kdelibs/plasma/paintutils.cpp

/*
 *   Copyright 2005 by Aaron Seigo <aseigo@kde.org>
 *   Copyright 2008 by Andrew Lake <jamboarder@yahoo.com>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Library General Public License as
 *   published by the Free Software Foundation; either version 2, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details
 *
 *   You should have received a copy of the GNU Library General Public
 *   License along with this program; if not, write to the
 *   Free Software Foundation, Inc.,
 *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#include <paintutils.h>

#include <QImage>
#include <QPainter>
#include <QPaintEngine>
#include <QPixmap>

#include "kiconeffect.h"
#include "private/effects/blur.cpp"
#include "private/effects/halopainter_p.h"
#include "svg.h"

namespace Plasma
{

namespace PaintUtils
{

void shadowBlur(QImage &image, int radius, const QColor &color)
{
    if (radius < 1 || image.isNull()) {
        return;
    }

    KIconEffect::shadowBlur(image, float(radius), color);
}

//TODO: we should have shadowText methods that paint the results directly into a QPainter passed in
QPixmap shadowText(QString text, QColor textColor, QColor shadowColor, QPoint offset, int radius)
{
    return shadowText(text, qApp->font(), textColor, shadowColor, offset, radius);
}

QPixmap shadowText(QString text, const QFont &font, QColor textColor, QColor shadowColor, QPoint offset, int radius)
{
    //don't try to paint stuff on a future null pixmap because the text is empty
    if (text.isEmpty()) {
        return QPixmap();
    }

    // Draw text
    QFontMetrics fm(font);
    QRect textRect = fm.boundingRect(text);
    QPixmap textPixmap(textRect.width(), fm.height());
    textPixmap.fill(Qt::transparent);
    QPainter p(&textPixmap);
    p.setPen(textColor);
    p.setFont(font);
    // FIXME: the center alignment here is odd: the rect should be the size needed by
    //        the text, but for some fonts and configurations this is off by a pixel or so
    //        and "centering" the text painting 'fixes' that. Need to research why
    //        this is the case and determine if we should be painting it differently here,
    //        doing soething different with the boundingRect call or if it's a problem
    //        in Qt itself
    p.drawText(textPixmap.rect(), Qt::AlignCenter, text);
    p.end();

    //Draw blurred shadow
    QImage img(textRect.size() + QSize(radius * 2, radius * 2), QImage::Format_ARGB32_Premultiplied);
    img.fill(0);
    p.begin(&img);
    p.drawImage(QPoint(radius, radius), textPixmap.toImage());
    p.end();
    shadowBlur(img, radius, shadowColor);

    //Compose text and shadow
    int addSizeX = qMax(0, qAbs(offset.x()) - radius);
    int addSizeY = qMax(0, qAbs(offset.y()) - radius);

    QPixmap finalPixmap(img.size() + QSize(addSizeX, addSizeY));
    finalPixmap.fill(Qt::transparent);
    p.begin(&finalPixmap);
    p.drawImage(qMax(0, offset.x()), qMax(0, offset.y()), img);
    p.drawPixmap(radius + qMax(0, -offset.x()), radius + qMax(0, -offset.y()), textPixmap);
    p.end();

    return finalPixmap;
}

QPixmap texturedText(const QString &text, const QFont &font, Plasma::Svg *texture)
{
    QFontMetrics fm(font);
    //the text will be moved a bit from contentsRect
    QRect contentsRect = fm.boundingRect(text).adjusted(0, 0, 2, 2);
    contentsRect.moveTo(0,0);

    QPixmap pixmap(contentsRect.size());
    pixmap.fill(Qt::transparent);

    QPainter buffPainter(&pixmap);
    buffPainter.setPen(Qt::black);

    buffPainter.setFont(font);
    buffPainter.drawText(contentsRect, Qt::AlignCenter, text);
    buffPainter.setCompositionMode(QPainter::CompositionMode_SourceIn);
    texture->paint(&buffPainter, contentsRect, "foreground");
    buffPainter.end();

    //do the shadow
    QImage image(pixmap.size() + QSize(2, 2), QImage::Format_ARGB32_Premultiplied);
    image.fill(Qt::transparent);
    buffPainter.begin(&image);
    buffPainter.setFont(font);
    buffPainter.drawText(contentsRect.translated(1, 1), Qt::AlignCenter, text);
    buffPainter.setCompositionMode(QPainter::CompositionMode_SourceIn);
    texture->paint(&buffPainter, contentsRect.adjusted(-1, -1, 1, 1), "shadow");
    buffPainter.end();

    expblur<16, 7>(image, 1);
    //hole in the shadow
    buffPainter.begin(&image);
    buffPainter.setCompositionMode(QPainter::CompositionMode_DestinationOut);
    buffPainter.setFont(font);
    buffPainter.drawText(contentsRect.translated(1, 1), Qt::AlignCenter, text);
    buffPainter.end();

