Add compose module and functions (#662)

src/compose.rs

@@ -0,0 +1,162 @@
+//! Functions for composing one or more images.
+
+use image::math::Rect;
+use image::Pixel;
+
+use crate::definitions::Image;
+
+/// Crops an image to a given rectangle.
+///
+/// # Panics
+///
+/// - If `rect.x + rect.width > image.width()`
+/// - If `rect.y + rect.height > image.height()`
+///
+/// # Examples
+/// ```
+/// use imageproc::compose::crop;
+/// use image::math::Rect;
+/// use imageproc::gray_image;
+///
+/// let image = gray_image!(
+///     0, 0, 0, 0, 0, 0;
+///     0, 0, 0, 1, 1, 0;
+///     0, 0, 0, 1, 1, 0;
+///     0, 0, 0, 1, 1, 0;
+///     0, 0, 0, 0, 0, 0;
+///     0, 0, 0, 0, 0, 0);
+///
+/// let cropped = crop(&image, Rect {x: 3, y: 1, width: 2, height: 3});
+///
+/// assert_eq!(cropped, gray_image!(
+///     1, 1;
+///     1, 1;
+///     1, 1));
+/// ```
+pub fn crop<P>(image: &Image<P>, rect: Rect) -> Image<P>
+where
+    P: Pixel,
+{
+    assert!(rect.x + rect.width <= image.width());
+    assert!(rect.y + rect.height <= image.height());
+
+    Image::from_fn(rect.width, rect.height, |x, y| {
+        *image.get_pixel(rect.x + x, rect.y + y)
+    })
+}
+#[cfg(feature = "rayon")]
+#[doc = generate_parallel_doc_comment!("crop")]
+pub fn crop_parallel<P>(image: &Image<P>, rect: Rect) -> Image<P>
+where
+    P: Pixel + Send + Sync,
+    P::Subpixel: Send + Sync,
+{
+    assert!(rect.x + rect.width <= image.width());
+    assert!(rect.y + rect.height <= image.height());
+
+    Image::from_par_fn(rect.width, rect.height, |x, y| {
+        *image.get_pixel(rect.x + x, rect.y + y)
+    })
+}
+
+/// Horizontally flips an image.
+///
+/// # Examples
+/// ```
+/// use imageproc::compose::flip_horizontal;
+/// use imageproc::gray_image;
+///
+/// let image = gray_image!(
+///     1, 2, 3, 4, 5, 6;
+///     1, 2, 3, 4, 5, 6;
+///     1, 2, 3, 4, 5, 6;
+///     1, 2, 3, 4, 5, 6;
+///     1, 2, 3, 4, 5, 6;
+///     1, 2, 3, 4, 5, 6);
+///
+/// let flipped = flip_horizontal(&image);
+///
+/// assert_eq!(flipped, gray_image!(
+///     6, 5, 4, 3, 2, 1;
+///     6, 5, 4, 3, 2, 1;
+///     6, 5, 4, 3, 2, 1;
+///     6, 5, 4, 3, 2, 1;
+///     6, 5, 4, 3, 2, 1;
+///     6, 5, 4, 3, 2, 1));
+/// ```
+pub fn flip_horizontal<P>(image: &Image<P>) -> Image<P>
+where
+    P: Pixel,
+{
+    let mut out = image.clone();
+    flip_horizontal_mut(&mut out);
+    out
+}
+#[doc=generate_mut_doc_comment!("flip_horizontal")]
+pub fn flip_horizontal_mut<P>(image: &mut Image<P>)
+where
+    P: Pixel,
+{
+    for y in 0..image.height() {
+        for x in 0..(image.width() / 2) {
+            let flipped_x = image.width() - x - 1;
+
+            let pixel = *image.get_pixel(x, y);
+            let flipped_pixel = *image.get_pixel(flipped_x, y);
+
+            image.put_pixel(x, y, flipped_pixel);
+            image.put_pixel(flipped_x, y, pixel);
+        }
+    }
+}
+
+/// Vertically flips an image.
+///
+/// # Examples
+/// ```
+/// use imageproc::compose::flip_vertical;
+/// use imageproc::gray_image;
+///
+/// let image = gray_image!(
+///     1, 1, 1, 1, 1, 1;
+///     2, 2, 2, 2, 2, 2;
+///     3, 3, 3, 3, 3, 3;
+///     4, 4, 4, 4, 4, 4;
+///     5, 5, 5, 5, 5, 5;
+///     6, 6, 6, 6, 6, 6);
+///
+/// let flipped = flip_vertical(&image);
+///
+/// assert_eq!(flipped, gray_image!(
+///     6, 6, 6, 6, 6, 6;
+///     5, 5, 5, 5, 5, 5;
+///     4, 4, 4, 4, 4, 4;
+///     3, 3, 3, 3, 3, 3;
+///     2, 2, 2, 2, 2, 2;
+///     1, 1, 1, 1, 1, 1));
+/// ```
+pub fn flip_vertical<P>(image: &Image<P>) -> Image<P>
+where
+    P: Pixel,
+{
+    let mut out = image.clone();
+    flip_vertical_mut(&mut out);
+    out
+}
+#[doc=generate_mut_doc_comment!("flip_vertical")]
+pub fn flip_vertical_mut<P>(image: &mut Image<P>)
+where
+    P: Pixel,
+{
+    for y in 0..(image.height() / 2) {
+        for x in 0..image.width() {
+            let flipped_y = image.height() - y - 1;
+
+            let pixel = *image.get_pixel(x, y);
+            let flipped_pixel = *image.get_pixel(x, flipped_y);
+
+            image.put_pixel(x, y, flipped_pixel);
+            image.put_pixel(x, flipped_y, pixel);
+        }
+    }
+}

src/lib.rs

@@ -18,6 +18,7 @@ pub mod utils;
 #[macro_use]
 pub mod doc_macros;
 pub mod binary_descriptors;
+pub mod compose;
 pub mod contours;
 pub mod contrast;
 pub mod corners;