matplotlib-devel Mailing List for matplotlib

Michael Droettboom wrote:
> Paul Kienzle wrote:
>   
>> On Mon, Apr 28, 2008 at 09:51:54AM -0400, Michael Droettboom wrote:
>>   
>>     
>>> Paul Kienzle wrote:
>>>     
>>>       
>>>> Thanks.  It looks much better in png, but pdf has the subscript raised much
>>>> higher, 
>>>>       
>>>>         
>>> That was a DPI-related bug, that is hopefully now fixed in SVN.
>>>     
>>>       
>>>> and svg isn't rendering fonts at all (see attached).
>>>>       
>>>>         
>> Yes.
>>
>>   
>>     
>>> Thanks.  The SVG was broken in SVN March 26 trying to workaround an 
>>> Inkscape copy/paste bug.  I think it is fixed now so it works in Mozilla 
>>> and Inkscape simultaneously.  But please let me know if you see anything 
>>> fishy -- there seems to be a great deal of variability between SVG viewers.
>>>     
>>>       
>> Works in Safari 3.1.1, Inkscape 0.45 and FF 2.0.0.14
>>
>>   
>>     
>>> Are you seeing this bug with 0.91.2 release, or just the 0.91.2 SVN 
>>> branch?  I'd be surprised by the former (and I can't reproduce it there).
>>>     
>>>       
>> 0.91.2 SVG does indeed work (with the old superscript position of course).
>>   
>>     
Apologies -- I was just confused.  The 0.91.2 *release* should (as you 
say) have working text but with the wrong superscript position.  The 
0.91.x *maintenance branch* should be working on both counts.

Cheers,
Mike

-- 
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

Paul Kienzle wrote:
> On Mon, Apr 28, 2008 at 09:51:54AM -0400, Michael Droettboom wrote:
>   
>> Paul Kienzle wrote:
>>     
>>> Thanks.  It looks much better in png, but pdf has the subscript raised much
>>> higher, 
>>>       
>> That was a DPI-related bug, that is hopefully now fixed in SVN.
>>     
>>> and svg isn't rendering fonts at all (see attached).
>>>       
>
> Yes.
>
>   
>> Thanks.  The SVG was broken in SVN March 26 trying to workaround an 
>> Inkscape copy/paste bug.  I think it is fixed now so it works in Mozilla 
>> and Inkscape simultaneously.  But please let me know if you see anything 
>> fishy -- there seems to be a great deal of variability between SVG viewers.
>>     
>
> Works in Safari 3.1.1, Inkscape 0.45 and FF 2.0.0.14
>
>   
>> Are you seeing this bug with 0.91.2 release, or just the 0.91.2 SVN 
>> branch?  I'd be surprised by the former (and I can't reproduce it there).
>>     
>
> 0.91.2 SVG does indeed work (with the old superscript position of course).
>   
I'm surprised by this.  Can you do a full rebuild and try again?  It is 
working for me now.

Cheers,
Mike

-- 
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

Andrew Straw wrote:
> Hi all,
> 
> I just discovered that attempting to plot a complex array using imshow()
> results in a not-very-helpful traceback (attached). Would it be worth
> catching this on the actual call to imshow() and raising a more
> transparent error? (The test script, slightly modified from Gaël
> Varoquaux's pyreport examples is attached and makes a beautiful plot and
> is also attached.)

The problem is most likely quite general, so the solution should be 
similarly general.  I suspect there is no place in mpl where a complex 
input makes sense.

Eric

Hi all,

I just discovered that attempting to plot a complex array using imshow()
results in a not-very-helpful traceback (attached). Would it be worth
catching this on the actual call to imshow() and raising a more
transparent error? (The test script, slightly modified from Gaël
Varoquaux's pyreport examples is attached and makes a beautiful plot and
is also attached.)

-Andrew

On Mon, Apr 28, 2008 at 09:51:54AM -0400, Michael Droettboom wrote:
> Paul Kienzle wrote:
> >
> > Thanks.  It looks much better in png, but pdf has the subscript raised much
> > higher, 
> That was a DPI-related bug, that is hopefully now fixed in SVN.
> > and svg isn't rendering fonts at all (see attached).

Yes.

> Thanks.  The SVG was broken in SVN March 26 trying to workaround an 
> Inkscape copy/paste bug.  I think it is fixed now so it works in Mozilla 
> and Inkscape simultaneously.  But please let me know if you see anything 
> fishy -- there seems to be a great deal of variability between SVG viewers.

