LegendItem: fix docs & minor bugs (#1437)

* LegendItem: fix spelling mistake

* LegendItem: remove unused curRow variable

* LegendItem: correct calculation of rowCount

Previously, rowCount would never be updated unless setColumnCount()
was called. This fixes that issue.
It also fixes that setColumnCount() rounded down (floored) the
number of rows, instead of providing an accurate number:
e.g. 4 items in 3 columns would yield rowCount=1, when it should be 2

* LegendItem: remove rowCount argument (not implemented)

Logic to actually use the rowCount argument was not implemented.
Users might expect rowCount to limit the number of rows to e.g. 1,
but that is not what the current code does (it only works with limiting
the number of columns).
Thus, we were exposing an unused/misleading parameter to users.

This can and should be reverted if the logic for limiting the number
of rows is added.

* LegendItem: add colCount docs

* test (LegendItem): remove unused curRow variable

* test (LegendItem): check increasing rowCount as add items

* Fixed logic in placement of items in legend with multiple columns

* Actual row count here should be 2, not 3

Co-authored-by: Ogi Moore <ognyan.moore@gmail.com>

examples/Legend.py

@@ -13,7 +13,7 @@ win = pg.plot()
 win.setWindowTitle('pyqtgraph example: BarGraphItem')
 
 # # option1: only for .plot(), following c1,c2 for example-----------------------
-# win.addLegend(frame=False, rowCount=1, colCount=2)
+# win.addLegend(frame=False, colCount=2)
 
 # bar graph
 x = np.arange(10)

pyqtgraph/graphicsItems/LegendItem.py

@@ -1,4 +1,6 @@
 # -*- coding: utf-8 -*-
+import math
+
 from .GraphicsWidget import GraphicsWidget
 from .LabelItem import LabelItem
 from ..Qt import QtGui, QtCore
@@ -30,8 +32,7 @@ class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
 
     def __init__(self, size=None, offset=None, horSpacing=25, verSpacing=0,
                  pen=None, brush=None, labelTextColor=None, frame=True,
-                 labelTextSize='9pt', rowCount=1, colCount=1,
+                 labelTextSize='9pt', colCount=1, sampleType=None, **kwargs):
-                 sampleType=None, **kwargs):
         """
         ==============  ===============================================================
         **Arguments:**
@@ -54,6 +55,10 @@ class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
                         accepted by :func:`mkPen <pyqtgraph.mkPen>` is allowed.
         labelTextSize   Size to use when drawing legend text. Accepts CSS style
                         string arguments, e.g. '9pt'.
+        colCount        Specifies the integer number of columns that the legend should
+                        be divided into. The number of rows will be calculated
+                        based on this argument. This is useful for plots with many
+                        curves displayed simultaneously. Default: 1 column.
         sampleType      Customizes the item sample class of the `LegendItem`.
         ==============  ===============================================================
 
@@ -71,8 +76,7 @@ class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
         self.offset = offset
         self.frame = frame
         self.columnCount = colCount
-        self.rowCount = rowCount
+        self.rowCount = 1
-        self.curRow = 0
         if size is not None:
             self.setGeometry(QtCore.QRectF(0, 0, self.size[0], self.size[1]))
 
@@ -231,29 +235,37 @@ class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
                 # FIND RIGHT COLUMN
                 if not self.layout.itemAt(row, col):
                     break
-            if col + 2 == nCol:
+            else:
-                # MAKE NEW ROW
+                if col + 2 == nCol:
-                col = 0
+                    # MAKE NEW ROW
-                row += 1
+                    col = 0
+                    row += 1
         self.layout.addItem(sample, row, col)
         self.layout.addItem(label, row, col + 1)
+        # Keep rowCount in sync with the number of rows if items are added
+        self.rowCount = max(self.rowCount, row + 1)
+        print(f"_addItemToLayout set self.rowCount = {self.rowCount} \t row = {row} \t col = {col}")
 
     def setColumnCount(self, columnCount):
         """change the orientation of all items of the legend
         """
         if columnCount != self.columnCount:
             self.columnCount = columnCount
-            self.rowCount = int(len(self.items) / columnCount)
+
+            self.rowCount = math.ceil(len(self.items) / columnCount)
+            print(f"setColumnCount set self.rowCount = {self.rowCount}")
             for i in range(self.layout.count() - 1, -1, -1):
                 self.layout.removeAt(i)  # clear layout
             for sample, label in self.items:
                 self._addItemToLayout(sample, label)
             self.updateSize()
+            print(f"end result is self.rowCount = {self.rowCount}")
+            print("\n")
 
     def getLabel(self, plotItem):
         """Return the labelItem inside the legend for a given plotItem
 
-        The label-text can be changed via labenItem.setText
+        The label-text can be changed via labelItem.setText
         """
         out = [(it, lab) for it, lab in self.items if it.item == plotItem]
         try:
@@ -297,13 +309,13 @@ class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
         width = 0
         for row in range(self.layout.rowCount()):
             row_height = 0
-            col_witdh = 0
+            col_width = 0
             for col in range(self.layout.columnCount()):
                 item = self.layout.itemAt(row, col)
                 if item:
-                    col_witdh += item.width() + 3
+                    col_width += item.width() + 3
                     row_height = max(row_height, item.height())
-            width = max(width, col_witdh)
+            width = max(width, col_width)
             height += row_height
         self.setGeometry(0, 0, width, height)
         return

pyqtgraph/graphicsItems/tests/test_LegendItem.py

@@ -13,7 +13,6 @@ def test_legend_item_basics():
 
     assert legend.columnCount == 1
     assert legend.rowCount == 1
-    assert legend.curRow == 0
 
     assert legend.labelTextColor() is None
     assert legend.labelTextSize() == '9pt'
@@ -65,21 +64,24 @@ def test_legend_item_basics():
     legend.addItem(scatter, name="Scatter")
     assert len(legend.items) == 2
     assert legend.columnCount == 1
-    assert legend.rowCount == 1
+    assert legend.rowCount == 2
 
     curve = pg.PlotDataItem(name="Curve")
     legend.addItem(curve, name="Curve")
     assert len(legend.items) == 3
+    assert legend.rowCount == 3
 
     scrabble = pg.PlotDataItem(name="Scrabble")
     legend.addItem(scrabble, name="Scrabble")
     assert len(legend.items) == 4
 
     assert legend.layout.rowCount() == 4
+    assert legend.rowCount == 4
     legend.setColumnCount(2)
+    assert legend.columnCount == 2
     assert legend.rowCount == 2
 
-    assert legend.layout.rowCount() == 3
+    assert legend.layout.rowCount() == 2
 
     # Remove items
     # ----------------------------------------------------
@@ -91,7 +93,7 @@ def test_legend_item_basics():
     assert len(legend.items) == 3
 
     legend.removeItem(curve)
-    assert legend.rowCount == 2
+    assert legend.rowCount == 2 # rowCount will never decrease when removing
     assert legend.layout.rowCount() == 1
     assert curve not in legend.items
     assert len(legend.items) == 2