Ordering an image rendered by a single thread is now possible.

client/main_window.cpp

@@ -2,13 +2,16 @@
 #include <QPixmap>
 #include <QPushButton>
 #include <QDebug>
+#include <QVBoxLayout>
 #include <Magick++.h>
 #include <string>
 
 main_window::main_window(unsigned int port, QWidget* parent) :
-    port(port), QWidget(parent)
+    QWidget(parent), socket(nullptr), port(port) 
 {
-    mandel_image = new QImage(1064, 800, QImage::Format_RGB30);
+    mandel_image = new QImage;
+
+    QVBoxLayout* layout = new QVBoxLayout(this);
 
     scene = new QGraphicsScene(this);
     scene->setSceneRect(0, 0, 1064, 800);
@@ -23,10 +26,17 @@ main_window::main_window(unsigned int port, QWidget* parent) :
 
     QPushButton* img_btn = new QPushButton("Show image", this);
     connect(img_btn, &QPushButton::clicked, this, &main_window::show_image);
+    layout->addWidget(img_btn);
+
+    QPushButton* rnd_btn = new QPushButton("Render image", this);
+    connect(rnd_btn, &QPushButton::clicked, this, &main_window::send_img_render);
+    layout->addWidget(rnd_btn);
 
     server = new mandel_tcp_server(this);
     connect(server, &QTcpServer::newConnection, this, &main_window::handle_new_connection);
     server->listen(QHostAddress::Any, port);
+
+    setLayout(layout);
 }
 
 main_window::~main_window()
@@ -40,6 +50,16 @@ void main_window::show_image()
     view->show();
 }
 
+void main_window::send_img_render()
+{
+    if (!socket)
+        return;
+
+    // Send an image request to the server.
+    data_packet rnd_packet(op_codes::RENDER_IMG, 0, nullptr);
+    socket->send_data_packet(rnd_packet);
+}
+
 void main_window::handle_new_connection()
 {
     socket = server->nextPendingConnection();
@@ -54,6 +74,8 @@ void main_window::handle_new_connection()
 void main_window::handle_socket_close()
 {
     socket->deleteLater();
+    socket = nullptr;
+
     // If we lose the cluster process we start listening again.
     server->listen(QHostAddress::Any, port);
 }
@@ -74,7 +96,10 @@ void main_window::handle_recv_data()
 
             mandel_image->loadFromData((const uchar*) blob.data(), blob.length());
             item->setPixmap(QPixmap::fromImage(*mandel_image));
+            break;
         }
+        default:
+            qDebug() << "Unrecognised op code received: " << static_cast<quint32>(packet->get_op_code());
     }
     
     delete packet;

client/main_window.h

@@ -29,6 +29,7 @@ class main_window : public QWidget
 
     public slots:
         void show_image();
+        void send_img_render();
 
     private slots:
         void handle_new_connection();

network/data_packet.cpp

@@ -16,17 +16,17 @@ data_packet::~data_packet()
     payload = nullptr;
 }
 
-op_codes data_packet::get_op_code()
+op_codes data_packet::get_op_code() const
 {
     return static_cast<op_codes>(op_code);
 }
 
-uint data_packet::get_payload_size()
+uint data_packet::get_payload_size() const
 {
     return payload_size;
 }
 
-const char* data_packet::get_payload()
+const char* data_packet::get_payload() const
 {
     return payload;
 }

network/data_packet.h

@@ -16,9 +16,9 @@ class data_packet
         data_packet(quint32 op_code, uint payload_size, char* payload);
         ~data_packet();
 
-        op_codes get_op_code();
-        uint get_payload_size();
-        const char* get_payload();
+        op_codes get_op_code() const;
+        uint get_payload_size() const;
+        const char* get_payload() const;
 
     private:
         quint32 op_code;

server/main.cpp

@@ -39,8 +39,6 @@ int main(int argc, char** argv)
                                  .iterations = ITERATIONS }; 
 
     mandel_render_srv srv(settings, "192.168.1.2", PORT, id, procs, nullptr);
-    srv.start_drawing();
-
 
     int exit_code = app.exec();
     MPI_Finalize();

server/mandel_render_srv.cpp

@@ -15,7 +15,10 @@ mandel_render_srv::mandel_render_srv(mandel_settings settings, std::string host,
 {
     // We only let the root process connect to the client.
     if (id == 0)
+    {
         socket = new mandel_socket(host.c_str(), port, this);
+        connect(socket, &mandel_socket::packet_ready, this, &mandel_render_srv::handle_recv_data);
+    }
     else
         socket = nullptr;
 }
@@ -79,8 +82,27 @@ void mandel_render_srv::root_process_handling(unsigned long *receive_buffer)
 
     std::string enc_img = image_data.base64();
     char* data = new char[enc_img.size() + 1];
-    memcpy(data, enc_img.c_str(), enc_img.size() + 1);
+    memcpy(data, enc_img.c_str(), enc_img.size());
+    data[enc_img.size()] = '\0';
 
     data_packet packet(op_codes::IMG_DATA, enc_img.size() + 1, data);
     socket->send_data_packet(packet);
 }
+
+void mandel_render_srv::handle_recv_data()
+{
+    data_packet* packet = socket->get_next_packet();
+
+    switch (packet->get_op_code())
+    {
+        case op_codes::RENDER_IMG:
+        {
+            start_drawing();
+            break;
+        }
+        default:
+            qDebug() << "Unrecognised op code received: " << static_cast<quint32>(packet->get_op_code());
+    }
+    
+    delete packet;
+}

server/mandel_render_srv.h

@@ -20,6 +20,9 @@ class mandel_render_srv : public QObject
         const int procs;
 
         mandel_socket* socket;
+
+    private slots:
+            void handle_recv_data();
 };
 
 #endif