Refactor modm:ui:display

[TomSaw]

Followup from #601

Color has nothing to do in any of the MonochromeGraphicDisplay but it inherits Color from GraphicDisplay. For MonochromeGraphicDisplay it shouldn't be color but pixel On / Off.

• LCD pixels will be blackish on light background. Background color is a hardware property.
• OLED pixels will be light on black background. Pixel color is a hardware property.

New inheritances

GraphicDisplay <-- ColoredGraphicDisplay (Color stuff in here) <-- ILI9341, ,,,
GraphicDisplay <-- MonochromeGraphicDisplay (Light / dark stuff in here) <-- SSD1306, KS0108, ...

• New specialised interface GraphicDisplay <- ColoredGraphicDisplay; move color-stuff in there
  • Test Displays inheriting ColoredGraphicDisplay
• New specialised interface GraphicDisplay <- MonochromeGraphicDisplay
  • Test Displays inheriting MonochromeGraphicDisplay
  • Implement optimized drawVerticalLine for MonochromeVerticalDisplay
• Modernize code
• Update docs

[TomSaw]

• Due to the work on graphicDisplay i also consequently dug into refactoring color.hpp.
• Since i have a ILI9341 around, i found it does not work properly and started touching it's driver too.

-> I'm going to create PRs for the two 🙄👆 but let's first get this PR shipped.

All interfaces remain the same, except that you have to replace pointers GraphicDisplay* -> ColorGraphicDisplay* in your source if you use any of setColor(...) / setForgeground / setBackground.

"Color"-control for monochrome Displays is a thing, i want to implement after my planned refactor-color PR is merged (or not ;P) so I struck it from here for now.

Would someone please review the commit !? @salkinium ? @rleh ? @chris-durand ?

[salkinium]

So far so good!

[salkinium]

The ext/modm-devices submodule shouldn't be modified

[TomSaw]

All done. Thanks @chris-durand and @salkinium for your always enriching comments. I did a few more addition improvements you propably want to check.

[salkinium]

I like it a lot!

[salkinium]

What about this?

[TomSaw]

Postponed. I'm not clear about a good solution yet. nothing is lost, it hasn't worked before.

There's some stuff that interacts with foreground and background color, like writing characters. Also there's already setPixel(), clearPixel()
I fell like there could be a general solution that works with color and monochrome uniformly. but I want to cleanup color first #616 and afterwards spent some time on the ili9341 driver.
When i have nice color-class and a good to read ili9341 driver i want to dive into setting and clearing pixels ;)

[TomSaw]

One possible solution: Define modm::color::Grayscale witch stores one byte with grayscale value.
For Monochrome, we only need a a boolean - storing Pixel On/Off - nut boolean will anyways consume a full byte.
So why not just using the Grayscale here too? If (value & 0x80) -> Monochrome pixel is On

All the color-types and diplays will be very compatible to each other. You will be able to use the same functions to write a colored image on a color, grayscale or monochrome display (very simplified) if you need to.

class modm::color::Grayscale{
  uint8_t value; // Grayscale value
};

But yea... that's just one idea

[salkinium]

I think 8-bit grayscale is fine, since it's only an intermediate value anyways and it's a simple solution.
You need have an optimized image format for binary images anyways.

You can convert RGB into grayscale using this formula, however that doesn't necessarily makes sense without dithering (which definitely needs to be done beforehand).
https://github.com/salkinium/upainter/blob/master/doc/surface/README.md#8bpp-grayscale

[TomSaw]

Cool, I check this tomorrow :)

[salkinium]

Update docs? I'm happy with the rest. (and squash pls).

[salkinium]

A few more touches:

[TomSaw]

Merge?

[salkinium]

Thanks for this good cleanup! Let's squash your commits into one or more with good messages, then we can merge this!

[TomSaw]

That was a nice warmup. Thanks @salkinium 🌻 and @chris-durand 🌻 for taking me by the hand until these pleassent sessions.

By the time (and of course due to the cleanification) i gained more overview about the display API. I did not really wanted to warp all around but... now has taken me over. After some polishing of ssd1306 and ili9341, witch i use as reference hardware, i would love to present plans for and discus "refactor modm:ui:display part 2" ;).

Enjoy the days.