Re: goffice and cairo

[Emmanuel Pacaud <emmanuel pacaud univ-poitiers fr>]

Le mardi 23 mai 2006 à 11:21 +0200, Jean Bréfort a écrit :
> Le mardi 23 mai 2006 à 11:04 +0200, Emmanuel Pacaud a écrit :
> > Hi,
> >
> > Here's some words on what I'm working on currently.
> >
> > Last weeks, I've tried to finalize the cairo SVG backend for its
> > inclusion as supported backend. So I hope next stable cairo will have
> > good PDF, PS and SVG backends.
> >
> > It will then be possible to ditch our current rendering engine and
> > replace it by a simplified one, based on cairo.
> >
> > So my plan is to implement this simplified engine, and validate it by
> > using it in two plot plugins, via a new GogView::cairo_render.
> >
> > Here's the current in-progress API:
> >
> > typedef struct _GOPathPoint           GOPathPoint;
> >
> > GOPath *go_path_new               (void);
> > GOPath *go_path_new_with_size (int size);
> > void    go_path_free          (GOPath *path);
> >
> > void go_path_set_sharp  (GOPath *path, gboolean sharp);
> >
> > void go_path_move_to        (GOPath *path, double x, double y);
> > void go_path_line_to        (GOPath *path, double x, double y);
> > void go_path_curve_to       (GOPath *path, double x0, double y0, 
> >                                    double x1, double y1, 
> >                                    double x2, double y2);
> > void go_path_rectangle  (GOPath *path, double x, double y, 
> >                                    double width, double height);
> > void go_path_ring_wedge (GOPath *path, double cx, double xy,
> >                                    double rx_out, double ry_out, 
> >                                    double rx_in, double ry_in, 
> >                                    double th0, double th1);
> > void go_path_arc    (GOPath *path, double cx, double cy, 
> >                                    double rx, double ry, 
> >                                    double th0, double th1);
> > void go_path_pie_wedge  (GOPath *path, double cx, double cy, 
> >                                    double rx, double ry, 
> >                                    double th0, double th1);
> > void go_path_marker         (GOPath *path);
> > void go_path_close  (GOPath *path);
> >
> > typedef struct _GOCairo GOCairo;
> >
> > GOCairo *go_cairo_new               (void);
> > void go_cairo_free          (GOCairo *gcairo);
> >
> > void go_cairo_push_style    (GOCairo *gcairo, GogStyle const *style);
> > void go_cairo_pop_style             (GOCairo *gcairo);
> >
> > void go_cairo_push_clip     (GOCairo *gcairo, GOPath const *path);
> > void go_cairo_pop_clip      (GOCairo *gcairo);
> >
> > void go_cairo_stroke                (GOCairo *gcairo, GOPath const *path);
> > void go_cairo_fill          (GOCairo *gcairo, GOPath const *path);
> > void go_cairo_draw_shape    (GOCairo *gcairo, GOPath const *path);
> > void go_cairo_draw_markers  (GOCairo *gcairo, GOPath const *path);
> > void go_cairo_draw_text             (GOCairo *gcairo, double x, double y, char
> > const *text, GtkAnchorType anchor);
> >
> > void go_cairo_get_text_OBR  (GOCairo *gcairo, char const *text,
> > GOGeometryOBR *obr);
> > void go_cairo_get_text_AABR (GOCairo *gcairo, char const *text,
> > GOGeometryAABR *aabr);
> >
> > double go_cairo_line_size   (GOCairo const *gcairo, double width);
> > double go_cairo_pt_2r_x             (GOCairo const *gcairo, double d);
> > double go_cairo_pt_2r_y             (GOCairo const *gcairo, double d);
> > double go_cairo_pt_2r               (GOCairo const *gcairo, double d);
> >
> > void go_cairo_render (GOCairo *gcairo, cairo_surface_t *surface);
>
> All that might be included in the GOImage code I'm currently working on,
> IMHO. I hope I can have something operational as soon as tomorrow ;-)

All what ? All of what's above ?

> > The final step would be to port all existing plot plugins. I think I'll
> > move pixbuf caching to gog_control_foo_canvas, and image_export and
> > get_pixbuf to GogGraphView.
> >
> > Regarding printing, since there's no gnome-print backend for cairo, I
> > guess we can just render graphs as raster image.
>
> Please, don't do that! It would be a serious regression (unless you use
> high resolution. Let's use the gnome-print renderer as long as we use
> gnome-print (hopefully not too long).

We could use a high resolution. My concern is if we keep a part of
GogRenderer, for its gnome-print support, we'll have either a lot of
duplicated code in plot plugins, or a mess of #ifdefs...

        Emmanuel.