Camera Raw filter's model and pixel kernels (12.8a)

src/Document/CameraRaw+Session.h

@@ -0,0 +1,28 @@
+// Swift's CameraRaw.swift session extension; in EditorSession's body.
+public:
+    // The panel's state, which Swift's panel writes on the edit.
+    void setCameraRawPanel(const CameraRawPanel &panel);
+    // The white-balance eyedropper: the clicked pixel turns neutral.
+    void sampleCameraRawWhiteBalance(QPointF point);
+    // White Balance Auto: the mode now, the sliders later.
+    void applyCameraRawAutoWhiteBalance(std::function<void()> done = {});
+    // The defringe eyedropper centres a range on the fringe.
+    void sampleCameraRawDefringe(QPointF point);
+    // The adjusted preview's RGB under the pointer.
+    void updateCameraRawReadout(QPointF point);
+    void beginCameraRawDrag(QPointF point);
+    void dragCameraRaw(QPointF point);
+    void sampleCameraRawPointColor(QPointF point);
+    void beginCameraRawGeometryGuide(QPointF point);
+    void continueCameraRawGeometryGuide(QPointF point);
+    void commitCameraRawGeometryGuide();
+
+private:
+    std::optional<QPointF> cameraRawNormalizedPoint(QPointF point) const;
+    struct CameraRawSample {
+        double tone;
+        double hue;
+        double saturation;
+        double luminance;
+    };
+    std::optional<CameraRawSample> cameraRawSample(QPointF point) const;