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Qt_阴影效果

一、控件阴影效果

为子部件添加阴影比较简单，使用如下方式：

QGraphicsDropShadowEffect *shadow_effect = new QGraphicsDropShadowEffect(this);
 
shadow_effect->setOffset(-5, 5);
 
shadow_effect->setColor(Qt::gray);
 
shadow_effect->setBlurRadius(8);
 
network_group_box->setGraphicsEffect(shadow_effect);

　　效果如下：

二、窗口阴影效果（代码实现）

void DropShadowWidget::paintEvent(QPaintEvent *event)
{ 
 
    QPainterPath path;
    path.setFillRule(Qt::WindingFill);
    path.addRect(10, 10, this->width()-20, this->height()-20);
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing, true);
    painter.fillPath(path, QBrush(Qt::white));
 
    QColor color(0, 0, 0, 50);
    for(int i=0; i<10; i++)
    {
        QPainterPath path;
        path.setFillRule(Qt::WindingFill);
        path.addRect(10-i, 10-i, this->width()-(10-i)*2, this->height()-(10-i)*2);
        color.setAlpha(150 - qSqrt(i)*50);
        painter.setPen(color);
        painter.drawPath(path);
    }
}

　　三、窗口阴影效果（图片绘制）

阴影边框很常见，诸如360以及其他很多软件都有类似效果，了解CSS3的同学们应该都知道box-shadow，它就是来设定阴影效果的，那么Qt呢？看过一些资料，说是QSS是基于CSS2的，既然如此，box-shadow是基于CSS3的！那么Qt定然就用不了！

搜了一些资料，每张图片都做成阴影效果的固然不可能，直接舍弃（即使可以，也不采纳）。如果实时的去画图，效率太低，最后选择了拼图的方式！

效果如下：

左上角、左下角、右上角、右下角、上、下、左、右，这几个方向都绘制对应的图即可！

#include "shadow_widget.h"
 
ShadowWidget::ShadowWidget(QWidget *parent)
   : QDialog(parent)
{
   setWindowFlags(Qt::FramelessWindowHint | Qt::Dialog);
   setAttribute(Qt::WA_TranslucentBackground);
}
ShadowWidget::~ShadowWidget()
{
}
void ShadowWidget::paintEvent(QPaintEvent *event)
{
   QPainter painter(this);
   this->drawShadow(painter);
   painter.setPen(Qt::NoPen);
   painter.setBrush(Qt::white);
   painter.drawRect(QRect(SHADOW_WIDTH, SHADOW_WIDTH, this->width()-2*SHADOW_WIDTH, this->height()-2*SHADOW_WIDTH));
}
void ShadowWidget::drawShadow(QPainter &painter)
{
   //绘制左上角、左下角、右上角、右下角、上、下、左、右边框
   QList pixmaps;
   pixmaps.append(QPixmap(":/shadow/shadow_left"));
   pixmaps.append(QPixmap(":/shadow/shadow_right"));
   pixmaps.append(QPixmap(":/shadow/shadow_top"));
   pixmaps.append(QPixmap(":/shadow/shadow_bottom"));
   pixmaps.append(QPixmap(":/shadow/shadow_left_top"));
   pixmaps.append(QPixmap(":/shadow/shadow_right_top"));
   pixmaps.append(QPixmap(":/shadow/shadow_left_bottom"));
   pixmaps.append(QPixmap(":/shadow/shadow_right_bottom"));
   painter.drawPixmap(0, 0, SHADOW_WIDTH, SHADOW_WIDTH, pixmaps[4]);
   painter.drawPixmap(this->width()-SHADOW_WIDTH, 0, SHADOW_WIDTH, SHADOW_WIDTH, pixmaps[5]);
   painter.drawPixmap(0,this->height()-SHADOW_WIDTH, SHADOW_WIDTH, SHADOW_WIDTH, pixmaps[6]);
   painter.drawPixmap(this->width()-SHADOW_WIDTH, this->height()-SHADOW_WIDTH, SHADOW_WIDTH, SHADOW_WIDTH, pixmaps[7]);
   painter.drawPixmap(0, SHADOW_WIDTH, SHADOW_WIDTH, this->height()-2*SHADOW_WIDTH, pixmaps[0].scaled(SHADOW_WIDTH, this->height()-2*SHADOW_WIDTH));
   painter.drawPixmap(this->width()-SHADOW_WIDTH, SHADOW_WIDTH, SHADOW_WIDTH, this->height()-2*SHADOW_WIDTH, pixmaps[1].scaled(SHADOW_WIDTH, this->height()- 2*SHADOW_WIDTH));
   painter.drawPixmap(SHADOW_WIDTH, 0, this->width()-2*SHADOW_WIDTH, SHADOW_WIDTH, pixmaps[2].scaled(this->width()-2*SHADOW_WIDTH, SHADOW_WIDTH));
   painter.drawPixmap(SHADOW_WIDTH, this->height()-SHADOW_WIDTH, this->width()-2*SHADOW_WIDTH, SHADOW_WIDTH, pixmaps[3].scaled(this->width()-2*SHADOW_WIDTH, SHADOW_WIDTH));
 
}