WIP: Centralize ImageJ2 gateway into nij object

This provides a place to keep track of not only the ImageJ2 gateway, but
also any affiliated data structures, such as our singleton ScriptREPL.

.github/workflows/build.yml

@@ -9,9 +9,6 @@ on:
       - main
     tags:
       - "*-[0-9]+.*"
-  pull_request:
-    branches:
-      - main
 
 env:
   NAPARI_IMAGEJ_TEST_TIMEOUT: 60000

src/napari_imagej/__init__.py

@@ -20,5 +20,9 @@
 
 import scyjava as sj
 
+from napari_imagej.model import NapariImageJ
+
 __author__ = "ImageJ2 developers"
 __version__ = sj.get_version("napari-imagej")
+
+nij = NapariImageJ()

src/napari_imagej/java.py

@@ -4,8 +4,6 @@
 Notable functions included in the module:
     * init_ij()
         - used to create the ImageJ instance.
-    * ij()
-        - used to access the ImageJ instance.
 
 Notable fields included in the module:
     * jc
@@ -33,57 +31,40 @@
     "sc.fiji:TrackMate": "7.11.0",
 }
 
-# -- ImageJ API -- #
-
-_ij = None
-
-def ij():
-    if _ij is None:
-        raise Exception(
-            "The ImageJ instance has not yet been initialized! Please run init_ij()"
-        )
-    return _ij
-
 # -- Public functions -- #
 
+
 def init_ij() -> "jc.ImageJ":
     """
     Create an ImageJ2 gateway.
     """
-    global _ij
-    if _ij:
-        return _ij
     log_debug("Initializing ImageJ2")
 
-    # determine whether imagej is already running
-    imagej_already_initialized: bool = hasattr(imagej, "gateway") and imagej.gateway
-
     # -- CONFIGURATION -- #
 
-    # Configure napari-imagej
     from napari_imagej.types.converters import install_converters
-
     install_converters()
-
     log_debug("Completed JVM Configuration")
 
     # -- INITIALIZATION -- #
 
     # Launch ImageJ
-    if imagej_already_initialized:
-        _ij = imagej.gateway
-    else:
-        _ij = imagej.init(**_configure_imagej())
+    ij = (
+        imagej.gateway
+        if hasattr(imagej, "gateway") and imagej.gateway
+        else imagej.init(**_configure_imagej())
+    )
 
     # Log initialization
-    log_debug(f"Initialized at version {_ij.getVersion()}")
+    log_debug(f"Initialized at version {ij.getVersion()}")
 
     # -- VALIDATION -- #
 
     # Validate PyImageJ
-    _validate_imagej()
+    _validate_imagej(ij)
+
+    return ij
 
-    return _ij
 
 # -- Private functions -- #
 
@@ -112,7 +93,7 @@ def _configure_imagej() -> Dict[str, Any]:
     return init_settings
 
 
-def _validate_imagej():
+def _validate_imagej(ij: "jc.ImageJ"):
     """
     Ensure minimum requirements on java component versions are met.
     """
@@ -131,7 +112,7 @@ def _validate_imagej():
         "org.scijava:scijava-common": jc.Module,
         "org.scijava:scijava-search": jc.Searcher,
     }
-    component_requirements.update(_optional_requirements())
+    component_requirements.update(_optional_requirements(ij))
     # Find version that violate the minimum
     violations = []
     for component, cls in component_requirements.items():
@@ -153,11 +134,11 @@ def _validate_imagej():
         raise RuntimeError(failure_str)
 
 
-def _optional_requirements():
+def _optional_requirements(ij: "jc.ImageJ"):
     optionals = {}
     # Add additional minimum versions for legacy components
-    if _ij.legacy and _ij.legacy.isActive():
-        optionals["net.imagej:imagej-legacy"] = _ij.legacy.getClass()
+    if ij.legacy and ij.legacy.isActive():
+        optionals["net.imagej:imagej-legacy"] = ij.legacy.getClass()
     # Add additional minimum versions for fiji components
     try:
         optionals["sc.fiji:TrackMate"] = jimport("fiji.plugin.trackmate.TrackMate")
@@ -267,10 +248,6 @@ def BigDecimal(self):
     def BigInteger(self):
         return "java.math.BigInteger"
 
