AutoCAD DevBlog

When using Editor.SelectAll(), how can I filter entities on frozen layers out? (.NET)

By Marat Mirgaleev

Issue

If I call Editor.SelectAll(), will it return only entities currently visible on the screen?

Solution

No, Editor.SelectAll() returns also entities, which are placed on frozen layers. In our program we need to check whether an entity's layer is frozen. Here is a sample:

[CommandMethod("_SANF")]

public static void SelectAllExceptFrozenLayers()

{

  Document doc = Application.DocumentManager.MdiActiveDocument;

  Editor ed = doc.Editor;

  PromptSelectionResult selection = ed.SelectAll();

  if (selection.Status == PromptStatus.OK)

  {

    using (Transaction tr =

                doc.Database.TransactionManager.StartTransaction())

    {

      foreach (ObjectId id in selection.Value.GetObjectIds())

      {

        Entity ent = (Entity)tr.GetObject(id, OpenMode.ForRead);

        LayerTableRecord layer = (LayerTableRecord)tr.GetObject(

                                    ent.LayerId, OpenMode.ForRead);

        if (!layer.IsFrozen)

          ed.WriteMessage("\n{0}", ent.ToString());

      }

      tr.Commit();

    } // using

  } // if

} // SelectAllExceptFrozenLayers()

Entity.GeometricExtents throws an exception (eNullExtents)

By Marat Mirgaleev

Issue

When I calculate the extents of entities in a drawing, for some entities an exception is thrown with the "eNullExtents" message. What is wrong?

Solution

This exception occurs for an insert of an empty block or for an empty block attribute. It is "as designed", it's just a notification to the developer about an empty object. An easy solution is to add a separate catch block for this particular exception:

      Extents3d extents;

      try

      {

        extents = pEntity.GeometricExtents;

      }

      catch (Autodesk.AutoCAD.Runtime.Exception ex)

      {

        if (ex.Message == "eNullExtents")

        // The entity is empty and has no extents

        {

          // TODO. We can simply skip this entity...

        }

        else

        //  something is wrong ...

          TODO!

      }

Create a copy of the current document into a new document

By Xiaodong Liang

Issue
How can I have an identical copy of the current document and create it as a new document?

Solution
One of the solution is to create a temporary drawing template file from the current database first, then create a new drawing with the template. Then delete it if necessary. Here is an outline of required steps followed by a code fragment.

1. Wblock the current open drawing.
2. Save the wblocked drawing as a template file (with a DWT extension) to a temporary location on your hard drive.
3. From the application context create a NEW document using the previously saved template file.
4. If necessary, 'remove' the temporary template file from your hard drive.

//help fuction: create a new document

void newDocHelper(void *pData)

{

   AcApDocument* pDoc = acDocManager->curDocument();

   if (acDocManager->isApplicationContext())

   {

    acDocManager->appContextNewDocument((const ACHAR *)pData);

   }

   else

   {

    acutPrintf(L"\nERROR: in Document context : %s\n",pDoc->fileName());

   }

} 

// Please note, here we are using "C:/temp.dwt" as a location

// for our temporary template file. Please change this location

// to suit your requirements as appropriate.

  void copydwg()

{

   // TODO: Implement the command

   AcDbDatabase *pDb = NULL;

   AcDbDatabase *pnewDb = NULL;

 

    pDb = acdbHostApplicationServices()->workingDatabase();

   assert( pDb != NULL );

 

   if( pDb->wblock(pnewDb) != Acad::eOk ) {

    acutPrintf(L"Couldn't wblock.\n");

    return;

   }

 

   if( pnewDb->saveAs(L"C:/temp.dwt") != Acad::eOk) {

    acutPrintf(L"Couldn't saveAs C:/temp.dwt file.\n");

    delete pnewDb;

    return;

   } 

   delete pnewDb;  

   static wchar_t pData[] = L"c:/temp.dwt";

   acDocManager->executeInApplicationContext(newDocHelper, (void *)pData); 

   // 'remove' is a C function to delete a file and its syntax is

    //int remove(const wchar_t *path );

     remove("c:/temp.dwt");

}

NOTE: Do not register this command with flag 'ACRX_CMD_SESSION' because
AcDbDatabase::wblock() will fail in this context.

AcGeVector3d::angleTo()

By Xiaodong Liang

Issue
The method AcGeVector3d::angleTo(
                                                  const AcGeVector3d &vec,
                                                  const AcGeVector3d&  refVec)  is described as follows in the ARXREF.HLP:

"Returns the angle between this vector and the vector 'vec' in the range [0, 2 * PI]; If ( refVec.dotProduct(crossProduct(vec)) >= 0.0 ) the return value coincides with the return value of the function angleTo( vec ). Otherwise the return value is 2*PI minus the return value of the function angleTo( vec )."

What exactly is meant when passing as refVec?

Solution

According to the online documentation, there are two overloaded functions for angleTo().

One is:

double AcGeVector3d::angleTo( const AcGeVector3d& vec) const;

Returns the angle between this vector and the vector vec in the range [0, Pi].

