[Lazarus] TCairoCanvas integration

[petr.kristan at epos.cz]

On Thu, Mar 11, 2010 at 02:23:15PM +0100, Michael Van Canneyt wrote:
>
>
> On Thu, 11 Mar 2010, petr.kristan at epos.cz wrote:
>
>> On Wed, Mar 10, 2010 at 03:22:31PM +0100, petr.kristan at epos.cz wrote:
>>> Hi.
>>>
>>> Main work on TCairoCanvas = class(TPrinterCanvas) is almost done.
>>>
>>> My question is how to integrate it into LCL?
>>> IMHO user should have a choice which TPrinterCanvas implementation use.
>>> Now in TCUPSPrinter is hard coded TPostscriptPrinterCanvas:
>>>
>>> function TCUPSPrinter.GetCanvasRef: TPrinterCanvasRef;
>>> begin
>>>   Result:=TPostscriptPrinterCanvas;
>>> end;
>>>
>>> Petr
>>>
>> Nobody here, who can halp me to integrate TCairoCanvas into LCL?
>>
>> Were in LCL directory structure place cairocanvas.pas (depends only on
>> libcairo) and gdkcairocanvas.pas (depends extra on libgdk).
>>
>> How should programer select which implementation of TPrinterCanvas will
>> be created in TPrinter.GetCanvas.
>>
>> Now TCUPSPrinter implementation use hard coded TPostscriptPrinterCanvas
>> and needs access to TPostscriptPrinterCanvas(Canvas).OutputFileName.
>> My TCairoCanvas implementation has the same needs.
>>
>> I do not want to waste my time if comunity do not have an interest to
>> include CairoCanvas into lcl.
>
> I think you should create an abstract TFilePrinterCanvas descendent of
> TPrinterCanvas (with the needed FileName property) and define a variable
>
> Type
>   TFilePrinterCanvas = Class of TFilePrinterCanvas;
>
> Var
>   CupsCanvasClass : TFilePrinterCanvas = TPostscriptPrinterCanvas;
>
> which the programmer can set, if so desired. then the
> TCUPSPrinter.GetCanvasRef
> implementation checks the CupsCanvasClass variable. If it is set,
> it uses the class defined there, and if not, it uses
> TPostscriptPrinterCanvas.
Thanks.

This corresponds with my idea. 

Where is recommeded place for cairocanvas.pas and gdkcairocanvas.pas in
lcl? CairoCanvas can work on Windows, Linux and Mac OS X. 

Petr

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Petr Kristan
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