DADiSP and ActiveX
ActiveX is a broad term that generally refers to a Microsoft binary
standard for sharing code and data between separate programs or
"components". The actual protocol is specified by the Component Object
Model (COM). COM has undergone many upgrades and enhancements since
its original introduction as Object Linking and Embedding (OLE).
ActiveX Automation
One important feature of COM is Automation. Automation allows a
"client" program to control a "server" or component program just as if
the component functionality was built into the client. For example,
DADiSP can fully control Microsoft Word, placing a DADiSP
Worksheet into a document and printing the results all from within
DADiSP. Likewise, a Visual Basic program can hand off data to DADiSP
for processing without DADiSP ever being visible to the user. In this
way, DADiSP acts as a powerful data analysis library for any program
that supports Automation.
ActiveX components generally expose three basic constructs:
- Properties
- Events
- Methods
Properties represent the various settings of the component such as color,
font, size, etc.
Events are notifications the component makes to the client program. Some possible
events are mouse was clicked, canvas was sized,
button was pushed, etc. After receipt of the notification, the client
can respond appropriately.
Methods are functions the client program can direct the component to execute.
DADiSP Automation Server
DADiSP as an ActiveX server or component supports several extremely powerful methods, including:
- Getdata(window or variable)
- Putdata(window or variable, data)
- Execute("command string")
Getdata retrieves data from a DADiSP Window or variable to the client.
For example, here's a Visual Basic code fragment that obtains the series in W2
of a DADiSP Worksheet into a Visual Basic variable:
Dim DADiSP As Object
Set DADiSP = CreateObject("DADiSP.Application")
VbVar = DADiSP.Getdata("W2")
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In this example, Visual Basic acts as the "client" and DADiSP the ActiveX "server".
We declare DADiSP as an ActiveX object with the
Dim DADiSP As Object
declaration.
Visual Basic establishes a connection
to DADiSP with the
Set DADiSP = CreateObject("DADiSP.Application")
statement. The connection is made by checking the Registry for ActiveX components and capabilities.
For faster ActiveX communication, DADiSP also provides a COM "Type Library" (dadisp.tlb) that provides in depth information
on the ActiveX capabilities offered by DADiSP.
Finally,
VbVar = DADiSP.Getdata("W2")
copies the series
or table in W2 into the Visual Basic array VbVar.
ActiveX data transfers are quite flexible and efficient. DADiSP transparently supports
multi-column data using the COM standard SafeArray. Byte, Integer,
Float, and Double scalar values are also supported.
Here's a code fragment that generates a Visual Basic array and then transfers
the array to DADiSP.
For i = 0 To 999
VBData(i) = Rnd()
Next i
Set DADiSP = CreateObject("DADiSP.Application")
Call DADiSP.PutData("W1", VBData)
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You can also "get" or "put" data to a DADiSP variable. For example:
Call DADiSP.PutData("DArray", VBData)
Call DADiSP.PutData("DNum", 12.3)
Vb1 = DADiSP.GetData("DArray")
Vb2 = DADiSP.GetData("DNum")
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Here we transfer an array and a scalar to the DADiSP variables DArray and
DNum and then retrieve the data from DADiSP back to Visual Basic.
The Execute method is perhaps the most powerful.
Execute allows any DADiSP command, including SPL
routines, built-in functions, macros and command files to be executed
from ActiveX. For example, the following code fragment creates a 2
Window Worksheet and generates a 1000 point random series in DADiSP:
Call DADiSP.Execute("NewWorksheet(2, 0)")
Call DADiSP.Execute("Grand(1000,.01)")
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Because Execute accepts any valid DADiSP command as input,
all the features, functions and capabilities of DADiSP are available to
any program that supports ActiveX Automation.
Now for a full example of ActiveX with Visual Basic controlling DADiSP.
We'll use each of the above methods to 1) create data in VB, 2)
transfer it to DADiSP, 3) use DADiSP to process the data and 4)
retrieve the processed result from DADiSP.
Sub DSPTest()
Dim DADiSP As Object
Dim VBData(1000) As Double
For i = 0 To 999
VBData(i) = Rnd()
Next i
Set DADiSP = CreateObject("DADiSP.Application")
Call DADiSP.Execute("NewWorksheet(2, 0)")
Call DADiSP.PutData("W1", VBData)
Call DADiSP.Execute("Label('Data from VB')")
Call DADiSP.Execute("Moveto(W2)")
Call DADiSP.Execute("PSD(Hamming(W1))")
Call DADiSP.Execute("SetyLog(1);GridSol;GridHV")
DADiSP.Visible = 1
newdata = DADiSP.GetData("W2")
End Sub
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To make DADiSP appear on the screen, we set the "visibility" property with:
DADiSP.Visible = 1
You could also
use the DADiSP SETVISIBLE function:
DADiSP.Execute("SetVisible(1)")
DADiSP Automation Client
So far, we've shown examples of controlling DADiSP from Visual Basic. In
this case, Visual Basic is the "client" and DADiSP acts as the
ActiveX "server". However, DADiSP can also function as an ActiveX client to control
and make use of the features of ActiveX servers such as Excel, Word, database
programs or data acquisition drivers.
The DADiSP SPL syntax for ActiveX is very similar to the
Visual Basic syntax mentioned above. For example, to connect to
an ActiveX object, you use the CreateObject function. Properties
can be set and retrieved with standard variable assignments and methods
executed with the "dot" syntax. For example, the following SPL code
fragment connects to Word and makes it visible:
ShowWord()
{
local word;
word = CreateObject("Word.Application");
word.Visible = 1;
}
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DADiSP can access any function exposed by the ActiveX Automation server. For
example, Word has a very elaborate ActiveX hierarchy, consisting of Documents,
Ranges, Tables and a host of other objects all accessible to DADiSP.
Finally, the full SPL example below demonstrates the use of these objects to
create and copy a DADiSP Worksheet to a Word document.
msw()
{
local word, doc;
if (newworksheet(2) == 0) return;
gnorm(1000,.01) * 0.1 + gsin(1000,.01);
setvunits("V");
label("Noisy Sinewave");
moveto(w2);
setxlog(1);
setylog(1);
psd(w1);
copyworksheet();
word = CreateObject("Word.Application");
doc = word.Documents;
range = doc.Add().Range();
word.Selection.PasteSpecial(0, 0, 0, 0, 9);
word.Visible = 1;
}
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In conclusion, ActiveX is a very powerful, standardized means of
sharing the capabilities of separate programs in a flexible and robust manner.
The SPL\ActiveX subdirectory included with your DADiSP distribution provides
several additional examples of using ActiveX with DADiSP.
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