fix(plot_grid): honor minor pen arguments in QwtPlotGrid.make

QwtPlotGrid.make raised a TypeError when only some of the minor pen
arguments (mincolor, minwidth, minstyle) were given, e.g.
QwtPlotGrid.make(mincolor="red"): the default minor width and style were
chosen by testing the major width and style arguments, which are never
None at that point, instead of the minor ones, so None was passed to QPen.

- Test minwidth and minstyle against None, as documented, and convert the
  minor width to float like the major one.
- Regression tests: every combination of minor pen arguments, and major
  pen unchanged; calls which already worked keep the same pens.
- Changelog entry.

Refs #115

Assisted-by: Claude Opus 5.5

Author: PierreRaybaut

CHANGELOG.md

@@ -11,6 +11,7 @@
 - Fixed [Issue #113](https://github.com/PlotPyStack/PythonQwt/issues/113): after replacing the scale draw of an axis (`QwtPlot.setAxisScaleDraw`), the axis ticks could be misaligned with the grid lines and plot items, until the next scale division change (e.g. after panning or zooming): a replot did not fix it. The new scale draw was laid out before getting the position and length of the previous one, so that the axis reserved space for its end labels that the canvas did not take into account. The new scale draw now takes the geometry of the previous one, and the axis stays aligned with the canvas
 - Fixed `QwtGraphic.toPixmap(size)`, `QwtGraphic.toImage()` and `QwtGraphic.toImage(size)`, which raised a `TypeError` (possibly aborting the process, as the painter was still active on the destroyed pixmap or image) instead of rendering the graphic: they now render it like `QwtGraphic.toPixmap()` ([Issue #115](https://github.com/PlotPyStack/PythonQwt/issues/115))
 - Fixed `QwtPlotMarker.legendIcon` for markers with a symbol, which raised an `AssertionError` or a `TypeError`: such markers can now be shown in a legend ([Issue #115](https://github.com/PlotPyStack/PythonQwt/issues/115))
+- Fixed `QwtPlotGrid.make`, which raised a `TypeError` when only some of the minor pen arguments (`mincolor`, `minwidth`, `minstyle`) were given: each of them is now honored, the missing ones taking their documented default value ([Issue #115](https://github.com/PlotPyStack/PythonQwt/issues/115))
 
 ## Version 0.16.3
 

qwt/plot_grid.py

@@ -106,8 +106,8 @@ def make(
         item.setPen(QPen(color, width, style))
         if mincolor is not None or minwidth is not None or minstyle is not None:
             mincolor = qcolor_from_str(mincolor, Qt.gray)
-            minwidth = 1.0 if width is None else minwidth
-            minstyle = Qt.DotLine if style is None else minstyle
+            minwidth = 1.0 if minwidth is None else float(minwidth)
+            minstyle = Qt.DotLine if minstyle is None else minstyle
             item.setMinorPen(QPen(mincolor, minwidth, minstyle))
         if enablemajor is not None:
             if isinstance(enablemajor, tuple) and len(enablemajor) == 2:

qwt/tests/test_issue115_porting_bugs.py

@@ -15,7 +15,14 @@
 from qtpy import QtGui as QG
 from qtpy import QtWidgets as QW
 
-from qwt import QwtLegend, QwtPlot, QwtPlotItem, QwtPlotMarker, QwtSymbol
+from qwt import (
+    QwtLegend,
+    QwtPlot,
+    QwtPlotGrid,
+    QwtPlotItem,
+    QwtPlotMarker,
+    QwtSymbol,
+)
 from qwt.graphic import QwtGraphic
 
 RED = QG.QColor(QC.Qt.red)
@@ -140,6 +147,55 @@ def test_marker_with_symbol_in_legend():
     del app
 
 
+# ---------------------------------------------------------------------------
+# QwtPlotGrid.make
+# ---------------------------------------------------------------------------
+
+
+def _pen_attrs(pen):
+    return pen.color().name(), pen.widthF(), pen.style()
+
+
+@pytest.mark.parametrize(
+    "kwargs, expected",
+    (
+        ({"mincolor": "red"}, ("#ff0000", 1.0, QC.Qt.DotLine)),
+        ({"minwidth": 2}, ("#a0a0a4", 2.0, QC.Qt.DotLine)),
+        ({"minstyle": QC.Qt.DashLine}, ("#a0a0a4", 1.0, QC.Qt.DashLine)),
+        ({"mincolor": "red", "minwidth": 2}, ("#ff0000", 2.0, QC.Qt.DotLine)),
+        (
+            {"mincolor": "red", "minstyle": QC.Qt.DashLine},
+            ("#ff0000", 1.0, QC.Qt.DashLine),
+        ),
+        (
+            {"minwidth": 3.0, "minstyle": QC.Qt.SolidLine},
+            ("#a0a0a4", 3.0, QC.Qt.SolidLine),
+        ),
+        (
+            {"mincolor": "blue", "minwidth": 0, "minstyle": QC.Qt.DashDotLine},
+            ("#0000ff", 0.0, QC.Qt.DashDotLine),
+        ),
+    ),
+)
+def test_grid_make_minor_pen(kwargs, expected):
+    """QwtPlotGrid.make honors each minor pen argument, with documented defaults"""
+    app = _ensure_app()  # keep a reference alive for the duration of the test
+    grid = QwtPlotGrid.make(color="green", width=4, style=QC.Qt.DashLine, **kwargs)
+    assert _pen_attrs(grid.minorPen()) == expected
+    assert _pen_attrs(grid.majorPen()) == ("#00ff00", 4.0, QC.Qt.DashLine)
+    del app
+
+
+def test_grid_make_without_minor_pen():
+    """Without minor pen arguments, both pens are built from the major ones"""
+    app = _ensure_app()  # keep a reference alive for the duration of the test
+    grid = QwtPlotGrid.make(color="green", width=0, style=QC.Qt.SolidLine)
+    expected = ("#00ff00", 0.0, QC.Qt.SolidLine)
+    assert _pen_attrs(grid.majorPen()) == expected
+    assert _pen_attrs(grid.minorPen()) == expected
+    del app
+
+
 if __name__ == "__main__":
     for name in ("toPixmap", "toImage"):
         test_graphic_conversion_default_size(name)
@@ -148,4 +204,5 @@ def test_marker_with_symbol_in_legend():
     for size in (QC.QSize(8, 8), QC.QSizeF(8.0, 8.0)):
         test_marker_legend_icon_with_symbol(size)
     test_marker_with_symbol_in_legend()
+    test_grid_make_without_minor_pen()
     print("OK")