我正在为一个添加了框架的 QGraphicsTextItem
制作动画。在动画期间,文本似乎在框架内轻微晃动,这非常烦人。
示例代码:
class MovingFrameText : public QGraphicsTextItem
{
Q_OBJECT;
public:
MovingFrameText( ) : QGraphicsTextItem(0)
{
setPlainText ( "human ");
QFont f = font();
f.setPixelSize(40);
setFont(f);
setFlags(QGraphicsItem::ItemIsMovable);
}
QRectF boundingRect() const
{
return QGraphicsTextItem::boundingRect().adjusted(-2,-2,+2,+2);
}
void paint(QPainter *painter,const QStyleOptionGraphicsItem *option,QWidget *widget)
{
QGraphicsTextItem::paint(painter,option,widget);
painter->setPen(Qt::black);
painter->drawRect(boundingRect());
}
};
int main(int argc, char *argv[])
{
QApplication app(argc,argv);
MovingFrameText t;
t.setPos(640,680);
QGraphicsScene scene;
scene.addItem(&t);
QGraphicsView view(&scene);
view.resize(640, 680);
view.show();
auto moveAnimation = new QPropertyAnimation( &t, "pos" );
moveAnimation->setDuration( 10000 );
moveAnimation->setStartValue( QPointF(640, 680) );
moveAnimation->setEndValue( QPointF(0, 0) );
moveAnimation->setEasingCurve( QEasingCurve::Linear );
moveAnimation->start(QAbstractAnimation::DeleteWhenStopped);
return app.exec();
}
有什么办法可以让动画更流畅吗?
最佳答案
解决方案
您可以通过以下方式显着改进动画:
- 使用
QVariantAnimation
而不是QPropertyAnimation
并调用QGraphicsItem::update
在每次迭代中 - 使用附加的
QPainter
缓冲绘画,将QPixmap
作为所有绘画操作的 Canvas ,然后使用传递给paint< 的画家绘画 Canvas
方法
注意QGraphicsTextItem
仍然会抖动一点,但至少它会表现为一个对象而不是几个独立的对象。
例子
这是我为您准备的示例,说明如何更改您的代码以实现建议的解决方案:
class MovingFrameText : public QGraphicsTextItem
{
public:
MovingFrameText(const QString &text, QGraphicsItem *parent = nullptr)
: QGraphicsTextItem(parent)
{
QFont f(font());
f.setPixelSize(40);
setFont(f);
setPlainText(text);
}
void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
painter->setClipping(true);
painter->setClipRect(option->rect);
painter->setRenderHint(QPainter::SmoothPixmapTransform);
QPixmap canvas(option->rect.size());
QPainter canvasPainter;
canvas.fill(Qt::transparent);
canvasPainter.begin(&canvas);
canvasPainter.setFont(font());
canvasPainter.drawRect(option->rect.adjusted(0, 0, -1, -1));
canvasPainter.drawText(option->rect, toPlainText());
painter->drawPixmap(0, 0, canvas);
}
};
int main(int argc, char *argv[])
{
QApplication app(argc,argv);
QGraphicsView view;
auto *t = new MovingFrameText("human");
view.setScene(new QGraphicsScene(&view));
view.setAlignment(Qt::AlignLeft | Qt::AlignTop);
view.setSceneRect(0, 0, 640, 680);
view.scene()->addItem(t);
view.show();
auto *moveAnimation = new QVariantAnimation();
moveAnimation->setDuration(10000);
moveAnimation->setStartValue(QPointF(640, 680));
moveAnimation->setEndValue(QPointF(0, 0));
moveAnimation->start(QAbstractAnimation::DeleteWhenStopped);
QObject::connect(moveAnimation, &QVariantAnimation::valueChanged, [t](const QVariant &value){
t->setPos(value.toPointF());
t->update();
});
return app.exec();
}
关于c++ - 带有框架的 QGraphicsTextItem 的 QPropertyAnimation 使文本不稳定,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/52853322/