Works in Safari 3.1.1, Inkscape 0.45 and FF 2.0.0.14

> Are you seeing this bug with 0.91.2 release, or just the 0.91.2 SVN 
> branch?  I'd be surprised by the former (and I can't reproduce it there).

0.91.2 SVG does indeed work (with the old superscript position of course).

- Paul

Paul Kienzle wrote:
> On Thu, Apr 24, 2008 at 08:38:02AM -0400, Michael Droettboom wrote:
>   
>> Paul Kienzle wrote:
>>     
>>> Hi,
>>>
>>> The superscripts in mpl don't seem to be placed at the correct height for
>>> small fonts.  The y-tics on the attached plot shows this.  The effect is
>>> similar in svg and pdf backends.
>>>   
>>>       
>> Thanks.  When looking up the x-height, the code was not taking the font 
>> size into account.  This has been fixed on the branch and trunk.
>>     
>
> Thanks.  It looks much better in png, but pdf has the subscript raised much
> higher, 
That was a DPI-related bug, that is hopefully now fixed in SVN.
> and svg isn't rendering fonts at all (see attached).
>   
Thanks.  The SVG was broken in SVN March 26 trying to workaround an 
Inkscape copy/paste bug.  I think it is fixed now so it works in Mozilla 
and Inkscape simultaneously.  But please let me know if you see anything 
fishy -- there seems to be a great deal of variability between SVG viewers.

Are you seeing this bug with 0.91.2 release, or just the 0.91.2 SVN 
branch?  I'd be surprised by the former (and I can't reproduce it there).

Cheers, and thanks for your patience,
Mike

-- 
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

John Hunter wrote:
> On Fri, Apr 25, 2008 at 2:12 PM, Michael Droettboom <md...@st...> wrote:
>
>   
>> I'm stumped.  It looks like the code (and even the inputs to
>> draw_text_image) are virtually identical, modulo the differences between Agg
>> 2.3 and 2.4.  Maybe the change is in Agg, and 2.4 is theoretically more
>> correct?  We can always experiment with different kernels and parameters
>> until finding one that looks right.
>>     
>
> I'll poke around with this then -- I was hoping the report would
> trigger some memory about a font change you made.  
I don't recall any font changes -- if you diff ft2font.cpp in 0.91.2 and 
trunk you'll see they're virtually identical.  And the unrotated text 
looks identical to me.
> The differences in
> the 2.3 and 2.4 agg incantations were all I could see too -- I wonder
> if some default template parameter that is different in 2. is creeping
> in.
>   
Perhaps.  I was going to check the Agg examples to see if the spline 
filters look different there, too, but I can't get 2.3 to compile 
anymore for some reason, so I gave up for now.

Cheers,
Mike

-- 
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

John Hunter wrote:
> On Sun, Apr 27, 2008 at 3:14 AM, Eric Firing <ef...@ha...> wrote:
>
>   
>>  1) The hline generated by frac is too long with dpi=50.
>>     
>
> The problem with the hline appears to be that the width of the line in
> the frac has a component that depends on the thickness
>
>     thickness = state.font_output.get_underline_thickness(
>             state.font, state.fontsize, state.dpi)
>     width = max(num.width, den.width) + thickness * 10.
>
> and get_underline_thickness here is defaulting to 1.0 because of this
> max call in get_underline_thickness
>
>      return max(1.0, cached_font.font.underline_thickness / 64.0 /
> fontsize * 10.0)
>   
I believe that this is where the dpi needs to be factored in.  Ft2font 
(well, freetype, really) seems to scale metrics for individual glyphs by 
dpi, but not the font-global metrics.  I had wrongly assumed they were 
all scaled by dpi.  So this is a subtler instance of the recent x-height 
bug that caused sub/superscripts to be incorrect at different dpi's.
> Michael -- what is the role of these 10.0 scale factors, which is
> showing up in both the frac call and the get_underline_thickness?  Is
> this something from Knuth, or is it a fudge factor that gets it mostly
> right?  I suspect we will need something like
>
>     width = max(num.width, den.width) + thickness * 10. * state.dpi/72.
>   
This 10.0 is from Knuth.  It is the amount of overhang of the fraction 
beam, and is meant to be relative to the thickness of the beam itself.  
The other 10.0 (in get_underline_thickness) is my own experimental fudge 
to deal with the peculiarities of how underline thickness is stored in 
Truetype fonts.  (Remember "pure" TeX uses a completely different font 
metric standard, so some mapping from TrueType/freetype etc. had to be 
fudged on.)

