Re: clickable QWTSymbols

[David S. <David_Stranz@MassSpec.com>]

Thomas,

You will have to implement such a feature yourself.  The QwtPlot does 
not know anything about where plot items are located - plot items draw 
themselves onto the canvas.

If you do not have many symbols, you can simply keep a list or vector of 
symbol rects as an additional data structure.  When the user clicks, you 
can search the list to see if the mouse is "near" a symbol (maybe a 
rectangle 10 pixels wide around each symbol?) and zoom.  Ordering the 
list from top left to lower right would allow you to do a quick binary 
search of the list.

If you have a large number of symbols or symbols that overlap, you may 
have to use a more complex data structure to store them, such as a 
quadtree, so you can search efficiently.

David

_______________________________________________________________
David Stranz, Ph.D.	david_stranz@MassSpec.com

Sierra Analytics, Inc.
5815 Stoddard Road, Suite 601
Modesto, CA  95356

Tel: (209) 545-8508
http://www.massspec.com
_______________________________________________________________


On 2/10/2011 8:09 AM, Thomas wrote:
> Hello,
>
> I want to make QWTSymbols clickable, for example to click and zoom in to a range
> around the symbol.
> Is there an implementation for clickable symbols or do you have any idea how or
> where to implement such a feature?
> Because I have the problem that the mainwindow with zoomer and picker has no
> access to the qwtsymbols.
>
>
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