77 lines
2.2 KiB
C++
77 lines
2.2 KiB
C++
#include "customshadoweffect.h"
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#include <QPainter>
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CustomShadowEffect::CustomShadowEffect(QObject *parent)
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: QGraphicsEffect(parent),
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_distance(4.0),
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_blurRadius(10.0),
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_color(0, 0, 0, 80)
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{
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}
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QT_BEGIN_NAMESPACE
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extern Q_WIDGETS_EXPORT void qt_blurImage(QPainter *p, QImage &blurImage, qreal radius, bool quality, bool alphaOnly, int transposed = 0);
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QT_END_NAMESPACE
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void CustomShadowEffect::draw(QPainter* painter)
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{
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// if nothing to show outside the item, just draw source
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if ((blurRadius() + distance()) <= 0) {
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drawSource(painter);
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return;
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}
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PixmapPadMode mode = QGraphicsEffect::PadToEffectiveBoundingRect;
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QPoint offset;
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const QPixmap px = sourcePixmap(Qt::DeviceCoordinates, &offset, mode);
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// return if no source
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if (px.isNull())
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return;
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// save world transform
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QTransform restoreTransform = painter->worldTransform();
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painter->setWorldTransform(QTransform());
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// Calculate size for the background image
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QSize szi(px.size().width() + 2 * distance(), px.size().height() + 2 * distance());
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QImage tmp(szi, QImage::Format_ARGB32_Premultiplied);
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QPixmap scaled = px.scaled(szi);
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tmp.fill(0);
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QPainter tmpPainter(&tmp);
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tmpPainter.setCompositionMode(QPainter::CompositionMode_Source);
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tmpPainter.drawPixmap(QPointF(-distance(), -distance()), scaled);
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tmpPainter.end();
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// blur the alpha channel
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QImage blurred(tmp.size(), QImage::Format_ARGB32_Premultiplied);
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blurred.fill(0);
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QPainter blurPainter(&blurred);
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qt_blurImage(&blurPainter, tmp, blurRadius(), false, true);
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blurPainter.end();
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tmp = blurred;
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// blacken the image...
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tmpPainter.begin(&tmp);
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tmpPainter.setCompositionMode(QPainter::CompositionMode_SourceIn);
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tmpPainter.fillRect(tmp.rect(), color());
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tmpPainter.end();
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// draw the blurred shadow...
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painter->drawImage(offset, tmp);
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// draw the actual pixmap...
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painter->drawPixmap(offset, px, QRectF());
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// restore world transform
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painter->setWorldTransform(restoreTransform);
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}
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QRectF CustomShadowEffect::boundingRectFor(const QRectF& rect) const
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{
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const qreal delta = blurRadius() + distance();
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return rect.united(rect.adjusted(-delta, -delta, delta, delta));
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}
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