feat: improve cmap combobox generalization and add right-click-to remove (#333)

* feat: add right-click "Remove" option for dropdown items in QColormapComboBox
refactor: improve layout handling in QColormapLineEdit

* fix: adjust colormap width and ensure swatch positioning in QColormapLineEdit

* fix: improve colormap addition and selection logic in QColormapComboBox

Author: tlambert03

src/superqt/cmap/_cmap_combo.py

@@ -1,16 +1,24 @@
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Any
+from typing import TYPE_CHECKING, Any, cast
 
 from cmap import Colormap
-from qtpy.QtCore import QSortFilterProxyModel, QStringListModel, Qt, Signal
+from qtpy.QtCore import (
+    QEvent,
+    QObject,
+    QSortFilterProxyModel,
+    QStringListModel,
+    Qt,
+    Signal,
+)
 from qtpy.QtWidgets import (
     QButtonGroup,
     QCheckBox,
     QComboBox,
     QCompleter,
     QDialog,
     QDialogButtonBox,
+    QMenu,
     QSizePolicy,
     QVBoxLayout,
     QWidget,
@@ -27,7 +35,7 @@
     from collections.abc import Sequence
 
     from cmap._colormap import ColorStopsLike
-    from qtpy.QtGui import QKeyEvent
+    from qtpy.QtGui import QKeyEvent, QMouseEvent
 
 
 CMAP_ROLE = Qt.ItemDataRole.UserRole + 1
@@ -109,6 +117,10 @@ def __init__(
         self.currentIndexChanged.connect(self._on_index_changed)
         line_edit.editingFinished.connect(self._on_editing_finished)
 
+        # Enable right-click "Remove" on dropdown items
+        if (view := self.view()) and (viewport := view.viewport()):
+            viewport.installEventFilter(self)
+
     def userAdditionsAllowed(self) -> bool:
         """Returns whether the user can add custom colors."""
         return self._allow_user_colors
@@ -204,7 +216,20 @@ def setCurrentColormap(self, color: Any) -> None:
 
         for idx in range(self.count()):
             if (item := self.itemColormap(idx)) and item.name == cmap.name:
+                # cmap_ is already here - just select it
                 self.setCurrentIndex(idx)
+                return
+
+        # cmap not in the combo box yet — add it, then select it
+        self.addColormap(cmap)
+        idx = self.findData(cmap, CMAP_ROLE)
+        if idx >= 0:
+            old_idx = self.currentIndex()
+            self.setCurrentIndex(idx)
+            if idx == old_idx:
+                # setCurrentIndex won't emit if the index didn't actually change
+                # (e.g. first item added at index 0 when current index is already 0)
+                self._on_index_changed(idx)
 
     def _on_activated(self, index: int) -> None:
         if self.itemText(index) != self._add_color_text:
@@ -217,8 +242,7 @@ def _on_activated(self, index: int) -> None:
                 if (item := self.itemColormap(i)) and cmap.name == item.name:
                     self.setCurrentIndex(i)
                     return
-            self.addColormap(cmap)
-            self.currentIndexChanged.emit(self.currentIndex())
+            self.setCurrentColormap(cmap)
         elif self._last_cmap is not None:
             # user canceled, restore previous color without emitting signal
             idx = self.findData(self._last_cmap, CMAP_ROLE)
@@ -257,6 +281,34 @@ def _on_editing_finished(self) -> None:
             if self.findData(cmap, CMAP_ROLE) < 0:
                 self.addColormap(cmap)
 
