wip: flesh out api, add preview call

Cargo.lock

@@ -1308,6 +1308,7 @@ dependencies = [
  "epd-waveshare",
  "image",
  "linux-embedded-hal",
+ "mime",
  "minijinja",
  "palette",
  "serde",

Cargo.toml

@@ -13,6 +13,7 @@ clap = { version = "4.5.7", features = ["derive"] }
 epd-waveshare = { git = "https://github.com/caemor/epd-waveshare.git"}
 image = "0.25.1"
 linux-embedded-hal = { version = "0.4.0"}
+mime = "0.3.17"
 minijinja = "2.1.0"
 palette = "0.7.6"
 serde = { version = "1.0.204", features = ["derive"] }

src/api.rs

@@ -1,21 +1,23 @@
-use crate::imageproc::{DitherMethod, EInkImage, };
+use crate::display::EInkPanel;
+use crate::imageproc::{DitherMethod, DitherPalette, EInkImage};
 use axum::extract::Multipart;
-use axum::http::StatusCode;
+use axum::http::{header, StatusCode};
 use axum::response::IntoResponse;
 use axum::{extract::State, response::Response, routing::post, Router};
-use image::{DynamicImage, ImageReader};
-use std::io::Cursor;
-use std::time::Duration;
-use tracing::{debug, error, info, instrument};
-
-use crate::display::EInkPanel;
+use image::{ImageReader, RgbImage};
+use std::io::{BufWriter, Cursor};
+use std::str;
+use std::str::FromStr;
 use std::sync::Arc;
+use std::time::Duration;
 use tokio::sync::mpsc::{self, Receiver, Sender};
 use tokio::task::JoinHandle;
+use tracing::{debug, error, info, instrument};
 
-pub enum ImageFormFields {
-    DitherType,
-    ImageFile,
+#[derive(thiserror::Error, Debug)]
+pub enum ApiError {
+    #[error("missing image field")]
+    MissingImage,
 }
 
 #[derive(Clone)]
@@ -86,45 +88,89 @@ pub async fn display_task(
 pub fn router() -> Router<Context> {
     Router::new()
         .route("/setimage", post(set_image))
-        .route("/process_image", post(process_image))
+        .route("/preview", post(preview_image))
 }
 
 #[derive(Debug)]
-pub struct ImageRequest {
-    image: Box<DynamicImage>,
+struct ImageRequest {
+    image: Box<RgbImage>,
+    dither_method: DitherMethod,
+    palette: DitherPalette,
+}
 
+impl ImageRequest {
+    async fn from_multipart(mut parts: Multipart) -> Result<Self, AppError> {
+        let mut img = None;
+        let mut palette = None;
+        let mut dither_method = None;
+        while let Some(field) = parts.next_field().await? {
+            match field.name() {
+                Some("image") => {
+                    let data = field.bytes().await?;
+                    let reader = ImageReader::new(Cursor::new(data))
+                        .with_guessed_format()
+                        .expect("cursor never fails");
+                    let image = reader.decode()?;
+                    img = Some(Box::new(image.into()));
+                }
+                Some("palette") => {
+                    let data = field.bytes().await?;
+                    let val = str::from_utf8(&data)?;
+                    palette = Some(DitherPalette::from_str(val)?);
+                }
+                Some("dither_method") => {
+                    let data = field.bytes().await?;
+                    let val = str::from_utf8(&data)?;
+                    dither_method = Some(DitherMethod::from_str(val)?);
+                }
+                _ => {}
+            }
+        }
+        if let Some(i) = img {
+            Ok(Self {
+                image: i,
+                dither_method: dither_method.unwrap_or(DitherMethod::NearestNeighbor),
+                palette: palette.unwrap_or(DitherPalette::Default),
+            })
+        } else {
+            Err(ApiError::MissingImage.into())
+        }
+    }
 }
 
