v2.9.0

PlotPy Version 2.9.0

💥 New features:

• Added QuiverItem for displaying 2D vector fields (quiver plots), similar to
  Matplotlib's quiver. This closes
  Issue #54:
  • New QuiverItem plot item class supporting X, Y, U, V arrays (1D or 2D)
  • Auto-meshgrid expansion when X, Y are 1D and U, V are 2D
  • Configurable arrow scale, head size, and color
  • New make.quiver() builder method for easy item creation
  • New quiver() function in the interactive plotting interface (plotpy.pyplot)
  • Integrated with plot autoscale (initial zoom and middle-click reset)
  • Item icon displayed in the item list widget
• Added "Invert colormap" checkbox directly in the Colormap Manager dialog. This
  closes Issue #53:
  • Reflects the current inversion state when the dialog is opened
  • Allows toggling inversion from the colormap selection widget
  • Updates the colormap preview in real-time when toggled
  • Inversion is treated as a display parameter, independent of the colormap
    definition (toggling does not mark the colormap as having unsaved changes)

🛠️ Bug fixes:

• Fixed marker style parameters being overwritten when updating selected markers:
  • MarkerParam.update_param now correctly reads back the selected or unselected
    visual state into the matching parameter set, instead of overwriting the base
    (normal) style with the selected style
  • This preserves distinct normal and selected appearance for markers
• Fixed error-bar curve cursor snapping: clicking near an error-bar bound on an
  ErrorBarCurveItem now correctly returns the closest bar end coordinate.
  Previously a typo (abs(y - y) / abs(x - x) instead of abs(y - yi) /
  abs(x - xi)) made the snap-to-bound branches dead code, so the closest
  coordinate was always the central curve point regardless of cursor position
• Fixed image export via Figure.print_ (plotpy.pyplot) leaking the underlying
  QPainter: the painter is now always released, even when an axis fails to
  render. This avoids "QPainter::begin: A paint device can only be painted by
  one painter at a time" warnings, GDI/GL resource leaks, and truncated output
  files on subsequent paints
• Fixed vector_projection raising a division-by-zero warning and returning NaN
  coordinates when the two reference points A and B coincided. The function now
  detects the degenerate zero-length AB vector and returns point B
• Fixed scale_data_to_dtype (plotpy.io) producing NaN values when the input
  array was constant (dmax == dmin). The function now returns a finite
  constant array set to the target dtype's minimum value instead of dividing by
  zero
• Fixed get_nan_min / get_nan_max (plotpy.mathutils.arrayfuncs) raising
  ValueError on empty arrays and emitting RuntimeWarning on all-NaN inputs.
  Both helpers now return NaN for empty or fully-NaN arrays without warnings

🔧 Other changes:

• CI: gate PyPI deployment on test suite passing
• Development environment: improved scripts/run_with_env.py to support multiple
  Python environment contexts (WinPython, venv, etc.) with legacy support for the
  WINPYDIRBASE environment variable