main.cpp
1 #include <QApplication>
2 #include "mywidget.h"
3
4 int main(int argc, char *argv[]) 5 { 6 QApplication a(argc, argv); 7
8 MyWidget w; 9 w.resize(300, 300); 10 w.show(); 11
12 return a.exec(); 13 }
mywidget.h
1 #ifndef MYWIDGET_H 2 #define MYWIDGET_H
3
4 #include <QWidget>
5 #include <QLabel>
6 #include <QMouseEvent>
7 #include <QLabel>
8
9 class MyWidget : public QWidget 10 { 11 Q_OBJECT 12 public: 13 explicit MyWidget(QWidget *parent = 0); 14
15 QLabel *startLabel; 16 QLabel *ctrlLabel1; 17 QLabel *ctrlLabel2; 18 QLabel *endLabel; 19
20 QLabel *ctrlLabel3; 21 QLabel *ctrlLabel4; 22 QLabel *endLabel2; 23
24 QWidget *selectedWidget; 25
26 private: 27 void paintEvent(QPaintEvent *event); 28 void mousePressEvent(QMouseEvent *event); 29 void mouseMoveEvent(QMouseEvent *event); 30 void mouseReleaseEvent(QMouseEvent *event); 31
32 }; 33
34 #endif // MYWIDGET_H
mywidget.cpp
1 #include "mywidget.h"
2 #include <QPainter>
3 #include <QPainterPath>
4 #include <QDebug>
5
6 MyWidget::MyWidget(QWidget *parent) : 7 QWidget(parent) 8 { 9
10 startLabel=new QLabel(this); 11 startLabel->resize(10, 10); 12 startLabel->setStyleSheet("QLabel{background-color:red;}"); 13 startLabel->move(100, 110); 14
15 ctrlLabel1=new QLabel(this); 16 ctrlLabel1->resize(10, 10); 17 ctrlLabel1->setStyleSheet("QLabel{background-color:green;}"); 18 ctrlLabel1->move(120, 120); 19
20 ctrlLabel2=new QLabel(this); 21 ctrlLabel2->resize(10, 10); 22 ctrlLabel2->setStyleSheet("QLabel{background-color:blue;}"); 23 ctrlLabel2->move(140, 130); 24
25 endLabel=new QLabel(this); 26 endLabel->resize(10, 10); 27 endLabel->setStyleSheet("QLabel{background-color:black;}"); 28 endLabel->move(160, 140); 29
30 ctrlLabel3=new QLabel(this); 31 ctrlLabel3->resize(10, 10); 32 ctrlLabel3->setStyleSheet("QLabel{background-color:yellow;}"); 33 ctrlLabel3->move(180, 150); 34
35 ctrlLabel4=new QLabel(this); 36 ctrlLabel4->resize(10, 10); 37 ctrlLabel4->setStyleSheet("QLabel{background-color:cyan;}"); 38 ctrlLabel4->move(200, 160); 39
40 endLabel2=new QLabel(this); 41 endLabel2->resize(10, 10); 42 endLabel2->setStyleSheet("QLabel{background-color:#AAAAEE;}"); 43 endLabel2->move(220, 170); 44
45 selectedWidget=NULL; 46 } 47
48
49 void MyWidget::paintEvent(QPaintEvent *event) 50 { 51 QPainter painter(this); 52 painter.setPen(Qt::black); 53 painter.drawLine(startLabel->pos(), ctrlLabel1->pos()); 54 painter.drawLine(ctrlLabel2->pos(), endLabel->pos()); 55 painter.drawLine(endLabel->pos(), ctrlLabel3->pos()); 56 painter.drawLine(ctrlLabel4->pos(), endLabel2->pos()); 57
58 QPainterPath myPath; 59 myPath.moveTo(startLabel->pos()); 60 myPath.cubicTo(ctrlLabel1->pos(), ctrlLabel2->pos(), endLabel->pos()); 61 myPath.cubicTo(ctrlLabel3->pos(), ctrlLabel4->pos(), endLabel2->pos()); 62 painter.setPen(Qt::red); 63 painter.drawPath(myPath); 64 } 65
66
67 void MyWidget::mousePressEvent(QMouseEvent *event) 68 { 69 QWidget *w=this->childAt(event->pos()); 70 if(w==NULL) return; 71 if(w->inherits("QLabel")){ 72 selectedWidget=w; 73 } 74 } 75
76 void MyWidget::mouseReleaseEvent(QMouseEvent *event) 77 { 78 selectedWidget=NULL; 79 } 80
81 void MyWidget::mouseMoveEvent(QMouseEvent *event) 82 { 83 if(selectedWidget!=NULL){ 84 selectedWidget->move(event->pos()); 85 this->update(); 86 } 87 }