    QPixmap ret(image.size());
    ret.fill(Qt::transparent);
    buffPainter.begin(&ret);
    buffPainter.setCompositionMode(QPainter::CompositionMode_SourceOver);
    buffPainter.drawImage(QPoint(0,0), image);
    buffPainter.drawPixmap(QPoint(1,1), pixmap);
    buffPainter.end();
    return ret;
}

void drawHalo(QPainter *painter, const QRectF &rect)
{
    HaloPainter::instance()->drawHalo(painter, rect.toRect());
}

QPainterPath roundedRectangle(const QRectF &rect, qreal radius)
{
    QPainterPath path(QPointF(rect.left(), rect.top() + radius));
    path.quadTo(rect.left(), rect.top(), rect.left() + radius, rect.top());         // Top left corner
    path.lineTo(rect.right() - radius, rect.top());                                 // Top side
    path.quadTo(rect.right(), rect.top(), rect.right(), rect.top() + radius);       // Top right corner
    path.lineTo(rect.right(), rect.bottom() - radius);                              // Right side
    path.quadTo(rect.right(), rect.bottom(), rect.right() - radius, rect.bottom()); // Bottom right corner
    path.lineTo(rect.left() + radius, rect.bottom());                               // Bottom side
    path.quadTo(rect.left(), rect.bottom(), rect.left(), rect.bottom() - radius);   // Bottom left corner
    path.closeSubpath();

    return path;
}

void centerPixmaps(QPixmap &from, QPixmap &to)
{
    if (from.size() == to.size() && from.hasAlphaChannel() && to.hasAlphaChannel()) {
        return;
    }

    QRect fromRect(from.rect());
    QRect toRect(to.rect());
 
    QRect actualRect = QRect(QPoint(0,0), fromRect.size().expandedTo(toRect.size()));
    fromRect.moveCenter(actualRect.center());
    toRect.moveCenter(actualRect.center());

    if (from.size() != actualRect.size() || !from.hasAlphaChannel()) {
        QPixmap result(actualRect.size());
        result.fill(Qt::transparent);
        QPainter p(&result);
        p.setCompositionMode(QPainter::CompositionMode_Source);
        p.drawPixmap(fromRect.topLeft(), from);
        p.end();
        from = result;
    }

    if (to.size() != actualRect.size() || !to.hasAlphaChannel()) {
        QPixmap result(actualRect.size());
        result.fill(Qt::transparent);
        QPainter p(&result);
        p.setCompositionMode(QPainter::CompositionMode_Source);
        p.drawPixmap(toRect.topLeft(), to);
        p.end();
        to = result;
    }
}

QPixmap transition(const QPixmap &from, const QPixmap &to, qreal amount)
{
    if (from.isNull() && to.isNull()) {
        return from;
    }

    if (qFuzzyCompare(amount + 1, qreal(1.0))) {
        return from;
    }

    QRect startRect(from.rect());
    QRect targetRect(to.rect());
    QSize pixmapSize = startRect.size().expandedTo(targetRect.size());
    QRect toRect = QRect(QPoint(0,0), pixmapSize);
    targetRect.moveCenter(toRect.center());
    startRect.moveCenter(toRect.center());

    // paint to in the center of from, skipping setAlphaF()
    QColor color(0, 0, 0, amount);

    QPixmap startPixmap(pixmapSize);
    startPixmap.fill(Qt::transparent);

    QPixmap targetPixmap(pixmapSize);
    targetPixmap.fill(Qt::transparent);

    QPainter p;
    p.begin(&targetPixmap);
    p.drawPixmap(targetRect, to);
    p.setCompositionMode(QPainter::CompositionMode_DestinationIn);
    p.fillRect(targetRect, color);
    p.end();

    p.begin(&startPixmap);
    p.drawPixmap(startRect, from);
    p.setCompositionMode(QPainter::CompositionMode_DestinationOut);
    p.fillRect(startRect, color);
    p.setCompositionMode(QPainter::CompositionMode_Plus);
    p.drawPixmap(targetRect, targetPixmap);
    p.end();

    return startPixmap;
}

} // PaintUtils namespace

} // Plasma namespace