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caemor / epd-waveshare

Drivers for various EPDs from Waveshare
ISC License
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Update to work with latest e-g and tinybmp #196

Open bemyak opened 4 months ago

bemyak commented 4 months ago

I had some issues with rendering simple black & white images with tinybmp crate, and had to apply these patches to make it work. Let me know if it makes sense.

avlec commented 3 months ago

I've had some success on the 3.7in (which doesn't have the best support) without any modifications but yes the color is inverted so I worked around that by just inverting the BMP.

Just wondering if this change makes working with these slightly easier (no color_converted() in the draw call?)

use embedded_graphics::pixelcolor::BinaryColor;
use embedded_graphics::{prelude::*, image::Image};

// ...
    let mut display = Display3in7::default();
    const SPLASH: &[u8] = include_bytes!("../splashnewbw.bmp");
    let splash_bmp = tinybmp::Bmp::<BinaryColor>::from_slice(SPLASH).unwrap();
    Image::new(&splash_bmp, Point::zero()).draw(&mut display.color_converted()).unwrap_or_else(|_| error!("failed to render splash screen"));
diajowe commented 2 months ago

Managed to draw some text with your PR for a epd7in5_v2::Display7in5, this currently doesn't work in master or version 0.5.0 as seen in issue #194

diajowe commented 1 month ago

I see this PR is a draft? Is there something missing for completion?

bemyak commented 1 month ago

Yeah, there were some arguable changes related to color inversion, so I was waiting to get any feedback.

I've dropped them for now, and users are encouraged to use display.color_converted() as mentioned by @avlec.

I'll mark this as ready for review now.

diajowe commented 1 month ago

Yeah, there were some arguable changes related to color inversion, so I was waiting to get any feedback.

I've dropped them for now, and users are encouraged to use display.color_converted() as mentioned by @avlec.

I'll mark this as ready for review now.

Would you mind going a bit more into detail on what could go wrong? Maybe I could test a bit further, as currently, I only displayed some data using 7.5inch BW version of waveshare EPD

bemyak commented 1 month ago

Would you mind going a bit more into detail on what could go wrong?

BinaryColor is supposed to represent something like a LED pixel, so BinaryColor::On means the LED is emitting light, thus the value should (in my opinion) correspond to Color::White on an EPD.

However, in the current implementation, it's the opposite: https://github.com/caemor/epd-waveshare/blob/1244f03591bcc5f001b6e634170eb99e29e768d0/src/color.rs#L297-L304

I guess it's because in most cases when rendering text, people expect to see white on black for LED panels and black on white for EPD. Displaying images becomes tricky now since you need to invert colours to display them properly.

Inverting all the colours to be "On=White, Off=Black" is a breaking change and it must be discussed thoroughly.