思路
首先我们先获取到当前桌面的完整图片，然后将其放到一个全屏的透明窗口之中，之后，我们在窗口上进行绘制矩形操作，然后获取到绘制的区域即可。
核心代码
新建一个screenview的界面，设置为全屏窗口模式
setWindowState(Qt::WindowActive|Qt::WindowFullScreen);
获取到桌面的完成图片，保存图片，之前我们已经知道如何获取全屏图片。
screen =QGuiApplication::primaryScreen(); if(const QWindow *window=windowHandle()) screen=window->screen(); if(!screen) return ; originalPixmap=screen->grabWindow(0);
重写四个方法paintEvent，mousePressEvent，mouseMoveEvent，mouseReleaseEvent，后面的3个鼠标方法，我们主要用来获取鼠标的位置，以便能够在绘制方法里头绘制出矩形区域。
//截图 void screenview::paintEvent(QPaintEvent *event){ painter.begin(this); painter.setPen(QPen(Qt::red,2)); painter.drawPixmap(0,0,originalPixmap); if(sx>=0&&sy>=0) { painter.drawRect(QRect(sx,sy,ex-sx,ey-sy)); } painter.end(); } void screenview::mousePressEvent(QMouseEvent *event) { if(event->button()==Qt::LeftButton){ sx=event->x(); sy=event->y(); startpoint=event->pos(); } update(); } void screenview::mouseMoveEvent(QMouseEvent *event){ ex=event->x(); ey=event->y(); endpoint=event->pos(); update(); } void screenview::mouseReleaseEvent(QMouseEvent *event){ this->close(); ex=event->x(); ey=event->y(); //获取到区域截图 sourcePixmap=originalPixmap.copy(sx*Scale,sy*Scale,(ex-sx)*Scale,(ey-sy)*Scale); }
完整代码
//screenview.h #ifndef SCREENVIEW_H #define SCREENVIEW_H #include <QWidget> #include <QPainter> #include <QScreen> #include <QWindow> #include <QPixmap> #include <QMouseEvent> #include <QRubberBand> #include <QDateTime> #include <QLabel> #include "editwindow.h" #include "mainwindow.h" //添加 class QRubberBand; namespace Ui { class screenview; } class screenview : public QWidget { Q_OBJECT public: screenview(QWidget *parent = nullptr,QList<QRect> *ListRect=nullptr,int screentype=0); ~screenview(); protected: void paintEvent(QPaintEvent *event); void mousePressEvent(QMouseEvent *event); void mouseMoveEvent(QMouseEvent *event); protected slots: void mouseReleaseEvent(QMouseEvent *event); void receiveData(QString str); //接收传递过来的数据的槽 private: Ui::screenview *ui; QPainter painter; QPixmap originalPixmap; QPixmap sourcePixmap; QScreen *screen; QRubberBand *rubberBand; QPoint startpoint; QPoint endpoint; //记录鼠标位置 int sx,sy,ex,ey; //记录矩形的大小 int rw,rh; //截图类型 int shottype; //固定截图的坐标 int fixedx,fixedy; //固定大小的矩形 QRect fixedRect; //窗口放大倍数 float Scale; //保存所有的矩形 QList<QRect> *ListRect; //当前选中的窗口 QRect CurrentWindow; signals: void senddata(QPixmap sourcePixmap); }; #endif // SCREENVIEW_H
#include "screenview.h" #include "ui_screenview.h" screenview::screenview(QWidget *parent,QList<QRect> *listRect,int screentype) :QWidget(parent),ui(new Ui::screenview) { ui->setupUi(this); rubberBand=NULL; shottype=screentype; screen =QGuiApplication::primaryScreen(); if(const QWindow *window=windowHandle()) screen=window->screen(); if(!screen) return ; originalPixmap=screen->grabWindow(0); //全屏窗口 setWindowState(Qt::WindowActive|Qt::WindowFullScreen); //解决只有鼠标按下时才捕捉鼠标移动 setMouseTracking(true); //获取系统设置的显示比例 float swidth=this->width(); float rwidth=originalPixmap.width(); Scale=rwidth/swidth; ListRect=listRect; } screenview::~screenview() { delete ui; } //截图 void screenview::paintEvent(QPaintEvent *event){ painter.begin(this); painter.setPen(QPen(Qt::red,2)); painter.drawPixmap(0,0,originalPixmap); if(shottype==1) { //固定窗口截图 rw=300; rh=200; int fixx=(ex-rw/2)>0?(ex-rw/2):0; int fixy=(ey-rh/2)>0?(ey-rh/2):0; fixedRect=QRect(fixx,fixy,rw,rh); painter.drawRect(fixedRect); painter.setPen(QPen(Qt::black,2)); painter.drawText(fixx,fixy+rh+10,"F2调整大小"); }else if(shottype==0) { if(sx>=0&&sy>=0) { painter.drawRect(QRect(sx,sy,ex-sx,ey-sy)); } } painter.end(); } void screenview::mousePressEvent(QMouseEvent *event) { if(event->button()==Qt::LeftButton){ sx=event->x(); sy=event->y(); startpoint=event->pos(); if(shottype==1){ this->close(); sourcePixmap=originalPixmap.copy(fixedRect.x()*Scale,fixedRect.y()*Scale,fixedRect.width()*Scale,fixedRect.height()*Scale); emit senddata(sourcePixmap); } else if(shottype==2){ this->close(); sourcePixmap=originalPixmap.copy(CurrentWindow.x()*Scale,CurrentWindow.y()*Scale,CurrentWindow.width()*Scale,CurrentWindow.height()*Scale); emit senddata(sourcePixmap); } } update(); } void screenview::mouseMoveEvent(QMouseEvent *event){ ex=event->x(); ey=event->y(); endpoint=event->pos(); update(); } void screenview::mouseReleaseEvent(QMouseEvent *event){ this->close(); ex=event->x(); ey=event->y(); sourcePixmap=originalPixmap.copy(sx*Scale,sy*Scale,(ex-sx)*Scale,(ey-sy)*Scale); //将获取到的图片内容发送到编辑窗口，可以直接保存到本地即可 emit senddata(sourcePixmap); }
