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.

Petr

Well, nobody said that it will not be included, but probably developers don't have enough spare time to review your work at the moment. Probably best way would be to open mantis issue about this and attach your changes as patch.

zeljko

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.

Michael.

Now I do not ask to review my work, I only need a little help with a few questions. In order to prepare complete include patch.

Petr

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

Good idea.

Mattias

lcl/interfaces/gtk2

Mattias

I think this is good place for gdkcairocanvas.pas. But cairocanvas.pas needs only libcairo. It do not needs gtk.

Petr

Well, it should be added to the fpc sources, but till this is in a release we have to add this unit to the lazarus sources too.

Mattias

Ok.

I place it into lcl/ along poscriptcanvas.pas.

Petr

On Thu, Mar 11, 2010 at 03:01:18PM +0100, Mattias Gaertner wrote:

[...]

lcl/ only contains platform independent sources (they must use a minimum of external libraries). Platform dependent things should be placed in lcl/interfaces/...
I think that non gtk users won't use cairo, so better place it in lcl/interfaces/gtk2.

Mattias

Windows or MacOSX user can use TCairoCanvas for export to pdf, ps, svg or png. He only needs libcairo which do not depends on gtk. Dependency is reversed, libgtk depends on libcairo.

For example Firefox 3 (gecko) uses Cairo on all platforms.

If will be interest we can easily make TWin32CairoCanvas, TX11CairoCanvas or TQuartzCairoCanvas (OSX) and render on screen. This should establish quite correct multiplatform WYSIWYG.

I myself think about to use it on Linux/gtk2 and Win32 for screen and printing in our DTP like project.

But if you still prefer lcl/interfaces/gtk2, I place it there.

Petr

I think it would be good to make it an independent package available in Lazarus, not necessarily linked to the LCL or FPC and at the same time available to users from different OS and widgetsets, the quality and the multi backend ability is certainly something that not only gtk users want.

Jesus Reyes A.

Encuentra las mejores recetas en Yahoo! Cocina.
http://mx.mujer.yahoo.com/cocina/

It sounds good.

I make CUPSPrinter switch:

Var
  CupsCanvasClass : TFilePrinterCanvas = TPostscriptPrinterCanvas;

and remaining can be easily independent.

Petr

Yes. A normal package is the best solution.

Mattias