adding_a_new_canvas_class.ipf

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:title.Adding a new Canvas class

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.nameit symbol=pubdate text='December 2016'
.nameit symbol=dv text='Docview'
.nameit symbol=fpg text='fpGUI Toolkit'
.nameit symbol=fpc text='Free Pascal Compiler'


:h1.Adding a new Canvas class
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Adding a new Canvas class
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Written by Andrew Haines
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:p.
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:row.
:c.Version
:c.v1.0
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:c.Pub Date
:c.&pubdate.
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:h2.Abstact
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 Abstract
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:p.This will hopefully help anyone in the future implementing a new canvas 
class in &fpg..

:h2.Steps
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þþþþþþþ
 Steps
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:ol.
:li.Create a new unit that uses :color fc=darkred.fpg_base:color fc=default..
:li.Add a new canvas class i.e. :color fc=darkred.TfpgCairoCanvas:color fc=default. derived from :color fc=darkred.TfpgCanvasBase:color fc=default..
:li.Copy/Paste the :hp2.virtual; abstract;:ehp2. methods to the new type.
:li.Start implementing those methods.
:eol.

:h2.Further Reading
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 Further Reading
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:ecgraphic.
:p.To get a better understanding of how &fpg.'s painting process works, what
methods get called, and how the various widget Canvas's work together, take a
look at 
the :link reftype=hd refid=1 database='alienwindow_design.inf'.alienwindow_design.inf:elink. file.

:euserdoc.