From cbe11b4dcd4c3259c11c28f9ab853cb5ddff8b55 Mon Sep 17 00:00:00 2001
From: asv <asv@opencascade.com>
Date: Wed, 22 Dec 2004 11:20:26 +0000
Subject: [PATCH] An improvement on link creation: if a link already exists
 between the ports, then on new link creation it is removed, and new link is
 created.  If link already exists - is important check for Input Gate ports,
 which can accept many incoming links.

---
 src/SUPERVGUI/SUPERVGUI_CanvasView.cxx | 39 ++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/src/SUPERVGUI/SUPERVGUI_CanvasView.cxx b/src/SUPERVGUI/SUPERVGUI_CanvasView.cxx
index ea908fc..0f78023 100644
--- a/src/SUPERVGUI/SUPERVGUI_CanvasView.cxx
+++ b/src/SUPERVGUI/SUPERVGUI_CanvasView.cxx
@@ -532,6 +532,41 @@ void SUPERVGUI_CanvasView::endSketch(SUPERVGUI_CanvasPort* thePort)
     if (SUPERV_isNull(aLinkEngine)) 
       return;    
 
+    // here, in fact, aLinkEngine may NOT be a newly created link.  If a link already existed between the
+    // the 2 given ports - it will be return (NOT created again).
+    // this should be checked and new presentation should NOT be created for existing link.
+    // Solution 1: NOT to allow creation of a link if it already exists between the ports in 
+    //             myLinkBuilder->canCreateEngine()
+    // Solution 2: check here if aLinkEngine is "new" or "old"
+    // Implement 2nd solution, because canCreateEngine() checks for types of ports, etc.. - it's another thing
+    // THE CHECK:
+    QObjectList* canvasLinks = canvas()->queryList("SUPERVGUI_CanvasLink");
+    SUPERVGUI_CanvasLink* canvasLink = 0;
+    QObjectListIt it(*canvasLinks);
+    bool prsAlreadyExists = false;
+    while ( (canvasLink=(SUPERVGUI_CanvasLink*)it.current()) ) {
+      ++it;
+      SUPERV_Link existingLinkWithPrs = canvasLink->getEngine();
+      if ( !SUPERV_isNull( existingLinkWithPrs ) ) {
+	if ( existingLinkWithPrs->IsEqual( aLinkEngine ) ) {
+	  prsAlreadyExists = true;
+	  break;
+	}	
+      }
+    }
+    delete canvasLinks;
+    if ( prsAlreadyExists ) { // aLinkEngine is already bound with a SUPERVGUI_CanvasLink object
+      //return;  // -> if return here, than the old CanvasLink is kept
+
+      // we want to delete old and create a new CanvasLink for this Link
+      delete canvasLink;
+      canvasLink = 0;
+      // clear old corrdinates in Engine link
+      for ( int i = 1; i <= aLinkEngine->CoordsSize(); i++ )
+	aLinkEngine->RemoveCoord( i );
+      // now we are ready to set coords for a link and create a new CanvasLink presentation that will use them.
+    }
+
     myLinkBuilder->setCoords(aLinkEngine.in());
 
     delete myLinkBuilder;
@@ -547,8 +582,8 @@ void SUPERVGUI_CanvasView::endSketch(SUPERVGUI_CanvasPort* thePort)
     if ( !aLinkEngine->IsValid() ) { 
       const int id = QAD_MessageBox::warn2( this, tr( "TLT_INVALID_LINK" ), tr( "MSG_INVALID_LINK" ), 
 					   tr( "Keep" ), tr( "Remove" ), 0, 1, 0 );
-      if ( id == 1 ) { // Remove selected
-	aLink->remove(); // it did not live long...
+      if ( id == 1 ) { // "Remove" was selected in Message Box
+	aLink->remove(); // the new link did not live long...
       }
     }
   }
-- 
2.39.2