What's causing the fraction bar to be too wide at lower dpi is the 
minimum underline thickness of 1.0 enforced in get_underline_thickness.  
I think that was a mistake -- enforcing 1.0 pixel lines should happen 
closer to the backend level -- so I've removed the max(1.0, ...) there.
> but with this change the frac bar looks a little too wide -- which is
> why I'm wondering if there is something magic about 10. or if another
> number might serve better.
>   

-- 
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

John Hunter wrote:
> On Sun, Apr 27, 2008 at 12:56 PM, Eric Firing <ef...@ha...> wrote:
> 
>>  The plot thickens.  The postscript backend is completely confused by the
>> quiver plot.  Try the attached example.
> 
> 
> Argg, that was a subtle one -- there was a bug in backend ps which was
> exposed only if you are using a path collection with offsets,
> transoffset and clippath and cliprect both None.  In that scenario,
> the translate in the bind def function was not getting wrapped in a
> gsave/grestore pair, which was causing the axes to be drawn in the
> wrong place because the translate from the offset remained in effect.
> I tried following the draw_markers logic and putting the
> gsave/grestore in the ps_cmd, eg in draw_markers Michael writes ijn a
> comment:
> 
>         ps_cmd = ['/o {', 'gsave', 'newpath', 'translate'] # dont want
> the translate to be global
> 
> so clearly he was bumping up against the same problem with markers.
> For some reason, trying the same thing in the path_collection was not
> working for me, so I resorted to the somewhat hackish approach of
> forcing _draw_ps to wrap a gsave/grestore if it wasn't getting one
> from the cliprect or clippath:
> 
>         needwrap = not (clippath or cliprect)
>         if needwrap:
>             # we need to make sure that there is at least 1
>             # save/grestore around each ps write so we'll force it if
>             # we're not getting one from the cliprecot or clippath.
>             # hackish, yes
>             write('gsave\n')
> 
> and then
> 
>         if needwrap:
>             write('grestore\n')
> 
> I think there will be cleaner way, but it will need some fresh
> eyeballs tomorrow and this will provide a temporary fix.

I went ahead and committed an alternative fix that I think is cleaner, 
and greatly reduces the number of needless gsave/grestore pairs.  Your 
version of the method is still there, with a mangled name, for easy 
reference and testing until we are sure which way to go.

Sorry for whatever duplicated effort there has been.  I did not intend 
to spend a fair chunk of the day working on this, but I let myself get 
sucked in.  It was a challenge.

As mentioned in a message a few minutes ago that I don't think went to 
the list, my gs interpreter is choking on the apostrophe (single quote) 
character, as in title or label strings.  I can't find any reason why 
this should cause trouble--maybe it is a particular version or 
configuration of gs.

Eric

On Sun, Apr 27, 2008 at 8:28 PM, John Hunter <jd...@gm...> wrote:


>  Argg, that was a subtle one -- there was a bug in backend ps which was
>  exposed only if you are using a path collection with offsets,
>  transoffset and clippath and cliprect both None.  In that scenario,
>  the translate in the bind def function was not getting wrapped in a

One thing I failed to make clear: the artist with said properties is
quiver.QuiverKey.vector

JDH

On Sun, Apr 27, 2008 at 12:56 PM, Eric Firing <ef...@ha...> wrote:

>  The plot thickens.  The postscript backend is completely confused by the
> quiver plot.  Try the attached example.


Argg, that was a subtle one -- there was a bug in backend ps which was
exposed only if you are using a path collection with offsets,
transoffset and clippath and cliprect both None.  In that scenario,
the translate in the bind def function was not getting wrapped in a
gsave/grestore pair, which was causing the axes to be drawn in the
wrong place because the translate from the offset remained in effect.
I tried following the draw_markers logic and putting the
gsave/grestore in the ps_cmd, eg in draw_markers Michael writes ijn a
comment:

        ps_cmd = ['/o {', 'gsave', 'newpath', 'translate'] # dont want
the translate to be global

so clearly he was bumping up against the same problem with markers.
For some reason, trying the same thing in the path_collection was not
working for me, so I resorted to the somewhat hackish approach of
forcing _draw_ps to wrap a gsave/grestore if it wasn't getting one
from the cliprect or clippath:

        needwrap = not (clippath or cliprect)
        if needwrap:
            # we need to make sure that there is at least 1
            # save/grestore around each ps write so we'll force it if
            # we're not getting one from the cliprecot or clippath.
            # hackish, yes
            write('gsave\n')

and then

        if needwrap:
            write('grestore\n')

I think there will be cleaner way, but it will need some fresh
eyeballs tomorrow and this will provide a temporary fix.

