From 82b259828ad7543f8bb84a3beac01643b01f624b Mon Sep 17 00:00:00 2001
From: janezd <janez.demsar@fri.uni-lj.si>
Date: Fri, 13 Sep 2024 20:24:04 +0200
Subject: [PATCH] Feature Statistics: Add legend

---
 Orange/widgets/data/owfeaturestatistics.py    | 55 ++++++++++++++++++-
 .../data/tests/test_owfeaturestatistics.py    | 33 +++++++++++
 2 files changed, 86 insertions(+), 2 deletions(-)

diff --git a/Orange/widgets/data/owfeaturestatistics.py b/Orange/widgets/data/owfeaturestatistics.py
index 2a133b4206c..1f74165b653 100644
--- a/Orange/widgets/data/owfeaturestatistics.py
+++ b/Orange/widgets/data/owfeaturestatistics.py
@@ -16,9 +16,10 @@
 import scipy.sparse as sp
 from AnyQt.QtCore import Qt, QSize, QRectF, QModelIndex, pyqtSlot, \
     QItemSelection, QItemSelectionRange, QItemSelectionModel
-from AnyQt.QtGui import QPainter, QColor, QPalette
+from AnyQt.QtGui import QPainter, QColor, QPalette, QFontMetrics
 from AnyQt.QtWidgets import QStyledItemDelegate, QGraphicsScene, QTableView, \
-    QHeaderView, QStyle, QStyleOptionViewItem
+    QHeaderView, QStyle, QStyleOptionViewItem, \
+    QGraphicsView, QGraphicsItemGroup
 
 import Orange.statistics.util as ut
 from Orange.data import Table, StringVariable, DiscreteVariable, \
@@ -31,6 +32,8 @@
 from Orange.widgets.utils.itemmodels import DomainModel, AbstractSortTableModel
 from Orange.widgets.utils.signals import Input, Output
 from Orange.widgets.utils.widgetpreview import WidgetPreview
+from Orange.widgets.visualize.utils import CanvasRectangle, CanvasText
+from Orange.widgets.visualize.utils.plotutils import wrap_legend_items
 
 
 def _categorical_entropy(x):
@@ -773,6 +776,15 @@ def __init__(self):
 
         box.layout().addWidget(self.table_view)
 
+        self.legend_items = []
+        self.legend = QGraphicsScene()
+        self.legend_view = u = QGraphicsView(self.legend)
+        u.setRenderHints(QPainter.Antialiasing | QPainter.TextAntialiasing)
+        u.setFrameStyle(QGraphicsView.NoFrame)
+        u.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
+        u.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
+        box.layout().addWidget(u)
+
         self.color_var_model = DomainModel(
             valid_types=(ContinuousVariable, DiscreteVariable),
             placeholder='None',
@@ -791,6 +803,10 @@ def __init__(self):
     def sizeHint():  # pylint: disable=arguments-differ
         return QSize(1050, 500)
 
+    def resizeEvent(self, event):
+        super().resizeEvent(event)
+        self.update_legend()
+
     @Inputs.data
     def set_data(self, data):
         # Clear outputs and reset widget state
@@ -853,6 +869,41 @@ def on_header_click(self, *_):
     def __color_var_changed(self, *_):
         if self.model is not None:
             self.model.set_target_var(self.color_var)
+            self.update_legend_items()
+            self.update_legend()
+
+    def update_legend_items(self):
+        self.legend.clear()
+        if self.color_var is None or not self.color_var.is_discrete:
+            self.legend_items = []
+            return
+        self.legend_items = []
+        size = QFontMetrics(self.font()).height()
+        for name, color in zip(self.color_var.values, self.color_var.palette.qcolors):
+            item = QGraphicsItemGroup()
+            item.addToGroup(
+                CanvasRectangle(None, -size / 2, -size / 2, size, size,
+                                Qt.gray, color))
+            item.addToGroup(
+                CanvasText(None, name, size, 0, Qt.AlignVCenter))
+            self.legend_items.append(item)
+
+    def update_legend(self):
+        view = self.legend_view
+
+        if not self.legend_items:
+            self.legend.clear()
+            view.hide()
+            return
+
+        size = QFontMetrics(self.font()).height()
+        legend = wrap_legend_items(
+            self.legend_items,
+            self.width() - 30, size, size * 1.75)
+        self.legend.addItem(legend)
+        legend.setPos(15, 0)
+        view.setFixedHeight(int(legend.boundingRect().height()) + size)
+        view.show()
 
     def on_select(self):
         selection_indices = list(self.model.mapToSourceRows([
diff --git a/Orange/widgets/data/tests/test_owfeaturestatistics.py b/Orange/widgets/data/tests/test_owfeaturestatistics.py
index 547cd2f91e3..7ff76a158f4 100644
--- a/Orange/widgets/data/tests/test_owfeaturestatistics.py
+++ b/Orange/widgets/data/tests/test_owfeaturestatistics.py
@@ -572,6 +572,39 @@ def test_report(self):
         self.assertIn("<table>", report_text)
         self.assertEqual(6, report_text.count("<tr>"))  # header + 5 rows
 
+    def test_color_legend(self):
+        w = self.widget
+        data = Table("heart_disease")
+        self.send_signal(self.widget.Inputs.data, data)
+
+        self.assertIs(w.color_var, data.domain.class_var)
+        self.assertEqual(len(w.legend_items), 2)
+        self.assertFalse(w.legend_view.isHidden())
+
+        w.cb_color_var.setCurrentIndex(4)  # age (numeric, no legend)
+        w.cb_color_var.activated.emit(4)
+        self.assertEqual(len(w.legend_items), 0)
+        self.assertTrue(w.legend_view.isHidden())
+
+        w.cb_color_var.setCurrentIndex(6)  # chest pain
+        w.cb_color_var.activated.emit(6)
+        self.assertEqual(len(w.legend_items), 4)
+        self.assertFalse(w.legend_view.isHidden())
+
+        w.cb_color_var.setCurrentIndex(0)  # None
+        w.cb_color_var.activated.emit(0)
+        self.assertEqual(len(w.legend_items), 0)
+        self.assertTrue(w.legend_view.isHidden())
+
+        # Show
+        w.cb_color_var.setCurrentIndex(6)  # chest pain
+        w.cb_color_var.activated.emit(6)
+
+        # to check that the legend is hidden when the data is removed
+        self.send_signal(self.widget.Inputs.data, None)
+        self.assertEqual(len(w.legend_items), 0)
+        self.assertTrue(w.legend_view.isHidden())
+
 
 class TestSummary(WidgetTest):
     def setUp(self):