On 2011-03-21 06:00:20 +1000, Alexander Klenin wrote: > On Mon, Mar 21, 2011 at 05:42, Leonardo M. Ramé <[email protected]> wrote: > > > > [Sun Mar 20 16:30:09 2011] [error] [client ::1] (cgicharts:16246): > > Gtk-WARNING **: cannot open display: > > [Sun Mar 20 16:30:09 2011] [error] [client ::1] Premature end of script > > headers: cgicharts > > Unfortunately, I am not an expert in GTK -- it seems that it tries to > initialize display even if there is nothing to draw. > I am not sure if it is fixable -- the demo I posted does work as a CGI > under Apache on Windows, so it may be GTK problem, Lazarus problem, > or X-server/GTK/Apache configuration problem. > You might want to try fpgui widgetset -- it depends only on X, > which may work even if GTK does not. > > Of course, it would be ideal to create a version of TAChart that does not > require a widgetset, but the task is complicated by compatibility > requirements. > I have already made some progress in this direction -- see > IChartDrawer infrastructure. > TAChart is mostly independent of TCanvas -- it only needs one for events > and interactive tools. > Few drawing back-ends exist -- AggPas, OpenGL, and more are planned, > in particular SVG, which will probably be most suitable for web apps. > Unfortunately, all back-ends have limitations compared to TCanvas > (for example OpenGL has very limited text rendering capabilities, > and "pure" TFPCanvas does not even support TColor). >
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? -- Leonardo M. Ramé http://leonardorame.blogspot.com -- _______________________________________________ Lazarus mailing list [email protected] http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