JDH

On Sun, Apr 27, 2008 at 3:14 AM, Eric Firing <ef...@ha...> wrote:

>  1) The hline generated by frac is too long with dpi=50.

The problem with the hline appears to be that the width of the line in
the frac has a component that depends on the thickness

    thickness = state.font_output.get_underline_thickness(
            state.font, state.fontsize, state.dpi)
    width = max(num.width, den.width) + thickness * 10.

and get_underline_thickness here is defaulting to 1.0 because of this
max call in get_underline_thickness

     return max(1.0, cached_font.font.underline_thickness / 64.0 /
fontsize * 10.0)

Michael -- what is the role of these 10.0 scale factors, which is
showing up in both the frac call and the get_underline_thickness?  Is
this something from Knuth, or is it a fudge factor that gets it mostly
right?  I suspect we will need something like

    width = max(num.width, den.width) + thickness * 10. * state.dpi/72.

but with this change the frac bar looks a little too wide -- which is
why I'm wondering if there is something magic about 10. or if another
number might serve better.

>  Along the way, I found that in backend_bases, print_figure was doing what
> appears to be a completely unnecessary draw operation after restoring the
> original dpi, so I commented that out.  This speeds up backend_driver.py agg
> by a few percent.

I think you are right here -- because we are creating a new
FigureCanvas and hence a new renderer in the switch_backend call we do
not need to redraw the original figure with the original facecolor,
edgecolor and dpi params.  In older versions of mpl, if memory serves
correctly, calling savefig would reuse the same renderer so after the
print to hardcopy we would redraw so the figure in the GUI window
would look right.  But I agree this looks superfluous in light of the
current code which is creating a new canvas with each savefig.

JDH

Eric Firing wrote:
> John,
> 
> I made some more changes in quiver, and I think they will ensure that 
> dpi changes are handled correctly as far as arrows are concerned, both 
> in the plot and in the key.
> 
> There is still a problem with the key label, and it can be seen clearly 
>  in the attached slight modification of quiver_demo.py.  There are 
> actually two visible problems:
> 
> 1) The hline generated by frac is too long with dpi=50.
> 
> 2) The positioning and sizing of the key bbox are also dpi-dependent, as 
> I verified by using your bbox-display trick.

The plot thickens.  The postscript backend is completely confused by the 
quiver plot.  Try the attached example.

pdf seems OK.

Eric

John,

I made some more changes in quiver, and I think they will ensure that 
dpi changes are handled correctly as far as arrows are concerned, both 
in the plot and in the key.

There is still a problem with the key label, and it can be seen clearly 
  in the attached slight modification of quiver_demo.py.  There are 
actually two visible problems:

1) The hline generated by frac is too long with dpi=50.

2) The positioning and sizing of the key bbox are also dpi-dependent, as 
I verified by using your bbox-display trick.

I went hunting through text.py, mathtext.py, backend_bases, and 
backend_agg without figuring out where the problem is.  The right dpi 
seems to be getting used at mathtext parsing time.  Maybe it is not 
actually getting propagated all the way into the code that gets the font 
metrics.  I did not try to trace it that far.

Along the way, I found that in backend_bases, print_figure was doing 
what appears to be a completely unnecessary draw operation after 
restoring the original dpi, so I commented that out.  This speeds up 
backend_driver.py agg by a few percent.