+    def eventFilter(self, obj: QObject | None, event: QEvent | None) -> bool:
+        if event and event.type() == QEvent.Type.MouseButtonRelease:
+            mouse_event = cast("QMouseEvent", event)
+            if mouse_event.button() == Qt.MouseButton.RightButton:
+                view = self.view()
+                if view and obj is view.viewport():
+                    index = view.indexAt(mouse_event.pos())
+                    if index.isValid():
+                        text = self.itemText(index.row())
+                        if text != self._add_color_text:
+                            self._show_remove_menu(view, mouse_event.pos(), index.row())
+                    return True  # consume the right-click
+        return super().eventFilter(obj, event)
+
+    def _show_remove_menu(self, view: Any, pos: Any, row: int) -> None:
+        menu = QMenu(view)
+        remove_action = menu.addAction("Remove")
+        if menu.exec(view.viewport().mapToGlobal(pos)) == remove_action:
+            was_current = row == self.currentIndex()
+            self.removeItem(row)
+            self._update_completer_model()
+            if was_current:
+                # select the first actual colormap, skipping "Add Colormap..."
+                for i in range(self.count()):
+                    if self.itemColormap(i) is not None:
+                        self.setCurrentIndex(i)
+                        return
+
     def keyPressEvent(self, e: QKeyEvent | None) -> None:
         if e and e.key() in (Qt.Key.Key_Enter, Qt.Key.Key_Return):
             # select the first completion when pressing enter if the popup is visible

src/superqt/cmap/_cmap_line_edit.py

@@ -4,7 +4,13 @@
 
 from qtpy.QtCore import QRect, Qt
 from qtpy.QtGui import QIcon, QPainter, QPaintEvent, QPalette
-from qtpy.QtWidgets import QApplication, QLineEdit, QStyle, QWidget
+from qtpy.QtWidgets import (
+    QApplication,
+    QLineEdit,
+    QStyle,
+    QStyleOptionFrame,
+    QWidget,
+)
 
 from ._cmap_utils import draw_colormap, pick_font_color, try_cast_colormap
 
@@ -56,7 +62,7 @@ def __init__(
         self,
         parent: QWidget | None = None,
         *,
-        fractional_colormap_width: float = 0.33,
+        fractional_colormap_width: float = 0.35,
         fallback_cmap: Colormap | str | None = "gray",
         missing_icon: QIcon | QStyle.StandardPixmap = MISSING,
         checkerboard_size: int = 4,
@@ -150,27 +156,35 @@ def setColormap(self, cmap: Colormap | str | None) -> None:
     def _cmap_is_full_width(self):
         return self._colormap_fraction >= 0.75
 
+    def _content_rect(self) -> QRect:
+        """Return the style-aware content rect for this line edit."""
+        opt = QStyleOptionFrame()
+        self.initStyleOption(opt)
+        return self.style().subElementRect(
+            QStyle.SubElement.SE_LineEditContents, opt, self
+        )
+
     def _cmap_rect(self) -> QRect:
-        cmap_rect = self.rect().adjusted(2, 0, 0, 0)
-        cmap_rect.setWidth(int(cmap_rect.width() * self._colormap_fraction))
-        return cmap_rect
+        cr = self._content_rect()
+        # Apply the horizontal content inset as vertical padding too,
+        # so the swatch sits inside the style's painted background.
+        v_pad = cr.x() - self.rect().x()
+        return QRect(
+            max(cr.x(), 2),
+            v_pad,
+            int(cr.width() * self._colormap_fraction),
+            self.rect().height() - 2 * v_pad,
+        )
 
     def resizeEvent(self, e: Any) -> None:
         left_margin = 6
         if not self._cmap_is_full_width():
-            # leave room for the colormap
-            left_margin += self._cmap_rect().width()
+            left_margin = self._cmap_rect().right() + 4 - self.rect().x()
         self.setTextMargins(left_margin, 2, 0, 0)
         super().resizeEvent(e)
 
     def paintEvent(self, e: QPaintEvent) -> None:
-        # don't draw the background
-        # otherwise it will cover the colormap during super().paintEvent
-        # FIXME: this appears to need to be reset during every paint event...
-        # otherwise something is resetting it
-        palette = self.palette()
-        palette.setColor(palette.ColorRole.Base, Qt.GlobalColor.transparent)
-        self.setPalette(palette)
+        super().paintEvent(e)  # let the style paint background + text first
 
         cmap_rect = self._cmap_rect()
         if self._cmap:
@@ -181,5 +195,3 @@ def paintEvent(self, e: QPaintEvent) -> None:
             if self._missing_cmap:
                 draw_colormap(self, self._missing_cmap, cmap_rect)
             self._missing_icon.paint(QPainter(self), cmap_rect.adjusted(4, 4, 0, -4))
-
-        super().paintEvent(e)  # draw text (must come after draw_colormap)