From 611739ee6dcdcb3d32c09a1675737c3c30d083c0 Mon Sep 17 00:00:00 2001
From: bendn <bend.n@outlook.com>
Date: Tue, 26 Sep 2023 07:47:51 +0700
Subject: [PATCH] add `points`

---
 Cargo.toml          |  2 +-
 src/drawing/line.rs |  6 ++--
 src/drawing/mod.rs  |  3 +-
 src/drawing/poly.rs | 74 +++++++++++++++++++++++++++++++++++++++++++++
 src/lib.rs          |  3 ++
 5 files changed, 83 insertions(+), 5 deletions(-)
 create mode 100644 src/drawing/poly.rs

diff --git a/Cargo.toml b/Cargo.toml
index ac759ae..cead450 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "fimg"
-version = "0.4.7"
+version = "0.4.8"
 authors = ["bend-n <bend.n@outlook.com>"]
 license = "MIT"
 edition = "2021"
diff --git a/src/drawing/line.rs b/src/drawing/line.rs
index 81fe162..d6453ca 100644
--- a/src/drawing/line.rs
+++ b/src/drawing/line.rs
@@ -45,7 +45,7 @@ impl Octant {
             octant += 1;
         }
 
-        Octant(octant)
+        Self(octant)
     }
 
     #[inline]
@@ -84,7 +84,7 @@ impl Bresenham {
     /// Creates a new iterator. Yields intermediate points between `start`
     /// and `end`. Includes `start` and `end`.
     #[inline]
-    pub const fn new(start: (i32, i32), end: (i32, i32)) -> Bresenham {
+    pub const fn new(start: (i32, i32), end: (i32, i32)) -> Self {
         let octant = Octant::from_points(start, end);
 
         let start = octant.to_octant0(start);
@@ -93,7 +93,7 @@ impl Bresenham {
         let dx = end.0 - start.0;
         let dy = end.1 - start.1;
 
-        Bresenham {
+        Self {
             x: start.0,
             y: start.1,
             dy,
diff --git a/src/drawing/mod.rs b/src/drawing/mod.rs
index 6ffdf23..87b4b88 100644
--- a/src/drawing/mod.rs
+++ b/src/drawing/mod.rs
@@ -1,4 +1,5 @@
-//! contains drawing operations, like {line, box, triangle} drawing
+//! contains drawing operations, like {line, box, triangle, polygon} drawing
 mod r#box;
 mod line;
+mod poly;
 mod tri;
diff --git a/src/drawing/poly.rs b/src/drawing/poly.rs
new file mode 100644
index 0000000..408aa47
--- /dev/null
+++ b/src/drawing/poly.rs
@@ -0,0 +1,74 @@
+//! draw polygons
+use std::{
+    cmp::{max, min},
+    ops::{Deref, DerefMut},
+};
+
+use crate::Image;
+
+impl<T: Deref<Target = [u8]> + DerefMut<Target = [u8]>, const CHANNELS: usize> Image<T, CHANNELS> {
+    /// Draws a filled polygon from a slice of points. Please close your poly. (first == last)
+    /// Borrowed from [imageproc](https://docs.rs/imageproc/latest/src/imageproc/drawing/polygon.rs.html#31), modified for less allocations.
+    /// ```
+    /// # use fimg::Image;
+    /// let mut i = Image::alloc(10, 10);
+    /// i.points(&[(1, 8), (3, 1), (8, 1), (6, 6), (8, 8), (1, 8)], [255]);
+    /// # assert_eq!(i.buffer(), b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\x00\x00\x00\xff\xff\xff\xff\xff\xff\xff\x00\x00\x00\xff\xff\xff\xff\xff\xff\xff\x00\x00\x00\xff\xff\xff\xff\xff\xff\x00\x00\x00\xff\xff\xff\xff\xff\xff\xff\x00\x00\x00\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\xff\x00\x00\x00\xff\xff\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00");
+    /// ```
+    pub fn points(&mut self, poly: &[(i32, i32)], c: [u8; CHANNELS]) {
+        if poly.len() <= 1 {
+            return;
+        }
+        let (mut y_max, mut y_min) = poly[..poly.len() - 1]
+            .iter()
+            .fold((i32::MIN, i32::MAX), |(max, min), &(_, y)| {
+                (y.max(max), y.min(min))
+            });
+        y_min = max(0, min(y_min, self.height() as i32 - 1));
+        y_max = max(0, min(y_max, self.height() as i32 - 1));
+        let mut intersections = vec![];
+        for y in y_min..=y_max {
+            for [p0, p1] in poly.array_windows::<2>() {
+                if p0.1 <= y && p1.1 >= y || p1.1 <= y && p0.1 >= y {
+                    if p0.1 == p1.1 {
+                        intersections.push(p0.0);
+                        intersections.push(p1.0);
+                    } else if p0.1 == y || p1.1 == y {
+                        if p1.1 > y {
+                            intersections.push(p0.0);
+                        }
+                        if p0.1 > y {
+                            intersections.push(p1.0);
+                        }
+                    } else {
+                        let fraction = (y - p0.1) as f32 / (p1.1 - p0.1) as f32;
+                        let inter = fraction.mul_add((p1.0 - p0.0) as f32, p0.0 as f32);
+                        intersections.push(inter.round() as i32);
+                    }
+                }
+            }
+            intersections.sort_unstable();
+            // SAFETY: must.
+            unsafe { crate::assert_unchecked!(intersections.len() % 2 == 0) };
+            for &[x, y_] in intersections.array_chunks::<2>() {
+                let mut from = min(x, self.width() as i32);
+                let mut to = min(y_, self.width() as i32 - 1);
+                if from < self.width() as i32 && to >= 0 {
+                    // check bounds
+                    from = max(0, from);
+                    to = max(0, to);
+
+                    for x in from..=to {
+                        // SAFETY: bounds are checked
+                        unsafe { self.set_pixel(x as u32, y as u32, c) };
+                    }
+                }
+            }
+            intersections.clear();
+        }
+
+        for &[(x1, y1), (x2, y2)] in poly.array_windows::<2>() {
+            self.line((x1, y1), (x2, y2), c);
+        }
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 3b62765..4d31ef3 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -9,6 +9,7 @@
     slice_as_chunks,
     unchecked_math,
     portable_simd,
+    array_windows,
     const_option,
     array_chunks,
     test
@@ -19,8 +20,10 @@
     clippy::undocumented_unsafe_blocks,
     clippy::missing_const_for_fn,
     clippy::missing_safety_doc,
+    clippy::suboptimal_flops,
     unsafe_op_in_unsafe_fn,
     clippy::dbg_macro,
+    clippy::use_self,
     missing_docs
 )]
 #![allow(clippy::zero_prefixed_literal, incomplete_features)]