c# - How do I open an already openeded presentation with PresentationDocument.Open() for PowerPoint Add in? -

i have powerpoint add in create, modify , save presentations. specific options opened presentation should stored in presentation file (.pptx) using open xml, when try ioexception:

**system.io.ioexception : process cannot access file 'test.pptx' because being used process.** 

this snippet code:

**

using (presentationdocument pptpackage = presentationdocument.open(filename, true)) { // add options pptx file. } 

**

thank you.

if need read opened presentation using open xml can way:

using (stream stream = new filestream(_filename, filemode.open, fileaccess.read, fileshare.readwrite)) using (presentationdocument pptpackage = presentationdocument.open(stream, false)) {     // read pptx file. } 

but can't change presentation way.