音视频学习 - Qt6.3.1版本下实现屏幕截图功能

一、主要参考

Qt项目中，实现屏幕截图功能的模块详细实现（可通用）_guaiwenshang889的博客-CSDN博客_qt实现窗口截图截屏https://blog.csdn.net/guaiwenshang889/article/details/125582942

Qt项目中，实现屏幕截图功能的模块详细实现（可通用） - 知乎总第52篇屏幕截图功能，在很多软件中都有使用。本文主要梳理一下这个功能的实现，方便在以后的项目中快速移植，对于这方面不太熟悉的，也可以参考一下其实现方式。 程序的实现效果图，见文章末尾。 头文件主要包含…https://zhuanlan.zhihu.com/p/212230990         不过其中兼容QT5的几句代码被删除掉了，我这里用不到。 

二、QDesktopWidget被废弃

        QDesktopWidget被废弃了，使用QGuiApplication替代。

//获取设备屏幕大小
QRect screenRect = QGuiApplication::primaryScreen()->geometry();
//获取设备像素比
double devicePixelRatio = QGuiApplication::primaryScreen()->devicePixelRatio();
int screenW = screenRect.width();
int screenH = screenRect.height();

三、参考代码

1、头文件

        和参考博客基本差别不大。头文件主要包含两个类，一个是截屏对象类，另一个是截屏窗口类，在截屏窗口中调用截屏对象。

#ifndef SCREEN_H
#define SCREEN_H

#include <QWidget>
#include <QMenu>
#include <QPoint>
#include <QSize>

//截屏对象类
class Screen
{
public:
    enum STATUS {SELECT, MOV, SET_W_H};
    Screen() {}
    Screen(QSize size);

    void setStart(QPoint pos);
    void setEnd(QPoint pos);
    QPoint getStart();
    QPoint getEnd();

    QPoint getLeftUp();
    QPoint getRightDown();

    STATUS getStatus();
    void setStatus(STATUS status);

    int width();
    int height();
    bool isInArea(QPoint pos);          // 检测pos是否在截图区域内
    void move(QPoint p);                // 按 p 移动截图区域

private:
    QPoint leftUpPos, rightDownPos;     //记录 截图区域 左上角、右下角
    QPoint startPos, endPos;            //记录 鼠标开始位置、结束位置
    int maxWidth, maxHeight;            //记录屏幕大小
    STATUS status;                      //三个状态: 选择区域、移动区域、设置width height

    void cmpPoint(QPoint &s, QPoint &e);//比较两位置，判断左上角、右下角
};

//截屏窗口类
class ScreenWidget : public QWidget
{
    Q_OBJECT
public:
    static ScreenWidget *Instance();
    explicit ScreenWidget(QWidget *parent = 0);

private:
    static QScopedPointer<ScreenWidget> self;
    QMenu *menu;            //右键菜单对象
    Screen *screen;         //截屏对象
    QPixmap *fullScreen;    //保存全屏图像
    QPixmap *bgScreen;      //模糊背景图
    QPoint movPos;          //坐标

protected:
    void contextMenuEvent(QContextMenuEvent *);
    void mousePressEvent(QMouseEvent *);
    void mouseMoveEvent(QMouseEvent *);
    void mouseReleaseEvent(QMouseEvent *);
    void paintEvent(QPaintEvent *);
    void showEvent(QShowEvent *);

private slots:
    void saveScreen();
    void saveFullScreen();
    void saveScreenOther();
    void saveFullOther();
};

#endif // SCREEN_H

2、cpp文件

        基本和参考的博客差不多，主要修改了ScreenWidget和showEvent方法。

        （1）ScreenWidget方修改了获取屏幕大小的方式。

QSize size(QGuiApplication::primaryScreen()->geometry().width(), QGuiApplication::primaryScreen()->geometry().height());
screen = new Screen(size);

        （2）showEvent方法主要修改了获取设备像素比，免得再高分辨率设备下截图有问题。

double devicePixelRatiovalue = QGuiApplication::primaryScreen()->devicePixelRatio();
qDebug()<<"设备像素比:"<<devicePixelRatiovalue;

QScreen *pscreen = QApplication::primaryScreen();
*fullScreen = pscreen->grabWindow(0/*this->winId()*/, 0, 0, screen->width()/devicePixelRatiovalue, screen->height()/devicePixelRatiovalue);

         完整代码

#include "Screen.h"
#include "qevent.h"
#include <QMutex>
#include <QApplication>
#include <QPainter>
#include <QFileDialog>
#include <QEvent>
#include <QDateTime>
#include <QStringList>
#include <QScreen>

#define STRDATETIME qPrintable (QDateTime::currentDateTime().toString("yyyy-MM-dd-HH-mm-ss"))