-    @JavaClasses.java_import
-    def ByteArrayOutputStream(self):
-        "java.io.ByteArrayOutputStream"
-
     @JavaClasses.java_import
     def Date(self):
         return "java.util.Date"

src/napari_imagej/model.py

@@ -0,0 +1,40 @@
+from jpype import JImplements, JOverride
+
+from napari_imagej.java import init_ij, jc
+
+
+class NapariImageJ:
+    """
+    An object offering a central access point to napari-imagej's core business logic.
+    """
+    def __init__(self):
+        self._ij = None
+        self._repl = None
+        self._repl_callbacks = []
+
+    @property
+    def ij(self):
+        if self._ij is None:
+            self._ij = init_ij()
+        return self._ij
+
+    @property
+    def repl(self) -> "jc.ScriptREPL":
+        if self._repl is None:
+            ctx = self.ij.context()
+            model = self
+
+            @JImplements("java.util.consumer.Consumer")
+            class REPLOutput:
+                @JOverride
+                def accept(self, t):
+                    s = str(t)
+                    for callback in model._repl_callbacks:
+                        callback(s)
+
+            self._repl = jc.ScriptREPL(ctx, "jython", REPLOutput())
+            self._repl.lang("jython")
+        return self._repl
+
+    def add_repl_callback(self, repl_callback) -> None:
+        self._repl_callbacks.append(repl_callback)

src/napari_imagej/readers/trackMate_reader.py

@@ -6,7 +6,8 @@
 from napari.utils import progress
 from scyjava import jimport
 
-from napari_imagej.java import ij, init_ij, jc
+from napari_imagej import nij
+from napari_imagej.java import jc
 from napari_imagej.types.converters.trackmate import (
     model_and_image_to_tracks,
     trackmate_present,
@@ -39,7 +40,7 @@ def napari_get_reader(path):
 
 def reader_function(path):
     pbr = progress(total=4, desc="Importing TrackMate XML: Starting JVM")
-    init_ij()
+    ij = nij.ij
     TmXMLReader = jimport("fiji.plugin.trackmate.io.TmXmlReader")
     pbr.update()
 
@@ -50,7 +51,7 @@ def reader_function(path):
     pbr.update()
 
     pbr.set_description("Importing TrackMate XML: Converting Image")
-    py_imp = ij().py.from_java(imp)
+    py_imp = ij.py.from_java(imp)
     pbr.update()
 
     pbr.set_description("Importing TrackMate XML: Converting Tracks and ROIs")

src/napari_imagej/types/converters/images.py

@@ -13,13 +13,14 @@
 from scyjava import Priority
 from xarray import DataArray
 
-from napari_imagej.java import ij, jc
+from napari_imagej import nij
+from napari_imagej.java import jc
 from napari_imagej.types.converters import java_to_py_converter, py_to_java_converter
 from napari_imagej.utilities.logging import log_debug
 
 
 @java_to_py_converter(
-    predicate=lambda obj: ij().convert().supports(obj, jc.DatasetView),
+    predicate=lambda obj: nij.ij.convert().supports(obj, jc.DatasetView),
     priority=Priority.VERY_HIGH + 1,
 )
 def _java_image_to_image_layer(image: Any) -> Image:
@@ -33,9 +34,9 @@ def _java_image_to_image_layer(image: Any) -> Image:
     :return: a napari Image layer
     """
     # Construct a DatasetView from the Java image
-    view = ij().convert().convert(image, jc.DatasetView)
+    view = nij.ij.convert().convert(image, jc.DatasetView)
     # Construct an xarray from the DatasetView
-    xarr: DataArray = java_to_xarray(ij(), view.getData())
+    xarr: DataArray = java_to_xarray(nij.ij, view.getData())
     # Construct a map of Image layer parameters
     kwargs = dict(
         data=xarr,
@@ -59,7 +60,7 @@ def _image_layer_to_dataset(image: Image, **kwargs) -> "jc.Dataset":
     :return: a Dataset
     """
     # Construct a dataset from the data
-    dataset: "jc.Dataset" = ij().py.to_dataset(image.data, **kwargs)
+    dataset: "jc.Dataset" = nij.ij.py.to_dataset(image.data, **kwargs)
 
