MATLAB®

Getting Interfaces to the Object

IUnknown and IDispatch Interfaces

When you invoke the actxserver or actxcontrol functions, the MATLAB software creates the server and returns a handle to the server interface as a means of accessing its properties and methods. The software uses the following process to determine which handle to return:

1. First get a handle to the IUnknown interface from the component. All COM components are required to implement this interface.

2. Attempt to get the IDispatch interface. If IDispatch is implemented, return a handle to this interface. If IDispatch is not implemented, return the handle to IUnknown.

Additional Interfaces

Components often provide additional interfaces, based on IDispatch, that are implemented as properties. Like any other property, you obtain these interfaces using the MATLAB get function.

For example, a Microsoft Excel component contains numerous interfaces. To list these interfaces, along with Excel properties, type:

h = actxserver('excel.application');
h.get

MATLAB displays information similar to:

    Application: [1x1 Interface.Microsoft_Excel_9.0_
Object_Library._Application]
        Creator: 'xlCreatorCode'
         Parent: [1x1 Interface.Microsoft_Excel_9.0_
Object_Library._Application]
     ActiveCell: []
    ActiveChart: [1x50 char]
                 .
                 .

To see if Workbooks is an interface, type:

w = h.Workbooks

MATLAB displays:

w =
   Interface.Microsoft_Excel_9.0_Object_Library.Workbooks

The information displayed depends on the version of the Excel software you have on your system.

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Custom Interfaces

The following client/server configurations support interface:

• MATLAB Client and In-Process Server

• MATLAB Client and Out-of-Process Server

Note   The MATLAB COM Interface does not support invoking functions with optional parameters.

Once you have created the server, you can query the server component to see if any custom interfaces are implemented using the interfaces function. interfaces returns the names in a cell array of strings.

For example, if you have a component with the ProgID mytestenv.calculator, you can see its custom interfaces using the commands:

h = actxserver('mytestenv.calculator');
customlist = h.interfaces

MATLAB displays the interfaces, which might be:

customlist =
   ICalc1
   ICalc2
   ICalc3

To get the handle to a particular interface, use the invoke function

c1 = h.invoke('ICalc1')
c1 =
   Interface.Calc_1.0_Type_Library.ICalc_Interface

Use this handle c1 to access the properties and methods of the object through this custom interface ICalc1.

For example, to list the properties, use:

c1.get
     background: 'Blue'
         height: 10
          width: 0

To list the methods, use:

c1.invoke
   Add = double Add(handle, double, double)
   Divide = double Divide(handle, double, double)
   Multiply = double Multiply(handle, double, double)
   Subtract = double Subtract(handle, double, double)

To add and multiply numbers using the Add and Multiply methods of the object, use:

sum = c1.Add(4, 7)
sum =
    11

prod = c1.Multiply(4, 7)
prod =
    28

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Using Events

Saving Your Work