Added new qml module for drawing lines

src/lineItem.cpp

@@ -0,0 +1,44 @@
+#include "rqt_demo_plugin/lineItem.hpp"
+#include <qquickitem.h>
+#include <qsgflatcolormaterial.h>
+#include <qsggeometry.h>
+#include <qsgnode.h>
+#include <qsize.h>
+
+LineItem::LineItem(QQuickItem *parent) 
+    : QQuickItem(parent)
+    , stupid_("") 
+{
+    setFlag(ItemHasContents, true);
+}
+
+LineItem::~LineItem() = default;
+
+
+QSGNode *LineItem::updatePaintNode(QSGNode *old, UpdatePaintNodeData *) 
+{
+    QSGGeometryNode *node = nullptr;
+    QSGGeometry *geometry = nullptr;
+
+    if(!old) {
+        node = new QSGGeometryNode;
+        geometry = new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), 4);
+        geometry->setLineWidth(5);
+        geometry->setDrawingMode(QSGGeometry::DrawLines);
+        node->setGeometry(geometry);
+        node->setFlag(QSGNode::OwnsGeometry);
+        auto *material = new QSGFlatColorMaterial;
+        material->setColor(QColor(255,0,0));
+        node->setMaterial(material);
+        node->setFlag(QSGNode::OwnsMaterial);
+
+        QSGGeometry::Point2D *verticies = geometry->vertexDataAsPoint2D();
+        QSizeF s = size();
+        verticies[0].set(0.1 * s.width(), 0.1 * s.height());
+        verticies[1].set(0.75 * s.width(), 0.75 * s.height());
+        verticies[2].set(0.1 * s.width(), 0.9 * s.height());
+        verticies[3].set(0.9 * s.width(), 0.1 * s.height());
+        node->markDirty(QSGNode::DirtyGeometry);
+    }
+    return  node;
+}

src/rqt_demo_plugin.cpp

@@ -1,4 +1,5 @@
 #include "rqt_demo_plugin/rqt_demo_plugin.hpp"
+#include "rqt_demo_plugin/lineItem.hpp"
 
 #include "pluginlib/class_list_macros.hpp"
 #include <qnamespace.h>
@@ -10,4 +11,9 @@ mg::DemoPluginMg::DemoPluginMg() : Plugin() {
   fmt.setSwapInterval(0);
   fmt.setRenderableType(QSurfaceFormat::OpenGLES);
   QSurfaceFormat::setDefaultFormat(fmt);
+  static bool typesRegistered = 0;
+  if(!typesRegistered) {
+    qmlRegisterType<LineItem>("LineItem", 1, 0, "LineItem");
+    typesRegistered = 1;
+  }
 }