Add some additional image effect nodes (#869)

* Move the Subpath type to graphene-std

* Add the transform subpath node

* Delete selected nodes

* Inserting node list on right click

* Add several bitmap manipulator nodes

* Convert add node to use f64

* Add posterize node

* Rename names randomly

* Fix naming

* Exposure node

* Fix typo

* Adjust exposure node range

* Comment out vector nodes

* Adjust exposure range again

* Posterise as ints

* Rename input

* Use >= in the to hsl function

node-graph/gstd/src/vector/consts.rs

@@ -0,0 +1,48 @@
+use std::ops::{Index, IndexMut};
+
+use serde::{Deserialize, Serialize};
+
+#[repr(usize)]
+#[derive(PartialEq, Eq, Clone, Debug, Copy, Serialize, Deserialize)]
+pub enum ManipulatorType {
+	Anchor,
+	InHandle,
+	OutHandle,
+}
+
+impl ManipulatorType {
+	pub fn from_index(index: usize) -> ManipulatorType {
+		match index {
+			0 => ManipulatorType::Anchor,
+			1 => ManipulatorType::InHandle,
+			2 => ManipulatorType::OutHandle,
+			_ => ManipulatorType::Anchor,
+		}
+	}
+
+	pub fn opposite_handle(self) -> ManipulatorType {
+		match self {
+			ManipulatorType::Anchor => ManipulatorType::Anchor,
+			ManipulatorType::InHandle => ManipulatorType::OutHandle,
+			ManipulatorType::OutHandle => ManipulatorType::InHandle,
+		}
+	}
+}
+
+// Allows us to use ManipulatorType for indexing
+impl<T> Index<ManipulatorType> for [T; 3] {
+	type Output = T;
+	fn index(&self, mt: ManipulatorType) -> &T {
+		&self[mt as usize]
+	}
+}
+
+// Allows us to use ManipulatorType for indexing, mutably
+impl<T> IndexMut<ManipulatorType> for [T; 3] {
+	fn index_mut(&mut self, mt: ManipulatorType) -> &mut T {
+		&mut self[mt as usize]
+	}
+}
+
+// Remove when no longer needed
+pub const SELECTION_THRESHOLD: f64 = 10.;