Fix BresenhamLineIter panic (#565)

src/corners.rs

@@ -297,12 +297,7 @@ fn is_corner_fast9(image: &GrayImage, threshold: u8, x: u32, y: u32) -> bool {
     //      y-coordinate in the range [y - 3, y + 3]. The precondition below
     //      guarantees that these are within image bounds.
     let (width, height) = image.dimensions();
-    if x >= u32::max_value() - 3
-        || y >= u32::max_value() - 3
-        || x < 3
-        || y < 3
-        || width <= x + 3
-        || height <= y + 3
+    if x >= u32::MAX - 3 || y >= u32::MAX - 3 || x < 3 || y < 3 || width <= x + 3 || height <= y + 3
     {
         return false;
     }
@@ -358,12 +353,7 @@ fn is_corner_fast12(image: &GrayImage, threshold: u8, x: u32, y: u32) -> bool {
     //      y-coordinate in the range [y - 3, y + 3]. The precondition below
     //      guarantees that these are within image bounds.
     let (width, height) = image.dimensions();
-    if x >= u32::max_value() - 3
-        || y >= u32::max_value() - 3
-        || x < 3
-        || y < 3
-        || width <= x + 3
-        || height <= y + 3
+    if x >= u32::MAX - 3 || y >= u32::MAX - 3 || x < 3 || y < 3 || width <= x + 3 || height <= y + 3
     {
         return false;
     }

src/definitions.rs

@@ -1,7 +1,6 @@
 //! Trait definitions and type aliases.
 
 use image::{ImageBuffer, Luma, LumaA, Pixel, Rgb, Rgba};
-use std::{i16, u16, u8};
 
 /// An `ImageBuffer` containing Pixels of type P with storage `Vec<P::Subpixel>`.
 /// Most operations in this library only support inputs of type `Image`, rather

src/distance_transform.rs

@@ -4,7 +4,6 @@
 use crate::definitions::Image;
 use image::{GenericImage, GenericImageView, GrayImage, ImageBuffer, Luma};
 use std::cmp::min;
-use std::{f64, u8};
 
 /// How to measure distance between coordinates.
 /// See the [`distance_transform`](fn.distance_transform.html) documentation for examples.

src/drawing/bezier.rs

@@ -2,8 +2,6 @@ use crate::definitions::Image;
 use crate::drawing::line::draw_line_segment_mut;
 use crate::drawing::Canvas;
 use image::{GenericImage, ImageBuffer};
-use std::f32;
-use std::i32;
 
 /// Draws a cubic Bézier curve on a new copy of an image.
 ///

src/drawing/conics.rs

@@ -3,8 +3,6 @@ use crate::drawing::draw_if_in_bounds;
 use crate::drawing::line::draw_line_segment_mut;
 use crate::drawing::Canvas;
 use image::{GenericImage, ImageBuffer};
-use std::f32;
-use std::i32;
 
 /// Draws the outline of an ellipse on a new copy of an image.
 ///

src/drawing/cross.rs

@@ -1,7 +1,6 @@
 use crate::definitions::Image;
 use crate::drawing::Canvas;
 use image::{GenericImage, ImageBuffer};
-use std::i32;
 
 /// Draws a colored cross on an image in place.
 ///

src/drawing/line.rs

@@ -1,8 +1,6 @@
 use crate::definitions::Image;
 use crate::drawing::Canvas;
 use image::{GenericImage, ImageBuffer, Pixel};
-use std::f32;
-use std::i32;
 use std::mem::{swap, transmute};
 
 /// Iterates over the coordinates in a line segment using
@@ -76,18 +74,14 @@ impl Iterator for BresenhamLineIter {
     }
 }
 
-fn clamp(x: f32, upper_bound: u32) -> f32 {
-    if x < 0f32 {
-        return 0f32;
-    }
-    if x >= upper_bound as f32 {
-        return (upper_bound - 1) as f32;
-    }
-    x
+fn in_bounds<I: GenericImage>((x, y): (i32, i32), image: &I) -> bool {
+    x >= 0 && x < image.width() as i32 && y >= 0 && y < image.height() as i32
 }
 
 fn clamp_point<I: GenericImage>(p: (f32, f32), image: &I) -> (f32, f32) {
-    (clamp(p.0, image.width()), clamp(p.1, image.height()))
+    let x = p.0.clamp(0.0, (image.width() - 1) as f32);
+    let y = p.1.clamp(0.0, (image.height() - 1) as f32);
+    (x, y)
 }
 
 /// Iterates over the image pixels in a line segment using
@@ -119,8 +113,8 @@ impl<'a, P: Pixel> Iterator for BresenhamLinePixelIter<'a, P> {
 
     fn next(&mut self) -> Option<Self::Item> {
         self.iter
-            .next()
-            .map(|p| self.image.get_pixel(p.0 as u32, p.1 as u32))
+            .find(|&p| in_bounds(p, self.image))
+            .map(|(x, y)| self.image.get_pixel(x as u32, y as u32))
     }
 }
 
@@ -146,7 +140,7 @@ impl<'a, P: Pixel> BresenhamLinePixelIterMut<'a, P> {
         // The next two assertions are for https://github.com/image-rs/imageproc/issues/281
         assert!(P::CHANNEL_COUNT > 0);
         assert!(
-            image.width() < i32::max_value() as u32 && image.height() < i32::max_value() as u32,
+            image.width() < i32::MAX as u32 && image.height() < i32::MAX as u32,
             "Image dimensions are too large"
         );
         let iter = BresenhamLineIter::new(clamp_point(start, image), clamp_point(end, image));
@@ -159,8 +153,8 @@ impl<'a, P: Pixel> Iterator for BresenhamLinePixelIterMut<'a, P> {
 
     fn next(&mut self) -> Option<Self::Item> {
         self.iter
-            .next()
-            .map(|p| self.image.get_pixel_mut(p.0 as u32, p.1 as u32))
+            .find(|&p| in_bounds(p, self.image))
+            .map(|(x, y)| self.image.get_pixel_mut(x as u32, y as u32))
             .map(|p| unsafe { transmute(p) })
     }
 }

src/drawing/polygon.rs

@@ -4,8 +4,6 @@ use crate::drawing::Canvas;
 use crate::point::Point;
 use image::{GenericImage, ImageBuffer};
 use std::cmp::{max, min};
-use std::f32;
-use std::i32;
 
 #[must_use = "the function does not modify the original image"]
 fn draw_polygon_with<I, L>(

src/morphology.rs

@@ -6,7 +6,6 @@ use crate::distance_transform::{
     distance_transform_impl, distance_transform_mut, DistanceFrom, Norm,
 };
 use image::GrayImage;
-use std::u8;
 
 /// Sets all pixels within distance `k` of a foreground pixel to white.
 ///

src/region_labelling.rs

@@ -200,7 +200,7 @@ where
                 }
                 next_label += 1;
             } else {
-                let mut min_label = u32::max_value();
+                let mut min_label = u32::MAX;
                 for n in 0..num_adj {
                     min_label = cmp::min(min_label, adj_labels[n]);
                 }

src/utils.rs

@@ -10,7 +10,6 @@ use std::collections::HashSet;
 use std::fmt;
 use std::fmt::Write;
 use std::path::Path;
-use std::u32;
 
 /// Helper for defining greyscale images.
 ///