Question: How "expensive" would measuring the text before doing the real output in X11 be?
Reasoning: In STR #2798 [1] there's a proposal to clip text before drawing in X11, because of the problem with 16-bit coordinates in X11 vs. 32-bit coordinates in FLTK. The proposed patch [2] is incomplete (and not correct), but a correct clipping algorithm would IMHO mean that we'd need to measure the text. The problem is that text that would normally be outside the clipping range could "wrap" into the display because X11 ignores the upper 16 bits of the (FLTK) coordinate space. Note that this is not a problem for Windows and OS X, since these are using 32-bit coordinates anyway. Does anybody here know how "expensive" this would be in terms of CPU usage and - probably *much* more important - X11 server interactions? The measuring would have to be right before calling XUtf8DrawString(fl_display, fl_window, font_descriptor()->font, fl_gc, x, y, c, n); in fl_font_x.cxx (isn't there another one for XFT?), so the font for measuring the text would probably be set up already. Would this introduce more X server messages, or would measuring be a local operation? Second question: What function should be used: fl_measure() or fl_text_extents()? Would there be a performance difference to be expected, or would it only be the small difference in the exact layout? The latter could IMHO be ignored, I'd suggest to use the faster method, because exactness wouldn't matter here, anyway. Albrecht [1] http://www.fltk.org/str.php?L2798 [2] http://www.fltk.org/strfiles/2798/patch.txt _______________________________________________ fltk-dev mailing list fltk-dev@easysw.com http://lists.easysw.com/mailman/listinfo/fltk-dev
