[reportlab-users] Absolute coordinates of rendered flowables?

[Robin Becker]

Dinu Gherman wrote:

> Robin Becker:

> 

>> Dinu flowable drawOn methods are the ones that are passed the x, y.

>>

>> f.drawOn(canvas,x,y,_sW)

>>

>> _sW is supposed to be the spare width available for purposes of 

>> horizontal adjustment ie available - flowable width.

>>

>.........

> I know about drawOn methods, but I'm not sure if they solve my problem.

> What want to do is use flowables like the following, which draw some-

> thing at absolute coordinates on the page while not consuming any space

> in the story themselves:

> 

> class AbsoluteRect(Flowable):

>     """A rectangle  given in absolute canvas coordinates.

> 

>     Use in a Platypus story like this: AbsoluteRect((x, y, w, h))

>     (This is mostly like XBox, but with absolute coordinates.)

>     """

> 

>     def __init__(self, rect):

>         Flowable.__init__(self)

>         self.width = 0

>         self.height = 0

>         self.rect = rect

> 

>     def __repr__(self):

>         return "AbsoluteRect(x=%s, y=%s, w=%s, h=%s)" % self.rect

> 

>     def draw(self):

>         x, y, w, h = self.rect

>         self.canv.rect(x, y, w, h)

>         self.canv.line(x, y, x+w, y+h)

>         self.canv.line(x, y+h, x+w, y)

> 

........

well OK you need to provide the drawOn method to eliminate any translation 
provided by the default behaviour. So I suspect your drawOn needs to look like this

     def drawOn(self, canv, x, y, _sW=0):
         try:
             self.canv = canv
             self.draw()
         finally:
             del self.canv

but this won't be sufficient if any other part of the process has modified the 
canvas transformation. In that case you probably need to reset the 
transformation in drawOn ie try doing


     def drawOn(self, canv, x, y, _sW=0):
         self.canv = canv
         self.canv.saveState()
         self.resetTransforms()
         try:
             self.draw()
         finally:
             del self.canv
             self.canv.restoreState()

so in this last version you're using the default user space
-- 
Robin Becker