 #[instrument(skip(ctx))]
-#[axum::debug_handler]
 async fn set_image(
     State(ctx): State<Context>,
-    mut parts: Multipart,
+    parts: Multipart,
 ) -> Result<impl IntoResponse, AppError> {
-    while let Some(field) = parts.next_field().await? {
-        let name = field.name().expect("fields always have names").to_string();
-        let data = field.bytes().await?;
-        debug!("Length of `{}` is {} bytes", name, data.len());
-        if &name == "image" {
-            let reader = ImageReader::new(Cursor::new(data))
-                .with_guessed_format()
-                .expect("Cursor io never fails");
-            debug!("Guessed format: {:?}", reader.format());
-
-            let mut buf = EInkImage::default();
-            {
-                let image = reader.decode()?;
-                let mut dither = DitherMethod::Atkinson.get_ditherer();
-                dither.dither(&image.into(), &mut buf);
-            }
-            let cmd = DisplaySetCommand { img: Box::new(buf) };
-            ctx.display_channel
-                .send_timeout(cmd, Duration::from_secs(10)).await?;
-        }
+    let call = ImageRequest::from_multipart(parts).await?;
+    let mut buf = EInkImage::new(call.palette.value().to_vec());
+    {
+        let mut dither = call.dither_method.get_ditherer();
+        dither.dither(&call.image, &mut buf);
     }
-    Ok(())
-}
-
-async fn process_image(mut parts: Multipart) -> Result<impl IntoResponse, AppError> {
+    let cmd = DisplaySetCommand { img: Box::new(buf) };
+    ctx.display_channel
+        .send_timeout(cmd, Duration::from_secs(10))
+        .await?;
     Ok(StatusCode::OK)
 }
+
+/// generates a dithered image based on the given image and the dithering parameters.
+/// Can be used to see how the dithering and palette choices affect the result.
+async fn preview_image(parts: Multipart) -> Result<impl IntoResponse, AppError> {
+    let call = ImageRequest::from_multipart(parts).await?;
+    let mut buf = EInkImage::new(call.palette.value().to_vec());
+    {
+        let mut dither = call.dither_method.get_ditherer();
+        dither.dither(&call.image, &mut buf);
+    }
+    // Convert buf into a png image.
+    let img = buf.into_rgbimage();
+
+    let mut buffer = Cursor::new(Vec::new());
+    img.write_to(&mut buffer, image::ImageFormat::Png)?;
+
+    let headers = [(header::CONTENT_TYPE, mime::IMAGE_PNG.to_string())];
+    Ok((StatusCode::OK, headers, buffer.into_inner()))
+}

src/imageproc.rs

@@ -20,9 +20,32 @@ const DISPLAY_PALETTE: [Srgb; 7] = [
     Srgb::new(0.757, 0.443, 0.165), // Orange
 ];
 
-pub enum DitherPalette {}
+const SIMPLE_PALETTE: [Srgb; 7] = [
+    Srgb::new(0.0,0.0,0.0), // Black
+    Srgb::new(1.0,1.0,1.0), // White
+    Srgb::new(0.0, 1.0, 0.0), // Green
+    Srgb::new(0.0, 0.0, 1.0), // Blue
+    Srgb::new(1.0, 0.0, 0.0), // Red
+    Srgb::new(1.0, 1.0, 0.0), // Yellow
+    Srgb::new(0.757, 0.443, 0.165), // Orange
+];
 
-#[derive(strum::EnumString, Serialize, Deserialize, PartialEq, Eq)]
+#[derive(strum::EnumString, Serialize, Deserialize, PartialEq, Eq, Debug)]
+pub enum DitherPalette {
+    Default,
+    Simple,
+}
+
+impl DitherPalette {
+    pub fn value(&self) -> &[Srgb] {
+        match self {
+            Self::Default => &DISPLAY_PALETTE,
+            Self::Simple => &DISPLAY_PALETTE, // FIXME: use simple pallete based on binary.
+        }
+    }
+}
+
+#[derive(strum::EnumString, Serialize, Deserialize, PartialEq, Eq, Debug)]
 pub enum DitherMethod {
     NearestNeighbor,
     FloydSteinberg,