matrixion/include/ui/DropShadow.h

#pragma once

#include <QColor>
#include <QLinearGradient>
#include <QPainter>

class DropShadow
{
public:
        static void draw(QPainter &painter,
                         qint16 margin,
                         qreal radius,
                         QColor start,
                         QColor end,
                         qreal startPosition,
                         qreal endPosition0,
                         qreal endPosition1,
                         qreal width,
                         qreal height)
        {
                painter.setPen(Qt::NoPen);

                QLinearGradient gradient;
                gradient.setColorAt(startPosition, start);
                gradient.setColorAt(endPosition0, end);

                // Right
                QPointF right0(width - margin, height / 2);
                QPointF right1(width, height / 2);
                gradient.setStart(right0);
                gradient.setFinalStop(right1);
                painter.setBrush(QBrush(gradient));
                painter.drawRoundRect(
                  QRectF(QPointF(width - margin * radius, margin), QPointF(width, height - margin)),
                  0.0,
                  0.0);

                // Left
                QPointF left0(margin, height / 2);
                QPointF left1(0, height / 2);
                gradient.setStart(left0);
                gradient.setFinalStop(left1);
                painter.setBrush(QBrush(gradient));
                painter.drawRoundRect(
                  QRectF(QPointF(margin * radius, margin), QPointF(0, height - margin)), 0.0, 0.0);

                // Top
                QPointF top0(width / 2, margin);
                QPointF top1(width / 2, 0);
                gradient.setStart(top0);
                gradient.setFinalStop(top1);
                painter.setBrush(QBrush(gradient));
                painter.drawRoundRect(
                  QRectF(QPointF(width - margin, 0), QPointF(margin, margin)), 0.0, 0.0);

                // Bottom
                QPointF bottom0(width / 2, height - margin);
                QPointF bottom1(width / 2, height);
                gradient.setStart(bottom0);
                gradient.setFinalStop(bottom1);
                painter.setBrush(QBrush(gradient));
                painter.drawRoundRect(
                  QRectF(QPointF(margin, height - margin), QPointF(width - margin, height)),
                  0.0,
                  0.0);

                // BottomRight
                QPointF bottomright0(width - margin, height - margin);
                QPointF bottomright1(width, height);
                gradient.setStart(bottomright0);
                gradient.setFinalStop(bottomright1);
                gradient.setColorAt(endPosition1, end);
                painter.setBrush(QBrush(gradient));
                painter.drawRoundRect(QRectF(bottomright0, bottomright1), 0.0, 0.0);

                // BottomLeft
                QPointF bottomleft0(margin, height - margin);
                QPointF bottomleft1(0, height);
                gradient.setStart(bottomleft0);
                gradient.setFinalStop(bottomleft1);
                gradient.setColorAt(endPosition1, end);
                painter.setBrush(QBrush(gradient));
                painter.drawRoundRect(QRectF(bottomleft0, bottomleft1), 0.0, 0.0);

                // TopLeft
                QPointF topleft0(margin, margin);
                QPointF topleft1(0, 0);
                gradient.setStart(topleft0);
                gradient.setFinalStop(topleft1);
                gradient.setColorAt(endPosition1, end);
                painter.setBrush(QBrush(gradient));
                painter.drawRoundRect(QRectF(topleft0, topleft1), 0.0, 0.0);

                // TopRight
                QPointF topright0(width - margin, margin);
                QPointF topright1(width, 0);
                gradient.setStart(topright0);
                gradient.setFinalStop(topright1);
                gradient.setColorAt(endPosition1, end);
                painter.setBrush(QBrush(gradient));
                painter.drawRoundRect(QRectF(topright0, topright1), 0.0, 0.0);

                // Widget
                painter.setBrush(QBrush("#FFFFFF"));
                painter.setRenderHint(QPainter::Antialiasing);
                painter.drawRoundRect(
                  QRectF(QPointF(margin, margin), QPointF(width - margin, height - margin)),
                  radius,
                  radius);
        }
};