PureBasic Forums - English

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Procedure.i Function1(intParam)
  Debug "Hello from 'Function1' - intParam = " + intParam
  ProcedureReturn 1
EndProcedure

Procedure.i Function2(intParam)
  Debug "Hello from 'Function2' - intParam = " + intParam
  ProcedureReturn  2
EndProcedure

;Declare a prototype which is a template for a new kind of variable (just like .l, .i, .s etc.)
;The following line simply says : 'We are interested in calling some functions which take a single integer parameter and returns an integer'.
  Prototype.i simpleProtoType(param)
  
;We can now declare a variable whose type matches our prototype. Just like defining any regular variable.
  ptr.simpleProtoType

;Our variable 'ptr' has been declared as a pointer to a function whose prototype happens to match both functions above.
;However, this  variable is currently null. Let us point it at Function1().
  ptr = @Function1() ;In words : 'Assign the variable ptr the address of Function1'.
  
;We can now call Function1 through the 'ptr' variable.
;We see that the prototype definition requires that we pass a single integer parameter.
  returnValue = ptr(10)
  Debug "Our function call returned the value : " + returnValue
  Debug "===="

;Let us now call Function2 through the 'ptr' variable.
;We just need to alter ptr so that it points at Function2.
  ptr = @Function2()
  returnValue = ptr(20)
  Debug "Our function call returned the value : " + returnValue
  Debug "===="

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; Callback example using prototype.
Prototype.i Fn1_CB(cb_trigger.i)

Procedure Fn1_CB(cb_trigger.i)
  Debug cb_trigger
EndProcedure

Procedure Fn1(nPts.i, delay_ms.i, CB.Fn1_CB=0)
  Protected.i i
  For i = 1 To nPts
    If CB <> 0  ; callback exists
      CB(i)
    EndIf
    Delay(delay_ms)
  Next i
EndProcedure

Fn1(32, 100, @Fn1_CB())
Fn1(32, 100);, @Fn1_CB())

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Procedure StringToBStr (string$) ; By Zapman Inspired by Fr34k 
  Protected Unicode$ = Space(Len(String$)* 2 + 2) 
  Protected bstr_string.l 
  PokeS(@Unicode$, String$, -1, #PB_Unicode) 
  bstr_string = SysAllocString_(@Unicode$) 
  ProcedureReturn bstr_string 
EndProcedure 

Structure GdiplusStartupInput 
  GdiPlusVersion.l 
  *DebugEventCallback.Debug_Event
  SuppressBackgroundThread.l 
  SuppressExternalCodecs.l 
EndStructure 

Prototype GdipLoadImageFromFile( *filename, *image )
Prototype GdiplusStartup( *token, *input, mode ) 
Prototype GdiplusShutdown( *token )
Prototype GdipDisposeImage( *image )

OpenLibrary(gdipluslib, "gdiplus.dll")

Global GdipLoadImageFromFile.GdipLoadImageFromFile = GetFunction(gdipluslib, "GdipLoadImageFromFile")
Global GdiplusStartup.GdiplusStartup               = GetFunction( 0, "GdiplusStartup" )  
Global GdiplusShutdown.GdiplusShutdown             = GetFunction( 0, "GdiplusShutdown" )  
Global GdipDisposeImage.GdipDisposeImage           = GetFunction( 0, "GdipDisposeImage" )

input.GdiplusStartupInput
input\GdiPlusVersion = 1
GdiplusStartup( @*token, @input, #Null)

file$ = #PB_Compiler_Home + "examples\sources\data\world.png"

GdipLoadImageFromFile( StringToBStr(file$), @*image )

Debug *image ; non-zero here means it worked

If *image
  GdipDisposeImage(*image)
EndIf

GdiplusShutdown(*token)

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Structure GdiplusStartupInput 
  GdiPlusVersion.l 
  *DebugEventCallback.Debug_Event
  SuppressBackgroundThread.l 
  SuppressExternalCodecs.l 
EndStructure 

Prototype GdipLoadImageFromFile( filename.p-unicode, *image )
Prototype GdiplusStartup( *token, *input, mode ) 
Prototype GdiplusShutdown( *token )
Prototype GdipDisposeImage( *image )

OpenLibrary(gdipluslib, "gdiplus.dll")

Global GdipLoadImageFromFile.GdipLoadImageFromFile = GetFunction(gdipluslib, "GdipLoadImageFromFile")
Global GdiplusStartup.GdiplusStartup               = GetFunction( 0, "GdiplusStartup" )  
Global GdiplusShutdown.GdiplusShutdown             = GetFunction( 0, "GdiplusShutdown" )  
Global GdipDisposeImage.GdipDisposeImage           = GetFunction( 0, "GdipDisposeImage" )

input.GdiplusStartupInput
input\GdiPlusVersion = 1
GdiplusStartup( @*token, @input, #Null)

file$ = #PB_Compiler_Home + "examples\sources\data\world.png"

GdipLoadImageFromFile( file$, @*image )

Debug *image ; non-zero here means it worked

If *image
  GdipDisposeImage(*image)
EndIf

GdiplusShutdown(*token)