Interacting with External Applications

Transcription

1 Interacting with External Applications DLLs - dynamic linked libraries: Libraries of compiled procedures/functions that applications link to at run time DLL can be updated independently of apps using them A DLL can be shared by several apps at once APIs/SDKs are often provided in the form of DLLs All you have to do is Declare the function that you wish to use, the DLL it is compiled into, and its parameters. Then you can call it directly, just like a native function that you have written yourself: Public Class Form1 Declare Function GetSystemMetrics Lib "User32.DLL" (ByVal n As Integer) As Integer Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load If GetSystemMetrics(19) Then MsgBox("Congratulations, you have a mouse installed!") End Class Windows API (application programming interface): A set of functions available to the Windows application programmer Composed of a few key DLLs that provide fundamental Windows activities The main Win32 (since Windows 95) API DLLs: DLL Name KERNEL32.DLL Description Low-level operating system functions

2 USER32.DLL GDI32.DLL Non-graphical Windows management functions Graphics Device Interface library OLE, COM, ActiveX, VBA These are all closely related Prior to ActiveX technology, two standards were becoming prevalent in Microsoft Windows. One was OLE (Object Linking and Embedding), and the other was COM (Component Object Model). Both schemes were designed for software interoperability, the former focusing on communicating and the latter focusing on implementation. In 1996, Microsoft combined the technologies and refitted them into ActiveX. VBA is Visual Basic For Applications and is the language used when programmatically controlling many OLE/COM/ActiveX servers such as MS Word or Excel VBA is almost exactly the same as VB6 so it will probably become.net-syntax soon To use a.net or COM library, you must add a Reference to it in your project:

3 Public Class Form1 Private Sub btnopeninword_click(byval sender As System.Object, ByVal e As System.EventArgs) Handles btnopeninword.click Dim oword As Word.Application Try ' check to see if Word is already running oword = GetObject(, "Word.Application") Catch ' if it's not, then launch a new instance oword = New Word.Application End Try Dim odoc As Word.Document odoc = oword.documents.add() oword.selection.typetext(textbox1.text) oword.visible = True End Class VBA sometimes still referred to as Macro programming - historical reasons! Automatic code building in Word, Project and Excel - macro recording - followed by code editing/ customising/ extending.. this is much more efficient than constructing the code yourself 1. In Word, use Tools > Macro > Record New Macro

4 2. Then just use Word as normal, e.g. insert a table: 3. Turn off Macro recording: 4. Tools > Macro > Macros > Edit to see the code that s built (this is VBA code, i.e. VB6 syntax): Sub Macro1() ' ' Macro1 Macro ' Macro recorded 17/04/2008 by sam ' ActiveDocument.Tables.Add Range:=Selection.Range, NumRows:=2, NumColumns:= 5, DefaultTableBehavior:=wdWord9TableBehavior, AutoFitBehavior:= wdautofitfixed

5 Now copy and paste it into VB, where you can: edit it, wrap loops around it, plug-in values from variables and otherwise to generalise it, write data from a database into the document, etc. e.g.: odoc.tables.add(range:=oword.selection.range, NumRows:=2, NumColumns:=5) oword.selection.typetext("some text here") oword.selection.moveright(unit:=1, Count:=1) oword.selection.typetext("some more here") Win32 API + Word OLE example: TimeTrackerv0.1.sln Public Class frmmain ' API functions Private Declare Function GetForegroundWindow Lib "user32" () As Integer Private Declare Function GetWindowText Lib "user32" Alias "GetWindowTextA" (ByVal hwnd As Integer, ByVal lpstring As System.Text.StringBuilder, ByVal cch As Integer) As Integer Private Declare Function GetWindowThreadProcessId Lib "user32" (ByVal hwnd As Integer, ByRef procid As Integer) As Integer Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick ' handle of foreground window Dim hwndforeground As Integer = GetForegroundWindow()

6 vbcrlf vbcrlf TextBox1.Text = "Foreground Window: " & hwndforeground & ' title of foreground window Dim sb As New System.Text.StringBuilder(256) Dim titleforeground As String = "" If GetWindowText(hwndForeground, sb, 256) Then titleforeground = sb.tostring() TextBox1.Text &= "Window Title: " & titleforeground & ' process ID and name that launched the foreground window Dim pid As Long If GetWindowThreadProcessId(hwndForeground, pid) Then TextBox1.Text &= "Process ID: " & pid & vbcrlf ' Process name Dim proc As Process = Process.GetProcessById(pid) TextBox1.Text &= "Process Name: " & proc.processname & vbcrlf ' document/path active in foreground window (probably specific to Word, Excel etc.?) If proc.processname = "WINWORD" Then Dim oword As Word.Application oword = GetObject(, "Word.Application") TextBox1.Text &= "Document Name: " & oword.activedocument.fullname & vbcrlf ElseIf proc.processname = "EXCEL" Then Dim oexcel As Excel.Application oexcel = GetObject(, "Excel.Application") If (Not oexcel.activeworkbook Is Nothing) Then TextBox1.Text &= "Spreadsheet Name: " & oexcel.activeworkbook.fullname & vbcrlf End Class