Re: proposal: gdk_draw_focus_rectangle

At 10:06 24.05.01 -0400, Owen Taylor wrote:
>Hans Breuer <hans breuer org> writes:
>> while trying to keep Gtk+2.0 up-to-date on win32, I stumbled
>> over just another limitation in the Windoze API. It is 
>> not possible to draw a really dotted line (one pixel drawn, one
>> pixel empty) with standard GDI (Win9x) functions. The 'dotted' line
>> style draws and leaves _four_ pixels instead. As a result
>> the focus indication looks somewhat ugly.
>Well the interface you need to implement in GTK+
>void   gdk_gc_set_dashes          (GdkGC            *gc,
>				   gint	             dash_offset,
>				   gint8             dash_list[],
>				   gint              n);
Which is obviously implemented long time ago (though it
still inherits the GDI limitations) ...

To give you an impression of what is possible with standard
GDI functions I've attached a small image. 
It contains vertical lines with all available linestyles.
The border is drawn with DrawFocusRect().

>>From gtkstyle.c/gtk_default_draw_focus:
>  if (detail && !strcmp (detail, "add-mode"))
>    gdk_gc_set_dashes (style->black_gc, 0, "\4\4", 2);
>  else
>    gdk_gc_set_dashes (style->black_gc, 0, "\1\1", 2);
>[ "add-mode" is basically unused ]
>So if you have to implement it with:
> You use the GDI dotted style if it is 4/4
> You use the GDI "focus" style if it is 1/1

The "focus" style isn't available for drawing lines with GDI (win9x).

It is only available from DrawFocusRect(), which can't be (miss-)used
to draw lines because of it's XOR semantics.

IMO it would be a really small compromise to wrap the focus
rectangle drawing into it's own gdk function, but obviously
it is simplier to put all the burden on the non X backends ...

> You draw lots of little lines if it is anything else
>Well, that would be painful, but...
... who cares for the win32 port ...


Attachment: lines.png
Description: Binary data

-------- Hans "at" Breuer "dot" Org -----------
Tell me what you need, and I'll tell you how to 
get along without it.                -- Dilbert

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