It is required to call .dirty() with appropriate arguments after modifications through the buffer protocol, or the display might not be updated correctly.
This is a modest code savings, but more importantly it reduces
boilerplate in bitmap-modifying routines.
Callers need only ensure they call displayio_bitmap_set_dirty_area in
advance of the bitmap modifications they perform.
(note that this assumes that no bitmap operation can enter background
tasks. If an operation COULD enter background tasks, it MUST re-dirty
the area it touches when it exits, simply by a fresh call to
set_dirty_area with the same area as before)
.. simplifying code in the process. For instance, now fill_region
uses area routines to order and constrain its coordinates.
Happily, this change also frees a modest amount of code space.
.. and simplify the implmentation of displayio_area_union
This _slightly_ changes the behavior of displayio_area_union:
Formerly, if one of the areas was empty, its coordinates were still
used in the min/max calculations.
Now, if one of the areas is empty, the result gets the other area's coords
In particular, taking the union of the empty area with coords (0,0,0,0)
with the non-empty area (x1,y1,x2,y2) would give the area (0,0,x2,y2)
before, and (x1,y1,x2,y2) after the change.
When reading uncompressed bitmap data directly, readinto can work
much more quickly than a Python-coded loop.
On a Raspberry Pi Pico, I benchmarked a modified version of
adafruit_bitmap_font's pcf reader which uses readinto instead of
the existing code. My test font was a 72-point file created from Arial.
This decreased the time to load all the ASCII glyphs from 4.9 seconds to
just 0.44 seconds.
While this attempts to support many pixel configurations (1/2/4/8/16/24/32
bpp; swapped words and pixels) only the single combination used by
PCF fonts was tested.
