如何使用 QPainter 缩放文本以适应边界框?
How to scale text to fit inside a bounding box with QPainter?
我需要在盒子上画一个标签。
理想情况下,我会根据框的大小缩放标签,但我不确定是否有任何内置功能可以进行这种缩放。
目前我正在将对象缩放到边界框的高度,但我不确定如何实现宽度缩放,因为绘制文本的宽度取决于符号的特定顺序(由于字距)。
这种缩放是否有一些内置功能?
void total_control_roi_item::paint(QPainter * painter, const QStyleOptionGraphicsItem * option, QWidget * widget)
{
QGraphicsRectItem::paint(painter, option, widget);
painter->save();
const auto rect = boundingRect();
auto font = painter->font();
auto height_of_box = rect.height()*0.7;
font.setPointSizeF(height_of_box);
painter->setFont(font);
const auto label = QString("%1").arg(id_);
painter->drawText(rect, label, Qt::AlignHCenter | Qt::AlignVCenter);
painter->restore();
}
您可以使用QFontMetrics的信息进行文字升级。
#include <QtWidgets>
class RectItem: public QGraphicsRectItem
{
public:
using QGraphicsRectItem::QGraphicsRectItem;
void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) override
{
const QString id_ = "Stack Overflow";
const auto label = QString("%1").arg(id_);
QGraphicsRectItem::paint(painter, option, widget);
if(label.isEmpty()) return;
const auto rect = boundingRect();
QFontMetrics fm(painter->font());
qreal sx = rect.width()*1.0/fm.width(id_);
qreal sy = rect.height()*1.0/fm.height();
painter->save();
painter->translate(rect.center());
painter->scale(sx, sy);
painter->translate(-rect.center());
painter->drawText(rect, label, Qt::AlignHCenter | Qt::AlignVCenter);
painter->restore();
}
};
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QGraphicsScene scene;
QGraphicsView w(&scene);
scene.addItem(new RectItem(0, 0, 300, 200));
w.resize(640, 480);
w.show();
return a.exec();
}
我需要在盒子上画一个标签。
理想情况下,我会根据框的大小缩放标签,但我不确定是否有任何内置功能可以进行这种缩放。
目前我正在将对象缩放到边界框的高度,但我不确定如何实现宽度缩放,因为绘制文本的宽度取决于符号的特定顺序(由于字距)。
这种缩放是否有一些内置功能?
void total_control_roi_item::paint(QPainter * painter, const QStyleOptionGraphicsItem * option, QWidget * widget)
{
QGraphicsRectItem::paint(painter, option, widget);
painter->save();
const auto rect = boundingRect();
auto font = painter->font();
auto height_of_box = rect.height()*0.7;
font.setPointSizeF(height_of_box);
painter->setFont(font);
const auto label = QString("%1").arg(id_);
painter->drawText(rect, label, Qt::AlignHCenter | Qt::AlignVCenter);
painter->restore();
}
您可以使用QFontMetrics的信息进行文字升级。
#include <QtWidgets>
class RectItem: public QGraphicsRectItem
{
public:
using QGraphicsRectItem::QGraphicsRectItem;
void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) override
{
const QString id_ = "Stack Overflow";
const auto label = QString("%1").arg(id_);
QGraphicsRectItem::paint(painter, option, widget);
if(label.isEmpty()) return;
const auto rect = boundingRect();
QFontMetrics fm(painter->font());
qreal sx = rect.width()*1.0/fm.width(id_);
qreal sy = rect.height()*1.0/fm.height();
painter->save();
painter->translate(rect.center());
painter->scale(sx, sy);
painter->translate(-rect.center());
painter->drawText(rect, label, Qt::AlignHCenter | Qt::AlignVCenter);
painter->restore();
}
};
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QGraphicsScene scene;
QGraphicsView w(&scene);
scene.addItem(new RectItem(0, 0, 300, 200));
w.resize(640, 480);
w.show();
return a.exec();
}