qmk_firmware/docs/quantum_painter_rle.md
Nick Brassel 1f2b1dedcc
Quantum Painter (#10174)
* Install dependencies before executing unit tests.

* Split out UTF-8 decoder.

* Fixup python formatting rules.

* Add documentation for QGF/QFF and the RLE format used.

* Add CLI commands for converting images and fonts.

* Add stub rules.mk for QP.

* Add stream type.

* Add base driver and comms interfaces.

* Add support for SPI, SPI+D/C comms drivers.

* Include <qp.h> when enabled.

* Add base support for SPI+D/C+RST panels, as well as concrete implementation of ST7789.

* Add support for GC9A01.

* Add support for ILI9341.

* Add support for ILI9163.

* Add support for SSD1351.

* Implement qp_setpixel, including pixdata buffer management.

* Implement qp_line.

* Implement qp_rect.

* Implement qp_circle.

* Implement qp_ellipse.

* Implement palette interpolation.

* Allow for streams to work with either flash or RAM.

* Image loading.

* Font loading.

* QGF palette loading.

* Progressive decoder of pixel data supporting Raw+RLE, 1-,2-,4-,8-bpp monochrome and palette-based images.

* Image drawing.

* Animations.

* Font rendering.

* Check against 256 colours, dump out the loaded palette if debugging enabled.

* Fix build.

* AVR is not the intended audience.

* `qmk format-c`

* Generation fix.

* First batch of docs.

* More docs and examples.

* Review comments.

* Public API documentation.
2022-04-13 18:00:18 +10:00

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Markdown

# QMK QGF/QFF RLE data schema :id=qmk-qp-rle-schema
There are two "modes" to the RLE algorithm used in both [QGF](quantum_painter_qgf.md)/[QFF](quantum_painter_qff.md):
* Non-repeating sections of octets, with associated length of up to `128` octets
* `length` = `marker - 128`
* A corresponding `length` number of octets follow directly after the marker octet
* Repeated octet with associated length, with associated length of up to `128`
* `length` = `marker`
* A single octet follows the marker that should be repeated `length` times.
Decoder pseudocode:
```
while !EOF
marker = READ_OCTET()
if marker >= 128
length = marker - 128
for i = 0 ... length-1
c = READ_OCTET()
WRITE_OCTET(c)
else
length = marker
c = READ_OCTET()
for i = 0 ... length-1
WRITE_OCTET(c)
```