topic Re: VP transparency in VBA Forum

VP transparency

jeremye86 — Tue, 29 Dec 2020 13:18:04 GMT

Is it possible to change the VP transparency of a layer? LISP, vba or whatever code?

Re: VP transparency

stefanveurink68AXD — Mon, 04 Jan 2021 11:44:08 GMT

Don't think this is possible in vba, but in .net api it must be possible.

reason i say this is with .net api is also possible to change vplineweight, vpcolor, so surely vptransparency must be there too.

only possible way i see in vba is by maybe using a dictionary. but dont know anything about this.

Re: VP transparency

norman.yuan — Mon, 04 Jan 2021 15:16:14 GMT

As @stefanveurink68AXD pointed out, with AutoCAD .NET API, you can write code to do it via LayerViewportProperties class.

While there is no direct API support with AutoCAD COM API/VBA, if you really have to do it in VBA, you have to dig into undocumented ExtensionDictionary of AcadLayer object. Something like:

1. Test if an AcadLayer has ExtensionDictionary or not;

2. If it has, test if the dictionary has key "ADSK_XREC_LAYER_ALPHA_OVR" (the other 2 keys for layer's viewport overrides are "ADSK_XREC_LAYER_LINETYPE_OVR" and "ADSK_XREC_LAYER_LINEWT_OVR");

3. If the key exists, get the value of the dictionary item (Xrecord) form that key;

4. Parse the Xrecord to find the Alpha value (0-255) of the transparency applied to specific viewport;

5. Change the Alpha value in the Xrecord as needed

Again, since it is not exposed via API/not documented, it is up to you to investigate how the data are stored in ExtensionDictionary and parse/change it correctly.