From 776c0bd72091a49afe165fb666833daf5c6544cb Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Sun, 9 Oct 2016 22:16:21 +0200
Subject: [PATCH] fix crash when creating a second view and closing the first
 view while the dragger task panel is open

---
 src/Gui/SoFCCSysDragger.cpp | 39 ++++++++++++++++++++++---------------
 src/Gui/SoFCCSysDragger.h   |  1 -
 2 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/src/Gui/SoFCCSysDragger.cpp b/src/Gui/SoFCCSysDragger.cpp
index 52e69a5b5836..9eedb61916c2 100644
--- a/src/Gui/SoFCCSysDragger.cpp
+++ b/src/Gui/SoFCCSysDragger.cpp
@@ -910,7 +910,6 @@ void SoFCCSysDragger::setUpAutoScale(SoCamera *cameraIn)
     //note: sofieldsensor checks if the current sensor is already attached
     //and takes appropriate action. So it is safe to attach to a field without
     //checking current attachment state.
-    camera = cameraIn;
     if (cameraIn->getTypeId() == SoOrthographicCamera::getClassTypeId())
     {
         SoOrthographicCamera *localCamera = dynamic_cast<SoOrthographicCamera *>(cameraIn);
@@ -943,28 +942,36 @@ void SoFCCSysDragger::cameraCB(void *data, SoSensor *)
 void SoFCCSysDragger::idleCB(void *data, SoSensor *)
 {
     SoFCCSysDragger *sudoThis = reinterpret_cast<SoFCCSysDragger *>(data);
-    assert(sudoThis->camera);
-
-    SbMatrix localToWorld = sudoThis->getLocalToWorldMatrix();
-    SbVec3f origin;
-    localToWorld.multVecMatrix(SbVec3f(0.0, 0.0, 0.0), origin);
-
-    SbViewVolume viewVolume = sudoThis->camera->getViewVolume();
-    float radius = sudoThis->draggerSize.getValue() / 2.0;
-    float localScale = viewVolume.getWorldToScreenScale(origin, radius);
-    SbVec3f scaleVector(localScale, localScale, localScale);
-    SoScale *localScaleNode = SO_GET_ANY_PART(sudoThis, "scaleNode", SoScale);
-    localScaleNode->scaleFactor.setValue(scaleVector);
-    sudoThis->autoScaleResult.setValue(localScale);
+    SoField* field = sudoThis->cameraSensor.getAttachedField();
+    if (field)
+    {
+        SoCamera* camera = static_cast<SoCamera*>(field->getContainer());
+        SbMatrix localToWorld = sudoThis->getLocalToWorldMatrix();
+        SbVec3f origin;
+        localToWorld.multVecMatrix(SbVec3f(0.0, 0.0, 0.0), origin);
+
+        SbViewVolume viewVolume = camera->getViewVolume();
+        float radius = sudoThis->draggerSize.getValue() / 2.0;
+        float localScale = viewVolume.getWorldToScreenScale(origin, radius);
+        SbVec3f scaleVector(localScale, localScale, localScale);
+        SoScale *localScaleNode = SO_GET_ANY_PART(sudoThis, "scaleNode", SoScale);
+        localScaleNode->scaleFactor.setValue(scaleVector);
+        sudoThis->autoScaleResult.setValue(localScale);
+    }
 }
 
 void SoFCCSysDragger::finishDragCB(void *data, SoDragger *)
 {
     SoFCCSysDragger *sudoThis = reinterpret_cast<SoFCCSysDragger *>(data);
 
-    if (sudoThis->camera)
+    // note: when creating a second view of the document and then closing
+    // the first viewer it deletes the camera. However, the attached field
+    // of the cameraSensor will be detached automatically.
+    SoField* field = sudoThis->cameraSensor.getAttachedField();
+    if (field)
     {
-        if (sudoThis->camera->getTypeId() == SoPerspectiveCamera::getClassTypeId())
+        SoCamera* camera = static_cast<SoCamera*>(field->getContainer());
+        if (camera->getTypeId() == SoPerspectiveCamera::getClassTypeId())
             cameraCB(sudoThis, nullptr);
     }
 }
diff --git a/src/Gui/SoFCCSysDragger.h b/src/Gui/SoFCCSysDragger.h
index 8d33c3e5cf1d..d21ee310d544 100644
--- a/src/Gui/SoFCCSysDragger.h
+++ b/src/Gui/SoFCCSysDragger.h
@@ -207,7 +207,6 @@ class GuiExport SoFCCSysDragger : public SoDragger
 
     SoIdleSensor idleSensor; //!< might be overkill, but want to make sure of performance.
     void setUpAutoScale(SoCamera *cameraIn); //!< used to setup the auto scaling of dragger.
-    SoCamera *camera = nullptr; //!< don't assign directly! use setUpAutoScale.
     
     //! @name Visibility Functions
     //@{