Eric

John Hunter wrote:
> On Sat, Apr 26, 2008 at 2:04 PM, Eric Firing <ef...@ha...> wrote:
> 
>> The attached script, run on svn mpl, illustrates a positioning problem: note
>> that the subplot titles are badly positioned in the 50 dpi version.  I
>> believe that changing from 150 to 50 dpi should yield a perfect scaling of
>> everything in the plot, but it doesn't.  There is a similar problem with a
>> quiver key positioned outside the axes frame, but I don't have a trivial
>> example yet; I am hoping that whatever solves the title positioning problem
>> will take care of that also.  If not, I will make a simple example and we
>> can attack it separately.
> 
> There were two problems with title positioning.  The first was that
> the title offset transformation was hardcoded in pixels and not dpi,
> and the second was that is was not getting notifed when the figure dpi
> was changed.  I changed the offset to read:
> 
> self.titleOffsetTrans = mtransforms.Affine2D().translate(
>             0.0, 5.0*self.figure.dpi/72.)
> 
> and added a callbacks registry to the figure instance so that
> observers could be notified when dpi was changed (dpi used to be a
> lazy value on the maintenance branch but is a plain-ol-value on the
> trunk).
> 
>      def on_dpi_change(fig):
>             self.titleOffsetTrans.clear().translate(
>                 0.0, 5.0*fig.dpi/72.)
> 
>         self.figure.callbacks.connect('dpi_changed', on_dpi_change)
> 
> It looks like the problem in the quiver code is that the "labelsep"
> property reads the dpi when the QuiverKey is intiitalized but does not
> get notified on dpi change.  I added a callback there too so you
> should test to see if this helps.  The dpi setting is also referenced
> in the _set_transform method.  Since you are more familiar with the
> quiver code that I am, and this hint may point you in the right
> direction, I'll let you take a look at that and see if a callback is
> needed.
> 
> On a related note, one trick I use when debugging text layout problems
> is to turn on the "bbox".  If the bbox is right but the text is in the
> wrong place, you know it is in the layout.  If the bbox is in the
> wrong place, you know the problem is in the font metrics:
> 
> boxprops = dict(facecolor='red')
> ax1.set_title('Top Plot', bbox=boxprops)
> 
> JDH

John,

Thank you very much--that's a big help. Some time today or tomorrow I 
will try to track down any remaining quiver problems.  I suspect similar 
dpi-related problems may lurk elsewhere as well.

Those lazy values worked pretty well!

One of the things that puzzles me is the following method of 
FigureCanvasAgg in backend_agg:

     def print_png(self, filename_or_obj, *args, **kwargs):
         FigureCanvasAgg.draw(self)
         renderer = self.get_renderer()
         original_dpi = renderer.dpi
         renderer.dpi = self.figure.dpi
         if type(filename_or_obj) in (str, unicode):
             filename_or_obj = open(filename_or_obj, 'w')
         self.get_renderer()._renderer.write_png(filename_or_obj, 
self.figure.dpi)
         renderer.dpi = original_dpi

The FigureCanvasAgg.draw(self) command gets turned into 
self.figure.draw(self.renderer), which is executed *before* the 
renderer.dpi gets set to self.figure.dpi, so it seems like there is the 
possibility of an inconsistency.  I suspect there is no problem in 
practice, but it is confusing.

Now that I look again, it looks like what is happening is that the 
get_renderer call in FigureCanvasAgg.draw is setting the renderer dpi to 
the figure dpi, as well as setting self.renderer, in which case most of 
the code in print_png seems to be superfluous.


Mostly unrelated question: is there any point in keeping 
backend_agg2.py, or at least keeping it in the backends directory? 
Maybe it is time to move that and backend_emf.py (and maybe others) to 
some sort of cold storage, in case someone is inspired later to 
resurrect them.

Eric


John Hunter wrote:
> On Sat, Apr 26, 2008 at 2:04 PM, Eric Firing <ef...@ha...> wrote:
> 
>> The attached script, run on svn mpl, illustrates a positioning problem: note
>> that the subplot titles are badly positioned in the 50 dpi version.  I
>> believe that changing from 150 to 50 dpi should yield a perfect scaling of
>> everything in the plot, but it doesn't.  There is a similar problem with a
>> quiver key positioned outside the axes frame, but I don't have a trivial
>> example yet; I am hoping that whatever solves the title positioning problem
>> will take care of that also.  If not, I will make a simple example and we
>> can attack it separately.
> 
> There were two problems with title positioning.  The first was that
> the title offset transformation was hardcoded in pixels and not dpi,
> and the second was that is was not getting notifed when the figure dpi
> was changed.  I changed the offset to read:
> 
> self.titleOffsetTrans = mtransforms.Affine2D().translate(
>             0.0, 5.0*self.figure.dpi/72.)
> 
> and added a callbacks registry to the figure instance so that
> observers could be notified when dpi was changed (dpi used to be a
> lazy value on the maintenance branch but is a plain-ol-value on the
> trunk).
> 
>      def on_dpi_change(fig):
>             self.titleOffsetTrans.clear().translate(
>                 0.0, 5.0*fig.dpi/72.)
> 
>         self.figure.callbacks.connect('dpi_changed', on_dpi_change)
> 
> It looks like the problem in the quiver code is that the "labelsep"
> property reads the dpi when the QuiverKey is intiitalized but does not
> get notified on dpi change.  I added a callback there too so you
> should test to see if this helps.  The dpi setting is also referenced
> in the _set_transform method.  Since you are more familiar with the
> quiver code that I am, and this hint may point you in the right
> direction, I'll let you take a look at that and see if a callback is
> needed.
> 
> On a related note, one trick I use when debugging text layout problems
> is to turn on the "bbox".  If the bbox is right but the text is in the
> wrong place, you know it is in the layout.  If the bbox is in the
> wrong place, you know the problem is in the font metrics:
> 
> boxprops = dict(facecolor='red')
> ax1.set_title('Top Plot', bbox=boxprops)
> 
> JDH

