Here are the reasons for rewriting mathtext2 that I can come up with:
* One of the reasons I started the complete rewrite of the parser is that
I'm a newbie at parsing, and I wanted to try it out a bit. I didn't understand
why was it so difficult to parse TeX (or anything a little bit complicated
for that matter). Well, now I know ;)
* The other reason was that I didn't understand fully the current parsing
code, or more precisely, the part when what's interpreted get's rendered.
And I'm not talking about glyphs, but about the complex constructs (scripts,
frac's etc.)
* The third reason was that I can now try out in pararel the new and the old
code. Also, because I'm not touching the PS and SVG backends for now we can
have the following code in the current mathtext:
if rcParams[some_parameter]:
from matplotlib.mathtext2 import math_parse_s_ft2font
else:
math_parse_s_ft2font = math_parse_s_ft2font_common('BMP')
math_parse_s_ft2font_svg = math_parse_s_ft2font_common('SVG')
math_parse_s_ps = math_parse_s_ft2font_common('PS')
math_parse_s_pdf = math_parse_s_ft2font_common('PDF')
Also, I thought that the author of the current code base did some design
mistakes at the begining. And, being a developer newbie, it's a lot easier
to start things from scratch, than make fixes to old stuff you don't
understand well.
As for the mathtext_demo.py part, even real TeX can't handle it :). The point
is that, i.e. \cal sets the current fontface to "cal", and the change is
propagated till the end of the current scope (or untill it hits \rm, for
example). Old mathtext applies it only to the first item after the command.
I promise that I'll post more about the implementation in a day or two.
I'll also post screenshots (TeX/mathtext/mathtext2 shootout).
Cheers,
Edin
On 8/18/06, John Hunter <[EMAIL PROTECTED]> wrote:
> >>>>> "Edin" == Edin Salkovi§ <[EMAIL PROTECTED]> writes:
>
> Edin> Hi all, Please John, take some time before SciPy conf to
> Edin> answer at least some of this questions, because the SoC
> Edin> deadline (21st August) is *very* near.
>
> Alas, I am already here and have been a little out of email contact
> while traveling. Sorry for the delay.
>
> Edin> 1) I'm having some problems regarding FT2Font. The problem
> Edin> is when I instantiate FT2Font like: font = FT2Font(filename)
> Edin> and when I call it's method font.set_text("Some text"), and
> Edin> afterwards, font.draw_glyphs_to_bitmap(), the latter simply
> Edin> deletes every glyph that was drawn before it, and just
> Edin> paints in the internal image buffer the text that was passed
> Edin> on last invocation of set_text (or load_char).
>
> This is a feature, not a bug :-) You can clear the image buffer if
> you want with the clear method, as we do in the mathtexy code
>
> for fontface in self.fonts.values():
> fontface.clear()
>
> Edin> This is a pain, because draw_glyphs_to_bitmap implements the
> Edin> layout (with kerning etc.), but if one wants to paint
> Edin> several words in different x,y positions in the same image
> Edin> buffer, he has to do the layout for every character in every
> Edin> word manually via draw_glyph_to_bitmap(x, y, glyph) (like
> Edin> you did with the BaKoMa fonts in mathtext).
>
> Edin> Why hasn't draw_glyphs_to_bitmap been implemented so that it
> Edin> takes x, y as arguments (draw_glyphs_to_bitmap(x, y)) and
> Edin> leaves the image buffer intact (as does
> Edin> draw_glyph_to_bitmap)?
