feat(dataset): add reactive numeric range editors

doc/examples.rst

@@ -48,6 +48,72 @@ Embedding guidata objects in GUI layouts
 
 .. image:: images/screenshots/editgroupbox.png
 
+Local automatic sliders
+~~~~~~~~~~~~~~~~~~~~~~~
+
+An embedded ``DataSetEditLayout`` can opt into sliders without changing shared
+``DataItem`` declarations or other forms::
+
+   editor = DataSetEditLayout(
+      parent, parameters, grid, change_callback=parameters_changed,
+      auto_sliders=True, slider_steps=1000,
+   )
+
+The policy is inherited by nested groups and tabs. Editable numeric items need
+finite, ordered, representable bounds; otherwise they remain text-only. Integer
+parity is respected, and ranges crossing zero for ``nonzero`` items are not
+automatically given sliders. For floats, a usable positive ``step`` is used when
+practical, otherwise ``slider_steps`` specifies the normalized resolution. The
+text field retains its exact value independently of the slider thumb.
+
+``slider=True`` retains its existing behavior. Set
+``item.set_prop("display", auto_slider=False)`` to exclude an item from the local
+automatic policy. No bounds are inferred. The optional layout callback
+``slider_callback(pressed)`` receives ``True`` at drag start and ``False`` at
+release; value changes still use the existing ``change_callback``. Neither
+callback automatically validates, accepts or applies the form. Use
+``check_all_values()`` before ``accept_changes()`` when collecting a draft.
+
+Histogram-backed interval selection
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+``HistogramRangeItem`` edits two distinct ``FloatItem`` fields in the same dataset.
+Its default presentation is a generic interval, suitable for measurements such as
+durations. The caller supplies histogram counts and range proposals; guidata does
+not inspect source arrays or choose an automatic range.
+
+The following tested dataset has bounded durations in seconds and a live dependent
+field. Import ``guidata.dataset as gds`` before using it:
+
+.. literalinclude:: ../guidata/tests/dataset/test_histogram_range_item.py
+   :pyobject: DurationRange
+
+Call ``DurationRange().edit()`` to display it. The hidden numeric fields retain
+their constraints, including ``nonzero`` and the ``check=False`` opt-out. A window
+outside those constraints stays visible but cannot be accepted. The histogram's
+``domain`` is only a drawing/slider domain, not an additional numeric constraint.
+If either linked field is read-only or inactive, the entire composite is disabled.
+
+The histogram payload is transient: only the linked numeric values are serialized.
+After loading a dataset, restore its histogram context before enabling editing.
+An empty context leaves the saved bounds visible and the controls disabled.
+Auto and Reset appear only when the caller supplies finite ordered proposals.
+
+The callback receives ``(instance, item, payload)`` once per valid changed pair.
+Both bounds are already on the working dataset, and dependent fields are refreshed.
+Without callbacks or computed fields, edits remain local until acceptance. With
+live dependencies, guidata updates the working dataset before acceptance, just as
+for ordinary items. Applications requiring transactional Cancel must edit a copy;
+the dialog cannot undo arbitrary callback side effects.
+
+For image applications, explicitly select the brightness/contrast presentation::
+
+   DurationRange.histogram.set_prop("display", presentation="brightness_contrast")
+
+This adds brightness/contrast controls and a linear transfer overlay. It changes
+only rendering metadata, never the stored parameters. The JSON Schema exporter
+emits ``x-guidata-histogram-presentation`` so portable renderers use the same mode.
+
 Data item groups and group selection
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

doc/reference/dataset/dataitems.rst

@@ -1,3 +1,19 @@
 :tocdepth: 3
 
 .. automodule:: guidata.dataset.dataitems
+
+Histogram range context
+-----------------------
+
+``HistogramRangeItem`` consumes a plain mapping with histogram ``counts``, a finite
+ordered ``domain`` pair, and an ``active`` boolean. Bins are always drawn uniformly
+across ``domain``: non-uniform bin edges are not supported, so callers must rebin
+beforehand. Optional ``y_max`` and ``minimum_width`` must be positive and finite.
+Optional ``auto_range`` and ``reset_range`` are finite ordered pairs. Additional
+keys are preserved for the caller. An empty mapping represents unavailable context.
+
+The default ``display.presentation`` is ``"range"``. The only specialization is
+``"brightness_contrast"``; unknown modes and links to anything other than two
+distinct ``FloatItem`` fields fail explicitly when constructing/exporting the form.
+See :ref:`examples` for a complete, tested duration-selection example and the live
+callback/Cancel contract.

