first step

monitor.cpp

@@ -0,0 +1,17 @@
+#include "monitor.h"
+#include <QPainter>
+
+Monitor::Monitor(QWidget *parent) : QWidget(parent)
+{
+    resize(800, 600);
+}
+
+void Monitor::paintEvent(QPaintEvent *) {
+    QPainter painter(this);
+    painter.drawLine(80, 100, 650, 500);
+    painter.setPen(Qt::red);
+    painter.drawRect(10, 10, 100, 400);
+    painter.setPen(QPen(Qt::green, 5));
+    painter.setBrush(Qt::blue);
+    painter.drawEllipse(50, 150, 400, 200);
+}