有没有办法模糊Qt中的小部件？例如,supose我想创建一个’Loading …’对话框并模糊背景(非活动窗口).
解决方法
这个答案是我的一系列与叠加相关的答案：
first,second,third.
如果您希望它可以在所有平台上运行,则需要一些小心.您无法直接将效果应用于顶级窗口.层次结构需要如下所示：
ContainerWidget
|
+----------+
| |
**Target** Overlay
您将效果应用于Target小部件(例如,QMainWindow). ContainerWidget是一个帮助程序类,可以让子项占用窗口小部件的完整大小.这消除了对显式零边距布局的需要.
以下工作,甚至在Mac上.如果放弃了ContainerWidget,它就不会.不幸的是,这仅适用于Qt 5.在Qt 4上,你的“跨平台”支持不包括Mac :(它在Windows上使用Qt 4(4.8.5)或Qt 5正常工作.
// https://github.com/KubaO/stackoverflown/tree/master/questions/overlay-blur-19383427
#include <QtGui>
#if QT_VERSION >= QT_VERSION_CHECK(5,0)
#include <QtWidgets>
#endif
class OverlayWidget : public QWidget {
void newParent() {
if (!parent()) return;
parent()->installEventFilter(this);
raise();
}
public:
explicit OverlayWidget(QWidget *parent = {}) : QWidget(parent) {
setAttribute(Qt::WA_NoSystemBackground);
setAttribute(Qt::WA_TransparentForMouseEvents);
newParent();
}
protected:
//! Catches resize and child events from the parent widget
bool eventFilter(QObject *obj,QEvent *ev) override {
if (obj == parent()) {
if (ev->type() == QEvent::Resize)
resize(static_cast<QResizeEvent*>(ev)->size());
else if (ev->type() == QEvent::ChildAdded)
raise();
}
return QWidget::eventFilter(obj,ev);
}
//! Tracks parent widget changes
bool event(QEvent *ev) override {
if (ev->type() == QEvent::ParentAbouttochange) {
if (parent()) parent()->removeEventFilter(this);
}
else if (ev->type() == QEvent::ParentChange)
newParent();
return QWidget::event(ev);
}
};
class ContainerWidget : public QWidget
{
public:
explicit ContainerWidget(QWidget *parent = {}) : QWidget(parent) {}
void setSize(QObject *obj) {
if (obj->isWidgetType()) static_cast<QWidget*>(obj)->setGeometry(rect());
}
protected:
//! Resizes children to fill the extent of this widget
bool event(QEvent *ev) override {
if (ev->type() == QEvent::ChildAdded) {
setSize(static_cast<QChildEvent*>(ev)->child());
}
return QWidget::event(ev);
}
//! Keeps the children appropriately sized
void resizeEvent(QResizeEvent *) override {
for(auto obj : children()) setSize(obj);
}
};
class LoadingOverlay : public OverlayWidget
{
public:
LoadingOverlay(QWidget *parent = {}) : OverlayWidget{parent} {
setAttribute(Qt::WA_TranslucentBackground);
}
protected:
void paintEvent(QPaintEvent *) override {
QPainter p{this};
p.fillRect(rect(),{100,100,128});
p.setPen({200,200,255});
p.setFont({"arial,helvetica",48});
p.drawText(rect(),"Loading...",Qt::AlignHCenter | Qt::AlignTop);
}
};
namespace compat {
#if QT_VERSION >= QT_VERSION_CHECK(5,4,0)
using QT_PREPEND_NAMESPACE(QTimer);
#else
using Q_QTimer = QT_PREPEND_NAMESPACE(QTimer);
class QTimer : public Q_QTimer {
public:
QTimer(QTimer *parent = nullptr) : Q_QTimer(parent) {}
template <typename F> static void singleShot(int period,F &&fun) {
struct Helper : public QObject {
F fun;
QBasicTimer timer;
void timerEvent(QTimerEvent *event) override {
if (event->timerId() != timer.timerId()) return;
fun();
deleteLater();
}
Helper(int period,F &&fun) : fun(std::forward<F>(fun)) {
timer.start(period,this);
}
};
new Helper(period,std::forward<F>(fun));
}
};
#endif
}
int main(int argc,char *argv[])
{
QApplication a{argc,argv};
ContainerWidget base;
QLabel label("Dewey,Cheatem and Howe,LLC.",&base);
label.setFont({"times,times new roman",32});
label.setAlignment(Qt::AlignCenter);
label.setGraphicsEffect(new QGraphicsBlurEffect);
LoadingOverlay overlay(&base);
base.show();
compat::QTimer::singleShot(2000,[&]{
overlay.hide();
label.setGraphicsEffect({});
});
return a.exec();
}
