Setting polygonal clip boundary for a raster image

By Balaji Ramamoorthy

Here is a sample ObjectARX code to set the clip boundary of a raster image based on a selected polyline.

// Select a closed polyline that defines the clip boundary
ads_name name2; 
ads_point pt2; 
 
int nReturn = acedEntSel(_T("nSelect a closed polylinen"), name2, pt2); 
 
if(nReturn != RTNORM) 
    return; 
 
//get the object Id of the entity 
AcDbObjectId Id2; 
if(acdbGetObjectId(Id2, name2) != Acad::eOk) 
    return; 
 
//open the selected entity 
AcDbEntity *pEntity2 = NULL; 
if(acdbOpenAcDbEntity(pEntity2, Id2, AcDb::kForRead) != Acad::eOk) 
    return; 
 
AcDbPolyline *pPline = AcDbPolyline::cast(pEntity2); 
if(pPline == NULL) 
    return;
 
 
AcDbExtents exts;
pPline->bounds(exts); 
AcGePoint3d minPt = exts.minPoint();
AcGePoint3d maxPt = exts.maxPoint();
AcGeVector3d vecx = (maxPt.x - minPt.x) * AcGeVector3d::kXAxis;
AcGeVector3d vecy = (maxPt.y - minPt.y) * AcGeVector3d::kYAxis;
 
AcGePoint2dArray ptRect; 
int numVerts = pPline->numVerts();
for(int i = 0; i < numVerts; i++)
{
    AcGePoint2d pt;
    pPline->getPointAt(i, pt);
    ptRect.append( pt); 
} 
AcGePoint2d ptBase( ptRect[0] ); 
ptRect.append( ptBase );
 
// Select a raster image
ads_name name1; 
ads_point pt3; 
 
nReturn = acedEntSel(_T("nSelect a raster imagen"), name1, pt3); 
 
if(nReturn != RTNORM) 
    return; 
 
//get the object Id of the entity 
AcDbObjectId Id1; 
if(acdbGetObjectId(Id1, name1) != Acad::eOk) 
    return; 
 
//open the selected entity 
AcDbEntity *pEntity1 = NULL; 
if(acdbOpenAcDbEntity(pEntity1, Id1, AcDb::kForWrite) != Acad::eOk) 
    return; 
 
AcDbRasterImage *pImage = AcDbRasterImage::cast(pEntity1); 
if(pImage == NULL) 
    return;
 
// Set the clip boundary of the raster image
AcGeMatrix3d mat; 
pImage->getPixelToModelTransform(mat); 
mat = mat.inverse(); 
 
for(int i=0;i < ptRect.length();i++ ) 
{ 
        AcGePoint3d pt = AcGePoint3d( ptRect[i].x, ptRect[i].y,0.0 ); 
        pt = mat*pt;      
        ptRect.setAt(i, AcGePoint2d(pt.x, pt.y)); 
} 
 
pImage->setClipBoundary( AcDbRasterImage::kPoly, ptRect ); 
pImage->setDisplayOpt( AcDbRasterImage::kShow, Adesk::kTrue ); 
pImage->setDisplayOpt( AcDbRasterImage::kClip, Adesk::kTrue ); 
pImage->setDisplayOpt( AcDbRasterImage::kShowUnAligned, Adesk::kTrue ); 
pImage->setDisplayOpt( AcDbRasterImage::kTransparent, Adesk::kTrue ); 
pImage->close();