Internal screen data rewrite for better 256 colour/UTF-8 support.

TODO

@@ -41,127 +41,10 @@
 
 -- For 0.5 --------------------------------------------------------------------
 
-XXX
-screen contains grid
-
-screen_write   <-- write to TTY and to screen using close-to-ANSI functions
-screen_redraw  <-- write areas of screen to TTY
-grid_view      <-- write to viewable area of grid
-grid	       <-- manipulate grid and history
-
-XXX
-grid_view has ox,oy
-XXX
-
-- FINISH UTF8: fix copy and paste
-- SPLIT u_short attr into attr,flags?
-- maybe rethink backend data structure?
-  	- utf8 can be 1-4 bytes
-	- most common is 1 bytes
-	- there can be double-width characters which take n bytes but 2 columns on screen
-	- they are not only drawn as two characters, they also require two backspaces to remove
-- three operations:
-  	- simultaneously update screen and ttys
-	- redraw screen or section of screen to ttys
-	- write to ttys without updating screen
-
----
-NEED to be able to:
-     resize screen
-     apply ops to both screen and tty simultaneously
-     	   both when parsing input and when eg scrolling history
-     draw on the top of the screen without modifying it
-     display arbitrary parts of the history
-     redraw arbitrary parts of the visible screen
----
-NEVER need to draw into the history
-
-split off grid manip:
-      16-bit characters
-      8-bit flags
-      8-bit attributes
-      8-bit fg colour
-      8-bit bg colour
-
-struct grid_data {
-	struct grid_cell **data;
-	int	*sizes;
-
-	int	sx;
-	int	sy;
-
-	int	hsize;
-	int	hlimit;
-};
-struct grid_cell {
-       u_short	data;
-       u_char	attr;
-       u_char	flags;
-       u_char	fg;
-       u_char	bg;
-};
-const struct grid_default_cell = { 0x20, 0, 0, 8, 8 };
-
-; grid logically split from
-;    -hlimit to 0 and 0 to sy
-
-; ALWAYS fill with default
-
-const struct grid_cell *grid_get(int x, int y);
-void		  grid_set(int x, int y, const struct grid_cell *cell);
-
-void		  grid_resize()
-void		  grid_shift() /* shift lines into history */
-
-struct grid_view {
-       int	ox;
-       int	oy;
-
-       int	sx;
-       int	sy;
-
-       struct grid_data	*gdata;
-       struct grid_view	*parent;
-};
-
-struct grid_cell *grid_view_get_cell(int x, int y)
-void		  grid_view_set_cell(int x, int y, const struct grid_cell *cell);
-
-int		  grid_view_absolute_x(int x);
-int		  grid_view_absolute_y(int y);
-
-int		  grid_view_relative_x(int x);
-int		  grid_view_relative_y(int y);
-
-void		  grid_view_delete_lines(int y, int ny)
-void		  grid_view_insert_lines(int y, int ny)
-void		  grid_view_clear_lines(int y, int ny)
-void		  grid_view_fill_lines(int y, int ny, const struct grid_cell *cell)
-
-void		  grid_view_delete_cells(int x, int y, int nx)
-void		  grid_view_insert_cells(int x, int y, int nx)
-void		  grid_view_clear_cells(int x, int y, int nx)
-void		  grid_view_fill_cells(int x, int nx, const struct grid_cell *cell)
-
-void		  grid_view_clear_area(int x, int y, int nx, int ny)
-void		  grid_view_fill_area(int x, int y, int nx, int ny, const struct grid_cell *cell)
-
----
-
-screen has two (both grid_view):
-       base and overlay
-
----
-screen_write writes into overlay if it exists and then base, also optionally to tty
-screen_draw  draws overlay + base to display
----
-
----
-
-Would it be better to just expand char to 16-bits and use it as an index only
-for >2-byte characters? or - better - don't support entire UTF range? only the BMP?
-this would get rid of UTF table and limits, but still leave double-width character annoyances
-also would double memory usage
+TODO -- 2 fix window-*.c
+	3 resizing
+	4 audit for leftover/unused code
+	5 next phase of tidying
 ----
 
 21:09 < merdely> NicM: if I run 'tmux attach -t main' and there is no tmux session named main, start a new one.