Add Detector class

examples/inspect_geom_class.py

+import sys
+
+from pycrystfel.bindings import Detector
+
+det = Detector.from_filename(sys.argv[1])
+print(f"{det.n_panels} panels:")
+for name in det.panel_names:
+    print(f"- {name}")

pycrystfel/bindings.pyx

@@ -44,8 +44,6 @@ cdef featurelist_to_dataframe(crystfel.ImageFeatureList *flist):
         arr.T, columns=['ss', 'fs', 'rx', 'ry', 'rz', 'intensity']
     )
 
-
-
 def find_peaks_single_panel(cnp.ndarray[cnp.npy_float, ndim=2] data, str geom_file):
     cdef:
         crystfel.beam_params beam
@@ -67,3 +65,40 @@ def find_peaks_single_panel(cnp.ndarray[cnp.npy_float, ndim=2] data, str geom_fi
     crystfel.free_detector_geometry(image.det)
 
     return featurelist_to_dataframe(image.features)
+
+
+# Pointer wrapper machinery based on Cython docs:
+# https://cython.readthedocs.io/en/latest/src/userguide/extension_types.html#instantiation-from-existing-c-c-pointers
+cdef class Detector:
+    cdef crystfel.detector* _ptr
+    cdef bint ptr_owner
+
+    def __cinit__(self):
+        self.ptr_owner = False
+
+    def __dealloc__(self):
+        # De-allocate if not null and flag is set
+        if self._ptr is not NULL and self.ptr_owner is True:
+            free(self._ptr)
+            self._ptr = NULL
+
+    @staticmethod
+    cdef Detector from_ptr(crystfel.detector* _ptr, bint owner=False):
+        # Call to __new__ bypasses __init__ constructor
+        cdef Detector det = Detector.__new__(Detector)
+        det._ptr = _ptr
+        det.ptr_owner = owner
+        return det
+
+    @classmethod
+    def from_filename(cls, path):
+        return Detector.from_ptr(
+            crystfel.get_detector_geometry(os.fsencode(path), NULL), owner=True
+        )
+
+    @property
+    def n_panels(self):
+        return self._ptr.n_panels if self._ptr is not NULL else 0
+
+    def panel_names(self):
+        return [self._ptr.panels[i].name for i in range(self.n_panels)]