vulkan: take transfer functions from color descriptions

src/gfx_apis/vulkan/transfer_functions.rs

@@ -1,2 +1,17 @@
+use crate::cmm::cmm_transfer_function::TransferFunction;
+
 pub const TF_SRGB: u32 = 0;
 pub const TF_LINEAR: u32 = 1;
+
+pub trait TransferFunctionExt: Sized {
+    fn to_vulkan(self) -> u32;
+}
+
+impl TransferFunctionExt for TransferFunction {
+    fn to_vulkan(self) -> u32 {
+        match self {
+            TransferFunction::Srgb => TF_SRGB,
+            TransferFunction::Linear => TF_LINEAR,
+        }
+    }
+}