- Added method DynamicImageViewMut::crop() to create cropped version of ImageViewMut.

- Added method `ImageViewMut::crop()` to create cropped version of `ImageViewMut`.

CHANGELOG.md

@@ -1,3 +1,11 @@
+## [Unreleased] - ReleaseDate
+
+### Crate
+
+- Added method `DynamicImageViewMut::crop()` to create cropped version of `ImageViewMut`
+  ([#13](https://github.com/Cykooz/fast_image_resize/issues/13)).
+- Added method `ImageViewMut::crop()` to create cropped version of `ImageViewMut`.
+
 ## [2.6.0] - 2023-03-01
 
 ### Crate

src/dynamic_image_view.rs

@@ -146,6 +146,11 @@ impl<'a> DynamicImageViewMut<'a> {
     pub fn pixel_type(&self) -> PixelType {
         dynamic_mut_map!(self, |typed_image| typed_image.pixel_type())
     }
+
+    /// Create cropped version of the view.
+    pub fn crop(self, crop_box: CropBox) -> Result<Self, CropBoxError> {
+        Ok(dynamic_mut_map!(self, typed_image => typed_image.crop(crop_box)?))
+    }
 }
 
 macro_rules! from_typed {

src/image_view.rs

@@ -388,6 +388,31 @@ where
             .for_each(|(d, s)| d.copy_from_slice(s));
         Ok(())
     }
+
+    /// Create cropped version of the view.
+    pub fn crop(self, crop_box: CropBox) -> Result<Self, CropBoxError> {
+        if crop_box.left >= self.width.get() || crop_box.top >= self.height.get() {
+            return Err(CropBoxError::PositionIsOutOfImageBoundaries);
+        }
+        let right = crop_box.left + crop_box.width.get();
+        let bottom = crop_box.top + crop_box.height.get();
+        if right > self.width.get() || bottom > self.height.get() {
+            return Err(CropBoxError::SizeIsOutOfImageBoundaries);
+        }
+        let row_range = (crop_box.left as usize)..=(right as usize);
+        let rows = self
+            .rows
+            .into_iter()
+            .skip(crop_box.top as usize)
+            .take(crop_box.height.get() as usize)
+            .map(|row| unsafe { row.get_unchecked_mut(row_range.clone()) })
+            .collect();
+        Ok(Self {
+            width: crop_box.width,
+            height: crop_box.height,
+            rows,
+        })
+    }
 }
 
 impl<'a, P> From<ImageViewMut<'a, P>> for ImageView<'a, P>

tests/images_tests.rs

@@ -1,11 +1,11 @@
 use fast_image_resize as fr;
 use fast_image_resize::pixels::U8;
-use std::num::NonZeroU32;
+use testing::nonzero;
 
 #[test]
 fn create_image_from_small_buffer() {
-    let width = NonZeroU32::new(64).unwrap();
-    let height = NonZeroU32::new(32).unwrap();
+    let width = nonzero(64);
+    let height = nonzero(32);
     let mut buffer = vec![0; 64 * 30];
 
     let res = fr::Image::from_slice_u8(width, height, &mut buffer, fr::PixelType::U8);
@@ -17,8 +17,8 @@ fn create_image_from_small_buffer() {
 
 #[test]
 fn create_image_view_from_small_buffer() {
-    let width = NonZeroU32::new(64).unwrap();
-    let height = NonZeroU32::new(32).unwrap();
+    let width = nonzero(64);
+    let height = nonzero(32);
     let mut buffer = vec![0; 64 * 30];
 
     let res = fr::ImageViewMut::<U8>::from_buffer(width, height, &mut buffer);
@@ -30,8 +30,8 @@ fn create_image_view_from_small_buffer() {
 
 #[test]
 fn create_image_from_big_buffer() {
-    let width = NonZeroU32::new(64).unwrap();
-    let height = NonZeroU32::new(32).unwrap();
+    let width = nonzero(64);
+    let height = nonzero(32);
     let mut buffer = vec![0; 65 * 32];
 
     let res = fr::Image::from_slice_u8(width, height, &mut buffer, fr::PixelType::U8);
@@ -43,8 +43,8 @@ fn create_image_from_big_buffer() {
 
 #[test]
 fn create_image_view_from_big_buffer() {
-    let width = NonZeroU32::new(64).unwrap();
-    let height = NonZeroU32::new(32).unwrap();
+    let width = nonzero(64);
+    let height = nonzero(32);
     let mut buffer = vec![0; 65 * 32];
 
     let res = fr::ImageViewMut::<U8>::from_buffer(width, height, &mut buffer);
@@ -53,3 +53,52 @@ fn create_image_view_from_big_buffer() {
     let res = fr::ImageView::<U8>::from_buffer(width, height, &buffer);
     assert!(res.is_ok());
 }
+
+#[test]
+fn crop_view_mut() {
+    // White source image
+    let src_image = fr::Image::from_vec_u8(
+        nonzero(64),
+        nonzero(32),
+        vec![255; 64 * 32],
+        fr::PixelType::U8,
+    )
+    .unwrap();
+    // Black destination image
+    let mut dst_image = fr::Image::new(nonzero(64), nonzero(32), fr::PixelType::U8);
+
+    let mut cropped_dst_view = dst_image
+        .view_mut()
+        .crop(fr::CropBox {
+            left: 10,
+            top: 10,
+            width: nonzero(44),
+            height: nonzero(12),
+        })
+        .unwrap();
+    assert_eq!(cropped_dst_view.width().get(), 44);
+    assert_eq!(cropped_dst_view.height().get(), 12);
+
+    let mut resizer = fr::Resizer::new(fr::ResizeAlg::Nearest);
+    resizer
+        .resize(&src_image.view(), &mut cropped_dst_view)
+        .unwrap();
+
+    let row_size: usize = 64;
+    let dst_buffer = dst_image.buffer();
+
+    let black_block = vec![0u8; 10 * row_size];
+    // Top border
+    assert_eq!(dst_buffer[0..10 * row_size], black_block);
+
+    // Middle rows
+    let mut middle_row = vec![0u8; 10];
+    middle_row.extend(vec![255u8; 44]);
+    middle_row.extend(vec![0u8; 10]);
+    for row in dst_buffer.chunks_exact(row_size).skip(10).take(12) {
+        assert_eq!(row, middle_row);
+    }
+
+    // Bottom border
+    assert_eq!(dst_buffer[22 * row_size..], black_block);
+}