LegendItem: Enable customization of label text size and tests (#1397)

* LegendItem: Enable customization of label text size and tests

* One more CI

* Remove deleteLater of QAPP in legend item test

* Remove assert statement in setLabelTextSize

* Modify legend test without assertion

pyqtgraph/graphicsItems/LegendItem.py

@@ -29,7 +29,7 @@ class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
 
     def __init__(self, size=None, offset=None, horSpacing=25, verSpacing=0,
                  pen=None, brush=None, labelTextColor=None, frame=True,
-                 rowCount=1, colCount=1, **kwargs):
+                 labelTextSize='9pt', rowCount=1, colCount=1, **kwargs):
         """
         ==============  ===============================================================
         **Arguments:**
@@ -50,6 +50,8 @@ class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
                         accepted by :func:`mkBrush <pyqtgraph.mkBrush>` is allowed.
         labelTextColor  Pen to use when drawing legend text. Any single argument
                         accepted by :func:`mkPen <pyqtgraph.mkPen>` is allowed.
+        labelTextSize   Size to use when drawing legend text. Accepts CSS style
+                        string arguments, e.g. '9pt'.
         ==============  ===============================================================
 
         """
@@ -75,6 +77,7 @@ class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
             'pen': fn.mkPen(pen),
             'brush': fn.mkBrush(brush),
             'labelTextColor': labelTextColor,
+            'labelTextSize': labelTextSize,
             'offset': offset,
         }
 
@@ -139,6 +142,21 @@ class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
 
         self.update()
 
+    def labelTextSize(self):
+        """Get the `labelTextSize` used for the item labels."""
+        return self.opts['labelTextSize']
+
+    def setLabelTextSize(self, size):
+        """Set the `size` of the item labels.
+
+        Accepts the CSS style string arguments, e.g. '8pt'.
+        """
+        self.opts['labelTextSize'] = size
+        for _, label in self.items:
+            label.setAttr('size', self.opts['labelTextSize'])
+
+        self.update()
+
     def setParentItem(self, p):
         """Set the parent."""
         ret = GraphicsWidget.setParentItem(self, p)
@@ -164,7 +182,7 @@ class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
         ==============  ========================================================
         """
         label = LabelItem(name, color=self.opts['labelTextColor'],
-                          justify='left')
+                          justify='left', size=self.opts['labelTextSize'])
         if isinstance(item, ItemSample):
             sample = item
         else:

pyqtgraph/graphicsItems/tests/test_LegendItem.py

@@ -0,0 +1,101 @@
+import pytest
+import pyqtgraph as pg
+
+
+def test_legend_item_basics():
+    app = pg.mkQApp()
+
+    legend = pg.LegendItem()
+
+    assert legend.opts['pen'] == pg.mkPen(None)
+    assert legend.opts['brush'] == pg.mkBrush(None)
+    assert legend.opts['labelTextColor'] is None
+    assert legend.opts['labelTextSize'] == '9pt'
+    assert legend.opts['offset'] is None
+
+    assert legend.columnCount == 1
+    assert legend.rowCount == 1
+    assert legend.curRow == 0
+
+    assert legend.labelTextColor() is None
+    assert legend.labelTextSize() == '9pt'
+    assert legend.brush() == pg.mkBrush(None)
+    assert legend.pen() == pg.mkPen(None)
+
+    # Set brush
+    # ----------------------------------------------------
+
+    brush = pg.mkBrush('b')
+    legend.setBrush(brush)
+    assert legend.brush() == brush
+    assert legend.opts['brush'] == brush
+
+    # Set pen
+    # ----------------------------------------------------
+
+    pen = pg.mkPen('b')
+    legend.setPen(pen)
+    assert legend.pen() == pen
+    assert legend.opts['pen'] == pen
+
+    # Set labelTextColor
+    # ----------------------------------------------------
+
+    text_color = pg.mkColor('b')
+    legend.setLabelTextColor(text_color)
+    assert legend.labelTextColor() == text_color
+    assert legend.opts['labelTextColor'] == text_color
+
+    # Set labelTextSize
+    # ----------------------------------------------------
+
+    text_size = '12pt'
+    legend.setLabelTextSize(text_size)
+    assert legend.labelTextSize() == text_size
+    assert legend.opts['labelTextSize'] == text_size
+
+    # Add items
+    # ----------------------------------------------------
+
+    assert len(legend.items) == 0
+    plot = pg.PlotDataItem(name="Plot")
+    legend.addItem(plot, name="Plot")
+    assert len(legend.items) == 1
+
+    scatter = pg.PlotDataItem(name="Scatter")
+    legend.addItem(scatter, name="Scatter")
+    assert len(legend.items) == 2
+    assert legend.columnCount == 1
+    assert legend.rowCount == 1
+
+    curve = pg.PlotDataItem(name="Curve")
+    legend.addItem(curve, name="Curve")
+    assert len(legend.items) == 3
+
+    scrabble = pg.PlotDataItem(name="Scrabble")
+    legend.addItem(scrabble, name="Scrabble")
+    assert len(legend.items) == 4
+
+    assert legend.layout.rowCount() == 4
+    legend.setColumnCount(2)
+    assert legend.rowCount == 2
+
+    assert legend.layout.rowCount() == 3
+
+    # Remove items
+    # ----------------------------------------------------
+
+    legend.removeItem(scrabble)
+    assert legend.rowCount == 2
+    assert legend.layout.rowCount() == 2
+    assert scrabble not in legend.items
+    assert len(legend.items) == 3
+
+    legend.removeItem(curve)
+    assert legend.rowCount == 2
+    assert legend.layout.rowCount() == 1
+    assert curve not in legend.items
+    assert len(legend.items) == 2
+
+    legend.clear()
+    assert legend.items == []