File indexing completed on 2024-04-28 16:55:26

 /*
  * shadowengine.cpp - Emerald window decoration for KDE
  *
  * Copyright (c) 2010 Christoph Feck <christoph@maxiom.de>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, 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 General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  *
  */
 
 #include "shadowengine.h"
 
 #include <QImage>
 
 #include <cmath>
 
 namespace Smaragd
 {
 
 QImage createShadowImage(const ShadowSettings &settings)
 {
     const int radius = settings.radius + 32;
     const int size = 2 * radius + 1;
 
     QImage shadowImage(size, size, QImage::Format_ARGB32_Premultiplied);
     shadowImage.fill(0);
 
     QRadialGradient gradient(radius + 0.5, radius + 0.5, radius + 0.5);
     for (qreal v = 0.0; v <= 1.0; v += 1.0 / 64) {
         qreal k;
         QColor color = settings.color;
         if (v * radius < radius - (32.0 + settings.size)) {
             k = 0.0;
         } else {
             qreal x = (radius - 32.0) / radius;
             k = (v - x) / (1.0 - x);
             k = pow(1.0 - k, settings.linearDecay) * exp(-settings.exponentialDecay * k);
         }
         color.setAlpha(qBound(0, qRound(color.alpha() * k), 255));
         gradient.setColorAt(v, color);
     }
 
     QPainter p(&shadowImage);
     p.setCompositionMode(QPainter::CompositionMode_Source);
     p.setRenderHint(QPainter::Antialiasing, true);
     p.setBrush(gradient);
     p.setPen(Qt::NoPen);
     p.drawEllipse(0, 0, size, size);
     p.end();
 
     return shadowImage;
 }
 
 void paintShadow(QPainter *p, const QRect &r, const ShadowSettings &settings, const QImage &shadowImage)
 {
     const int s = -settings.size;
     QRect rect = r.adjusted(s - 32, s - 32, 32 - s, 32 - s);
     rect.adjust(settings.offsetX, settings.offsetY, settings.offsetX, settings.offsetY);
     int radius = shadowImage.width() / 2;
 
     // corners
     for (int i = 0; i < 4; ++i) {
         const int x = i & 1 ? rect.x() : rect.x() + rect.width() - radius;
         const int y = i & 2 ? rect.y() : rect.y() + rect.height() - radius;
         p->drawImage(x, y, shadowImage,
             i & 1 ? 0 : radius + 1, i & 2 ? 0 : radius + 1, radius, radius);
     }
 
     // sides
     for (int i = 0; i < 2; ++i) {
         const int x = rect.x() + radius;
         const int y = i & 1 ? rect.y() : rect.y() + rect.height() - radius;
         p->drawTiledPixmap(x, y, rect.width() - 2 * radius, radius,
             QPixmap::fromImage(shadowImage.copy(radius, i & 1 ? 0 : radius + 1, 1, radius)));
     }
     for (int i = 0; i < 2; ++i) {
         const int x = i & 1 ? rect.x() : rect.x() + rect.width() - radius;
         const int y = rect.y() + radius;
         p->drawTiledPixmap(x, y, radius, rect.height() - 2 * radius,
             QPixmap::fromImage(shadowImage.copy(i & 1 ? 0 : radius + 1, radius, radius, 1)));
     }
 
     // center
     QRgb pixel = shadowImage.pixel(radius, radius);
     if (shadowImage.format() == QImage::Format_ARGB32_Premultiplied) {
         const int alpha = qAlpha(pixel);
         if (alpha != 0 && alpha != 255) {
             pixel = qRgba(qBound(0, qRed(pixel) * 255 / alpha, 255),
                 qBound(0, qGreen(pixel) * 255 / alpha, 255),
                 qBound(0, qBlue(pixel) * 255 / alpha, 255),
                 alpha);
         }
     }
     p->fillRect(rect.adjusted(radius, radius, -radius, -radius), QColor::fromRgba(pixel));
 }
 
 }; // namespace Smaragd