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不删除组件的Qt绘图

qt c++

BUY · 技术社区 · 6 年前

有办法吗。现在,按钮被删除,我只有椭圆。如果有人能指导我,我会很高兴的。

提前谢谢。

这是我的.h文件:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private:
    Ui::MainWindow *ui;

protected:
    void paintEvent(QPaintEvent *e);
    void setBackGroundColorToBlack();
};

#endif // MAINWINDOW_H

这是我的.cpp文件:

#include "mainwindow.h"
#include "ui_mainwindow.h"

#include <QtGui>
    MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    setBackGroundColorToBlack();
}

MainWindow::~MainWindow()
{
    delete ui;
}


void MainWindow::paintEvent(QPaintEvent *event) {
    setUpdatesEnabled(false);
    QPainter painterObj;
    painterObj.begin(this);
    painterObj.setPen(QPen(Qt::green, 2, Qt::SolidLine, Qt::RoundCap));
    painterObj.drawEllipse(0, 0, 318, 390);//456
    painterObj.drawEllipse(53, 65, 212, 260);//304
    painterObj.drawEllipse(106, 130, 106, 130);//152

    painterObj.end();
}



void MainWindow::setBackGroundColorToBlack() {
    QPalette pal = palette();

    // set black background
    pal.setColor(QPalette::Background, Qt::black);
    this->setAutoFillBackground(true); // This enables the qt to fill the         background before the paint event.
    this->setPalette(pal);
    //update();
}

我的用户界面文件如下:

1 回复 | 直到 6 年前

Kuba hasn't forgotten Monica 6 年前

一般来说-不要使用 QMainWindows QDialog 甚至只是 QWidget . 你可以自己画背景,所以不需要弄乱托盘。下面是最简单的例子。如果 Bar

// https://github.com/KubaO/stackoverflown/tree/master/questions/painted-with-children-51498155
// This project is compatible with Qt 4 and Qt 5
#include <QtGui>
#if QT_VERSION >= QT_VERSION_CHECK(5,0,0)
#include <QtWidgets>
#endif

QRectF scaled(const QRectF &rect, qreal scale) {
   auto const center = rect.center();
   auto const w = rect.width()*scale;
   auto const h = rect.height()*scale;
   return {center.x() - w/2.0, center.y() - h/2.0, w, h};
}

QRectF marginAdded(const QRectF &rect, qreal margin) {
   return rect.adjusted(margin, margin, -margin, -margin);
}

const char buttonQSS[] =
      "* { background-color: white; border-width: 2px; border-style:solid; border-color: red;"
      "    border-radius: 3px; padding: 3px; }"
      "*:pressed { padding-left: 5px; padding-top: 5px; background-color: lightGray; }";

class MyWindow : public QWidget {
   Q_OBJECT
   QPushButton m_restoreButton{"Restore Size"};
   QPushButton m_otherButton{"Bar"};
   QGridLayout m_layout{this};
   Q_SLOT void onRestore() { resize(sizeHint()); }
public:
   explicit MyWindow(QWidget *parent = {}) : QWidget(parent) {
      setAttribute(Qt::WA_OpaquePaintEvent);
      m_layout.addItem(new QSpacerItem(0, 100, QSizePolicy::Minimum, QSizePolicy::MinimumExpanding), 0, 0);
      m_layout.addWidget(&m_restoreButton, 1, 0);
      m_layout.addWidget(&m_otherButton, 1, 1);
      m_restoreButton.setStyleSheet(buttonQSS);
      connect(&m_restoreButton, SIGNAL(clicked(bool)), SLOT(onRestore()));
   }
protected:
   void paintEvent(QPaintEvent *) override {
      qreal const penWidth = 2.0;
      // Cover the area above all the children
      QRectF const area = marginAdded(QRect(0, 0, width(), childrenRect().top() - 10), penWidth);
      QPainter p(this);
      p.fillRect(rect(), Qt::black);
      p.setPen({Qt::green, penWidth});
      p.drawEllipse(scaled(area, 3./3.));
      p.drawEllipse(scaled(area, 2./3.));
      p.drawEllipse(scaled(area, 1./3.));
   }
   QSize sizeHint() const override { return {320, 568}; /* iPhone 5 */ }
};

int main(int argc, char *argv[])
{
   QApplication a(argc, argv);
   MyWindow w;
   w.show();
   return a.exec();
}
#include "main.moc"