Re: Dia 0.88.1: Problems with exporting to xfig

On Tue, 12 Jun 2001, Cyrille Chepelov wrote:

Le mar, jun 12, 2001, à 01:53:50 -0500, Lars Clausen a écrit:
A third idea I came up with for this: Have the renderer only define the
most basic shapes as fixed function pointers, and everything else
(rectangles, arrows, polylines, even complete shapes if the renderer
wants) be in a hashtable.  Then things like Visio or Kivio export can
try to retain more complex objects through a plug-in.

I'm not sure I understand what you want to do... basically, do you want
objects, in their draw routine, to do stuff like:

      def mycoolobject_draw(self,renderer):
          if renderer.ops.extra.has_key("mycoolobject"):
          <do normal processing using primitives>

Preferably have the render check outside the objects own draw routine:

  char *typename = obj->get_type()->name;
  if (renderer.ops.extra.has_key(typename))

The problem is to limit the time spent doing lookup for this.  The good
part is that it is flexible enough to allow complex shapes being rendered
this way.

What I was thinking was more something like:
      def roundedrectangle_draw(self,renderer):
          # set up line styles, etc.
          featurehint = (FEATURE_ROUNDED_RECTANGLE,
          renderer.ops.begingroup(renderer, GROUP_TYPE_FEATURE, featurehint)
          # if the renderer knows about rounded rectangles, it'll hijack
          # the rendering until endgroup() is called. Otherwise it'll
          # write the primitives as asked by the object.
            for corner in [nw,se,sw,ne]:
            for border in [n,w,s,e]:
          renderer.ops.endgroup(renderer,GROUP_TYPE_FEATURE, featurehint)

That could work, though it's somewhat messy.

Then, unlinke Python, C has a very efficient built-in way to make a hash
table associating an identifier to snippets of executable code: a switch
statement. Hint-using renderers just have to put a 
      switch (type) {
          /* ... */
          case GROUP_TYPE_FEATURE: {
              FeatureStruct *fs = (FeatureStruct *)hint;
              switch(fs->feature) {
                 case FEATURE_ROUNDED_RECTANGLE:
   if they provide a begin_group() hint routine.              

That's exactly what I want to avoid.  That inner case could be quite long.  


Lars Clausen ( | Hårdgrim of Numenor
"I do not agree with a word that you say, but I    | Retainer of Sir Kegg
will defend to the death your right to say it."    |   of Westfield
    --Evelyn Beatrice Hall paraphrasing Voltaire   | Chaos Berserker of Khorne

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