Re: Patch to fix the Bar Cursor Too Narrow problem on Mac OS X

[Jan Djärv]

2011-02-23 21:06, Chong Yidong skrev:
> Adrian Robert<address@hidden>  writes:
>
> > OK, I'll bite on this since it's my code originally.  :-) I
> > deliberately chose not to break into subfunctions like X since the
> > clarity of having the whole implementation in one block seemed greater
> > than that gained by splitting out.  Also a number of redundancies in
> > x_draw_bar_cursor() and x_draw_hollow_cursor() are saved.
>
> Nothing wrong with choosing not to break into subfunctions, but there
> some differences in the basic logic that make it hard to maintain.
>
> Consider the xterm behavior.  For FILLED_BOX_CURSOR, we call
> draw_phys_cursor_glyph to redraw that glyph with the cursor face
> (DRAW_CURSOR).  No additional repainting is necessary.  For bar cursors,
> we paint an extra thin bar on top of the screen area for the existing
> glyph; there is no need to call draw_phys_cursor_glyph.
> In contrast, ns_draw_window_cursor repaints via NSRectFill (for both box
> and bar cursors), and then calls draw_phys_cursor_glyph (for both box
> and bar cursors).

You are simplifying things.  For X a different GC with different background 
and foreground from normal text is used when drawing the glyph (the cursor 
face).  What X in fact does is filling with the background and then paint the 
glyph with the foreground.
There is no such thing in NS.  You have to set the background of the cursor 
face with NSRectFill, and then paint the foreground of the cursor face by 
painting the glyph. It is basically the same thing, but NS does not have one 
call for it.

> The NS terminal seems not to use DRAW_CURSOR for
> drawing filled box cursors.  So the basic handling for box cursors seems
> to be completely different, and I don't understand the rationale.

I don't know what you mean, NS do use DRAW_CURSOR, just search for it in 
nsterm.m

        Jan D.