On Sat, Apr 26, 2008 at 2:04 PM, Eric Firing <ef...@ha...> wrote:

> The attached script, run on svn mpl, illustrates a positioning problem: note
> that the subplot titles are badly positioned in the 50 dpi version.  I
> believe that changing from 150 to 50 dpi should yield a perfect scaling of
> everything in the plot, but it doesn't.  There is a similar problem with a
> quiver key positioned outside the axes frame, but I don't have a trivial
> example yet; I am hoping that whatever solves the title positioning problem
> will take care of that also.  If not, I will make a simple example and we
> can attack it separately.

There were two problems with title positioning.  The first was that
the title offset transformation was hardcoded in pixels and not dpi,
and the second was that is was not getting notifed when the figure dpi
was changed.  I changed the offset to read:

self.titleOffsetTrans = mtransforms.Affine2D().translate(
            0.0, 5.0*self.figure.dpi/72.)

and added a callbacks registry to the figure instance so that
observers could be notified when dpi was changed (dpi used to be a
lazy value on the maintenance branch but is a plain-ol-value on the
trunk).

     def on_dpi_change(fig):
            self.titleOffsetTrans.clear().translate(
                0.0, 5.0*fig.dpi/72.)

        self.figure.callbacks.connect('dpi_changed', on_dpi_change)

It looks like the problem in the quiver code is that the "labelsep"
property reads the dpi when the QuiverKey is intiitalized but does not
get notified on dpi change.  I added a callback there too so you
should test to see if this helps.  The dpi setting is also referenced
in the _set_transform method.  Since you are more familiar with the
quiver code that I am, and this hint may point you in the right
direction, I'll let you take a look at that and see if a callback is
needed.

On a related note, one trick I use when debugging text layout problems
is to turn on the "bbox".  If the bbox is right but the text is in the
wrong place, you know it is in the layout.  If the bbox is in the
wrong place, you know the problem is in the font metrics:

boxprops = dict(facecolor='red')
ax1.set_title('Top Plot', bbox=boxprops)

JDH

The attached script, run on svn mpl, illustrates a positioning problem: 
note that the subplot titles are badly positioned in the 50 dpi version. 
  I believe that changing from 150 to 50 dpi should yield a perfect 
scaling of everything in the plot, but it doesn't.  There is a similar 
problem with a quiver key positioned outside the axes frame, but I don't 
have a trivial example yet; I am hoping that whatever solves the title 
positioning problem will take care of that also.  If not, I will make a 
simple example and we can attack it separately.

I have made a first attempt to figure out the cause of the positioning 
problem, and I have failed; I hope someone else will find it easier to 
track down.  I also find that following the chain of events involved in 
savefig, and following the dpi setting, is rather difficult, and I 
wonder whether it might be possible to clarify and simplify anything.

In any case, the dpi-related positioning bug (or bugs) is a significant 
problem for me now.

Eric

On Fri, Apr 25, 2008 at 2:12 PM, Michael Droettboom <md...@st...> wrote:

> I'm stumped.  It looks like the code (and even the inputs to
> draw_text_image) are virtually identical, modulo the differences between Agg
> 2.3 and 2.4.  Maybe the change is in Agg, and 2.4 is theoretically more
> correct?  We can always experiment with different kernels and parameters
> until finding one that looks right.

I'll poke around with this then -- I was hoping the report would
trigger some memory about a font change you made.  The differences in
the 2.3 and 2.4 agg incantations were all I could see too -- I wonder
if some default template parameter that is different in 2. is creeping
in.

