feat: Change icon used in Collapsible widget

examples/qcollapsible.py

@@ -6,6 +6,8 @@
 app = QApplication([])
 
 collapsible = QCollapsible("Advanced analysis")
+collapsible.setCollapsedIcon("+")
+collapsible.setExpandedIcon("-")
 collapsible.addWidget(QLabel("This is the inside of the collapsible frame"))
 for i in range(10):
     collapsible.addWidget(QPushButton(f"Content button {i + 1}"))

src/superqt/collapsible/_collapsible.py

@@ -1,15 +1,17 @@
 """A collapsible widget to hide and unhide child widgets"""
-from typing import Optional
+from typing import Optional, Union
 
 from qtpy.QtCore import (
     QEasingCurve,
     QEvent,
     QMargins,
     QObject,
     QPropertyAnimation,
+    QRect,
     Qt,
     Signal,
 )
+from qtpy.QtGui import QIcon, QPainter, QPalette, QPixmap
 from qtpy.QtWidgets import QFrame, QPushButton, QVBoxLayout, QWidget
 
 
@@ -21,18 +23,24 @@ class QCollapsible(QFrame):
     Based on https://stackoverflow.com/a/68141638
     """
 
-    _EXPANDED = "▼  "
-    _COLLAPSED = "▲  "
-
     toggled = Signal(bool)
 
-    def __init__(self, title: str = "", parent: Optional[QWidget] = None):
+    def __init__(
+        self,
+        title: str = "",
+        parent: Optional[QWidget] = None,
+        expandedIcon: Optional[Union[QIcon, str]] = "▼",
+        collapsedIcon: Optional[Union[QIcon, str]] = "▲",
+    ):
         super().__init__(parent)
         self._locked = False
         self._is_animating = False
+        self._text = title
 
-        self._toggle_btn = QPushButton(self._COLLAPSED + title)
+        self._toggle_btn = QPushButton(title)
         self._toggle_btn.setCheckable(True)
+        self.setCollapsedIcon(icon=collapsedIcon)
+        self.setExpandedIcon(icon=expandedIcon)
         self._toggle_btn.setStyleSheet("text-align: left; border: none; outline: none;")
         self._toggle_btn.toggled.connect(self._toggle)
 
@@ -58,12 +66,12 @@ def __init__(self, title: str = "", parent: Optional[QWidget] = None):
 
     def setText(self, text: str):
         """Set the text of the toggle button."""
-        current = self._toggle_btn.text()[: len(self._EXPANDED)]
+        current = self._toggle_btn.text()
         self._toggle_btn.setText(current + text)
 
     def text(self) -> str:
         """Return the text of the toggle button."""
-        return self._toggle_btn.text()[len(self._EXPANDED) :]
+        return self._toggle_btn.text()
 
     def setContent(self, content: QWidget):
         """Replace central widget (the widget that gets expanded/collapsed)."""
@@ -75,6 +83,42 @@ def content(self) -> QWidget:
         """Return the current content widget."""
         return self._content
 
+    def _convert_string_to_icon(self, symbol: str) -> QIcon:
+        """Create a QIcon from a string."""
+        size = self._toggle_btn.font().pointSize()
+        pixmap = QPixmap(size, size)
+        pixmap.fill(Qt.transparent)
+        painter = QPainter(pixmap)
+        color = self._toggle_btn.palette().color(QPalette.WindowText)
+        painter.setPen(color)
+        painter.drawText(QRect(0, 0, size, size), Qt.AlignCenter, symbol)
+        painter.end()
+        return QIcon(pixmap)
+
+    def setExpandedIcon(self, icon: Optional[Union[QIcon, str]] = None):
+        """Set the icon on the toggle button when the widget is expanded."""
+        if icon and isinstance(icon, QIcon):
+            self._expanded_icon = icon
+        elif icon and isinstance(icon, str):
+            self._expanded_icon = self._convert_string_to_icon(icon)
+
+    def expandedIcon(self):
+        """Returns the icon used when the widget is expanded."""
+        return self._expanded_icon
+
+    def setCollapsedIcon(self, icon: Optional[Union[QIcon, str]] = None):
+        """Set the icon on the toggle button when the widget is collapsed."""
+        if icon and isinstance(icon, QIcon):
+            self._collapsed_icon = icon
+        elif icon and isinstance(icon, str):
+            self._collapsed_icon = self._convert_string_to_icon(icon)
+
+        self._toggle_btn.setIcon(self._collapsed_icon)
+
+    def collapsedIcon(self):
+        """Returns the icon used when the widget is collapsed."""
+        return self._collapsed_icon
+
     def setDuration(self, msecs: int):
         """Set duration of the collapse/expand animation."""
         self._animation.setDuration(msecs)
@@ -121,10 +165,10 @@ def _expand_collapse(
             return
 
