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.
This is a first go at it, done by naive replacing of all array
operations with corresponding operations on the list. Note that
there is a lot of unnecessary type conversions, here. Also, list_pop
has been copied, because it's decalerd STATIC in py/objlist.h
Since we want to expose the list of group's children to the user,
we should only have the original objects in it, without any other
additional data, and compute the native object as needed.
Microsoft documentation says:
> If biCompression equals BI_RGB and the bitmap uses 8 bpp or less, the bitmap has a color table immediatelly following the BITMAPINFOHEADER structure. The color table consists of an array of RGBQUAD values. The size of the array is given by the biClrUsed member. If biClrUsed is zero, the array contains the maximum number of colors for the given bitdepth; that is, 2^biBitCount colors.
Formerly, we treated 0 colors as "no image palette" during construction,
but then during common_hal_displayio_ondiskbitmap_get_pixel indexed into
the palette anyway. This could have unpredictable results. On a pygamer,
it gave an image that was blue and black. On magtag, it gave a crash.
The transparent_color field was never initialized. I _think_ this means
its value was always set to 0, or the blackest of blacks. Instead,
initialize it to the sentinel value, newly given the name
NO_TRANSPARENT_COLOR.
This exposed a second problem: The test for whether there was an existing
transparent color was wrong (backwards). I am guessing that this was not
found due to the first bug; since the converter had a transparent color,
the correct test would have led to always getting the error "Only one
color can be transparent at a time".
Closes#3723
* Initialize the EPaper display on the MagTag at start.
* Tweak the display send to take a const buffer.
* Correct Luma math
* Multiply the blue component, not add.
* Add all of the components together before dividing. This
reduces the impact of truncated division.
@cwalther determined that for boards with 2 displays (monster m4sk),
start_terminal would be called for each one, leaking supervisor heap
entries.
Determine, by comparing addresses, whether the display being acted on
is the first display (number zero) and do (or do not) call start_terminal.
stop_terminal can safely be called multiple times, so there's no need
to guard against calling it more than once.
Slight behavioral change: The terminal size would follow the displays[0]
size, not the displays[1] size