Screen::Screen(QSize size)
{
    maxWidth = size.width();
    maxHeight = size.height();

    startPos = QPoint(-1, -1);
    endPos = startPos;
    leftUpPos = startPos;
    rightDownPos = startPos;
    status = SELECT;
}

int Screen::width()
{
    return maxWidth;
}

int Screen::height()
{
    return maxHeight;
}

Screen::STATUS Screen::getStatus()
{
    return status;
}

void Screen::setStatus(STATUS status)
{
    this->status = status;
}

void Screen::setEnd(QPoint pos)
{
    endPos = pos;
    leftUpPos = startPos;
    rightDownPos = endPos;
    cmpPoint(leftUpPos, rightDownPos);
}

void Screen::setStart(QPoint pos)
{
    startPos = pos;
}

QPoint Screen::getEnd()
{
    return endPos;
}

QPoint Screen::getStart()
{
    return startPos;
}

QPoint Screen::getLeftUp()
{
    return leftUpPos;
}

QPoint Screen::getRightDown()
{
    return rightDownPos;
}

bool Screen::isInArea(QPoint pos)
{
    if (pos.x() > leftUpPos.x() && pos.x() < rightDownPos.x() && pos.y() > leftUpPos.y() && pos.y() < rightDownPos.y()) {
        return true;
    }

    return false;
}

void Screen::move(QPoint p)
{
    int lx = leftUpPos.x() + p.x();
    int ly = leftUpPos.y() + p.y();
    int rx = rightDownPos.x() + p.x();
    int ry = rightDownPos.y() + p.y();

    if (lx < 0) {
        lx = 0;
        rx -= p.x();
    }

    if (ly < 0) {
        ly = 0;
        ry -= p.y();
    }

    if (rx > maxWidth)  {
        rx = maxWidth;
        lx -= p.x();
    }

    if (ry > maxHeight) {
        ry = maxHeight;
        ly -= p.y();
    }

    leftUpPos = QPoint(lx, ly);
    rightDownPos = QPoint(rx, ry);
    startPos = leftUpPos;
    endPos = rightDownPos;
}

void Screen::cmpPoint(QPoint &leftTop, QPoint &rightDown)
{
    QPoint l = leftTop;
    QPoint r = rightDown;

    if (l.x() <= r.x()) {
        if (l.y() <= r.y()) {
            ;
        } else {
            leftTop.setY(r.y());
            rightDown.setY(l.y());
        }
    } else {
        if (l.y() < r.y()) {
            leftTop.setX(r.x());
            rightDown.setX(l.x());
        } else {
            QPoint tmp;
            tmp = leftTop;
            leftTop = rightDown;
            rightDown = tmp;
        }
    }
}

QScopedPointer<ScreenWidget> ScreenWidget::self;
ScreenWidget *ScreenWidget::Instance()
{
    if (self.isNull()) {
        static QMutex mutex;
        QMutexLocker locker(&mutex);
        if (self.isNull()) {
            self.reset(new ScreenWidget);
        }
    }

    return self.data();
}

ScreenWidget::ScreenWidget(QWidget *parent) : QWidget(parent)
{
    menu = new QMenu(this);
    menu->addAction("保存当前截图", this, SLOT(saveScreen()));
    menu->addAction("保存全屏截图", this, SLOT(saveFullScreen()));
    menu->addAction("截图另存为", this, SLOT(saveScreenOther()));
    menu->addAction("全屏另存为", this, SLOT(saveFullOther()));
    menu->addAction("退出截图", this, SLOT(hide()));

    //取得屏幕大小
    QSize size(QGuiApplication::primaryScreen()->geometry().width(), QGuiApplication::primaryScreen()->geometry().height());
    screen = new Screen(size);
    //保存全屏图像
    fullScreen = new QPixmap();
}

void ScreenWidget::paintEvent(QPaintEvent *)
{
    int x = screen->getLeftUp().x();
    int y = screen->getLeftUp().y();
    int w = screen->getRightDown().x() - x;
    int h = screen->getRightDown().y() - y;

    QPainter painter(this);

    QPen pen;
    pen.setColor(Qt::green);
    pen.setWidth(2);
    pen.setStyle(Qt::DotLine);
    painter.setPen(pen);
    painter.drawPixmap(0, 0, *bgScreen);

    if (w != 0 && h != 0) {
        painter.drawPixmap(x, y, fullScreen->copy(x, y, w, h));
    }

    painter.drawRect(x, y, w, h);

    pen.setColor(Qt::yellow);
    painter.setPen(pen);
    painter.drawText(x + 2, y - 8, tr("截图范围：( %1 x %2 ) - ( %3 x %4 )  图片大小：( %5 x %6 )").arg(x).arg(y).arg(x + w).arg(y + h).arg(w).arg(h));
}

void ScreenWidget::showEvent(QShowEvent *)
{
    QPoint point(-1, -1);
    screen->setStart(point);
    screen->setEnd(point);

    double devicePixelRatiovalue = QGuiApplication::primaryScreen()->devicePixelRatio();
    qDebug()<<"设备像素比:"<<devicePixelRatiovalue;

