How do I use/call functions in the DebenuQuickPDF v10.13 DLL?

[RedOctober]

OS: Windows Server 2016.  DLL: DebenuPDFLibrary64DLL1013.dll
Lazarus 3.4 (rev lazarus_3_4) FPC 3.2.2 x86_64-win64-win32/win64

I have never done this before.
I am stuck at how to properly load the library, and also how to use functions in the library.

According to the Getting Started:
("DPLDrawText" and "DPLSaveToFile" are just example function calls to demonstrate)

Code: Pascal  [Select][+][-]

1. int InstanceID;
2. InstanceID = DPLCreateLibrary();
3. if (DPLUnlockKey(InstanceID, "your license key") == 1) {
4. DPLDrawText(InstanceID, 100, 500, "Hello world");
5. DPLSaveToFile(InstanceID, "C:\Docs\HelloFromDLL.pdf");
6. }
7. DPLReleaseLibrary(InstanceID);
8.  

Further from the same document: Sending Strings

Code: Pascal  [Select][+][-]

1. char * Buffer;
2. char * Content = ...; // pointer to the data
3. Buffer = DPLCreateBuffer(10000);
4. DPLAddToBuffer(InstanceID, Buffer, Content, 10000);
5. DPLStoreCustomDataFromString(InstanceID,
6. "MyData", Buffer, 1, 0);
7. DPLReleaseBuffer(InstanceID, Buffer);
8.  

Further from the same document: Receiving Strings

Code: Pascal  [Select][+][-]

1. unsigned char * Content;
2. int ContentLength;
3. Content = DPLRetrieveCustomDataToString("MyData", 1);
4. ContentLength = DPLAnsiStringResultLength(// copy the data in Content now
5.  

This is my own code, so far:

Code: Pascal  [Select][+][-]

1. unit u_dll_pdf;
2.  
3. {$mode ObjFPC}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, u_gv;
9.  
10. type
11.    TfunStringBack = function(strIn : string) : PChar;  stdcall;
12.    TfunCreateLibrary = function() : PChar;  stdcall;
13.  
14. function GetPgImgStrFromPDF(const fnm: String; const pg, zm: Integer; var pgc: Integer; var img_str: String): Boolean;
15.  
16. implementation
17.  
18. function GetPgImgStrFromPDF(const fnm: String; const pg, zm: Integer; var pgc: Integer; var img_str: String): Boolean;
19. var LibHandle: THandle; fncPtr: Pointer;  InstanceID: Integer;  funCreateLibrary: TfunCreateLibrary;
20. begin
21.   Result := True;
22.   try
23.     LibHandle := LoadLibrary(PChar(GV.RBI.QPDF_lib_fnm));
24.     if LibHandle = 0 then
25.       begin
26.         Result := False;
27.         Exit;
28.       end;
29.  
30.     fncPtr := GetProcAddress(LibHandle, 'DPLCreateLibrary');
31.     if not Assigned(fncPtr) then //-- Error! Unknown data.
32.       begin
33.         Result := False;
34.         Exit;
35.       end;
36.  
37.     // Everything is lined up.  Time to call the function
38.  
39.   finally
40.     if LibHandle > 0 then
41.       FreeLibrary(LibHandle);
42.   end;
43. end;
44.  
45. end.
46.  

Ultimately, the function I need to get working is this one:
(I need to get a page from the .pdf file, to an HTML string)
 

RenderPageToString

Description
This function renders a page from the selected document to a string. The data in the returned
string depends on the Options parameter.

Syntax
Delphi
function TDebenuPDFLibrary1013.RenderPageToString(DPI: Double; Page, Options: Integer): AnsiString;

DLL
char * DPLRenderPageToString(int InstanceID, double DPI, int Page,
int Options);

Parameters
DPI The DPI to use when rendering the page. Values over 300 will cause excessive memory usage.
Page The page number to render

Options 0 = BMP output
1 = JPEG output
2 = WMF output
3 = EMF output
4 = EPS output
5 = PNG output
6 = GIF output
7 = TIFF output
8 = EMF+ output
9 = HTML5 output
10 = TIFF (G4) output

Many thanks to anyone who can get me over this learning curve.

[Fibonacci]

Remove GetPgImgStrFromPDF from implementation section, and in interface section change to

Code: Pascal  [Select][+][-]

1. function GetPgImgStrFromPDF(const fnm: String; const pg, zm: Integer; var pgc: Integer; var img_str: String): Boolean; stdcall; external 'DebenuPDFLibrary64DLL1013.dll';

Thats all, add more functions and call them

[RedOctober]

I was on the wrong track.

Solution:

• In the folder "/Import/Delphi"  find the library's .pas file:

DebenuPDFLibraryDLL1013.pas
Place this file in with your project source code.
Put {$MODE Delphi}  at the very top line of this Debenu file.

• Using the Project Inspector, add this file to the Project
• In your unit, in the uses clause, add the same .pas file

Classes, SysUtils, DebenuPDFLibraryDLL1013;

• Then see below for the source code

Code: Pascal  [Select][+][-]

1. unit u_dll_pdf;
2.  
3. {$mode ObjFPC}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, DebenuPDFLibraryDLL1013;
9.  
10. const
11.   quick_pdf_license_key: WideString = 'YOUR LICENSE KEY'; // 10.13
12.  
13. function GetPgImgStrFromPDF(const fnm: String; const pg, zm: Integer; var pgc: Integer; var img_str: AnsiString): Boolean;
14.  
15. implementation
16.  
17. uses u_gv;
18.  
19. function GetPgImgStrFromPDF(const fnm: String; const pg, zm: Integer; var pgc: Integer; var img_str: AnsiString): Boolean;
20. var
21.   QwkPDFLib: TDebenuPDFLibraryDLL1013;
22.   ID: LongInt; key_ok: Integer;
23. begin
24.   Result := True;
25.   QwkPDFLib := nil;
26.   try
27.     QwkPDFLib := TDebenuPDFLibraryDLL1013.Create(GV.RBI.QPDF_lib_fnm);
28.     if not Assigned(QwkPDFLib) then
29.       Exit;
30.  
31.     key_ok := QwkPDFLib.UnlockKey(quick_pdf_license_key);
32.     if key_ok = 0 then
33.       Exit;
34.     QwkPDFLib.LoadFromFile(fnm, '');
35.     img_str := QwkPDFLib.RenderPageToString(100, 1, 9);
36.   finally
37.     QwkPDFLib.Free;
38.   end;
39. end;
40.  
41. end.
42.  

The result of the RenderPageToString() call will be a complete HTML document, with a JavaScript function call that uses a bunch of ctx. (canvas) draws and moves and fills, that will render the image in a browser.  Really cool.

THANKS to those who replied, it helped get me onto the right track.