Add pixel-transform

crates/lib/pixel-transform/src/transformers/maxdim.rs

@@ -0,0 +1,82 @@
+use std::fmt::Display;
+
+use image::{DynamicImage, imageops::FilterType};
+
+use crate::{pixeldim::PixelDim, transformers::ImageTransformer};
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct MaxDimTransformer {
+	w: PixelDim,
+	h: PixelDim,
+}
+
+impl MaxDimTransformer {
+	pub fn new(w: PixelDim, h: PixelDim) -> Self {
+		Self { w, h }
+	}
+
+	fn target_dim(&self, img_width: u32, img_height: u32) -> (u32, u32) {
+		let max_width = match self.w {
+			PixelDim::Pixels(w) => Some(w),
+			PixelDim::WidthPercent(pct) => Some(((img_width as f32) * pct / 100.0) as u32),
+			PixelDim::HeightPercent(_) => None,
+		};
+
+		let max_height = match self.h {
+			PixelDim::Pixels(h) => Some(h),
+			PixelDim::HeightPercent(pct) => Some(((img_height as f32) * pct / 100.0) as u32),
+			PixelDim::WidthPercent(_) => None,
+		};
+
+		if max_width.map(|x| img_width <= x).unwrap_or(true)
+			&& max_height.map(|x| img_height <= x).unwrap_or(true)
+		{
+			return (img_width, img_height);
+		}
+
+		let width_ratio = max_width
+			.map(|x| x as f32 / img_width as f32)
+			.unwrap_or(1.0);
+
+		let height_ratio = max_height
+			.map(|x| x as f32 / img_height as f32)
+			.unwrap_or(1.0);
+
+		let ratio = width_ratio.min(height_ratio);
+
+		(
+			(img_width as f32 * ratio) as u32,
+			(img_height as f32 * ratio) as u32,
+		)
+	}
+}
+
+impl Display for MaxDimTransformer {
+	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+		write!(f, "maxdim({},{})", self.w, self.h)
+	}
+}
+
+impl ImageTransformer for MaxDimTransformer {
+	fn parse_args(args: &str) -> Result<Self, String> {
+		let args: Vec<&str> = args.split(",").collect();
+		if args.len() != 2 {
+			return Err(format!("expected 2 args, got {}", args.len()));
+		}
+
+		let w = args[0].parse::<PixelDim>()?;
+		let h = args[1].parse::<PixelDim>()?;
+
+		Ok(Self { w, h })
+	}
+
+	fn transform(&self, input: &mut DynamicImage) {
+		let (img_width, img_height) = (input.width(), input.height());
+		let (target_width, target_height) = self.target_dim(img_width, img_height);
+
+		// Only resize if needed
+		if target_width != img_width || target_height != img_height {
+			*input = input.resize(target_width, target_height, FilterType::Lanczos3);
+		}
+	}
+}