PGPT with some symbols draws extra lines between points

[xspector]

Using PGPT with symbols 4, 8, 10, 20-27 causes extra lines to be drawn between the points. The reason is that cairo_arc starts by drawing a line from the current position to the start of the arc requested. The solution is to call cairo_new_sub_path before the call to cairo_arc.

To fix this change in giza-points.c the routines _giza_point, _giza_rect_concave, and giza_circle_size. Note that in _giza_circle you could also replace the call to cairo_move_to by cairo_new_sub_path for simplicity and code parellelism.

The diff between fixed and original versions of giza-points.c is
411d410
< cairo_new_sub_path (Dev[id].context);
446d444
< cairo_new_sub_path(Dev[id].context);
531d528
< cairo_new_sub_path (Dev[id].context);

[danieljprice]

Thanks very much for reporting this, will patch and fix.

May I ask from your username if you've had success using Xspec with Giza as the backend?

[xspector]

Yes, I have been able to use xspec with giza plotting. There was a speed problem when plotting error bars for spectra with tens of thousands of bins but I was able to fix that in our code. We were using PGMOVE and PGDRAW instead of PGERRX and PGERRY, doubtless for historical reasons. I still have an issue with plotting to eg postscript files when I end up with three pages (blank page, plot, blank page) which I have not worked out yet. The only other problem I know about does not matter for xspec but when plotting multiple images in the same page only the first appears. I need to make simple standalone program to illustrate this.