RetroShare/retroshare-gui/src/gui/common/ElidedLabel.cpp

/****************************************************************************
 **
 ** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
 ** Contact: http://www.qt-project.org/legal
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
 **
 ** $QT_BEGIN_LICENSE:BSD$
 ** You may use this file under the terms of the BSD license as follows:
 **
 ** "Redistribution and use in source and binary forms, with or without
 ** modification, are permitted provided that the following conditions are
 ** met:
 **   * 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
 **     distribution.
 **   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
 **     of its contributors may be used to endorse or promote products derived
 **     from this software without specific prior written permission.
 **
 **
 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
 **
 ** $QT_END_LICENSE$
 **
 ****************************************************************************/

#include "ElidedLabel.h"

#include <QPainter>
#include <QTextLayout>
#include <QDebug>
#include <QStyleOption>

ElidedLabel::ElidedLabel(const QString &text, QWidget *parent)
  : QLabel(parent)
  , mElided(false)
  , mContent(text)
{
	setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Preferred);
}

ElidedLabel::ElidedLabel(QWidget *parent)
  : QLabel(parent)
  , mElided(false)
{
	setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Preferred);
}

void ElidedLabel::setText(const QString &newText)
{
	mContent = newText;
	update();
}

void ElidedLabel::clear()
{
	mContent.clear();
	update();
}

void ElidedLabel::paintEvent(QPaintEvent *event)
{
	QLabel::paintEvent(event);
	
	QPainter painter(this);
	QFontMetrics fontMetrics = painter.fontMetrics();
	QRect cr = contentsRect();
	cr.adjust(margin(), margin(), -margin(), -margin());
	
	bool didElide = false;
	int lineSpacing = fontMetrics.lineSpacing();
	int x, y = x =cr.top()+(cr.height()-lineSpacing)/2;
	
	QTextLayout textLayout(mContent, painter.font());
	textLayout.beginLayout();
	forever {
		QTextLine line = textLayout.createLine();
		
		if (!line.isValid())
			break;
		
		line.setLineWidth(cr.width()+2*x);
		int nextLineY = y + lineSpacing;
		
		if (cr.height() >= nextLineY + lineSpacing) {
			line.draw(&painter, QPoint(x, y));
			y = nextLineY;
		} else {
			QString lastLine = mContent.mid(line.textStart());
			QString elidedLastLine = fontMetrics.elidedText(lastLine, Qt::ElideRight, cr.width());
			painter.drawText(QPoint(x, y + fontMetrics.ascent()), elidedLastLine);
			line = textLayout.createLine();
			didElide = line.isValid();
			break;
		}
	}
	textLayout.endLayout();
	
	if (didElide != mElided) {
		mElided = didElide;
		emit elisionChanged(didElide);
	}
}