Before, when an OnDiskBitmap was a paletted bitmap type, the palette
was internal to the OnDiskBitmap, and it internally performed the palette
conversion itself. When using with a tilegrid, a ColorConverter() object
always had to be passed.
Now, an OnDiskBitmap has a "pixel_shader" property. If the bitmap is
a paletted bitmap type, it is a (modifiable) Palette object. Otherwise,
it is a ColorConverter() object as before. This allows palette effects
to be applied to paletted OnDiskBitmaps.
Code that used to say:
```python
face = displayio.TileGrid(odb, pixel_shader=displayio.ColorConverter())
```
must be updated to say:
```python
face = displayio.TileGrid(odb, pixel_shader=odb.pixel_shader)
```
Compatible code for 6.x and 7.x can say
```python
face = displayio.TileGrid(odb, pixel_shader=getattr(odb, 'pixel_shader', ColorConverter())
```
This also improves Palette so it stores the original RGB888 colors.
Lastly, it adds I2CDisplay as a display bus to talk over I2C. Particularly
useful for the SSD1306.
Fixes#1828. Fixes#1956
It's designed to minimize RAM footprint by using Sprites to
represent objects on the screen. The object model also facilitates
partial screen updating which reduces the bandwidth needed to display.
This is all handled in C. Python simply manipulates the objects with
the ability to synchronize to frame timing.
Jeff Epler
microDev
Scott Shawcroft
Matthew Newberg
Radomir Dopieralski