>
> You can add optional x and y args to draw_glyphs_to_bitmap if you need
> them. Just make sure any changes you make pass
> examples/backend_driver.py and unit/memleak_hawaii3.py
>
> Edin> 2) As I have said before, I have started the complete
> Edin> rewrite of mathtext (the parsing stuff etc.). I have
> Edin> completely removed the dependency on pyparsing (please don't
> Edin> yell at me :), and I was wondering about how much of TeX
>
> OK, I won't yell. Quietly scold maybe :-)
>
> I am skeptical of your -- or anyone's except Robert's -- ability to
> parse TeX mathematical expressions w/o a true recursive descent
> parser. I took a look at your code but w/o any running examples I
> could not test it. From reading it, I do not think it will be able to
> handle the deeply recursive structures that are currently supported by
> the existing, working parser. Can you handle recursively nested
> super/sub scripts? Can it parse this
>
> tex = r'$\cal{R}\prod_{i=\alpha_{i+1}}^\infty a_i\rm{sin}(2 \pi f x_i)$'
>
>
> If so, I apologize for my skepticism, but my working assumption is you
> will need a proper parser to parse tex and string methods aren't going
> to get you there. What I really need to see before even considering a
> system that replaces the working system is an argument about why it
> needs to be replaced, and more importantly, code that can do
> everything the old code can do, such as render the mathtext_demo.py
> example?
>
> Edin> should mathtext support. I'm not talking about support for
> Edin> \frac, \above, \choose (which I plan to add one by one)
> Edin> etc., but about more general things - macros (\def etc.). I
>
> \above, \frac and \sqrt yes, \def no. Others I'm not sure about.
>
> Edin> was thinking of just simulating them, at least to a
> Edin> tolerable extent, via notion of an enviroment. Example: \rm
> Edin> in plain TeX sets the current font to roman (until the end
> Edin> of the current scope - 'till it hits "}"). Implementation:
> Edin> At render time, when the parser hits "\rm", it does the
> Edin> folowing: env["facetype"] = "rm", where env is the
> Edin> environment in the current scope.
>
> Can we use classes here rather than dictionaries? Syntactically, I
> prefer env.facetype = "rm" to the dictionary syntax.
>
> Edin> Also, I am planing to create a separate class for every new
> Edin> layout item that gets implemented. Example:
> Edin> sub/superscripted item (nucleus_sub^sup) gets translated to
> Edin> an instance of class Scripted that has the attributes
> Edin> nucleus, superscript and subscript.
>
> Edin> 3) I was thinking of focusing on just the Agg backend for
> Edin> now (that is till' the deadline). Is this OK? 4) I think
> Edin> that we should move the job of math_parse_s_ft2font,
> Edin> math_parse_s_ft2font_svg, and math_parse_s_ps etc. to the
> Edin> corresponding backends, and that some general function like:
> Edin> math_parse_s(x, y, s, prop, angle) should be implemented
> Edin> directly in mathtext.py (perhaps even without the "angle"
> Edin> parameter) so that it returns a list of the following type:
> Edin> [(x1, y1, s1, prop1, angle1), ... , (xn, yn, sn, propn,
> Edin> anglen)]
>
> I can't address these questions until I understand why you are trying
> to rewrite, rather than extend or fix, the existing code. The agg and
> the postscript backends work with the existing frameowork. As far as
> I can see, you could fix the layout engine in the existing framework
> and not have to think too much about backends, with the exception that
> you need a basic backend line drawing API for things like the
> horizontal line in \frac.
>
> Edin> 5) What would be the consequences of distributing a GPL font
> Edin> (FreeFont) with matplotlib. I mean, it's not that using a
> Edin> GPL font in some non-GPL app could be a breach of the
> Edin> GPL. Is there any interest in this?
>
> Don't underestimate the zealousness of GPL advocates. I have been
> informed by the FSF that merely providing a backend that does
>
> import qt
>
> in a backend that is optionally included at runtime by a user who may
> be using a GPL version of QT or may be using a commercially licensed
> version of qt (we can't know which) makes the entire code base of mpl
> GPL'd. This claim was provided w/o argument and I frankly find it
> ludicrous. Robert can probably tell you the IANAL response to
> including GPL'd fonts but I'm not too interested in distributing them.
> We can always point the user to a web site and they can download them
> from.
>
> Edin> The new mathtext.py is attached. Please do not try it at
> Edin> home ;) because nothing visible yet works.
>
> OK.
>
> JDH
>
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