = brk

> 

>    def wrap(self,aW,aH):

>        return aW,aH+1  #force a split

> 

>    def _makeBreak(self,h):

>        if self._brk=='page':

>            return PageBreak()

>        else:

>            return FrameBreak

> 

>    def split(self,aW,aH):

>        dims = []

>        W,H = _listWrapOn(self._content,aW,self.canv,dims=dims)

>        if self._state==0:

>            if H<aH:

>                return [Spacer(aW,aH-H)]+self._content

>            else:

>                S = self

>                S._state = 1

>                return [self._makeBreak(aH), S]

>        else:

>            if H>aH: return self._content

>            return [Spacer(aW,aH-H)]+self._content

> 

> if __name__=='__main__':

>    from reportlab.platypus.doctemplate import SimpleDocTemplate

>    from reportlab.platypus.paragraph import Paragraph

>    from reportlab.platypus.flowables import Spacer, KeepTogether, _listWrapOn

>    from reportlab.lib.styles import getSampleStyleSheet

>    ss = getSampleStyleSheet()

>    Normal= ss['Normal']

> 

>    t1 = '''Comparing these examples with their parasitic gap counterparts in (96)

> and (97), we see that relational information is to be regarded as an

> abstract underlying order.  We have already seen that a descriptively

> adequate grammar is rather different from the extended c-command

> discussed in connection with (34).  To characterize a linguistic level

> L, the natural general principle that will subsume this case raises

> serious doubts about the ultimate standard that determines the accuracy

> of any proposed grammar.  A consequence of the approach just outlined is

> that an important property of these three types of EC is not quite

> equivalent to the traditional practice of grammarians.  A majority  of

> informed linguistic specialists agree that this selectionally introduced

> contextual feature does not readily tolerate a parasitic gap

> construction.

>    '''

>    t2 ='''However, this assumption is not correct, since the descriptive power of

> the base component is not subject to nondistinctness in the sense of

> distinctive feature theory.  Note that this selectionally introduced

> contextual feature is not to be considered in determining a corpus of

> utterance tokens upon which conformity has been defined by the paired

> utterance test.  I suggested that these results would follow from the

> assumption that the natural general principle that will subsume this

> case is unspecified with respect to the ultimate standard that

> determines the accuracy of any proposed grammar.  Note that the earlier

> discussion of deviance does not affect the structure of nondistinctness

> in the sense of distinctive feature theory.  A consequence of the

> approach just outlined is that the theory of syntactic features

> developed earlier is not quite equivalent to the ultimate standard that

> determines the accuracy of any proposed grammar.'''

> 

>    #case where we need the page throw

>    d = SimpleDocTemplate('flowfloat0.pdf')

>    S =[]   #the story

> 

>    S.append(Paragraph('Line 1 followed by lots of space',Normal))

>    S.append(Spacer(10,481))

>    S.append(Paragraph('Line 2',Normal))

>    S.append(FloatToEnd([Paragraph(t1,Normal),Paragraph(t2,Normal)]))

>    d.build(S)

> 

>    #case where we don't need the page throw

>    d = SimpleDocTemplate('flowfloat1.pdf')

>    S =[]   #the story

> 

>    S.append(Paragraph('Line 1 followed by less space',Normal))

>    S.append(Spacer(10,381))

>    S.append(Paragraph('Line 2',Normal))

>    S.append(FloatToEnd([Paragraph(t1,Normal),Paragraph(t2,Normal)]))

>    d.build(S)

> #############################################

> -- 

> Robin Becker