Regarding the issue of encapsulating TLazVirtualDrawTree as a DLL library

[energy]

Hello, I am using Golang to package Lazarus's LCL component library into a dynamic link library for Go to use.
I encountered an issue while packaging the API for the TLazVirtualDrawTree component.
Creating object TLazVirtualDrawTree.Create
In the CreateCheckImageList function, when calling CreateBitmapFromResourceName (0, resname) to create a bitmap object, find the LAZ_VT_CHECK_DARK resource. The invalid address exception is thrown because the passed in resource is 0
There is no problem with directly creating and executing the exe program in Lazarus. Only available in the DLL library.
Solution: CreateBitmapFromResourceName(HINSTANCE, resname); Only by passing in resource instances here can we create them correctly
Is there any other way besides that? Because I don't want to modify the Lazarus source code.

[jamie]

I think you should report that because I see two things wrong here.

Looking for a DARK resource and assuming 0 is ok.

There is also the VirtualTree package that is not part of the Lazarus directly but it the same, it make not be modified in such way.

You can install that on top of the Laz version.

[energy]

This issue is with the LAZ library project. After compiling the DLL, when the host program loads the DLL.
When creating BitmapFromResourceName to search for resources, 0 is passed in, and the exe host program that loads the DLL is used to search for resources.
If the passed in 0 is replaced with the current DLL module handle HINSTANCE, this problem can be solved. That is to search for this resource in the DLL
I found it impossible to set this HINSTANCE externally, nor can I rewrite functions related to it.

 `You can install that on top of the Laz version.` What does it mean?

Code: Pascal  [Select][+][-]

1. function CreateCheckImageList(CheckKind: TCheckImageKind): TImageList;
2. {$IF LCL_FullVersion >= 2000000}
3. var
4.   bm: TCustomBitmap;
5.   resName: String;
6. {$ENDIF}
7. begin
8.   Result := TImageList.Create(nil);
9.   Result.Height := 16;
10.   Result.Width := 16;
11.   {$IF LCL_FullVersion >= 2000000}
12.   Result.RegisterResolutions([16, 24, 32]);
13.   Result.Scaled := true;
14.   resname := BuildResourceName(CheckImagesStrings[CheckKind]);
15.   bm := CreateBitmapFromResourceName(HINSTANCE, resname);
16.   try
17.     bm.Transparent := true;
18.     Result.AddSliced(bm, 25, 1);
19.   finally
20.     bm.Free;
21.   end;
22.   {$ELSE}
23.   Result.AddResourceName(0, CheckImagesStrings[CheckKind], clFuchsia);
24.   {$IFEND}
25. end;
26.  

[KodeZwerg]

Try

Code: Pascal  [Select][+][-]

1. HInstance := GetModuleHandle(nil);

[jamie]

if you go to the online package manager and download and install the VirtualTree package, which is the same as the Laz one and then you can modify that same partial of code and rebuild the IDE, it will not disrupt the LAZ version but you will be able to use that one instead.

[wp]

Just committed a version to Laz/main (and requested backporting to Laz/fixes) in which the "0" with respect to resources has been replaced by HINSTANCE at all places.

[jamie]

Does this also cover the non-Laz version of the package ?

[wp]

Does this also cover the non-Laz version of the package ?

No, only laz.virtualtrees. Somebody should post a bugreport on the non-laz version's repository.

[jamie]

Ok, looks like I need an account there, I thought I had one, but guess not.

I'll get one later and report it.
Thanks.

[energy]

Thank you.