doc/release_notes/release_3.16.md

@@ -0,0 +1,11 @@
+# Version 3.16 #
+
+## guidata Version 3.16.0 ##
+
+✨ New features:
+
+* **Local automatic sliders for numeric `DataSet` items** — `DataSetEditLayout` (and derived group boxes/dialogs) can now opt into adding sliders to editable, bounded numeric items without changing shared `DataItem` declarations or affecting other forms. Enable it with `DataSetEditLayout(..., auto_sliders=True)`; the policy is inherited by nested groups and tabs. Editable items need finite, ordered, representable bounds to receive a slider — integer parity (`even`) and `nonzero` ranges crossing zero are respected, unusable items remain text-only. For floats, a usable positive `step` is reused when practical, otherwise the new `slider_steps` parameter sets the normalized resolution (default 1000). The text field always keeps the exact underlying value, independently of the slider thumb resolution. Use `item.set_prop("display", auto_slider=False)` to exclude a specific item from the policy. An optional `slider_callback(pressed)` reports drag start/end without affecting the existing `change_callback` value-change notifications. `slider=True` on individual items keeps its previous behavior unchanged.
+
+* **`HistogramRangeItem` — histogram-backed interval selection** — added a new `DataItem` that edits two distinct `FloatItem` fields of the same dataset through a single histogram-backed range editor widget. The caller supplies a rendering payload (bin `counts`, a finite ordered `domain`, optional `y_max`, `minimum_width`, `auto_range` and `reset_range` proposals); guidata never inspects source arrays or computes a range on its own. The default `"range"` presentation shows a plain interval selector suitable for generic measurements (durations, thresholds, …); setting `display.presentation` to `"brightness_contrast"` adds brightness/contrast sliders and a linear transfer function overlay for image-oriented use cases. The item is transient: only the two linked numeric fields are persisted (HDF5/JSON/INI), so applications must restore the histogram context after loading before editing is possible. A `display.callback(instance, item, value)` is invoked once per valid edited pair, with both bounds already applied to the working dataset, matching the behavior of other guidata live callbacks. The JSON Schema exporter emits a dedicated `"histogram_range"` kind with `x-guidata-minimum-field`, `x-guidata-maximum-field` and `x-guidata-histogram-presentation` extension keywords so portable renderers can reproduce the same behavior. See the [examples](../examples.rst) and [`HistogramRangeItem` reference](../reference/dataset/dataitems.rst) documentation for a complete, tested duration-selection walkthrough.
+
+🛠 Bug fixes:

guidata/dataset/__init__.py

@@ -36,6 +36,7 @@
     FloatArrayItem,
     FloatItem,
     FontFamilyItem,
+    HistogramRangeItem,
     ImageChoiceItem,
     IntItem,
     LabeledEnum,

guidata/dataset/conv.py

@@ -24,6 +24,10 @@
 Serialize datasets as JSON
 --------------------------
 
+Items whose ``data.transient`` property is ``True`` are omitted from the
+serialized output and left untouched when loading: they carry presentation
+context supplied by the host application, not dataset state.
+
 .. autofunction:: guidata.dataset.dataset_to_json
 
 .. autofunction:: guidata.dataset.json_to_dataset
@@ -396,11 +400,13 @@ def _resolve_dataset_class(
 
 
 def _dataset_items(dataset_class: type[gdt.DataSet]) -> dict[str, gdt.DataItem]:
-    """Return persisted DataItems, excluding structural and callback items."""
+    """Return persisted DataItems, excluding structural and transient items."""
     return {
         item.get_name(): item
         for item in dataset_class._items
-        if item.get_name() and not isinstance(item, _NON_SERIALIZED_ITEM_TYPES)
+        if item.get_name()
+        and not isinstance(item, _NON_SERIALIZED_ITEM_TYPES)
+        and not item.get_prop("data", "transient", False)
     }
 
 

guidata/dataset/dataitems.py

@@ -86,6 +86,9 @@
 .. autoclass:: guidata.dataset.DictItem
     :members:
 
+.. autoclass:: guidata.dataset.HistogramRangeItem
+    :members:
+
 .. autoclass:: guidata.dataset.FontFamilyItem
     :members:
 
@@ -1531,6 +1534,94 @@ def get_value_from_reader(self, reader):
         return reader.read_dict()
 
