[OpendTect_Developers] How to save oneself from 2D Viewer Annotation repainting overhead

[Umesh Sinha]

Dear Fellow Developer,

Good to see that popularity of 2D Viewer is growing day by day. Hard 
work at our end is certainly paying dividend.

Today I'm going to let you know how to save yourself from repainting all 
annotation overhead in 2D Viewer.

First of all let us see how we do 'Annotation Painting' with help of our 
AuxData.

Let us say, we have a bunch of 2D points and we know where they should 
go in 2D Viewer layout, then first thing we do is initialize an AuxData 
as given below,

FlatView::Annotation::AuxData* myauxdata = new 
FlatView::Annotation::AuxData( "name" );

then we initialize display property of our choice for AuxData as 
described below,

myauxdata->markerstyles_ += your_marker_style;
myauxdata->linestyle_ = your_linestyle;
myauxdata->linestyle_.color_ = your_color

and so on...

and then convert all 2D points to FlatView::Point and add then to 
myauxdata->poly_. For example, if one of the points is having coordinate 
x and y, then following code will add your data to AuxData points

myauxdata->poly_ = FlatView::Point( x, y );

then we make sure AuxData is enabled and add it to 2D Viewer system, as 
shown below

myauxdata->enabled_ = true;
viewer_.appearance().annot_.auxdata_ += auxdata;

here 'viewer_' represents '2D Viewer' and I'm assuming we all know how 
to get correct '2D Viewer' instance.

Finally we ask '2D Viewer' system to handle the change with respect to 
Annotation as shown below.

viewer_.handleChange( FlatView::Viewer::Annot );

So far as good, but problem with 'viewer_.handleChange(Annot)' approach 
is if we have already so many things painted on 2D Viewer and ask 2D 
Viewer system to handle change with respect to Annotation then it 
repaints the entire AuxData again, which is a bit of overhead.

I have added some functionalities in Viewer which can help you in 
dealing with your individual AuxData only, those are

void        showAuxDataObjects(Annotation::AuxData&,bool);
void        updateProperties(const Annotation::AuxData&);
void        reGenerate(Annotation::AuxData&) ;
void        remove(const Annotation::AuxData&);

Hoping these are self explanatory, do let me know if you have any 
questions or confusion.

Happy coding with less overhead :-)

With Regards,
Umesh

-- 
- Umesh Sinha
- Geoscientific Software Developer
-
- dGB Earth Sciences
- 304, Gateway Plaza, Hiranandani Gardens,
- Powai, Mumbai 400 076, India
- Phone: +91 22 25704984 , Fax: +91 22 25704977
- Mobile: +91 9930126183
- mailto:umesh.sinha at dgbes.com, http://www.dgbes.com