Add ball deletion logic

src/ball.cpp

@@ -1,6 +1,8 @@
 #include "ball.h"
+#include <QDebug>
 #include <QRect>
 #include <QWidget>
+#include <qglobal.h>
 #include <random>
 
 #define RADIUS 15
@@ -41,15 +43,19 @@ void Ball::timerEvent(QTimerEvent*) {
     }
     // Bottom collision (only if no longer spawning)
     if (!m_isSpawning && m_y > rct.height() - RADIUS) {
-        // TODO: Destroy ball
+        emit deleted(this);
+        stop();
+        m_parent->update();
+        return;
     }
 
     m_x += m_kx;
     m_y += m_ky;
 
-    // Once we get into the window, we're no longer "spawning"
-    if (m_isSpawning && m_y < rct.width() - RADIUS)
+    // Once we get above half point of the window, we're no longer "spawning"
+    if (m_isSpawning && m_y < rct.height() / 2.0 - RADIUS) {
         m_isSpawning = false;
+    }
 
     // Update the window
     m_parent->update();

src/ball.h

@@ -3,13 +3,19 @@
 
 #include <QPainter>
 #include <QTimer>
+#include <qobjectdefs.h>
 
 class Ball : public QTimer {
+    Q_OBJECT
+
   public:
     Ball(QWidget* parent);
 
     void draw(QPainter& painter);
 
+  signals:
+    void deleted(Ball* ball);
+
   protected:
     virtual void timerEvent(QTimerEvent*) override;
 

src/mainwindow.cpp

@@ -1,9 +1,13 @@
 #include "mainwindow.h"
 #include "./ui_mainwindow.h"
+#include <QDebug>
 
 MainWindow::MainWindow(QWidget* parent) : QMainWindow(parent), ui(new Ui::MainWindow) {
     ui->setupUi(this);
-    balls.append(std::make_shared<Ball>(this));
+
+    auto ball = std::make_shared<Ball>(this);
+    connect(ball.get(), &Ball::deleted, this, &MainWindow::onDeleteBall);
+    balls.append(ball);
 }
 
 MainWindow::~MainWindow() {
@@ -22,3 +26,15 @@ void MainWindow::paintEvent(QPaintEvent*) {
         ball->draw(painter);
     }
 }
+
+void MainWindow::onDeleteBall(Ball* ball) {
+    // Remove the ball from the list by checking the raw pointer
+    // This will also free it (smart ptrs).
+    for (auto it = balls.begin(); it != balls.end(); ++it) {
+        if (it->get() == ball) {
+            qDebug() << "Deleting ball";
+            balls.erase(it);
+            break;
+        }
+    }
+}

src/mainwindow.h

@@ -17,6 +17,9 @@ class MainWindow : public QMainWindow {
     MainWindow(QWidget* parent = nullptr);
     ~MainWindow();
 
+  private slots:
+    void onDeleteBall(Ball* ball); // Slot to handle the ball deletion
+
   protected:
     virtual void paintEvent(QPaintEvent*) override;