match color to palette in qt

src/magicgui/backends/_qtpy/widgets.py

@@ -17,8 +17,10 @@
 from qtpy.QtGui import (
     QFont,
     QFontMetrics,
+    QIcon,
     QImage,
     QKeyEvent,
+    QPalette,
     QPixmap,
     QResizeEvent,
     QTextDocument,
@@ -48,10 +50,13 @@ def _signals_blocked(obj: QtW.QWidget) -> Iterator[None]:
 class EventFilter(QObject):
     parentChanged = Signal()
     valueChanged = Signal(object)
+    paletteChanged = Signal()
 
     def eventFilter(self, obj: QObject, event: QEvent) -> bool:
         if event.type() == QEvent.Type.ParentChange:
             self.parentChanged.emit()
+        if event.type() == QEvent.Type.PaletteChange:
+            self.paletteChanged.emit()
         return False
 
 
@@ -426,6 +431,8 @@ class QBaseButtonWidget(
 
     def __init__(self, qwidg: type[QtW.QAbstractButton], **kwargs: Any) -> None:
         super().__init__(qwidg, "isChecked", "setChecked", "toggled", **kwargs)
+        self._event_filter.paletteChanged.connect(self._update_icon)
+        self._icon: tuple[str | None, str | None] | None = None
 
     def _mgui_set_text(self, value: str) -> None:
         """Set text."""
@@ -435,15 +442,36 @@ def _mgui_get_text(self) -> str:
         """Get text."""
         return self._qwidget.text()
 
-    def _mgui_set_icon(self, value: str, color: str | None) -> None:
-        self._qwidget.setIcon(superqt.QIconifyIcon(value, color=color))
+    def _update_icon(self) -> None:
+        # Called when palette changes or icon is set
+        if self._icon is None:
+            return
+
+        value, color = self._icon
+        if not value:
+            self._qwidget.setIcon(QIcon())
+            return
+
+        if not color or color == "auto":
+            # use foreground color
+            pal = self._qwidget.palette()
+            color = pal.color(QPalette.ColorRole.WindowText).name()
+
+        try:
+            self._qwidget.setIcon(superqt.QIconifyIcon(value, color=color))
+        except (OSError, ValueError) as e:
+            warnings.warn(f"Could not set iconify icon: {e}", stacklevel=2)
+            self._icon = None  # don't try again
+
+    def _mgui_set_icon(self, value: str | None, color: str | None) -> None:
+        self._icon = (value, color)
+        self._update_icon()
 
 
 class PushButton(QBaseButtonWidget):
     def __init__(self, **kwargs: Any) -> None:
-        QBaseValueWidget.__init__(
-            self, QtW.QPushButton, "isChecked", "setChecked", "clicked", **kwargs
-        )
+        super().__init__(QtW.QPushButton, **kwargs)
+        self._onchange_name = "clicked"
         # make enter/return "click" the button when focused.
         self._qwidget.setAutoDefault(True)
 

src/magicgui/widgets/bases/_button_widget.py

@@ -94,5 +94,5 @@ def clicked(self) -> SignalInstance:
         """Alias for changed event."""
         return self.changed
 
-    def set_icon(self, value: str, color: str | None) -> None:
-        self._widget._mgui_set_icon(str(value), color)
+    def set_icon(self, value: str | None, color: str | None = None) -> None:
+        self._widget._mgui_set_icon(value, color)

src/magicgui/widgets/protocols.py

@@ -442,8 +442,13 @@ class SupportsIcon(Protocol):
     """Widget that can be reoriented."""
 
     @abstractmethod
-    def _mgui_set_icon(self, value: str, color: str | None) -> None:
-        """Set icon. Value is a font-awesome v5 icon name."""
+    def _mgui_set_icon(self, value: str | None, color: str | None) -> None:
+        """Set icon.
+
+        Value is an "prefix:name" from iconify: https://icon-sets.iconify.design
+        Color is any valid CSS color string.
+        Set value to `None` or an empty string to remove icon.
+        """
 
 
 @runtime_checkable