qt-course/drawing/exer681-polygon/MyWidget.cpp

   1 #include <QPainter>
   2 #include <QPolygon>
   3
   4 #include "MyWidget.h"
   5
   6 MyWidget::MyWidget(QWidget *parent)
   7 : QWidget(parent)
   8 {
   9 }
  10
  11 MyWidget::~MyWidget()
  12 {
  13 }
  14
  15 void MyWidget::paintEvent(QPaintEvent *event)
  16 {
  17         QPainter p(this);
  18
  19         if (m_points.size() == 1) {
  20                 // draw only one Point
  21                 p.drawPoint(m_points[0]);
  22                 return;
  23         }
  24
  25         // draw the Polygon
  26         QPolygon poly(m_points);
  27         p.setBrush(Qt::green);
  28         p.setRenderHints(QPainter::Antialiasing, true);
  29         p.drawPolygon(poly);
  30 }
  31
  32 void MyWidget::mousePressEvent(QMouseEvent *event)
  33 {
  34         if (event->button() == Qt::LeftButton)
  35                 m_points.append(event->pos());
  36         else if (event->button() == Qt::RightButton)
  37                 m_points.clear();
  38         else
  39                 return;
  40
  41         update();
  42 }