From a9b66a4e1287a7228e93c03740fb766b12231764 Mon Sep 17 00:00:00 2001
From: AndreaRigoni <andrea.rigoni@igi.cnr.it>
Date: Wed, 18 Mar 2026 21:44:29 +0000
Subject: [PATCH] add grid annotation

---
 src/Vtk/vtkViewport.cpp | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/Vtk/vtkViewport.cpp b/src/Vtk/vtkViewport.cpp
index ccb1bf7..10e2fea 100644
--- a/src/Vtk/vtkViewport.cpp
+++ b/src/Vtk/vtkViewport.cpp
@@ -55,9 +55,12 @@ void Viewport::SetupPipeline(vtkRenderWindowInteractor* iren)
     m_Annotation->GetTextProperty()->SetFontFamilyToArial();
     m_Annotation->GetTextProperty()->SetOpacity(0.5);
     m_Annotation->SetMaximumFontSize(10);
-    m_Annotation->SetText(0, "uLib VTK Viewer - OpenCMT all right reserved.");
+    m_Annotation->SetText(0, "uLib VTK Viewer - OpenCMT viewer.");
     m_Renderer->AddViewProp(m_Annotation);
 
+    // right corner annotation
+    m_Annotation->SetText(1, "Grid: -");
+
     // Orientation axes marker (bottom-left corner)
     vtkNew<vtkAxesActor> axes;
     m_Marker->SetInteractor(iren);
@@ -376,6 +379,17 @@ void Viewport::UpdateGrid()
     if (m_OriginAxes) {
         m_OriginAxes->SetScaleFactor(spacing);
     }
+
+    // Update annotation for grid size
+    char gridLabel[32];
+    if (spacing >= 1000.0) {
+        sprintf(gridLabel, "Grid: %.0f m", spacing / 1000.0);
+    } else if (spacing >= 10.0) {
+        sprintf(gridLabel, "Grid: %.0f cm", spacing / 10.0);
+    } else {
+        sprintf(gridLabel, "Grid: %.0f mm", spacing);
+    }
+    m_Annotation->SetText(1, gridLabel);
 }