Qt之QGraphicsEffect阴影、模糊效果

Qt之QGraphicsEffect阴影、模糊效果

 

• • Qt之QGraphicsEffect阴影模糊效果
    • 效果图
      • 阴影和模糊效果
      • 正常效果
    • 代码
      • customshadoweffecth
      • customshadoweffectcpp
      • QGraphicsBlurEffect 模糊度setBlurRadius参考文献
      • Applying It
    • 结尾
    • 参考地址

 

效果图

阴影和模糊效果

正常效果

代码

customshadoweffect.h

#ifndef CUSTOMSHADOWEFFECT_H
#define CUSTOMSHADOWEFFECT_H

#include <QGraphicsDropShadowEffect>
#include <QGraphicsEffect>

class CustomShadowEffect : public QGraphicsEffect
{
 Q_OBJECT
public:
explicit CustomShadowEffect(QObject *parent = 0);

void draw(QPainter* painter);
 QRectF boundingRectFor(const QRectF& rect) const;

inline void setDistance(qreal distance) { _distance = distance; updateBoundingRect(); }
inline qreal distance() const { return _distance; }

inline void setBlurRadius(qreal blurRadius) { _blurRadius = blurRadius; updateBoundingRect(); }
inline qreal blurRadius() const { return _blurRadius; }

inline void setColor(const QColor& color) { _color = color; }
inline QColor color() const { return _color; }

private:
 qreal _distance;
 qreal _blurRadius;
 QColor _color;
};

#endif // CUSTOMSHADOWEFFECT_H

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customshadoweffect.cpp

#include "customshadoweffect.h"
#include <QPainter>

CustomShadowEffect::CustomShadowEffect(QObject *parent) :
 QGraphicsEffect(parent),
 _distance(4.0f),
 _blurRadius(10.0f),
 _color(0, 0, 0, 80)
{
}

QT_BEGIN_NAMESPACE
 extern Q_WIDGETS_EXPORT void qt_blurImage(QPainter *p, QImage &blurImage, qreal radius, bool quality, bool alphaOnly, int transposed = 0 );
QT_END_NAMESPACE

void CustomShadowEffect::draw(QPainter* painter)
{
// if nothing to show outside the item, just draw source
if ((blurRadius() + distance()) <= 0) {
 drawSource(painter);
return;
 }

 PixmapPadMode mode = QGraphicsEffect::PadToEffectiveBoundingRect;
 QPoint offset;
 const QPixmap px = sourcePixmap(Qt::DeviceCoordinates, &offset, mode);

// return if no source
if (px.isNull())
return;

// save world transform
 QTransform restoreTransform = painter->worldTransform();
 painter->setWorldTransform(QTransform());

// Calculate size for the background image
 QSize szi(px.size().width() + 2 * distance(), px.size().height() + 2 * distance());

 QImage tmp(szi, QImage::Format_ARGB32_Premultiplied);
 QPixmap scaled = px.scaled(szi);
 tmp.fill(0);
 QPainter tmpPainter(&tmp);
 tmpPainter.setCompositionMode(QPainter::CompositionMode_Source);
 tmpPainter.drawPixmap(QPointF(-distance(), -distance()), scaled);
 tmpPainter.end();

// blur the alpha channel
 QImage blurred(tmp.size(), QImage::Format_ARGB32_Premultiplied);
 blurred.fill(0);
 QPainter blurPainter(&blurred);
 qt_blurImage(&blurPainter, tmp, blurRadius(), false, true);
 blurPainter.end();

 tmp = blurred;

// blacken the image...
 tmpPainter.begin(&tmp);
 tmpPainter.setCompositionMode(QPainter::CompositionMode_SourceIn);
 tmpPainter.fillRect(tmp.rect(), color());
 tmpPainter.end();

// draw the blurred shadow...
 painter->drawImage(offset, tmp);

// draw the actual pixmap...
 painter->drawPixmap(offset, px, QRectF());

// restore world transform
 painter->setWorldTransform(restoreTransform);
}

QRectF CustomShadowEffect::boundingRectFor(const QRectF& rect) const
{
 qreal delta = blurRadius() + distance();
return rect.united(rect.adjusted(-delta, -delta, delta, delta));
}

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QGraphicsBlurEffect 模糊度setBlurRadius参考文献

Applying It

CustomShadow::CustomShadow(QWidget *parent)
 : QWidget(parent)
{
 ui.setupUi(this);
 ui.pushButton->installEventFilter(this);
 ui.widget->installEventFilter(this);
//模糊效果
 auto blurEffect = new QGraphicsBlurEffect(ui.lineEdit);
 blurEffect->setBlurRadius(2);
 ui.lineEdit->setGraphicsEffect(blurEffect);
}

bool CustomShadow::eventFilter(QObject *obj, QEvent *event)
{
if (obj == ui.pushButton) {
if (event->type() == QEvent::Enter) 
 {
 Shadow* bodyShadow = new Shadow(ui.pushButton);
 ui.pushButton->setGraphicsEffect(bodyShadow);
return true;
 }
else if (event->type() == QEvent::Leave)
 {
 ui.pushButton->setGraphicsEffect(nullptr);
return true;
 }
else {
return false;
 }
 }
else if (obj == ui.widget) {
if (event->type() == QEvent::Enter)
 {
 Shadow* bodyShadow = new Shadow(ui.widget);
 ui.widget->setGraphicsEffect(bodyShadow);
return true;
 }
else if (event->type() == QEvent::Leave)
 {
 ui.widget->setGraphicsEffect(nullptr);
return true;
 }
else {
return false;
 }
 }
else {
// pass the event on to the parent class
return __super::eventFilter(obj, event);
 }
}

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结尾

只为记录，只为分享! 愿所写能对你有所帮助。不忘记点个赞，谢谢~

参考地址

Qt: shadow around window 

http://blog.csdn.net/ly305750665/article/details/79209774