Qt自定义下拉列表-可为选项设置标题、可禁用选项

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资源介绍:

项目开发中，很可能简单的QComboBox满足不了需求，就需要自定义QComboBox。本示例创建一个自定义的下拉列表，并为选项设置标题、可禁用选项

#include "CustomCombo.h" #include #include CustomCombo::CustomCombo(QWidget *parent) :QComboBox(parent), list_(nullptr) { list_ = new QListWidget; list_->setItemDelegate(new CustomComboDelegate(this)); setModel(list_->model()); setView(list_); } void CustomCombo::addTitle(const QString &text) { list_->addItem(new CustomComboTitle(this, text)); resetCurrentInd(); } void CustomCombo::addItem(const QString &text) { list_->addItem(new CustomComboItem(this, text)); resetCurrentInd(); } void CustomCombo::setIsTitle(int ind, bool b) { auto *item = dynamic_cast(list_->item(ind)); item->setIsTitle(b); resetCurrentInd(); } void CustomCombo::setSelectable(int ind, bool b) { auto *item = dynamic_cast(list_->item(ind)); item->setSelectable(b); resetCurrentInd(); } void CustomCombo::resetCurrentInd() { auto *item = static_cast(list()->item(currentIndex())); if (item->isSelectable()) return; for (int i = 0; i < count(); ++i) { auto *item = static_cast(list()->item(i)); if (item->isSelectable()) { setCurrentIndex(i); break; } } } //CustomComboItem //------------------------------------------------------------------------------------------------------------ CustomComboItem::CustomComboItem(CustomCombo *combo, const QString &str) : QListWidgetItem(str), combo_(combo), isTitle_(false), selectable_(true){ } void CustomComboItem::setIsTitle(bool b) { isTitle_ = b; if (isTitle_) setSelectable(false); } void CustomComboItem::setSelectable(bool selectable) { selectable_ = selectable; if (selectable_) setFlags(flags() | (Qt::ItemIsSelectable | Qt::ItemIsUserCheckable | Qt::ItemIsEnabled)); else setFlags(flags() & ~(Qt::ItemIsSelectable | Qt::ItemIsUserCheckable | Qt::ItemIsEnabled)); } //CustomComboDelegate //------------------------------------------------------------------------------------------------------------ CustomComboDelegate::CustomComboDelegate(CustomCombo *combo) :combo_(combo) { } void CustomComboDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const { auto *item = static_cast(combo_->list()->item(index.row())); QStyleOptionMenuItem opt = getStyleOption(option, index, item); painter->fillRect(opt.rect, opt.palette.window()); combo_->style()->drawControl(QStyle::CE_MenuItem, &opt, painter, combo_); } QSize CustomComboDelegate::sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const { auto *item = static_cast(combo_->list()->item(index.row())); QStyleOptionMenuItem opt = getStyleOption(option, index, item); return combo_->style()->sizeFromContents(QStyle::CT_MenuItem, &opt, option.rect.size(), combo_); } QStyleOptionMenuItem CustomComboDelegate::getStyleOption(const QStyleOptionViewItem &option, const QModelIndex &index, CustomComboItem *item) const { QStyleOptionMenuItem menuOption; QPalette resolvedpalette = option.palette.resolve(QApplication::palette("QMenu")); QBrush textBrush = resolvedpalette.brush(QPalette::Active, QPalette::Text); QVariant value = index.data(Qt::ForegroundRole); if (value.canConvert()) textBrush = qvariant_cast(value); if (! item->isSelectable()) textBrush = resolvedpalette.brush(QPalette::Disabled, QPalette::Text); if (item->isTitle()) textBrush = resolvedpalette.brush(QPalette::Active, QPalette::HighlightedText); resolvedpalette.setBrush(QPalette::WindowText, textBrush); resolvedpalette.setBrush(QPalette::ButtonText, textBrush); resolvedpalette.setBrush(QPalette::Text , textBrush); menuOption.palette = resolvedpalette; menuOption.state = QStyle::State_None; if (combo_->window()->isActiveWindow()) menuOption.state = QStyle::State_Active; if ((option.state & QStyle::State_Enabled) && (index.model()->flags(index) & Qt::ItemIsEnabled)) menuOption.state |= QStyle::State_Enabled; else menuOption.palette.setCurrentColorGroup(QPalette::Disabled); if (option.state & QStyle::State_Selected) menuOption.state |= QStyle::State_Selected; menuOption.checkType = QStyleOptionMenuItem::NonExclusive; menuOption.checked = (combo_->currentIndex() == index.row()); if (isSeparator(index)) menuOption.menuItemType = QStyleOptionMenuItem::Separator; else menuOption.menuItemType = QStyleOptionMenuItem::Normal; QBrush bgBrush = menuOption.palette.brush(QPalette::Window); if (index.data(Qt::BackgroundRole).canConvert()) bgBrush = qvariant_cast(index.data(Qt::BackgroundRole)); if (item->isTitle()) bgBrush = resolvedpalette.brush(QPalette::Active, QPalette::Highlight); menuOption.palette.setBrush(QPalette::All, QPalette::Window, bgBrush); menuOption.text = index.model()->data(index, Qt::DisplayRole).toString(); menuOption.tabWidth = 0; menuOption.maxIconWidth = option.decorationSize.width() + 4; menuOption.menuRect = option.rect; menuOption.rect = option.rect; menuOption.font = combo_->font(); menuOption.fontMetrics = QFontMetrics(menuOption.font); if (item->isTitle()) menuOption.font.setBold(true); return menuOption; }

资源文件列表:

CustomComboDemo.zip 大约有7个文件

CustomComboDemo/
CustomComboDemo/CustomCombo.cpp 5.48KB
CustomComboDemo/CustomCombo.h 2.23KB
CustomComboDemo/CustomComboDemo.pro 668B
CustomComboDemo/main.cpp 172B
CustomComboDemo/mainwindow.cpp 793B
CustomComboDemo/mainwindow.h 217B