如何从中裁剪 QLabel 中的图像以进行舍入？

Posted 2023-02-18

【中文标题】如何从中裁剪 QLabel 中的图像以进行舍入？

【英文标题】：How do I get a crop an image in a QLabel from it to be rounded?

【发布时间】：2021-08-02 19:53:27

【问题描述】：

我已经尝试使用 QLabelborder-radius : 5px; 将其包含在样式表中，但我一直得到相同的 Result

这是我为生成该窗口而编写的代码：

userPreview::userPreview(QString username, QString image_path)

this->setFixedSize(200,80);
this->setStyleSheet("background : rgb(42,45,49); border-radius : 2px; border : 2px; border-color : (90,92,95);");

name = new QLabel(username, this);
name->move(90,30);
name->setStyleSheet("color : rgb(255,255,255); font-weight : bold; text-transform : uppercase;");

image = new QLabel(this);
image->setPixmap(QPixmap(image_path).scaled(40,40));
image->move(20,20);
image->setStyleSheet("border-radius : 5px;");

我如何修改它以使图像变圆？提前感谢任何试图帮助我的人:-)

【参考方案1】：

可以在paintEvent() 中使用painter.setClipPath(const QPainterPath&) 轻松实现为自定义QWidget。

////////////////////////// roundedlabel.h

#ifndef ROUNDEDLABEL_H
#define ROUNDEDLABEL_H

#include <QWidget>

class RoundedLabel : public QWidget

    Q_OBJECT
public:
    explicit RoundedLabel(QWidget *parent = nullptr);
    void setPixmap(const QPixmap& pixmap);
    void setBorderRadius(int value);
    QSize sizeHint() const;

protected:
    void paintEvent(QPaintEvent *event);
    int mBorderRadius;
    QPixmap mPixmap;
;

#endif // ROUNDEDLABEL_H

////////////////////////// roundedlabel.cpp

#include "roundedlabel.h"

#include <QPainter>
#include <QPainterPath>

RoundedLabel::RoundedLabel(QWidget *parent) : QWidget(parent), mBorderRadius(0)




void RoundedLabel::setPixmap(const QPixmap &pixmap)

    mPixmap = pixmap;
    updateGeometry();
    update();


void RoundedLabel::setBorderRadius(int value)

    mBorderRadius = value;
    update();


void RoundedLabel::paintEvent(QPaintEvent *event)

    if (mPixmap.isNull()) 
        return;
    
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing);
    QRect r = this->rect();
    int radius = mBorderRadius;
    QPainterPath clipPath;
    clipPath.moveTo(radius, 0);
    clipPath.arcTo(r.right() - radius, 0, radius, radius, 90, -90);
    clipPath.arcTo(r.right() - radius, r.bottom() - radius, radius, radius, 0, -90);
    clipPath.arcTo(r.left(), r.bottom() - radius, radius, radius, 270, -90);
    clipPath.arcTo(r.left(), r.top(), radius, radius, 180, -90);
    clipPath.closeSubpath();
    painter.setClipPath(clipPath);
    painter.drawPixmap(QPoint(0,0),mPixmap);


QSize RoundedLabel::sizeHint() const

    return mPixmap.isNull() ? QSize(40,40) : mPixmap.size();


////////////////////////// main.cpp

#include <QApplication>
#include <QVBoxLayout>
#include "roundedlabel.h"

int main(int argc, char *argv[])

    QApplication a(argc, argv);

    QString image_path = ":/images/photo.png";

    RoundedLabel* label = new RoundedLabel();
    label->setPixmap(QPixmap(image_path).scaled(40,40));
    label->setBorderRadius(5);

    QWidget widget;
    QVBoxLayout* layout = new QVBoxLayout();
    layout->addWidget(label, 0, Qt::AlignCenter);
    widget.setLayout(layout);
    widget.setStyleSheet("background : rgb(42,45,49); border-radius : 2px; border : 2px; border-color : (90,92,95);");
    widget.show();
    widget.setGeometry(QRect(widget.pos(), QSize(200,100)));

    return a.exec();

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