[Lazarus] Get JPEG from TAChart in CGI app

Alexander Klenin klenin at gmail.com
Sun Mar 20 21:21:50 CET 2011


On Mon, Mar 21, 2011 at 06:14, Leonardo M. Ramé <l.rame at griensu.com> wrote:
> Thanks for the explanation Alexander.
>
> Looking at the TChart.PaintOnCanvas method, I see you use a TCanvasDrawer class to draw over a TCanvas. I
> think it shouldn't be too difficult to use a TFPImageCanvas when using
> NoGui widgetset. What do you think?

There are two problems here:
1) I suspect that the error you see is generated at the application
startup, not when TChart tries to paint something.
So to work around it, it is not enough to remove TCanvas in one place
-- EVERY instance of TCanvas should be removed
(so that Graphics unit is not used any more).
Unfortunately, this is poses a serious compatibility hazard.
2) Even is the previous is possible (I believe it is, although difficult --
TChart should be split into several classes in different units, with
only the descendants depending on Graphics),
TFPCanvas version it will still have serious limitations -- no TColor,
no font orientation, etc.

-- 
Alexander S. Klenin




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