Add the image segmentation node (#1122)

* Add image segmentation node

This is a node which receives as input:
- An image.
- A mask, which consists of colors that define the image segments.

Each unique color in the mask defines an area where a segmen resides.
The node generates a `Vec<ImageFrame>` where the length of the result
is the number of unique colors in the mask.

Signed-off-by: Ică Alexandru-Gabriel <alexandru@seyhanlee.com>

* Add the Index node for image segments

Since the output of the image segmentation node is a `Vec<ImageFrame>`,
we want a way to access the segments individually. The Index node receives
a `Vec<ImageFrame>` as input and an index, and returns the image found
at that index in the vec.

Signed-off-by: Ică Alexandru-Gabriel <alexandru@seyhanlee.com>

* Integrate the image segmentation and index nodes into the editor

Signed-off-by: Ică Alexandru-Gabriel <alexandru@seyhanlee.com>

* Initialize the input of the index node with an empty image frame

Signed-off-by: Ică Alexandru-Gabriel <alexandru@seyhanlee.com>

* Don't expose the parameter for the index node

Signed-off-by: Ică Alexandru-Gabriel <alexandru@seyhanlee.com>

* Don't crash the editor when the number of segments exceeds the accepted limit

Signed-off-by: Ică Alexandru-Gabriel <alexandru@seyhanlee.com>

* Print a warning in the console when the number of segments exceeds the accepted limit

Signed-off-by: Ică Alexandru-Gabriel <alexandru@seyhanlee.com>

* Add a few more checks so that the editor doesn't crash on invalid input

Signed-off-by: Ică Alexandru-Gabriel <alexandru@seyhanlee.com>

* Replace the tagged value for the index node

Signed-off-by: Ică Alexandru-Gabriel <alexandru@seyhanlee.com>

* Fix merge conflicts

---------

Signed-off-by: Ică Alexandru-Gabriel <alexandru@seyhanlee.com>
Co-authored-by: Dennis Kobert <dennis@kobert.dev>

node-graph/gcore/src/raster/adjustments.rs

@@ -513,3 +513,18 @@ fn exposure(color: Color, exposure: f64, offset: f64, gamma_correction: f64) ->
 	// TODO: Remove conversion to linear when the whole node graph uses linear color
 	result.to_gamma_srgb()
 }
+
+#[derive(Debug)]
+pub struct IndexNode<Index> {
+	pub index: Index,
+}
+
+#[node_macro::node_fn(IndexNode)]
+pub fn index_node(input: Vec<super::ImageFrame<Color>>, index: u32) -> super::ImageFrame<Color> {
+	if (index as usize) < input.len() {
+		input[index as usize].clone()
+	} else {
+		warn!("The number of segments is {} and the requested segment is {}!", input.len(), index);
+		super::ImageFrame::empty()
+	}
+}