Qt：窗口周围的阴影

问题描述

我可以添加阴影到小部件：

  QGraphicsDropShadowEffect * bodyShadow = new QGraphicsDropShadowEffect; 
 bodyShadow-> setBlurRadius（9.0）; 
 bodyShadow-> setColor（QColor（0，0，0，160））; 
 bodyShadow-> setOffset（4.0）; 
 ui-> widget-> setGraphicsEffect（bodyShadow）; 
  

但是这个阴影只会在左边和下边。我需要阴影周围的部件。如何添加？

解决方案

您可以创建自定义效果。

<$ p $

p> #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


customshadoweffect.cpp

  #includecustomshadoweffect.h
 #include< QPainter> 
 // #include< QGraphicsEffect> 
 
 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）
 {
 //如果在项外没有显示，只需绘制源
 if （（blurRadius（）+ distance（））< = 0）{
 drawSource（painter）; 
 return; 
} 
 
 PixmapPadMode mode = QGraphicsEffect :: PadToEffectiveBoundingRect; 
 QPoint offset; 
 const QPixmap px = sourcePixmap（Qt :: DeviceCoordinates，& offset，mode）; 
 
 //返回如果没有源
 if（px.isNull（））
 return; 
 
 //保存世界变换
 QTransform restoreTransform = painter-> worldTransform（）; 
 painter-> setWorldTransform（QTransform（））; 
 
 //计算背景图像的大小
 QSize szi（px.size（）。width（）+ 2 * distance（），px.size（）。height * 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（）; 
 
 //模糊Alpha通道
 QImage blur（tmp.size（），QImage :: Format_ARGB32_Premultiplied）; 
 blurred.fill（0）; 
 QPainter blurPainter（& blurred）; 
 qt_blurImage（& blurPainter，tmp，blurRadius（），false，true）; 
 blurPainter.end（）; 
 
 tmp = blurred; 
 
 //黑色图像... 
 tmpPainter.begin（& tmp）; 
 tmpPainter.setCompositionMode（QPainter :: CompositionMode_SourceIn）; 
 tmpPainter.fillRect（tmp.rect（），color（））; 
 tmpPainter.end（）; 
 
 //绘制模糊的阴影... 
 painter-> drawImage（offset，tmp）; 
 
 //绘制实际的像素图... 
 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））; 
} 
  

将其应用于图形项目

  // ... 
 CustomShadowEffect * bodyShadow = new CustomShadowEffect（）; 
 bodyShadow-> setBlurRadius（20.0）; 
 bodyShadow-> setDistance（6.0）; 
 bodyShadow-> setColor（QColor（0，0，0，80））; 
 item-> setGraphicsEffect（bodyShadow）; 
 // ... 
  

应用

  // ... 
 CustomShadowEffect * bodyShadow = new CustomShadowEffect 
 bodyShadow-> setBlurRadius（20.0）; 
 bodyShadow-> setDistance（6.0）; 
 bodyShadow-> setColor（QColor（0，0，0，80））; 
 ui-> widget-> setAutoFillBackground（true）; 
 ui-> widget-> setGraphicsEffect（bodyShadow）; 
 // ... 
  

结果：

I can add shadow to widget:

QGraphicsDropShadowEffect *bodyShadow = new QGraphicsDropShadowEffect;
bodyShadow->setBlurRadius(9.0);
bodyShadow->setColor(QColor(0, 0, 0, 160));
bodyShadow->setOffset(4.0);
ui->widget->setGraphicsEffect(bodyShadow);

But this shadow will be only at left and down. I need shadow around widget. How to add this?

解决方案

You can create your custom effect. I'll share an implementation that works.

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

customshadoweffect.cpp

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

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));
}

Applying it (to a graphics item):

// ...
CustomShadowEffect *bodyShadow = new CustomShadowEffect();
bodyShadow->setBlurRadius(20.0);
bodyShadow->setDistance(6.0);
bodyShadow->setColor(QColor(0, 0, 0, 80));
item->setGraphicsEffect(bodyShadow);
// ...

Applying it (to a child widget):

//...
CustomShadowEffect *bodyShadow = new CustomShadowEffect();
bodyShadow->setBlurRadius(20.0);
bodyShadow->setDistance(6.0);
bodyShadow->setColor(QColor(0, 0, 0, 80));
ui->widget->setAutoFillBackground(true);
ui->widget->setGraphicsEffect(bodyShadow);
// ...

Result:

这篇关于Qt：窗口周围的阴影的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！