QPainterStateGuard Class

The QPainterStateGuard is a RAII convenience class for balanced QPainter::save () 和 QPainter::restore () 调用。 更多...

头：	#include <QPainterStateGuard>
CMake:	find_package(Qt6 REQUIRED COMPONENTS Gui) target_link_libraries(mytarget PRIVATE Qt6::Gui)
qmake:	QT += gui
Since:	Qt 6.9

• 所有成员列表，包括继承成员
• QPainterStateGuard is part of 描绘类 .

注意： 此类的所有函数 可重入 .

公共函数

	QPainterStateGuard (QPainter * painter , QPainterStateGuard::InitialState state = InitialState::Save)
	QPainterStateGuard (QPainterStateGuard && other )
	~QPainterStateGuard ()
void	restore ()
void	save ()
void	swap (QPainterStateGuard & other )
QPainterStateGuard &	operator= (QPainterStateGuard && other )

详细描述

QPainterStateGuard should be used everywhere as a replacement for QPainter::save () to make sure that the corresponding QPainter::restore () is called upon finishing of the painting routine to avoid unbalanced calls between those two functions.

Example with QPainter::save ()/ QPainter::restore ():

void MyWidget::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    painter.setPen(Qt::red);
    if (drawText) {
        painter.save();
        painter.setPen(Qt::blue);
        painter.setFont(QFont("Arial", 30));
        painter.drawText(rect(), Qt::AlignCenter, "Qt");
        painter.restore();  // don't forget to restore previous painter state
    }
    painter.drawLine(line);
}
					

Example with QPainterStateGuard:

void MyGuardWidget::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    painter.setPen(Qt::red);
    if (drawText) {
        QPainterStateGuard guard(&painter)
        painter.setPen(Qt::blue);
        painter.setFont(QFont("Arial", 30));
        painter.drawText(rect(), Qt::AlignCenter, "Qt");
    }
    painter.drawLine(line);
}
					

另请参阅 QPainter .

成员函数文档编制

[explicit] QPainterStateGuard:: QPainterStateGuard ( QPainter * painter , QPainterStateGuard::InitialState state = InitialState::Save)

Constructs a QPainterStateGuard and calls save () 在 painter if state is InitialState::Save (which is the default). When QPainterStateGuard is destroyed, restore () is called as often as save () was called to restore the QPainter 's state.

[noexcept] QPainterStateGuard:: QPainterStateGuard ( QPainterStateGuard && other )

Move-constructs a painter state guard from other .

[noexcept] QPainterStateGuard:: ~QPainterStateGuard ()

销毁 QPainterStateGuard instance and calls restore () as often as save () was called to restore the QPainter 's state.

void QPainterStateGuard:: restore ()

调用 QPainter::restore () if the internal save/restore counter is greater than zero.

注意： This function asserts in debug builds if the counter has already reached zero.

void QPainterStateGuard:: save ()

调用 QPainter::save () and increases the internal save/restore counter by one.

[noexcept] void QPainterStateGuard:: swap ( QPainterStateGuard & other )

Swaps the other with this painter state guard. This operation is very fast and never fails.

[noexcept] QPainterStateGuard &QPainterStateGuard:: operator= ( QPainterStateGuard && other )

移动赋值 other to this painter state guard.

内容

1. 公共函数

2. 详细描述