JDH

On Thu, Apr 24, 2008 at 08:38:02AM -0400, Michael Droettboom wrote:
> Paul Kienzle wrote:
> > Hi,
> >
> > The superscripts in mpl don't seem to be placed at the correct height for
> > small fonts.  The y-tics on the attached plot shows this.  The effect is
> > similar in svg and pdf backends.
> >   
> Thanks.  When looking up the x-height, the code was not taking the font 
> size into account.  This has been fixed on the branch and trunk.

Thanks.  It looks much better in png, but pdf has the subscript raised much
higher, and svg isn't rendering fonts at all (see attached).


> > I'm using 0.91.2 because the latest svn version gives me a KeyError for
> > ufunc isfinite.
> >   
> Can you provide the full traceback here so we can diagnose and fix this 
> problem?  The only reference to isfinite seems to be in the PDF backend, 
> which is working for me, and is identical in 0.91.2 and trunk in that 
> respect.  There is probably a more complex Numpy version interaction 
> going on.

I recompiled with Numpy 1.1 and the problem went away.  I'm going to
ignore the issue for now.

	- Paul

I'm stumped.  It looks like the code (and even the inputs to 
draw_text_image) are virtually identical, modulo the differences between 
Agg 2.3 and 2.4.  Maybe the change is in Agg, and 2.4 is theoretically 
more correct?  We can always experiment with different kernels and 
parameters until finding one that looks right.

Cheers,
Mike

John Hunter wrote:
> On Fri, Apr 25, 2008 at 1:08 PM, Michael Droettboom <md...@st...> wrote:
>   
>> They don't look non-antialiased to me (in your attachment or a file I
>> generated locally).  Remember, the rotation happens in raster (not vector)
>> space, because that was the path of least resistance, but is a bit of a
>> hack.
>>
>>  The difference is that the trunk appears slightly darker than 0.91.x.  (And
>> 0.90.x, if I recall correctly, didn't support non-90 degree rotations of
>> text at all).  0.91.x is using spline36 interpolation, trunk is using
>> spline16.  I *think* I changed it because I thought spline16 looked slightly
>> cleaner (though technically less accurate), and of course is faster, but I'm
>> not sure anymore -- SVN blame isn't helping me remember.  It could have just
>> been the example I was using at the time looked better.
>>
>>  In any case, you should be able to change this line in
>> _backend_agg.cpp:2197
>>
>>   filter.calculate(agg::image_filter_spline16());
>>
>>  to any of the interpolation kernels that Agg offers, and experiment until
>> you find something suitable.
>>     
>
> Hmm, I tried setting the interpolation back to what it is on the
> branch, but this doesn't explain it.  If you run
>
> t = text(0.5, 0.5, 'hi mom', fontsize=20)
> t.set_rotation(30); draw()
>
> and save the results from the trunk and the branch (using
> agg::image_filter_spline36) on both, it appears (as you say) that the
> font weight is darker for rotated text, but not for non-rotated text.
>
> JDH
>   

-- 
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

On Fri, Apr 25, 2008 at 1:08 PM, Michael Droettboom <md...@st...> wrote:
> They don't look non-antialiased to me (in your attachment or a file I
> generated locally).  Remember, the rotation happens in raster (not vector)
> space, because that was the path of least resistance, but is a bit of a
> hack.
>
>  The difference is that the trunk appears slightly darker than 0.91.x.  (And
> 0.90.x, if I recall correctly, didn't support non-90 degree rotations of
> text at all).  0.91.x is using spline36 interpolation, trunk is using
> spline16.  I *think* I changed it because I thought spline16 looked slightly
> cleaner (though technically less accurate), and of course is faster, but I'm
> not sure anymore -- SVN blame isn't helping me remember.  It could have just
> been the example I was using at the time looked better.
>
>  In any case, you should be able to change this line in
> _backend_agg.cpp:2197
>
>   filter.calculate(agg::image_filter_spline16());
>
>  to any of the interpolation kernels that Agg offers, and experiment until
> you find something suitable.

Hmm, I tried setting the interpolation back to what it is on the
branch, but this doesn't explain it.  If you run

t = text(0.5, 0.5, 'hi mom', fontsize=20)
t.set_rotation(30); draw()

and save the results from the trunk and the branch (using
agg::image_filter_spline36) on both, it appears (as you say) that the
font weight is darker for rotated text, but not for non-rotated text.

