feat: add QColorComboBox for picking single colors (#194)

* feat: add QColorCombo

* more features

* test: add some tests

* fix: import the future

* more tests

* style: [pre-commit.ci] auto fixes [...]

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

tests/test_color_combo.py

@@ -0,0 +1,86 @@
+from unittest.mock import patch
+
+import pytest
+from qtpy import API_NAME
+from qtpy.QtGui import QColor, QPainter
+from qtpy.QtWidgets import QStyleOptionViewItem
+
+from superqt import QColorComboBox
+from superqt.combobox import _color_combobox
+
+
+def test_q_color_combobox(qtbot):
+    wdg = QColorComboBox()
+    qtbot.addWidget(wdg)
+    wdg.show()
+    wdg.setUserColorsAllowed(True)
+
+    # colors can be any argument that can be passed to QColor
+    # (tuples and lists will be expanded to QColor(*color)
+    COLORS = [QColor("red"), "orange", (255, 255, 0), "green", "#00F", "indigo"]
+    wdg.addColors(COLORS)
+
+    colors = [wdg.itemColor(i) for i in range(wdg.count())]
+    assert colors == [
+        QColor("red"),
+        QColor("orange"),
+        QColor("yellow"),
+        QColor("green"),
+        QColor("blue"),
+        QColor("indigo"),
+        None,  # "Add Color" item
+    ]
+
+    # as with addColors, colors will be cast to QColor when using setColors
+    wdg.setCurrentColor("indigo")
+    assert wdg.currentColor() == QColor("indigo")
+    assert wdg.currentColorName() == "#4b0082"
+
+    wdg.clear()
+    assert wdg.count() == 1  # "Add Color" item
+    wdg.setUserColorsAllowed(False)
+    assert not wdg.count()
+
+    wdg.setInvalidColorPolicy(wdg.InvalidColorPolicy.Ignore)
+    wdg.setInvalidColorPolicy(2)
+    wdg.setInvalidColorPolicy("Raise")
+    with pytest.raises(TypeError):
+        wdg.setInvalidColorPolicy(1.0)  # type: ignore
+
+    with pytest.raises(ValueError):
+        wdg.addColor("invalid")
+
+
+def test_q_color_delegate(qtbot):
+    wdg = QColorComboBox()
+    view = wdg.view()
+    delegate = wdg.itemDelegate()
+    qtbot.addWidget(wdg)
+    wdg.show()
+
+    # smoke tests:
+    painter = QPainter()
+    option = QStyleOptionViewItem()
+    index = wdg.model().index(0, 0)
+    delegate.paint(painter, option, index)
+
+    wdg.addColors(["red", "orange", "yellow"])
+    view.selectAll()
+    index = wdg.model().index(1, 0)
+    delegate.paint(painter, option, index)
+
+
+@pytest.mark.skipif(API_NAME == "PySide2", reason="hangs on CI")
+def test_activated(qtbot):
+    wdg = QColorComboBox()
+    qtbot.addWidget(wdg)
+    wdg.show()
+    wdg.setUserColorsAllowed(True)
+
+    with patch.object(_color_combobox.QColorDialog, "getColor", lambda: QColor("red")):
+        wdg._on_activated(wdg.count() - 1)  # "Add Color" item
+    assert wdg.currentColor() == QColor("red")
+
+    with patch.object(_color_combobox.QColorDialog, "getColor", lambda: QColor()):
+        wdg._on_activated(wdg.count() - 1)  # "Add Color" item
+    assert wdg.currentColor() == QColor("red")