combo_popup.py

"""QComboBox helpers for a compact non-native popup."""

from __future__ import annotations

import ctypes
import logging
import sys
from typing import Optional

from PyQt6.QtCore import QEvent, QPoint, QSize, Qt
from PyQt6.QtGui import QRegion
from PyQt6.QtWidgets import (
    QApplication,
    QComboBox,
    QFrame,
    QListWidget,
    QListWidgetItem,
    QStyledItemDelegate,
    QVBoxLayout,
    QWidget,
)

LOGGER = logging.getLogger(__name__)


POPUP_STYLE = """
QFrame#ComboPopup {
    background: #202020;
    border: none;
    border-radius: 0px;
}
QListWidget {
    background: #202020;
    color: #D6D6D6;
    border: none;
    border-radius: 0px;
    outline: 0px;
    padding: 0px;
    font: 10pt "Segoe UI";
}
QListWidget::item {
    min-height: 32px;
    padding: 0px 10px;
    border: none;
    border-radius: 0px;
}
QListWidget::item:selected {
    background: #202020;
    color: #D6D6D6;
}
QListWidget::item:hover {
    background: #5B3A8C;
}
QScrollBar {
    width: 0px;
    height: 0px;
    border: none;
    background: transparent;
}
"""


class CompactComboItemDelegate(QStyledItemDelegate):
    def sizeHint(self, option, index) -> QSize:  # noqa: N802 - Qt API name
        size = super().sizeHint(option, index)
        return QSize(size.width(), 32)


def _disable_windows_rounded_corners(widget: QFrame) -> None:
    if sys.platform != "win32":
        return
    try:
        preference = ctypes.c_int(1)  # DWMWCP_DONOTROUND
        ctypes.windll.dwmapi.DwmSetWindowAttribute(
            int(widget.winId()),
            33,  # DWMWA_WINDOW_CORNER_PREFERENCE
            ctypes.byref(preference),
            ctypes.sizeof(preference),
        )
    except Exception as exc:  # noqa: BLE001
        LOGGER.debug("DwmSetWindowAttribute failed: %s", exc)


class SquarePopupComboBox(QComboBox):
    """QComboBox with a compact square popup instead of the native rounded one."""

    def __init__(self, parent: Optional[QWidget] = None) -> None:
        super().__init__(parent)
        self.setMaxVisibleItems(20)
        self._popup: QFrame | None = None
        self._event_filter_installed = False

    def mousePressEvent(self, event) -> None:  # noqa: N802 - Qt API name
        if self._popup is not None and self._popup.isVisible():
            self._close_popup()
            event.accept()
            return
        self.showPopup()
        event.accept()

    def eventFilter(self, watched, event) -> bool:  # noqa: N802 - Qt API name
        if self._popup is None or not self._popup.isVisible():
            return False
        if event.type() == QEvent.Type.KeyPress and event.key() == Qt.Key.Key_Escape:
            self._close_popup()
            return True
        if event.type() != QEvent.Type.MouseButtonPress:
            return False

        pos = event.globalPosition().toPoint()
        clicked = QApplication.widgetAt(pos)
        if clicked is None:
            self._close_popup()
            return False
        if clicked is self or self.isAncestorOf(clicked):
            return False
        if clicked is self._popup or self._popup.isAncestorOf(clicked):
            return False

        self._close_popup()
        return False

    def showPopup(self) -> None:
        if self.count() == 0:
            return

        if self._popup is not None and self._popup.isVisible():
            self._close_popup()
            return

        if self._popup is not None:
            self._close_popup()

        popup = QFrame(
            None,
            Qt.WindowType.Tool
            | Qt.WindowType.FramelessWindowHint
            | Qt.WindowType.NoDropShadowWindowHint,
        )
        popup.setObjectName("ComboPopup")
        popup.setFrameShape(QFrame.Shape.NoFrame)
        popup.setStyleSheet(POPUP_STYLE)
        popup.setFont(self.font())

        layout = QVBoxLayout(popup)
        layout.setContentsMargins(0, 0, 0, 0)
        layout.setSpacing(0)

        items = QListWidget(popup)
        items.setFrameShape(QFrame.Shape.NoFrame)
        items.setVerticalScrollBarPolicy(Qt.ScrollBarPolicy.ScrollBarAlwaysOff)
        items.setHorizontalScrollBarPolicy(Qt.ScrollBarPolicy.ScrollBarAlwaysOff)
        items.setSpacing(0)
        items.setFont(self.font())
        items.setItemDelegate(CompactComboItemDelegate(items))
        items.setStyleSheet(POPUP_STYLE)

        current_row = self.currentIndex()
        for row in range(self.count()):
            if row == current_row:
                continue
            item = QListWidgetItem(self.itemText(row))
            item.setFont(self.font())
            item.setData(Qt.ItemDataRole.UserRole, row)
            item.setSizeHint(QSize(self.width(), 32))
            items.addItem(item)

        if items.count() == 0:
            popup.deleteLater()
            return

        def activate(item: QListWidgetItem) -> None:
            row = item.data(Qt.ItemDataRole.UserRole)
            self._close_popup()
            if isinstance(row, int):
                self.setCurrentIndex(row)

        items.itemClicked.connect(activate)
        layout.addWidget(items)

        visible_count = min(items.count(), self.maxVisibleItems())
        popup.setFixedSize(self.width(), visible_count * 32)
        popup.move(self.mapToGlobal(QPoint(0, self.height())))

        self._popup = popup
        popup.destroyed.connect(self._on_popup_destroyed)
        app = QApplication.instance()
        if app is not None and not self._event_filter_installed:
            app.installEventFilter(self)
            self._event_filter_installed = True
        _disable_windows_rounded_corners(popup)
        popup.show()
        _disable_windows_rounded_corners(popup)
        popup.setMask(QRegion(popup.rect()))
        items.setMask(QRegion(items.rect()))
        items.viewport().setMask(QRegion(items.viewport().rect()))

    def _close_popup(self) -> None:
        popup = self._popup
        self._popup = None
        app = QApplication.instance()
        if app is not None and self._event_filter_installed:
            app.removeEventFilter(self)
            self._event_filter_installed = False
        if popup is not None:
            popup.hide()
            popup.deleteLater()

    def _on_popup_destroyed(self, *_args) -> None:
        self._popup = None
        app = QApplication.instance()
        if app is not None and self._event_filter_installed:
            app.removeEventFilter(self)
            self._event_filter_installed = False