Re: [pyGEF-develop] Using enthought.kiva as rendering backend

[<pyg...@li...>]

On 04 Aug 2007, at 1:44 AM, <pyg...@li...> wrote:

> pyg...@li... wrote:
> > Hi there
> >
> > Just to let you know that we have one new member, Louis Jordaan.
> > He is one of my students and will be doing his final year  
> engineering
> > project for the next five to six months. A large portion of his  
> work is to
> > make pyGEF usable
>
> Great news -- I'm looking forward to the results!
>
> > I have been looking at Kiva for the last day or so. Have any of  
> you ever
> > used it?
>
> No
>
> > Read about it?
>
> Yes.
>
> > As far as I could figure out it uses agg as a
> > renderer/back-end.
>
> Well, it's supposed to a multi-back-end thing, like many, but Agg  
> is the
> most-used one. I think the wx back-end for instance, renders with Agg,
> then blits to wx -- like Matplotlib wxAgg.
>
> It's modeled after DisplayPDF, so it should work with on OS-X, and I"d
> think the PDF back-end would be pretty simple! Having a PDF option  
> sure
> would be nice.
>
>  > Which you have previously suggested agg.
>
> That may have been me -- it does have very nice output, and it's
> reported to be very fast.
>
> > It looks like it's rendering is much, MUCH faster than using the  
> GC directly
>
> I'm getting more disappointed with GC's performance. But does it  
> support
> everything you need?
>
> > 1. Can or should pyGEF use Kiva as its primary backend?
> > 2. In the current version of pyGEF I use a Plotter class to draw  
> my graphic
> > objects. This Plotter Interface class (abstraction layer) allows  
> for the use
> > of multiple rendering back-ends. The problem is that an API for  
> this Plotter
> > Interface needs to be defined. I would appreciate suggestions,  
> with special
> > considerations for that fact that pyGEF must be usable as a base  
> for a SVG
> > type graphic drawing tool.
>
> Have you seen any of Chris Mellon's work with a wxPython SVG renderer?
> Search the wxPython mailing list for more info.
>
>
I will have a look.
>
> > I'm trying to teach +-480 first year students to program
>
> yow! Using Python, I hope!
>
>
Good old fashion C.
> > Bill, I saw that enthought has a very basic affine transform  
> module in kiva
> > (all python),
>
> Are you sure. I see this on the Wiki:
>
> """
> AffineMatrix:
>
> (kiva_affine_matrix.h and affine_matrix.i) All of the following member
> functions modify the instance on which they are called:
>
>      * __init__(v0, v1, v2, v3, v4, v5) or __init__()
>      * reset() # sets this matrix to the identity
>      * multiply(AffineMatrix) # multiples this matrix by another
>      * invert() # sets this matrix to the inverse of itself
>      * flip_x() # mirrors around X
>      * flip_y() # mirrors around Y
>      * scale() -> float # returns the average scale of this matrix
>      * determinant() -> float # returns the determinant
>
> The following factory methods are available in the top-level "agg"
> namespace to create specific kinds of AffineMatrix instances:
>
>      * translation_matrix(float X, float Y)
>      * rotation_matrix(float angle_in_radians)
>      * scaling_matrix(float x_scale, float y_scale)
>      * skewing_matrix(float x_shear, float y_shear)
>
> FontType
>
> """
> This makes it look like there is a C/C++ implementation of some sort.
>
>
I found affine.py in the kiva/agg sources, it's all python, while  
also using some numpy (which I assumes uses some pyrex). However the  
API is slightly different.
--retief