    QScreen *pscreen = QApplication::primaryScreen();
    *fullScreen = pscreen->grabWindow(0/*this->winId()*/, 0, 0, screen->width()/devicePixelRatiovalue, screen->height()/devicePixelRatiovalue);

    //设置透明度实现模糊背景
    QPixmap pix(screen->width(), screen->height());
    pix.fill((QColor(160, 160, 160, 50)));
    bgScreen = new QPixmap(*fullScreen);
    QPainter p(bgScreen);
    p.drawPixmap(0, 0, pix);
}

void ScreenWidget::saveScreen()
{
    int x = screen->getLeftUp().x();
    int y = screen->getLeftUp().y();
    int w = screen->getRightDown().x() - x;
    int h = screen->getRightDown().y() - y;

    QString fileName = QString("%1/screen_%2.png").arg(qApp->applicationDirPath()).arg(STRDATETIME);
    fullScreen->copy(x, y, w, h).save(fileName, "png");
    close();
}

void ScreenWidget::saveFullScreen()
{
    QString fileName = QString("%1/full_%2.png").arg(qApp->applicationDirPath()).arg(STRDATETIME);
    fullScreen->save(fileName, "png");
    close();
}

void ScreenWidget::saveScreenOther()
{
    QString name = QString("%1.png").arg(STRDATETIME);
    QString fileName = QFileDialog::getSaveFileName(this, "保存图片", name, "png Files (*.png)");
    if (!fileName.endsWith(".png")) {
        fileName += ".png";
    }

    if (fileName.length() > 0) {
        int x = screen->getLeftUp().x();
        int y = screen->getLeftUp().y();
        int w = screen->getRightDown().x() - x;
        int h = screen->getRightDown().y() - y;
        fullScreen->copy(x, y, w, h).save(fileName, "png");
        close();
    }
}

void ScreenWidget::saveFullOther()
{
    QString name = QString("%1.png").arg(STRDATETIME);
    QString fileName = QFileDialog::getSaveFileName(this, "保存图片", name, "png Files (*.png)");
    if (!fileName.endsWith(".png")) {
        fileName += ".png";
    }

    if (fileName.length() > 0) {
        fullScreen->save(fileName, "png");
        close();
    }
}

void ScreenWidget::mouseMoveEvent(QMouseEvent *e)
{
    if (screen->getStatus() == Screen::SELECT) {
        screen->setEnd(e->pos());
    } else if (screen->getStatus() == Screen::MOV) {
        QPoint p(e->position().x() - movPos.x(), e->position().y() - movPos.y());
        screen->move(p);
        movPos = e->pos();
    }

    this->update();
}

void ScreenWidget::mousePressEvent(QMouseEvent *e)
{
    int status = screen->getStatus();

    if (status == Screen::SELECT) {
        screen->setStart(e->pos());
    } else if (status == Screen::MOV) {
        if (screen->isInArea(e->pos()) == false) {
            screen->setStart(e->pos());
            screen->setStatus(Screen::SELECT);
        } else {
            movPos = e->pos();
            this->setCursor(Qt::SizeAllCursor);
        }
    }

    this->update();
}

void ScreenWidget::mouseReleaseEvent(QMouseEvent *)
{
    if (screen->getStatus() == Screen::SELECT) {
        screen->setStatus(Screen::MOV);
    } else if (screen->getStatus() == Screen::MOV) {
        this->setCursor(Qt::ArrowCursor);
    }
}

void ScreenWidget::contextMenuEvent(QContextMenuEvent *)
{
    this->setCursor(Qt::ArrowCursor);
    menu->exec(cursor().pos());
}

3、调用代码

        代码中的p是最底层窗口的指针，先从最底层将窗口最小化，然后再显示截图层。

void TextRecognition::on_pushButton_3_clicked()
{
    //截图之前隐去窗体，不然截图之中就会有窗体的存在
    if(p->windowState() != Qt::WindowMinimized )
    {
         p->setWindowState( Qt::WindowMinimized );//最小化父窗体
    }

    //延时等待父窗体最小化 延时250毫秒
    QTime _Timer = QTime::currentTime().addMSecs(250);
    while( QTime::currentTime() < _Timer )
    {
        QCoreApplication::processEvents(QEventLoop::AllEvents, 100);
    }

    ScreenWidget::Instance()->showFullScreen();
}

4、示意图片