How can I write a (very) basic custom QAbstractTextDocumentLayout subclass? - c++

Question

I'm trying to create a simple notepad-style Qt application. Since I think I might want a lot of control over exactly how text is rendered, I'm trying to write a custom QAbstractTextDocumentLayout class. The code below compiles and runs, but the text area is blank, no matter how much I type. The debug statements in my draw() function correctly show the entered text, so I know my input is in some form making it all the way to the draw() function, but it's not being rendered.
I just want to tweak this in a minimal way so I can at least see some text being rendered, even if the implementation is incomplete. I also haven't been able to find any documentation whatsoever on writing custom QAbstractTextDocumentLayout, so if anyone had a reference I'd also appreciate that.
main.cpp
#include <QtWidgets/QApplication>
#include <QtWidgets/QMainWindow>
#include <QtWidgets/QTextEdit>
#include <QKeyEvent>
#include "./DocumentLayout.cpp"
class MainContent : public QWidget
{
Q_OBJECT
QTextEdit textEdit;
DocumentLayout layout;
public:
MainContent() : textEdit(this), layout(textEdit.document())
{
int innerPadding = 20;
textEdit.document()->setDocumentMargin(innerPadding);
int textColor = 0xD8DEE9;
int backgroundColor = 0x2E3440;
int selectionColor = 0x2E3440;
int selectionBackgroundColor = 0x81A1C1;
QPalette palette = textEdit.palette();
palette.setColor(QPalette::Base, QColor(backgroundColor));
palette.setColor(QPalette::Text, QColor(textColor));
palette.setColor(QPalette::Highlight, QColor(selectionBackgroundColor));
palette.setColor(QPalette::HighlightedText, QColor(selectionColor));
textEdit.setPalette(palette);
textEdit.setFrameStyle(QFrame::NoFrame);
textEdit.document()->setDocumentLayout(&layout);
};
void resizeEvent(QResizeEvent *event)
{
textEdit.setGeometry(0, 0, this->width(), this->height());
}
void keyPressEvent(QKeyEvent *event)
{
if (event->key() == Qt::Key_W && event->modifiers() == Qt::ControlModifier)
{
qApp->quit();
}
}
};
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QMainWindow window;
window.setWindowTitle("Hello, world!");
window.resize(400, 500);
MainContent content;
window.setCentralWidget(&content);
window.show();
return app.exec();
}
#include "main.moc"
DocumentLayout.cpp
#include <QAbstractTextDocumentLayout>
#include <QPainter>
#include <QTextBlock>
#include <QDebug>
class DocumentLayout : public QAbstractTextDocumentLayout
{
public:
DocumentLayout(QTextDocument *document) : QAbstractTextDocumentLayout(document)
{
}
void draw(QPainter *painter, const PaintContext &context)
{
QTextDocument *document = this->document();
QTextBlock block = document->begin();
QPointF position(20, 20);
painter->setPen(context.palette.color(QPalette::Text));
QTextLayout *layout = block.layout();
layout->draw(painter, position);
position.ry() += layout->boundingRect().height();
qDebug() << "drew" << block.text() << "at" << position;
}
int hitTest(const QPointF &point, Qt::HitTestAccuracy accuracy) const
{
return 0;
}
int pageCount() const
{
return 1;
}
QSizeF documentSize() const
{
return QSizeF(400, 800);
}
QRectF frameBoundingRect(QTextFrame *frame) const
{
return QRectF(0, 0, 400, 800);
}
QRectF blockBoundingRect(const QTextBlock &block) const
{
return QRectF(0, 0, 400, 800);
}
void documentChanged(int from, int charsRemoved, int charsAdded)
{
}
};