         forward = direction == QPropertyAnimation.Direction.Forward
-        text = self._EXPANDED if forward else self._COLLAPSED
+        text = self._expanded_icon if forward else self._collapsed_icon
+        self._toggle_btn.setIcon(text)
 
         self._toggle_btn.setChecked(forward)
-        self._toggle_btn.setText(text + self._toggle_btn.text()[len(self._EXPANDED) :])
 
         _content_height = self._content.sizeHint().height() + 10
         if animate:

tests/test_collapsible.py

@@ -1,11 +1,24 @@
 """A test module for testing collapsible"""
 
+import pytest
 from qtpy.QtCore import QEasingCurve, Qt
-from qtpy.QtWidgets import QPushButton
+from qtpy.QtGui import QIcon
+from qtpy.QtWidgets import QPushButton, QStyle, QWidget
 
 from superqt import QCollapsible
 
 
+def _get_builtin_icon(name):
+    """Get a built-in icon from the Qt library."""
+    widget = QWidget()
+    try:
+        pixmap = getattr(QStyle.StandardPixmap, f"SP_{name}")
+    except AttributeError:
+        pixmap = getattr(QStyle, f"SP_{name}")
+
+    return widget.style().standardIcon(pixmap)
+
+
 def test_checked_initialization(qtbot):
     """Test simple collapsible"""
     wdg1 = QCollapsible("Advanced analysis")
@@ -84,7 +97,7 @@ def test_changing_text(qtbot):
     wdg = QCollapsible()
     wdg.setText("Hi new text")
     assert wdg.text() == "Hi new text"
-    assert wdg._toggle_btn.text() == QCollapsible._COLLAPSED + "Hi new text"
+    assert wdg._toggle_btn.text() == "Hi new text"
 
 
 def test_toggle_signal(qtbot):
@@ -98,3 +111,33 @@ def test_toggle_signal(qtbot):
 
     with qtbot.waitSignal(wdg.toggled, timeout=500):
         wdg.collapse()
+
+
+@pytest.mark.filterwarnings("ignore::DeprecationWarning")
+def test_getting_icon(qtbot):
+    """Test setting string as toggle button."""
+    wdg = QCollapsible("test")
+    assert isinstance(wdg.expandedIcon(), QIcon)
+    assert isinstance(wdg.collapsedIcon(), QIcon)
+
+
+@pytest.mark.filterwarnings("ignore::DeprecationWarning")
+def test_setting_icon(qtbot):
+    """Test setting icon for toggle button."""
+    icon1 = _get_builtin_icon("ArrowRight")
+    icon2 = _get_builtin_icon("ArrowDown")
+    wdg = QCollapsible("test", expandedIcon=icon1, collapsedIcon=icon2)
+    assert wdg._expanded_icon == icon1
+    assert wdg._collapsed_icon == icon2
+
+
+@pytest.mark.filterwarnings("ignore::DeprecationWarning")
+def test_setting_symbol_icon(qtbot):
+    """Test setting string as toggle button."""
+    wdg = QCollapsible("test")
+    icon1 = wdg._convert_string_to_icon("+")
+    icon2 = wdg._convert_string_to_icon("-")
+    wdg.setCollapsedIcon(icon=icon1)
+    assert wdg._collapsed_icon == icon1
+    wdg.setExpandedIcon(icon=icon2)
+    assert wdg._expanded_icon == icon2