The editor now has context aware completions

pglab/codeeditor/CompletionPopup.cpp

@@ -0,0 +1,112 @@
+#include "CompletionPopup.h"
+#include <QApplication>
+#include <QPainter>
+#include <QScreen>
+#include <QStyledItemDelegate>
+
+namespace {
+
+constexpr int DetailRole = Qt::UserRole + 1;
+constexpr int AmbiguousRole = Qt::UserRole + 2;
+
+class CompletionDelegate : public QStyledItemDelegate {
+public:
+	using QStyledItemDelegate::QStyledItemDelegate;
+
+	void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const override
+	{
+		QStyleOptionViewItem opt = option;
+		initStyleOption(&opt, index);
+		const QString display = opt.text;
+		opt.text.clear();
+		const QWidget *w = opt.widget;
+		(w ? w->style() : QApplication::style())->drawControl(QStyle::CE_ItemViewItem, &opt, painter, w);
+
+		const bool selected = opt.state & QStyle::State_Selected;
+		const QPalette &pal = opt.palette;
+		const QString detail = index.data(DetailRole).toString();
+		const bool ambiguous = index.data(AmbiguousRole).toBool();
+
+		painter->save();
+		painter->setPen(selected ? pal.highlightedText().color() : pal.text().color());
+		QRect r = opt.rect.adjusted(4, 0, -4, 0);
+		painter->drawText(r, Qt::AlignVCenter | Qt::AlignLeft, display);
+		if (!detail.isEmpty()) {
+			const int x = painter->fontMetrics().horizontalAdvance(display) + 12;
+			QColor dim = selected ? pal.highlightedText().color() : pal.color(QPalette::Disabled, QPalette::Text);
+			painter->setPen(dim);
+			if (ambiguous) {
+				QFont f = painter->font();
+				f.setBold(true);
+				painter->setFont(f);
+			}
+			painter->drawText(r.adjusted(x, 0, 0, 0), Qt::AlignVCenter | Qt::AlignLeft, QStringLiteral("\u2014 ") + detail);
+		}
+		painter->restore();
+	}
+
+	QSize sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const override
+	{
+		QSize s = QStyledItemDelegate::sizeHint(option, index);
+		const QFontMetrics fm(option.font);
+		s.setWidth(fm.horizontalAdvance(index.data(Qt::DisplayRole).toString())
+			+ fm.horizontalAdvance(index.data(DetailRole).toString()) + 40);
+		return s;
+	}
+};
+
+} // namespace
+
+CompletionPopup::CompletionPopup(QWidget *parent)
+	: QListWidget(parent)
+{
+	setWindowFlags(Qt::ToolTip);
+	setAttribute(Qt::WA_ShowWithoutActivating);
+	setFocusPolicy(Qt::NoFocus);
+	setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+	setUniformItemSizes(true);
+	setItemDelegate(new CompletionDelegate(this));
+	connect(this, &QListWidget::itemClicked, this, [this](QListWidgetItem *item) {
+		emit itemAccepted(row(item));
+	});
+}
+
+void CompletionPopup::setItems(const std::vector<EditorCompletionItem> &items)
+{
+	clear();
+	int width = 150;
+	const QFontMetrics fm(font());
+	for (const auto &i : items) {
+		auto *item = new QListWidgetItem(i.display, this);
+		item->setData(DetailRole, i.detail);
+		item->setData(AmbiguousRole, i.ambiguous);
+		width = std::max(width, fm.horizontalAdvance(i.display) + fm.horizontalAdvance(i.detail) + 50);
+	}
+	if (!items.empty())
+		setCurrentRow(0);
+	const int rows = static_cast<int>(std::min<size_t>(items.size(), 10));
+	const int rowHeight = fm.height() + 6;
+	resize(std::min(width, 600), rows * rowHeight + 2 * frameWidth() + 2);
+}
+
+void CompletionPopup::moveSelection(int delta)
+{
+	const int n = count();
+	if (n == 0)
+		return;
+	int r = QListWidget::currentRow() + delta;
+	r = std::clamp(r, 0, n - 1);
+	setCurrentRow(r);
+}
+
+void CompletionPopup::showAt(const QPoint &globalPos)
+{
+	QPoint p = globalPos;
+	if (auto *screen = QApplication::screenAt(globalPos)) {
+		const QRect avail = screen->availableGeometry();
+		if (p.x() + width() > avail.right())
+			p.setX(std::max(avail.left(), avail.right() - width()));
+	}
+	move(p);
+	show();
+}