Qt: OpenIGTLink: add an option to vertically flip the streamed image

Author: ClaudioHoffmann

examples/solum_qt/solum/openigtlink.cpp

@@ -47,6 +47,11 @@ void SolumIGTL::setNodeName(const QString &name)
     nodeName_ = name.toStdString();
 }
 
+void SolumIGTL::setFlip(bool flip)
+{
+    flip_ = flip;
+}
+
 void SolumIGTL::sendImage(const void* img, int w, int h, int bpp, size_t sz)
 {
     if (!isClientConnected())
@@ -69,9 +74,27 @@ void SolumIGTL::sendImage(const void* img, int w, int h, int bpp, size_t sz)
     // Also necessary to force a repack below.
     msg_->SetMessageID(msg_->GetMessageID() + 1);
 
-    // Even C++23 does not have output ranges anyway...
-    // (https://thephd.dev/output-ranges)
-    memcpy(msg_->GetScalarPointer(), img, sz);
+    if (flip_)
+    {
+        // Copy the image upside down
+        const auto stride = (w * (bpp / 8));
+        auto* dst_row = reinterpret_cast<std::byte *>(msg_->GetScalarPointer());
+        const auto* src_row = (
+            reinterpret_cast<const std::byte *>(img) + sz - stride
+        );
+        for (int y = 0; y < h; y++)
+        {
+            memcpy(dst_row, src_row, stride);
+            dst_row += stride;
+            src_row -= stride;
+        }
+    }
+    else
+    {
+        // Even C++23 does not have output ranges anyway...
+        // (https://thephd.dev/output-ranges)
+        memcpy(msg_->GetScalarPointer(), img, sz);
+    }
 
     msg_->Pack();
     if (client_->Send(msg_->GetPackPointer(), msg_->GetPackSize()) == 0)

examples/solum_qt/solum/openigtlink.h

@@ -15,6 +15,7 @@ class SolumIGTL : public QObject
     void close();
 
     void setNodeName(const QString& name);
+    void setFlip(bool flip);
     void sendImage(const void* img, int w, int h, int bpp, size_t sz);
 
     bool isServing() const;
@@ -32,6 +33,7 @@ class SolumIGTL : public QObject
     igtl::Socket::Pointer client_;
     QTimer clientConnectTimer_;
     std::string nodeName_;
+    bool flip_ = false;
 
     // Sharing an allocation for all images of the same size.
     igtl::ImageMessage::Pointer msg_;

examples/solum_qt/solum/solumqt.cpp

@@ -75,6 +75,7 @@ Solum::Solum(QWidget *parent) : QMainWindow(parent), imaging_(false)
         ui_.igtlport->setText(igtlport);
     auto igtlnode = settings_->value("OpenIGTLink/node").toString();
     ui_.igtlnode->setText(igtlnode.isEmpty() ? "Ultrasound" : igtlnode);
+    igtl_.setFlip(settings_->value("OpenIGTLink/flip").toBool());
 
     ui_.certtable->setColumnCount(4);
     ui_.certtable->setHorizontalHeaderLabels({tr("Serial number"),
@@ -1137,3 +1138,10 @@ void Solum::onIGTLServe()
         ui_.igtlserve->setText(tr("Serve"));
     }
 }
+
+void Solum::onIGTLFlip(int check)
+{
+    const auto value = (check == Qt::Checked);
+    igtl_.setFlip(value);
+    settings_->setValue("OpenIGTLink/flip", value);
+}

examples/solum_qt/solum/solumqt.h

@@ -273,6 +273,7 @@ public slots:
     void tgcMid(int);
     void tgcBottom(int);
     void onIGTLServe();
+    void onIGTLFlip(int check);
 
 private:
     QString bleConnectedProbe_;     ///< serial of the probe connected via BLE

examples/solum_qt/solum/solumqt.ui

@@ -1009,9 +1009,16 @@ After clicking the button, wait for the SSID to be published via BLE, then conne
           </property>
          </widget>
         </item>
-        <item row="1" column="1" colspan="2">
+        <item row="1" column="1">
          <widget class="QLineEdit" name="igtlnode"/>
         </item>
+        <item row="1" column="2">
+         <widget class="QCheckBox" name="igtlflip">
+          <property name="text">
+           <string>Flip vertically</string>
+          </property>
+         </widget>
+        </item>
         <item row="2" column="0" colspan="3">
          <layout class="QGridLayout">
           <item row="0" column="0">
@@ -1550,6 +1557,22 @@ After clicking the button, wait for the SSID to be published via BLE, then conne
     </hint>
    </hints>
   </connection>
+  <connection>
+   <sender>igtlflip</sender>
+   <signal>stateChanged(int)</signal>
+   <receiver>Solum</receiver>
+   <slot>onIGTLFlip(int)</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>20</x>
+     <y>20</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>20</x>
+     <y>20</y>
+    </hint>
+   </hints>
+  </connection>
  </connections>
  <slots>
   <slot>onTcpConnect()</slot>
@@ -1581,5 +1604,6 @@ After clicking the button, wait for the SSID to be published via BLE, then conne
   <slot>onAutoFocus(int)</slot>
   <slot>onFocus(int)</slot>
   <slot>onIGTLServe()</slot>
+  <slot>onIGTLFlip(int)</slot>
  </slots>
 </ui>