feat: add support for pyqtgraph (#32)

README.md

@@ -92,8 +92,17 @@ to an integer array (like an image) you must apply any contrast limits and resca
 
 ## Third Party Library Support
 
-The `cmap.Colormap` object has convenience methods that allow it to be used with a number of third-party colormap objects (like
-`matplotlib`, `vispy`, `napari`, `plotly`, etc...).
+The `cmap.Colormap` object has convenience methods that export it to a number of known
+third-party colormap objects, including:
+
+- [matplotlib](https://matplotlib.org/)
+- [napari](https://napari.org/)
+- [vispy](https://vispy.org/)
+- [pygfx](https://pygfx.readthedocs.io/en/latest/) (& [fastplotlib](https://github.com/fastplotlib/fastplotlib))
+- [plotly](https://plotly.com/python/)
+- [bokeh](https://docs.bokeh.org/en/latest/)
+- [altair](https://altair-viz.github.io/)
+- [pyqtgraph](https://www.pyqtgraph.org/)
 
 See [documentation](https://cmap-docs.readthedocs.io/en/latest/colormaps/#usage-with-external-visualization-libraries)
 for details.
@@ -104,7 +113,6 @@ If you would like to see support added for a particular library, please open an
 
 Other libraries providing colormaps:
 
-
 - [matplotlib](https://matplotlib.org/stable/tutorials/colors/colormaps.html)
 - [seaborn](https://seaborn.pydata.org/tutorial/color_palettes.html)  (subclasses matplotlib)
 - [proplot](https://proplot.readthedocs.io/en/latest/colormaps.html)  (subclasses matplotlib)
@@ -128,4 +136,4 @@ Other libraries providing colormaps:
 - [Color Map Advice for Scientific Visualization](https://www.kennethmoreland.com/color-advice/)
 - <https://colorcet.com/>, Peter Kovesi
 - [Kovesi: Good Colour Maps: How to Design Them.](https://arxiv.org/abs/1509.03700)
-- https://www.fabiocrameri.ch/colourmaps/
+- <https://www.fabiocrameri.ch/colourmaps/>

docs/colormaps.md

@@ -234,6 +234,15 @@ external visualization libraries.  To that end, `cmap.Colormap` provides
 
     Returns a list of hexadecimal color strings.
 
+- [pyqtgraph](https://pyqtgraph.org/)
+
+    ```python
+    Colormap("viridis").to_pyqtgraph()
+    ```
+
+    Returns an instance of
+    [`pyqtgraph.ColorMap`](https://pyqtgraph.readthedocs.io/en/latest/api_reference/colormap.html#pyqtgraph.ColorMap)
+
 ## Usage with pydantic
 
 `Colormap` can be used as a field type in

pyproject.toml

@@ -59,6 +59,7 @@ thirdparty = [
     "rich",
     "viscm",
     "vispy",
+    "pyqtgraph",
 ]
 dev = [
     "black",

src/cmap/_colormap.py

@@ -21,6 +21,7 @@
     import matplotlib.figure
     import napari.utils.colormaps
     import pygfx
+    import pyqtgraph
     import vispy.color
     from numpy.typing import ArrayLike, NDArray
     from pydantic import GetCoreSchemaHandler
@@ -546,6 +547,10 @@ def to_viscm(
         """
         return _external.viscm_plot(self, dpi, dest)
 
+    def to_pyqtgraph(self) -> pyqtgraph.ColorMap:
+        """Return a `pyqtgraph.ColorMap`."""
+        return _external.to_pyqtgraph(self)
+
 
 class ColorStop(NamedTuple):
     """A color stop in a color gradient."""

src/cmap/_external.py

@@ -14,6 +14,7 @@
     from matplotlib.colors import LinearSegmentedColormap as MplLinearSegmentedColormap
     from matplotlib.figure import Figure as MplFigure
     from napari.utils.colormaps import Colormap as NapariColormap
+    from pyqtgraph import ColorMap as PyqtgraphColorMap
     from vispy.color import Colormap as VispyColormap
 
     from ._color import Color
@@ -97,6 +98,17 @@ def to_altair(cm: Colormap, N: int = 256) -> list[str]:
     return [color.hex for color in cm.iter_colors(N)]
 
 
+def to_pyqtgraph(cm: Colormap) -> PyqtgraphColorMap:
+    """Return a `pyqtgraph.Colormap`."""
+    from pyqtgraph import ColorMap
+
+    colors = (cm.color_stops.color_array * 255).astype(np.uint8)
+    return ColorMap(cm.color_stops.stops, colors, name=cm.name)
+
+
+# ==========================================
+
+
 def viscm_plot(
     cmap: Colormap | MplColormap, dpi: int = 100, dest: str | None = None
 ) -> MplFigure:

tests/test_third_party.py

@@ -141,6 +141,16 @@ def test_viscm(tmp_path: Path) -> None:
     assert out.is_file()
 
 
+def test_pyqtgraph() -> None:
+    pytest.importorskip("pyqtgraph")
+    cmap1 = Colormap(["red", "green", "blue"])
+    cm = cmap1.to_pyqtgraph()
+
+    cm.getGradient()
+    cm.linearize()
+    cm.reverse()
+
+
 # def microvis_imshow(img_data: np.ndarray, cmap: cmap.Colormap) -> None:
 #     from microvis import _util, imshow