 
+class HistogramRangeItem(DataItem):
+    """Histogram-backed editor for two distinct FloatItem fields in one dataset.
+
+    The item value is a JSON-compatible rendering payload. It is deliberately
+    transient: only the linked minimum and maximum fields belong to the
+    persistent dataset state.
+
+    Set ``display.presentation`` to ``"brightness_contrast"`` to enable the
+    brightness/contrast controls and linear transfer display. The default
+    ``"range"`` presentation only selects an interval. Linked fields should be
+    hidden from the ordinary form; their validation and readonly properties
+    still apply. The histogram domain does not constrain their values.
+
+    The payload describes ``counts`` spread uniformly over a finite ordered
+    ``domain``, plus optional positive ``y_max`` and ``minimum_width``. Bin
+    positions are always derived from ``domain``: non-uniform bin edges are not
+    supported, so callers must rebin beforehand. ``active`` enables editing;
+    ``auto_range`` and ``reset_range`` optionally supply button targets.
+    An empty payload disables editing until context is provided. Extra keys
+    are allowed, but no image objects or computation callbacks belong here.
+
+    A ``display.callback(instance, item, value)`` receives the unchanged payload;
+    both edited bounds are available on the working instance. Like other
+    guidata live callbacks, it updates the working dataset before acceptance.
+    Hosts needing transactional cancellation must edit a copy of their data.
+
+    Args:
+        label: Item label
+        minimum: Name of the linked minimum field
+        maximum: Name of the linked maximum field
+        default: Initial rendering payload
+        help: Text shown in the tooltip
+    """
+
+    type: type[dict[str, Any]] = dict
+
+    def __init__(
+        self,
+        label: str,
+        minimum: str,
+        maximum: str,
+        default: dict[str, Any] | None = None,
+        help: str = "",
+    ) -> None:
+        super().__init__(label, default=default or {}, help=help, check=False)
+        self.set_prop(
+            "data",
+            transient=True,
+            minimum_field=minimum,
+            maximum_field=maximum,
+        )
+        self.set_prop("display", presentation="range")
+
+    def get_presentation(self) -> str:
+        """Return the validated portable presentation name."""
+        presentation = self.get_prop("display", "presentation", "range")
+        if presentation not in ("range", "brightness_contrast"):
+            raise ValueError(f"Unknown histogram presentation: {presentation!r}")
+        return presentation
+
+    def get_range_items(self, instance: DataSet) -> tuple[FloatItem, FloatItem]:
+        """Resolve and validate the two linked fields without changing them."""
+        minimum = self.get_prop("data", "minimum_field")
+        maximum = self.get_prop("data", "maximum_field")
+        items = {item.get_name(): item for item in instance.get_items()}
+        if minimum == maximum or any(
+            not isinstance(items.get(name), FloatItem) for name in (minimum, maximum)
+        ):
+            raise ValueError(
+                "HistogramRangeItem requires two distinct FloatItem fields"
+            )
+        return items[minimum], items[maximum]
+
+    def serialize(
+        self,
+        instance: DataSet,
+        writer: HDF5Writer | JSONWriter | INIWriter,
+    ) -> None:
+        """Skip the renderer payload when persisting the dataset."""
+
+    def deserialize(
+        self,
+        instance: DataSet,
+        reader: HDF5Reader | JSONReader | INIReader,
+    ) -> None:
+        """Keep the current renderer payload when loading persisted values."""
+
+
 class ButtonItem(DataItem):
     """Construct a simple button that calls a method when hit
 

guidata/dataset/jsonschema.py

@@ -70,7 +70,7 @@
 
 ``int``, ``float``, ``bool``, ``string``, ``text``, ``choice``,
 ``multiple_choice``, ``image_choice``, ``color``, ``date``, ``datetime``,
-``file``, ``float_array``, ``dict``.
+``file``, ``float_array``, ``dict``, ``histogram_range``.
 
 Items not supported (raise :class:`NotImplementedError`):
 ``ButtonItem`` (callbacks cannot cross JSON), and conditional visibility
@@ -140,6 +140,9 @@ def dataset_to_schema(dataset_cls: type[gdt.DataSet]) -> dict[str, Any]:
     # Use a transient instance to obtain the title/comment computed by
     # ``DataSetMeta`` from the docstring, without paying for it twice.
     instance = dataset_cls()
+    for item in instance.get_items():
+        if isinstance(item, gdi.HistogramRangeItem):
+            item.get_range_items(instance)
     title = instance.get_title()
     comment = instance.get_comment()
 
@@ -455,7 +458,9 @@ def _item_to_property(item: gdt.DataItem, order: int) -> dict[str, Any]:
         )
 
     # Dispatch in MRO-friendly order (most specific first).
-    if isinstance(item, gdi.FloatArrayItem):
+    if isinstance(item, gdi.HistogramRangeItem):
+        prop = _histogram_range_to_property(item)
+    elif isinstance(item, gdi.FloatArrayItem):
         prop = _float_array_to_property(item)
     elif isinstance(item, gdi.DictItem):
         prop = _dict_to_property(item)
@@ -514,6 +519,8 @@ def _numeric_to_property(item: gdi.NumericTypeItem, kind: str) -> dict[str, Any]
         "type": json_type,
         "x-guidata-kind": kind,
     }
+    if item.get_prop("data", "check_value", True) is False:
+        prop["x-guidata-check-value"] = False
     minv = item.get_prop("data", "min", None)
     maxv = item.get_prop("data", "max", None)
     if minv is not None:
@@ -687,6 +694,21 @@ def _dict_to_property(item: gdi.DictItem) -> dict[str, Any]:
     }
 
 
+def _histogram_range_to_property(
+    item: gdi.HistogramRangeItem,
+) -> dict[str, Any]:
+    """Return the portable contract for a histogram-backed range editor."""
+    return {
+        "type": "object",
+        "additionalProperties": True,
+        "x-guidata-kind": "histogram_range",
+        "x-guidata-transient": True,
+        "x-guidata-minimum-field": item.get_prop("data", "minimum_field"),
+        "x-guidata-maximum-field": item.get_prop("data", "maximum_field"),
+        "x-guidata-histogram-presentation": item.get_presentation(),
+    }
+
+
 # ---------------------------------------------------------------------------
 # Common per-property keys and helpers
 # ---------------------------------------------------------------------------