JDH

They don't look non-antialiased to me (in your attachment or a file I 
generated locally).  Remember, the rotation happens in raster (not 
vector) space, because that was the path of least resistance, but is a 
bit of a hack.

The difference is that the trunk appears slightly darker than 0.91.x.  
(And 0.90.x, if I recall correctly, didn't support non-90 degree 
rotations of text at all).  0.91.x is using spline36 interpolation, 
trunk is using spline16.  I *think* I changed it because I thought 
spline16 looked slightly cleaner (though technically less accurate), and 
of course is faster, but I'm not sure anymore -- SVN blame isn't helping 
me remember.  It could have just been the example I was using at the 
time looked better.

In any case, you should be able to change this line in _backend_agg.cpp:2197

  filter.calculate(agg::image_filter_spline16());

to any of the interpolation kernels that Agg offers, and experiment 
until you find something suitable.

Cheers,
Mike

John Hunter wrote:
> On the trunk, it appears that font anti-aliasing is turned off on
> rotated text, as in this example:
>
> n [26]: import datetime
>
> In [27]: dt = datetime.date.today()
>
> In [28]: dates = [dt-datetime.timedelta(days=i) for i in range(10)]
>
> In [29]: plot(dates, range(10))
> Out[29]: [<matplotlib.lines.Line2D object at 0x98f96ac>]
>
> # after rotation the fonts are pixelated
> In [34]: gcf().autofmt_xdate ()
>
> In [35]: draw()
>   
>
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-- 
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

On the trunk, it appears that font anti-aliasing is turned off on
rotated text, as in this example:

n [26]: import datetime

In [27]: dt = datetime.date.today()

In [28]: dates = [dt-datetime.timedelta(days=i) for i in range(10)]

In [29]: plot(dates, range(10))
Out[29]: [<matplotlib.lines.Line2D object at 0x98f96ac>]

# after rotation the fonts are pixelated
In [34]: gcf().autofmt_xdate ()

In [35]: draw()

On Thursday 24 April 2008 10:45:33 pm John Hunter wrote:
> On Thu, Apr 24, 2008 at 9:23 PM, Darren Dale <dar...@co...> 
wrote:
> >  I have been developing a data acquisition and analysis program for my
> > lab, and we are actually in the process of using it it this week and next
> > to run experiments with our visiting scientists. I've been running
> > matplotlib from svn for as long as I can remember and hadn't anticipated
> > trouble. I guess I just wasn't reading the dev list closely enough since
> > I rely on the trunk for daily use.
>
> I can appreciate that you are in production mode and have very little
>
> of any time for distraction, but if you get a minute try:
>   > svn co http://svn.scipy.org/svn/numpy/trunk numpy
>   > cd numpy/
>   > python setup.py build
>   > sudo python setup.py install
>
> Make sure you "rm -rf build" your mpl build dir and get a clean mpl
> rebuild afterward.  I would be very surprised if you encounter any
> troubles.   The numpy folks have been doing a tremendous amount of
> work to get svn ready for a 1.1 release, and you owe it to yourself to
> be on the latest.

I think I'm up and running. I'm not sure that the gentoo's lapack and blas 
were recognized, but thats because gentoo does some non standard naming of 
the f77blas. Also, there were a few changes I had to make for my project to 
work with numpy-svn, related to the behavior of ndarray.flat. Hopefully none 
of the other tools I depend on will have much trouble with numpy-1.1.

On Thu, Apr 24, 2008 at 9:23 PM, Darren Dale <dar...@co...> wrote:

>  I have been developing a data acquisition and analysis program for my lab, and
>  we are actually in the process of using it it this week and next to run
>  experiments with our visiting scientists. I've been running matplotlib from
>  svn for as long as I can remember and hadn't anticipated trouble. I guess I
>  just wasn't reading the dev list closely enough since I rely on the trunk for
>  daily use.

I can appreciate that you are in production mode and have very little
of any time for distraction, but if you get a minute try:

  > svn co http://svn.scipy.org/svn/numpy/trunk numpy
  > cd numpy/
  > python setup.py build
  > sudo python setup.py install

Make sure you "rm -rf build" your mpl build dir and get a clean mpl
rebuild afterward.  I would be very surprised if you encounter any
troubles.   The numpy folks have been doing a tremendous amount of
work to get svn ready for a 1.1 release, and you owe it to yourself to
be on the latest.

JDH