From 9a997d1bfa22426f1c1a409d6399dfdc94f04ce1 Mon Sep 17 00:00:00 2001
From: "G.K.MacGregor" <gkthemac@gmail.com>
Date: Fri, 12 Feb 2021 21:33:06 +0000
Subject: [PATCH] Implement Delete key command

---
 levelonecommands.cpp | 53 ++++++++++++++++++++++++++++++++++++++++++++
 levelonecommands.h   | 18 +++++++++++++++
 mainwidget.cpp       |  4 ++++
 3 files changed, 75 insertions(+)

diff --git a/levelonecommands.cpp b/levelonecommands.cpp
index 9b64c79..331ab3c 100644
--- a/levelonecommands.cpp
+++ b/levelonecommands.cpp
@@ -185,6 +185,58 @@ bool BackspaceCommand::mergeWith(const QUndoCommand *command)
 }
 
 
+DeleteKeyCommand::DeleteKeyCommand(TeletextDocument *teletextDocument, QUndoCommand *parent) : QUndoCommand(parent)
+{
+	m_teletextDocument = teletextDocument;
+	m_subPageIndex = teletextDocument->currentSubPageIndex();
+	m_row = teletextDocument->cursorRow();
+	m_column = teletextDocument->cursorColumn();
+	for (int c=0; c<40; c++)
+		m_oldRowContents[c] = m_newRowContents[c] = m_teletextDocument->currentSubPage()->character(m_row, c);
+
+	setText(QObject::tr("delete"));
+}
+
+void DeleteKeyCommand::redo()
+{
+	m_teletextDocument->selectSubPageIndex(m_subPageIndex);
+
+	for (int c=m_column; c<39; c++)
+		m_newRowContents[c] = m_newRowContents[c+1];
+	m_newRowContents[39] = 0x20;
+
+	for (int c=0; c<40; c++)
+		m_teletextDocument->currentSubPage()->setCharacter(m_row, c, m_newRowContents[c]);
+
+	m_teletextDocument->moveCursor(m_row, m_column);
+	emit m_teletextDocument->contentsChange(m_row);
+}
+
+void DeleteKeyCommand::undo()
+{
+	m_teletextDocument->selectSubPageIndex(m_subPageIndex);
+
+	for (int c=0; c<40; c++)
+		m_teletextDocument->currentSubPage()->setCharacter(m_row, c, m_oldRowContents[c]);
+
+	m_teletextDocument->moveCursor(m_row, m_column);
+	emit m_teletextDocument->contentsChange(m_row);
+}
+
+bool DeleteKeyCommand::mergeWith(const QUndoCommand *command)
+{
+	const DeleteKeyCommand *newerCommand = static_cast<const DeleteKeyCommand *>(command);
+
+	if (m_subPageIndex != newerCommand->m_subPageIndex || m_row != newerCommand->m_row || m_column != newerCommand->m_column)
+		return false;
+
+	for (int c=0; c<40; c++)
+		m_newRowContents[c] = newerCommand->m_newRowContents[c];
+
+	return true;
+}
+
+
 InsertRowCommand::InsertRowCommand(TeletextDocument *teletextDocument, bool copyRow, QUndoCommand *parent) : QUndoCommand(parent)
 {
 	m_teletextDocument = teletextDocument;
@@ -318,6 +370,7 @@ void DeleteSubPageCommand::undo()
 	m_teletextDocument->selectSubPageIndex(m_subPageToDelete, true);
 }
 
+
 SetColourCommand::SetColourCommand(TeletextDocument *teletextDocument, int colourIndex, int newColour, QUndoCommand *parent) : QUndoCommand(parent)
 {
 	m_teletextDocument = teletextDocument;
diff --git a/levelonecommands.h b/levelonecommands.h
index f62b940..29a6196 100644
--- a/levelonecommands.h
+++ b/levelonecommands.h
@@ -80,6 +80,24 @@ private:
 	bool m_firstDo;
 };
 
+class DeleteKeyCommand : public QUndoCommand
+{
+public:
+	enum { Id = 104 };
+
+	DeleteKeyCommand(TeletextDocument *, QUndoCommand *parent = 0);
+
+	void redo() override;
+	void undo() override;
+	bool mergeWith(const QUndoCommand *) override;
+	int id() const override { return Id; }
+
+private:
+	TeletextDocument *m_teletextDocument;
+	unsigned char m_oldRowContents[40], m_newRowContents[40];
+	int m_subPageIndex, m_row, m_column;
+};
+
 class InsertSubPageCommand : public QUndoCommand
 {
 public:
diff --git a/mainwidget.cpp b/mainwidget.cpp
index b4f9fd0..9d09dab 100644
--- a/mainwidget.cpp
+++ b/mainwidget.cpp
@@ -332,6 +332,10 @@ void TeletextWidget::keyPressEvent(QKeyEvent *event)
 		case Qt::Key_Backspace:
 			backspaceEvent();
 			break;
+		case Qt::Key_Delete:
+			m_teletextDocument->undoStack()->push(new DeleteKeyCommand(m_teletextDocument));
+			break;
+
 		case Qt::Key_Up:
 			m_teletextDocument->cursorUp();
 			update();