     # Clean up the axes
     axes = [
@@ -94,7 +95,7 @@ def _image_layer_to_dataset(image: Image, **kwargs) -> "jc.Dataset":
     properties = dataset.getProperties()
     for k, v in image.metadata.items():
         try:
-            properties.put(ij().py.to_java(k), ij().py.to_java(v))
+            properties.put(nij.ij.py.to_java(k), nij.ij.py.to_java(v))
         except Exception:
             log_debug(f"Could not add property ({k}, {v}) to dataset {dataset}:")
     return dataset

src/napari_imagej/types/converters/labels.py

@@ -7,7 +7,8 @@
 from napari.layers import Labels
 from scyjava import Priority
 
-from napari_imagej.java import ij, jc
+from napari_imagej import nij
+from napari_imagej.java import jc
 from napari_imagej.types.converters import java_to_py_converter, py_to_java_converter
 
 
@@ -41,7 +42,7 @@ def _imglabeling_to_layer(imgLabeling: "jc.ImgLabeling") -> Labels:
     :param imgLabeling: the Java ImgLabeling
     :return: a Labels layer
     """
-    labeling: Labeling = imglabeling_to_labeling(ij(), imgLabeling)
+    labeling: Labeling = imglabeling_to_labeling(nij.ij, imgLabeling)
     return _labeling_to_layer(labeling)
 
 
@@ -55,4 +56,4 @@ def _layer_to_imglabeling(layer: Labels) -> "jc.ImgLabeling":
     :return: the Java ImgLabeling
     """
     labeling: Labeling = _layer_to_labeling(layer)
-    return ij().py.to_java(labeling)
+    return nij.ij.py.to_java(labeling)

src/napari_imagej/types/converters/trackmate.py

@@ -6,8 +6,7 @@
 from napari.layers import Labels, Tracks
 from scyjava import JavaClasses, Priority
 
-from napari_imagej import settings
-from napari_imagej.java import ij
+from napari_imagej import nij, settings
 from napari_imagej.types.converters import java_to_py_converter
 
 
@@ -36,7 +35,7 @@ def track_overlay_predicate(obj):
     if not trackmate_present():
         return False
     # TrackMate data is wrapped in ImageJ Rois - we need ImageJ Legacy
-    if not (ij().legacy and ij().legacy.isActive()):
+    if not (nij.ij.legacy and nij.ij.legacy.isActive()):
         return False
     # TrackMate data will be wrapped within a ROITree
     if not isinstance(obj, jc.ROITree):
@@ -106,7 +105,7 @@ def model_and_image_to_tracks(model: "jc.Model", imp: "jc.ImagePlus"):
     java_label_img = jc.LabelImgExporter.createLabelImagePlus(
         model, imp, False, False, False
     )
-    py_label_img = ij().py.from_java(java_label_img)
+    py_label_img = nij.ij.py.from_java(java_label_img)
     labels = Labels(data=py_label_img.data, name=rois_name)
 
     return (tracks, labels)
@@ -119,7 +118,7 @@ def _trackMate_model_to_tracks(obj: "jc.ROITree"):
     """
     Converts a TrackMate overlay into a napari Tracks layer
     """
-    trackmate_plugins = ij().object().getObjects(jc.TrackMate)
+    trackmate_plugins = nij.ij.object().getObjects(jc.TrackMate)
     if len(trackmate_plugins) == 0:
         raise IndexError("Expected a TrackMate instance, but there was none!")
     model: jc.Model = trackmate_plugins[-1].getModel()

src/napari_imagej/types/type_conversions.py

@@ -21,7 +21,8 @@
 from jpype import JObject
 from scyjava import Priority
 
-from napari_imagej.java import ij, jc
+from napari_imagej import nij
+from napari_imagej.java import jc
 from napari_imagej.types.enum_likes import enum_like
 from napari_imagej.types.enums import py_enum_for
 from napari_imagej.types.type_hints import type_hints
@@ -201,6 +202,6 @@ def canConvertChecker(item: "jc.ModuleItem") -> Optional[Type]:
     """
 
     def isAssignable(from_type, to_type) -> bool:
-        return ij().convert().supports(from_type, to_type)
+        return nij.ij.convert().supports(from_type, to_type)
 
     return _checkerUsingFunc(item, isAssignable)