How to display inlay hints in QPlainTextEdit

Hu Junhao

How to display inlay hints(vscode/Clion) or VirtualText(in vim) in QPlainTextEdit?

Pl45m4

@Hu-Junhao said in How to display inlay hints in QPlainTextEdit:

How to display inlay hints(vscode/Clion) or VirtualText(in vim) in QPlainTextEdit?

There is no such feature in QPlainTextEdit.

@JonB These are the "non-copyable" text hints you discovered on woboq ( codebrowser.dev/qt6 ) :)

JoeCFD

@Hu-Junhao does the following help?

#include <QPlainTextEdit>
#include <QList>
#include <QPair>
#include <QString>

class InlayHintEditor : public QPlainTextEdit
{
    Q_OBJECT

public:
    InlayHintEditor(QWidget *parent = nullptr);

    void addInlayHint(int line, int col, const QString &hintText);

protected:
    void paintEvent(QPaintEvent *event) override;
    void resizeEvent(QResizeEvent *event) override;

private:
    QList<QPair<QPair<int, int>, QString>> inlayHints;

    void updateInlayHints();
};

#endif // INLAYHINTEDITOR_H

#include "InlayHintEditor.h"
#include <QPainter>
#include <QTextBlock>

InlayHintEditor::InlayHintEditor(QWidget *parent)
    : QPlainTextEdit(parent)
{
}

void InlayHintEditor::addInlayHint(int line, int col, const QString &hintText)
{
    inlayHints.append(qMakePair(qMakePair(line, col), hintText));
    viewport()->update();
}

void InlayHintEditor::paintEvent(QPaintEvent *event)
{
    QPlainTextEdit::paintEvent(event);

    QPainter painter(viewport());
    painter.setPen(QColor(150, 150, 150));
    QFontMetrics fontMetrics = painter.fontMetrics();

    for (const auto &hint : inlayHints)
    {
        int line = hint.first.first;
        int col = hint.first.second;
        QString hintText = hint.second;

        QTextBlock block = document()->findBlockByNumber(line);
        if (block.isValid())
        {
            QTextLayout *layout = block.layout();
            QTextLine textLine = layout->lineAt(0);
            QPointF position = textLine.cursorToX(col);

            QRect hintRect(position.x(), block.layout()->position().y(), fontMetrics.horizontalAdvance(hintText), fontMetrics.height());
            painter.drawText(hintRect, Qt::AlignLeft, hintText);
        }
    }
}

void InlayHintEditor::resizeEvent(QResizeEvent *event)
{
    QPlainTextEdit::resizeEvent(event);
    updateInlayHints();
}

void InlayHintEditor::updateInlayHints()
{
    viewport()->update();
}

#include <QApplication>
#include "InlayHintEditor.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    InlayHintEditor editor;
    editor.setPlainText("def hello_world():\n    print('Hello, world!')\n");
    editor.addInlayHint(0, 4, " <- function definition");
    editor.addInlayHint(1, 4, " <- function call");
    editor.resize(400, 300);
    editor.show();

    return app.exec();
}