suggestions

src/bindings.rs

@@ -1,6 +1,8 @@
 //! This module contains the bindings to the Philips Open Pathology C++ library
 //!
 
+use crate::errors::PhilipsSlideError;
+
 #[cxx::bridge]
 pub(crate) mod ffi {
     /// Simple struct Size with width and height for an image/tile
@@ -129,10 +131,31 @@ impl ffi::Size {
     pub fn new(w: u32, h: u32) -> Self {
         Self { w, h }
     }
-    pub fn from_dimensions_range(range: &ffi::DimensionsRange) -> Self {
-        Self {
-            w: (range.end_x - range.start_x) / range.step_x,
-            h: (range.end_y - range.start_y) / range.step_y,
+}
+impl TryFrom<&ffi::DimensionsRange> for ffi::Size {
+    type Error = PhilipsSlideError;
+
+    fn try_from(value: &ffi::DimensionsRange) -> Result<Self, Self::Error> {
+        if value.step_x == 0 || value.step_y == 0 {
+            return Err(PhilipsSlideError::ConversionError(
+                "Step is zero!".to_string(),
+            ));
+        }
+        if let Some(width) = value.end_x.checked_sub(value.start_x) {
+            if let Some(height) = value.end_y.checked_sub(value.start_y) {
+                Ok(Self {
+                    w: width / value.step_x,
+                    h: height / value.step_y,
+                })
+            } else {
+                Err(PhilipsSlideError::ConversionError(
+                    "Height is less than zero!".to_string(),
+                ))
+            }
+        } else {
+            Err(PhilipsSlideError::ConversionError(
+                "Width is less than zero!".to_string(),
+            ))
         }
     }
 }

src/errors.rs

@@ -5,7 +5,7 @@ use cxx::Exception;
 use std::str::Utf8Error;
 use thiserror::Error;
 
-/// Enum defining all possible error when manipulating OpenSlide struct
+/// Enum defining all possible error when manipulating Philips struct
 #[derive(Error, Debug)]
 pub enum PhilipsSlideError {
     /// CxxString to &str conversion error
@@ -21,6 +21,8 @@ pub enum PhilipsSlideError {
     #[cfg(feature = "image")]
     #[error(transparent)]
     ImageError(#[from] ImageError),
+    #[error("{0}")]
+    ConversionError(String),
 }
 
 #[cfg(feature = "image")]

src/lib.rs

@@ -3,6 +3,7 @@ pub mod errors;
 mod facade;
 mod pixel_engine;
 mod sub_image;
+#[cfg(feature = "image")]
 mod utils;
 mod view;
 

src/utils.rs

@@ -1,14 +1,10 @@
 use crate::{Result, Size};
-use std::cmp;
-
-#[cfg(feature = "image")]
 use fast_image_resize as fr;
-#[cfg(feature = "image")]
+use std::cmp;
 use {crate::errors::ImageError, image::RgbImage};
 
 // Get the appropriate level for the given dimensions: i.e. the level with at least one
 // dimensions (i.e along one axis) greater than the dimension requested
-#[cfg(feature = "image")]
 pub fn get_best_level_for_dimensions(
     dimension: &Size,
     dimension_level_0: &Size,
@@ -18,21 +14,13 @@ pub fn get_best_level_for_dimensions(
         f64::from(dimension_level_0.w) / f64::from(dimension.w),
         f64::from(dimension_level_0.h) / f64::from(dimension.h),
     );
-    let level_dowsamples: Vec<f64> = (0..level_count)
+    (0..level_count)
         .map(|level| 2_u32.pow(level) as f64)
-        .collect();
-    if downsample < 1.0 {
-        return 0;
-    }
-    for i in 1..level_count {
-        if downsample < level_dowsamples[i as usize] {
-            return i - 1;
-        }
-    }
-    level_count - 1
+        .enumerate()
+        .rfind(|(_, ds)| ds <= &downsample)
+        .map_or(0, |(index, _)| index) as u32
 }
 
-#[cfg(feature = "image")]
 pub(crate) fn resize_rgb_image(image: RgbImage, new_size: &Size) -> Result<RgbImage> {
     let src_image = fr::images::Image::from_vec_u8(
         image.width(),
@@ -57,7 +45,6 @@ pub(crate) fn resize_rgb_image(image: RgbImage, new_size: &Size) -> Result<RgbIm
     Ok(image)
 }
 
-#[cfg(feature = "image")]
 pub(crate) fn preserve_aspect_ratio(size: &Size, dimension: &Size) -> Size {
     // Code adapted from https://pillow.readthedocs.io/en/latest/_modules/PIL/Image.html#Image.thumbnail
     fn round_aspect<F: FnMut(f32) -> f32>(number: f32, mut key: F) -> u32 {
@@ -91,7 +78,6 @@ pub(crate) fn preserve_aspect_ratio(size: &Size, dimension: &Size) -> Size {
 }
 
 #[cfg(test)]
-#[cfg(feature = "image")]
 mod tests {
     use super::*;
     use rstest::rstest;
@@ -110,8 +96,8 @@ mod tests {
     //     9: Size { w: 307, h: 175 },
     // }
     #[rstest]
-    #[case(Size::new(500, 500), 8)]
     #[case(Size::new(100, 100), 9)]
+    #[case(Size::new(500, 500), 8)]
     #[case(Size::new(800, 800), 7)]
     #[case(Size::new(100000, 100000), 0)]
     #[case(Size::new(200000, 200000), 0)]

src/view.rs

@@ -131,7 +131,7 @@ impl<'a> View<'a> {
     #[cfg(feature = "image")]
     pub fn read_thumbnail(&self, engine: &PhilipsEngine, size: &Size) -> Result<RgbImage> {
         let level_count = self.num_derived_levels() + 1;
-        let dimension_level_0 = Size::from_dimensions_range(&self.dimension_ranges(0)?);
+        let dimension_level_0 = Size::try_from(&self.dimension_ranges(0)?)?;
         let best_level = get_best_level_for_dimensions(&size, &dimension_level_0, level_count);
         let dimensions_range = self.dimension_ranges(best_level)?;
         let region_request = RegionRequest {
@@ -144,8 +144,7 @@ impl<'a> View<'a> {
             level: best_level,
         };
         let image = self.read_image(engine, &region_request)?;
-        let final_size =
-            preserve_aspect_ratio(&size, &Size::from_dimensions_range(&dimensions_range));
+        let final_size = preserve_aspect_ratio(&size, &Size::try_from(&dimensions_range)?);
         let image = resize_rgb_image(image, &final_size)?;
         Ok(image)
     }

tests/test_read_thumbnail.rs

@@ -26,7 +26,17 @@ fn test_thumbnail(
     let view = image.view().unwrap();
 
     let thumbnail = view.read_thumbnail(&engine, &size).unwrap();
-    thumbnail.save(format!("thumbnail{0}.jpg", size.w)).unwrap();
+    thumbnail
+        .save(format!(
+            "{0}_thumbnail_{1}.jpg",
+            filename
+                .file_stem()
+                .expect("Invalid file name")
+                .to_str()
+                .expect("Invalide file name"),
+            size.w
+        ))
+        .unwrap();
 
     // Make sure one of the dimensions is equal to the requested one
     // and the other one is smaller than the requested one