Failed to load dynamic library dartcv.dll

[redcurry]

After upgrading to opencv_dart 1.4.3 (from 1.4.1) and updating Visual Studio, I am now getting the following error when I try to open an image using imdecodeAsync:

ArgumentError (Invalid argument(s): Failed to load dynamic library 'dartcv.dll': The specified module could not be found. (error code: 126))

I'm building on Windows 11.

[rainyl]

@redcurry Please attach more detailed logs, i.e., run flutter with -v option

[redcurry]

I ran my app with flutter run -d windows -v > log.txt and replaced some sensitive information with [user] and [app]. Please see the attached file. Thank you.

log.txt

[rainyl]

Well, it's strange, looks like dartcv.dll has already been built and copied correctly.

Would you please tell me whether your <app>.exe is located in build/windows/x64/runner/Debug/ too? Please also attach the generated dartcv.dll in build/windows/x64/runner/Debug/.

Have you tried flutter clean? Since I can't see the actual dartcv.dll build process, it's because the previous cmake build cache is used.

Also, which version of Flutter do you use? if possible, please provide a minimum example to reproduce.

[redcurry]

Yes, it's very strange. I can confirm that my <app>.exe is in build/windows/x64/runner/Debug. dartcv.dll is also in that directory (I've attached it here in a .zip file).

Yes, I've tried flutter clean as well as git clean -fxd and I get the same issue.

My current version of flutter is 3.35.1. Dart is 3.9.0.

dartcv.zip

[rainyl]

Oh, wait, is ffmpeg libs also inside build/windows/x64/runner/Debug? like avcodec-61.dll

Since you enabled videoio, dartcv.dll will depends on ffmpeg, if these libs are absent, the loading of dartcv.dll will fail.

In such circumstance, a temporary solution is manually copy them from build/windows/x64/_deps/libopencv-src/ffmpeg/bin.

I am not sure why these libs are not automatically copied, in my demo project it works as expected, for further analysis, please attach the logs after cleaning, i.e., flutter clean

the expected log should contain:

Also, if videoio is not used in your project, consider using opencv_core, https://pub.dev/packages/opencv_core, you can also use dartcv 2.x if native-assets feature can be used. https://pub.dev/packages/dartcv4/versions/2.1.0-dev.2

[redcurry]

Thank you for investigating. I incorrectly said I was using opencv_dart. I'm actually using opencv_core (as you recommended). Here are my dependencies:

cupertino_icons: ^1.0.8
flutter_svg: ^2.0.17
image_picker: ^1.1.2
opencv_core: ^1.4.3
logger: ^2.5.0
vector_math: ^2.1.4
phosphor_flutter: ^2.1.0
flutter_riverpod: ^2.6.1
intl: ^0.20.2

After running flutter clean, I then ran flutter build windows -v > build_log.txt and I've attached the build log file (with sensitive information redacted).

build_log.txt

[rainyl]

oh, it may be a bug if you are using opencv_core, since we support optional modules now, if users do not configure modules, all modules will be enabled even for opencv_core, but ffmpeg libs will not be copied.

for now, you can configure needed modules in pubspec.yaml according to https://github.com/rainyl/opencv_dart/tree/main/packages/opencv_core#example-pubspecyaml-configuration , remember to at least disable videoio if you want to use opencv_core, will fix it tomorrow.

[redcurry]

That was it! I excluded videoio like this:

hooks:
  user_defines:
    dartcv4:
      exclude_modules:
        - videoio

And now it works. Again, thanks a million for your help on this!