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 ** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
 ** Contact: http://www.qt-project.org/legal
 **
 ** This file is part of the examples of the Qt Toolkit.
 **
 ** $QT_BEGIN_LICENSE:BSD$
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 ** modification, are permitted provided that the following conditions are
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 **   * Redistributions of source code must retain the above copyright
 **     notice, this list of conditions and the following disclaimer.
 **   * Redistributions in binary form must reproduce the above copyright
 **     notice, this list of conditions and the following disclaimer in
 **     the documentation and/or other materials provided with the
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 ****************************************************************************/

#include <QtGui>

#include "codeeditor.h"


CodeEditor::CodeEditor(QWidget *parent) : QPlainTextEdit(parent)
{
	lineNumberArea = new LineNumberArea(this);

	connect(this, SIGNAL(blockCountChanged(int)),
	        this, SLOT(updateLineNumberAreaWidth(int)));
	connect(this, SIGNAL(updateRequest(QRect,int)),
	        this, SLOT(updateLineNumberArea(QRect,int)));
	connect(this, SIGNAL(cursorPositionChanged()),
	        this, SLOT(highlightCurrentLine()));

	QFont font;
	font.setFamily("Courier");
	font.setStyleHint(QFont::Monospace);
	font.setFixedPitch(true);
	font.setPointSize(12);
	setFont(font);

	updateLineNumberAreaWidth(0);
	highlightCurrentLine();

	setTabStopWidth(fontMetrics().width("  "));
}

int CodeEditor::lineNumberAreaWidth()
{
	int digits = 1;
	int max = qMax(1, blockCount());
	while(max >= 10)
	{
		max /= 10;
		++digits;
	}

	int space = 3 + fontMetrics().width(QLatin1Char('9')) * digits;

	return space;
}

void CodeEditor::updateLineNumberAreaWidth(int /* newBlockCount */)
{
	setViewportMargins(lineNumberAreaWidth(), 0, 0, 0);
}

void CodeEditor::updateLineNumberArea(const QRect &rect, int dy)
{
	if(dy)
	{
		lineNumberArea->scroll(0, dy);
	}
	else
	{
		lineNumberArea->update(0, rect.y(), lineNumberArea->width(), rect.height());
	}

	if(rect.contains(viewport()->rect()))
	{
		updateLineNumberAreaWidth(0);
	}
}

void CodeEditor::resizeEvent(QResizeEvent *e)
{
	QPlainTextEdit::resizeEvent(e);

	QRect cr = contentsRect();
	lineNumberArea->setGeometry(QRect(cr.left(), cr.top(), lineNumberAreaWidth(),
	                                  cr.height()));
}

void CodeEditor::highlightCurrentLine()
{
	QList<QTextEdit::ExtraSelection> extraSelections;

	if(!isReadOnly())
	{
		QTextEdit::ExtraSelection selection;

		QColor lineColor = QColor(Qt::yellow).lighter(160);

		selection.format.setBackground(lineColor);
		selection.format.setProperty(QTextFormat::FullWidthSelection, true);
		selection.cursor = textCursor();
		selection.cursor.clearSelection();
		extraSelections.append(selection);
	}

	setExtraSelections(extraSelections);
}

void CodeEditor::runningLine(int lineno)
{
	lineNumber = lineno;
	errorLineNumber = 0; // no error
	repaint();
}

void CodeEditor::errorLine(QString file, int lineno, QString msg)
{
	(void)file;
	(void)msg;
	lineNumber = 0;
	errorLineNumber = lineno;
	repaint();
}

void CodeEditor::lineNumberAreaPaintEvent(QPaintEvent *event)
{
	QPainter painter(lineNumberArea);
	painter.fillRect(event->rect(), Qt::lightGray);

	QTextBlock block = firstVisibleBlock();
	int blockNumber = block.blockNumber();
	int top =
		(int) blockBoundingGeometry(block).translated(contentOffset()).top();
	int bottom = top + (int) blockBoundingRect(block).height();

	while(block.isValid() && top <= event->rect().bottom())
	{
		if(block.isVisible() && bottom >= event->rect().top())
		{
			QString number = QString::number(blockNumber + 1);
			if(blockNumber + 1 == lineNumber)
			{
				painter.setPen(Qt::green);
			}
			else if(blockNumber + 1 == errorLineNumber)
			{
				painter.setPen(Qt::red);
			}
			else
			{
				painter.setPen(Qt::black);
			}
			painter.drawText(0, top, lineNumberArea->width(), fontMetrics().height(),
			                 Qt::AlignRight, number);
		}

		block = block.next();
		top = bottom;
		bottom = top + (int) blockBoundingRect(block).height();
		++blockNumber;
	}
}