make drawing functions safe

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "fimg"
-version = "0.4.2"
+version = "0.4.3"
 authors = ["bend-n <bend.n@outlook.com>"]
 license = "MIT"
 edition = "2021"

src/drawing/box.rs

@@ -1,65 +1,51 @@
 //! `Box<cat>`
+use std::ops::Range;
+
 use crate::Image;
 
 impl<const CHANNELS: usize> Image<&mut [u8], CHANNELS> {
     /// Draw a bordered box
-    ///
-    /// # Safety
-    ///
-    /// UB if the box is out of bounds
     /// ```
     /// # use fimg::Image;
     /// let mut b = Image::alloc(10, 9);
-    /// unsafe { b.as_mut().r#box((1, 1), 7, 6, [255]) };
+    /// b.as_mut().r#box((1, 1), 7, 6, [255]);
     /// # assert_eq!(b.buffer(), b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\xff\xff\x00\x00\xff\x00\x00\x00\x00\x00\x00\xff\x00\x00\xff\x00\x00\x00\x00\x00\x00\xff\x00\x00\xff\x00\x00\x00\x00\x00\x00\xff\x00\x00\xff\x00\x00\x00\x00\x00\x00\xff\x00\x00\xff\x00\x00\x00\x00\x00\x00\xff\x00\x00\xff\xff\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00")
     /// ```
-    pub unsafe fn r#box(
+    pub fn r#box(&mut self, (x1, y1): (u32, u32), width: u32, height: u32, c: [u8; CHANNELS]) {
-        &mut self,
-        (x1, y1): (u32, u32),
-        width: u32,
-        height: u32,
-        c: [u8; CHANNELS],
-    ) {
         // skip sides, leave that to second loop
-        for x in x1 + 1..width + x1 {
+        for x in clamp(x1 + 1..width + x1, 0..self.width()) {
             // top line
-            // SAFETY: responsibility is on caller
+            // SAFETY: clamped to bounds
             unsafe { self.set_pixel(x, x1, c) };
-            // bottom line
+            // SAFETY: clamped to bounds
-            // SAFETY: shift responsibility
             unsafe { self.set_pixel(x, x1 + height, c) };
         }
-        for y in y1..=height + y1 {
+        for y in clamp(y1..height + y1 + 1, 0..self.height()) {
-            // SAFETY: >> responsibility
+            // SAFETY: clamped to bounds
             unsafe { self.set_pixel(y1, y, c) };
-            // SAFETY: << responsibility
+            // SAFETY: clamped to bounds
             unsafe { self.set_pixel(y1 + width, y, c) };
         }
     }
 
     /// Draw a *filled* box.
-    ///
-    /// # Safety
-    ///
-    /// UB if box is out of bounds
     /// ```
     /// # use fimg::Image;
     /// let mut b = Image::alloc(10, 9);
-    /// unsafe { b.as_mut().filled_box((1, 1), 7, 6, [255]) };
+    /// b.as_mut().filled_box((1, 1), 7, 6, [255]);
     /// # assert_eq!(b.buffer(), b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\xff\xff\x00\x00\xff\xff\xff\xff\xff\xff\xff\xff\x00\x00\xff\xff\xff\xff\xff\xff\xff\xff\x00\x00\xff\xff\xff\xff\xff\xff\xff\xff\x00\x00\xff\xff\xff\xff\xff\xff\xff\xff\x00\x00\xff\xff\xff\xff\xff\xff\xff\xff\x00\x00\xff\xff\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00")
     /// ```
-    pub unsafe fn filled_box(
+    pub fn filled_box(&mut self, (x1, y1): (u32, u32), width: u32, height: u32, c: [u8; CHANNELS]) {
-        &mut self,
+        for x in clamp(x1..1 + width + x1, 0..self.width()) {
-        (x1, y1): (u32, u32),
+            for y in clamp(y1..1 + height + y1, 0..self.height()) {
-        width: u32,
+                // SAFETY: clamped to bounds
-        height: u32,
-        c: [u8; CHANNELS],
-    ) {
-        for x in x1..=width + x1 {
-            for y in y1..=height + y1 {
-                // SAFETY: fill it
                 unsafe { self.set_pixel(x, y, c) };
             }
         }
     }
 }
+
+/// clamp a range with another range
+fn clamp(r: Range<u32>, within: Range<u32>) -> Range<u32> {
+    r.start.clamp(within.start, within.end)..r.end.clamp(within.start, within.end)
+}

src/drawing/tri.rs

@@ -3,19 +3,15 @@ use crate::Image;
 
 impl<const CHANNELS: usize> Image<&mut [u8], CHANNELS> {
     /// Draw a (filled) triangle
-    ///
-    /// # Safety
-    ///
-    /// UB if any point is out of bounds
     /// ```
     /// # use fimg::*;
     /// let mut a = Image::alloc(10, 10);
     /// // draw a triangle from point a v   point b v    point c v
     /// //                                               with color white
-    /// unsafe { a.as_mut().tri((3.0, 2.0), (8.0, 7.0), (1.0, 8.0), [255]) };
+    /// a.as_mut().tri((3.0, 2.0), (8.0, 7.0), (1.0, 8.0), [255]);
     /// # assert_eq!(a.buffer(), b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00");
     /// ```
-    pub unsafe fn tri(
+    pub fn tri(
         &mut self,
         (x1, y1): (f32, f32),
         (x2, y2): (f32, f32),
@@ -33,10 +29,11 @@ impl<const CHANNELS: usize> Image<&mut [u8], CHANNELS> {
                 }
 
                 let d = (x3 - x2) * (y as f32 - y2) - (y3 - y2) * (x as f32 - x2);
-                if d == 0.0 || (d < 0.0) == (s + t <= 0.0) {
+                if (d == 0.0 || (d < 0.0) == (s + t <= 0.0))
-                    // SAFETY:
+                    && x < self.width()
-                    // caller gurantees triangle is in bounds, this loops over the
+                    && y < self.height()
-                    // bounding box of the triangle, therefore this is fine.
+                {
+                    // SAFETY: we just checked the bounds
                     unsafe { self.set_pixel(x, y, c) };
                 }
             }