feat(engine): add fn for getting subview into image

1 files changed, 72 insertions, 0 deletions

diff --git a/engine/src/image.rs b/engine/src/image.rs
index 1dc129e..68eac65 100644
--- a/engine/src/image.rs
+++ b/engine/src/image.rs
@@ -115,6 +115,19 @@ impl Image
         }
     }
 
+    /// Returns a immutable view of a subsection of this image.
+    /// The `offset` argument sets the position of the top left corner of the view.
+    ///
+    /// # Panics
+    /// Panics if the view would be out of bounds
+    pub fn sub_view(&self, offset: Vec2<u32>, size: Dimens<u32>) -> SubView<'_>
+    {
+        assert!(offset.x + size.width <= self.dimensions().width);
+        assert!(offset.y + size.height <= self.dimensions().height);
+
+        SubView { image: &self.inner, offset, size }
+    }
+
     pub fn to_rgba8(&self) -> Self
     {
         Self { inner: self.inner.to_rgba8().into() }
@@ -286,6 +299,65 @@ impl Format
     }
 }
 
+pub struct SubView<'image>
+{
+    image: &'image image_rs::DynamicImage,
+    offset: Vec2<u32>,
+    size: Dimens<u32>,
+}
+
+impl SubView<'_>
+{
+    pub fn to_image(&self) -> Image
+    {
+        fn create_sub_image<Image>(
+            image: Image,
+            sub_view: &SubView<'_>,
+        ) -> image_rs::SubImage<Image>
+        {
+            let SubView { image: _, offset, size } = sub_view;
+
+            image_rs::SubImage::new(image, offset.x, offset.y, size.width, size.height)
+        }
+
+        Image {
+            inner: match self.image {
+                image_rs::DynamicImage::ImageLuma8(image) => {
+                    create_sub_image(image, self).to_image().into()
+                }
+                image_rs::DynamicImage::ImageLumaA8(image) => {
+                    create_sub_image(image, self).to_image().into()
+                }
+                image_rs::DynamicImage::ImageRgb8(image) => {
+                    create_sub_image(image, self).to_image().into()
+                }
+                image_rs::DynamicImage::ImageRgba8(image) => {
+                    create_sub_image(image, self).to_image().into()
+                }
+                image_rs::DynamicImage::ImageLuma16(image) => {
+                    create_sub_image(image, self).to_image().into()
+                }
+                image_rs::DynamicImage::ImageLumaA16(image) => {
+                    create_sub_image(image, self).to_image().into()
+                }
+                image_rs::DynamicImage::ImageRgb16(image) => {
+                    create_sub_image(image, self).to_image().into()
+                }
+                image_rs::DynamicImage::ImageRgba16(image) => {
+                    create_sub_image(image, self).to_image().into()
+                }
+                image_rs::DynamicImage::ImageRgb32F(image) => {
+                    create_sub_image(image, self).to_image().into()
+                }
+                image_rs::DynamicImage::ImageRgba32F(image) => {
+                    create_sub_image(image, self).to_image().into()
+                }
+                _ => unimplemented!(),
+            },
+        }
+    }
+}
+
 #[derive(Debug, thiserror::Error)]
 pub enum Error
 {