Another is:

double AcGeVector3d::angleTo(
                    const AcGeVector3d& vec,
                    const AcGeVector3d& refVec) const;

Returns the angle between this vector and the vector vec in the range [0, 2 x  Pi]. If (refVec.dotProduct(crossProduct(vec)) >= 0.0), then the return value  coincides with the return value of the function angleTo(vec). Otherwise, the  return value is 2 x Pi minus the return value of the function angleTo(vec). Therefore, the return angle's range is different. That's exactly why the refVec  is needed. Dot Product, as you know, is a method to find out how parallel two
lines are. The result of the calculation is a scalar. This is most useful if you  use unit vectors (get a number between -1 and 1), such as our usage here  (vectors).

|x1| |x2|

|y1| . |y2| = (x1 * x2) + (y1 * y2) + (z1 * z2)

|z1| |z2|

Cross Product is the process of multiplying two vectors together to get a  normal to the plane they describe with the Vector (0,0,0).

|x1| |x2| |y1*z2 - z1*y2|

|y1| x |y2| = |z1*x2 - x1*z2|

|z1| |z2| |x1*y2 - y1*x2|

Therefore, in the code,

refVec.dotProduct(crossProduct(vec))

it first checks the angle between the normal (for the plane which 'this' vector  and 'vec' vector is on) and the refVec. As it states, if
(refVec.dotProduct(crossProduct(vec)) >= 0.0), then the return value coincides with the return value of the function angleTo(vec). Otherwise the return value is 2 x Pi minus the return value of the function angleTo(vec). You can actually use the normal vector for the plane that 'this' vector is on,  as the refVec, to check the 'vec'. Of course, you can choose other vectors that  are not the same as the normal vector depends on your application needs.

How to convert AcGeMatrix3d to VARIANT

By Gopinath Taget

AcAxMatrix3d converts VARIANT to AcGeMatrix3d but not vice-versa. How can I do the reverse conversion?

The code below does the conversion from AcGeMatrix3d to VARIANT:

HRESULT GetVariantFromMatrix(VARIANT* pVal, AcGeMatrix3d mat)

{

 // Declare our Variant to be an array of doubles.

pVal->vt = VT_ARRAY | VT_R8;

 

SAFEARRAYBOUND rgsaBound[2];// 2 dimensional array...

rgsaBound[0].lLbound = 0L;// First dimension size is 4

rgsaBound[0].cElements = 4;

rgsaBound[1].lLbound = 0L;// Second dimension size is 4

rgsaBound[1].cElements = 4;

 

pVal->parray = SafeArrayCreate(VT_R8, 2, &rgsaBound[0]);// Create the VARIANT

 if (! pVal->parray)

  return E_OUTOFMEMORY;

 

 // Now populate it.

HRESULT hr;

 long i[2];

 for (i[0]=0;i[0]<4;i[0]++)

  for(i[1]=0;i[1]<4;i[1]++)

   if (hr = SafeArrayPutElement(pVal->parray, &i[0],

    (void*)&mat.operator()(i[0],i[1])) != S_OK)

    return hr;

 

 return S_OK;

}

Quick tip: Getting extended entity data from an xref'ed drawing

By Gopinath Taget

An xref'ed DWG file is like an INSERT for AutoCAD. This means that AutoCAD loads the xref'ed DWG file into a AcDbBlockTableRecord (block definition) in the current drawing. Therefore, if XDATA was attached to a line in the XREF drawing
file, a copy of that line (with XDATA) is present in the block definition. In this case, iterate the block definition to retrieve the XDATA information.

Calling an AutoLISP function if the function name is a string?

By Gopinath Taget

This can be achieved by using (eval (list (read "string"))). Here is some sample code:

(defun adts_function ()
   (princ "\nDeveloper Technical Services")
   (princ)
)
(defun c:test ()
   (setq fname "adts_function")
   (eval (list (read fname)))
  
)
(prompt "\nCommand c:test defined")
(princ)

Convert AcGePoint3d to ads_point and vice versa

By Gopinath Taget

There is a function named 'asDblArray()' that casts AcGePoint3d to ads_point wherever it is necessary.

The following sample code demonstrates this:

#include "geassign.h"

AcGePoint3d pt;

acedGetPoint (NULL, L"Get a point: ",asDblArray (pt)) ;

If you want to convert from ads_point to AcGePoint3d, use its complimenting function, 'asPnt3d()'.

How to convert an AcGeCircArc3d to an AcDbArc and vice versa?

By Gopinath Taget

The following ARX code does this:

void convertArc2Arc( AcGeCircArc3d*pGeArc, AcDbArc*&pDbArc )

{

AcGePoint3d center = pGeArc->center();

AcGeVector3d normal = pGeArc->normal();

AcGeVector3d refVec = pGeArc->refVec();

AcGePlane plane = AcGePlane(center, normal);

 double ang = refVec.angleOnPlane(plane);

pDbArc = new AcDbArc(center, normal,

  pGeArc->radius(),pGeArc->startAng() + ang,

  pGeArc->endAng() + ang );

}

 

void convertArc2Arc( AcDbArc*pDbArc, AcGeCircArc3d*&pGeArc)

{

pGeArc = new AcGeCircArc3d(

pDbArc->center(),

pDbArc->normal(),

pDbArc->normal().perpVector(),

pDbArc->radius(),

pDbArc->startAngle(),

pDbArc->endAngle());

}

create the tooltip for a bitmap button

By Xiaodong Liang

Issue

I have created a CAcUiBitmapButton. How do I create the tooltip text that
displays when the cursor is placed over the button?

Solution

CAcUiBitmapButton has implemented everything necessary for doing this; you only need to provide the tooltip string within the caption, such as SAMP|Sample Button1.

Notice the SAMP before the vertical bar is the bitmap's resource ID name. This is when you design the dialog button and set the properties. Also, make sure you choose owner draw style for the button.

In addition, you can create multiple lines of tooltip by overriding OnGetTipText() and modifying the reference parameter to the text string you want.

To test these approaches, the attached sample application has two separate buttons; one uses CAcUiBitmapButton and the other is derived from CAdUiOwnerDrawButton. In addition, it shows how to draw a text button that changes it appearance when it is clicked. Note that this approach also applies to all CAxUiWhatever control classes, such as CAcUiColorComboBox, CAcUiAngleComboBox, CAcUiAngleEdit, and so on.

Download Create_tooltip_bitmap_button_VS2008