Get image clip boundary coordinates

By Xiaodong Liang

Issue
I can set image’s clip by AcadRasterImage.ClipBoundary, but how do I get the AcadRasterImage's clip boundary coordinates? I know if it is rectangular, I can get its bounding box, width and height. But, if the clip boundary is of a irregular shape, I can't find any exposed methods to get such data.

Solution
The ObjectARX AcDbRasterImage::clipBoundary() equivalent functionality is not exposed in the current ActiveX Automation Model.

We can work around this limitation by exposing an interface that does exactly that. The whole project is attached: 
Download ImgClipBoundary

STDMETHODIMP CClipBoundaryObj::GetImageClipBoundary(
    VARIANT* pVarDblArray, 
    VARIANT acadImage)
{
    // TODO: Add your implementation code here
    try
    {
        CComQIPtr 
            pAcadImage(acadImage.punkVal);
        if(!pAcadImage)
            throw E_POINTER;
        CComQIPtr 
            pBaseObj(pAcadImage);
        if(!pBaseObj)
            throw E_POINTER;
        AcDbObjectId id;
        pBaseObj->GetObjectId(&id);
        AcDbObjectPointer 
            pImage(id, AcDb::kForRead);
 
        if(pImage.openStatus() != Acad::eOk)
            throw E_UNEXPECTED;
        AcGePoint2dArray array =                    pImage->clipBoundary();
 
        int len = array.length();
        if(len == 0)
            throw E_FAIL;
 
        AcGeMatrix3d mat;
        pImage->getPixelToModelTransform(mat);
        mat.inverse();
        AcAxPoint2dArray pts;
        for(int i=0; i

To use the ability above,
1. build the attached project, load it in AutoCAD
2.  open VBA IDE
3. Tools >> Reference: select ARX. now you can see one library is available in the list.

1. Run the VBA code below. It creates an image and set its clip, and gets its clip boundary by the method provided in asdkImgClipBoundary.

Sub Example_ClipBoundary()
    ' This example adds a raster image in model space.
    ' It then clips the image based on a clip boundary.
    ' This example uses the "downtown.jpg" found in the sample
    ' directory. If you do not have the image, or it is located
    ' in a different directory, insert a valid path and name for the
    ' imageName variable below.
    Dim insertionPoint(0 To 2) As Double

    Dim scalefactor As Double
    Dim rotationAngle As Double
    Dim imageName As String
    Dim rasterObj As AcadRasterImage
    imageName = "C:1_SDKObjectARX 2012samplesgraphicsAsdkTransientGraphicsSampFolderAirport-Image.jpg"
    insertionPoint(0) = 5#: insertionPoint(1) = 5#: insertionPoint(2) = 0#
    scalefactor = 2#
    rotationAngle = 0
    On Error Resume Next

    ' Creates a raster image in model space
    Set rasterObj = ThisDrawing.ModelSpace.AddRaster(imageName, insertionPoint, scalefactor, rotationAngle)
    If Err.Description = "Filer error" Then
        MsgBox imageName & " could not be found."
        Exit Sub
    End If
    ZoomAll
    MsgBox "Clip the image?", , "ClipBoundary Example"
    ' Establish the clip boundary with an array of points

    Dim clipPoints(0 To 9) As Double
    clipPoints(0) = 6: clipPoints(1) = 6.75
    clipPoints(2) = 7: clipPoints(3) = 6
    clipPoints(4) = 6: clipPoints(5) = 5
    clipPoints(6) = 5: clipPoints(7) = 6
    clipPoints(8) = 6: clipPoints(9) = 6.75
    ' Clip the image
    rasterObj.ClipBoundary clipPoints
    ' Enable the display of the clip

    rasterObj.ClippingEnabled = True
    ThisDrawing.Regen acActiveViewport
    'MsgBox "The image has been clipped.", , "ClipBoundary Example"
    On Error GoTo 0
    Dim xObj As asdkImgClipBoundaryLib.ClipBoundaryObj
    Set xObj = ThisDrawing.Application.GetInterfaceObject("ImgClipBoundary.ClipBoundaryObj.1")
    Dim boundary As Variant
    xObj.GetImageClipBoundary boundary, rasterObj
End Sub