ScreenshotCapturedDelegate is never called in HDR

Development Programming & Scripting
, ,
1

Hi,

in UGameViewportClient::ProcessScreenShots when bHdrEnabled is true Bitmap array is never filled (capture code uses BitmapHDR) so ScreenshotCapturedDelegate is never called in the snippet below:

  if (bScreenshotSuccessful)
  {
    if (Bitmap.Num() > 0) // this is always Empty in HDR)
    {
      if (ScreenshotCapturedDelegate.IsBound() && CVarScreenshotDelegate.GetValueOnGameThread())
      {
        // Ensure that all pixels' alpha is set to 255
        for (auto& Color : Bitmap)
        {
          Color.A = 255;
        }

        // If delegate subscribed, fire it instead of writing out a file to disk
        ScreenshotCapturedDelegate.Broadcast(Size.X, Size.Y, Bitmap);
      }
      else
      {
        bIsScreenshotSaved = ProcessScreenshotData(Bitmap, Size, 255, bHdrEnabled, bIsUI, TEXT(".png"));
      }
    }
    else
    {
      bIsScreenshotSaved = ProcessScreenshotData(BitmapHDR, Size, 1.0f, bHdrEnabled, bIsUI, TEXT(".exr"));
    }
  }

Project cannot use ScreenshotCapturedDelegate to capture both LDR and HDR input.

Possible quick fix

    if (bScreenshotSuccessful)
    {
//@CYA EDIT convert HDR to Bitmap in order to get ScreenshotCapturedDelegate triggered in the if below
        if (Bitmap.IsEmpty() && !BitmapHDR.IsEmpty() && ScreenshotCapturedDelegate.IsBound() && CVarScreenshotDelegate.GetValueOnGameThread())
        {
            Bitmap.Reserve(BitmapHDR.Num());
            for (FLinearColor& Color : BitmapHDR)
            {
                Bitmap.Add(Color.ToFColor(true));
            }
        }
//@CYA END
        if (Bitmap.Num() > 0)
            {
...

Regards

Cø

2

Steps to Reproduce
On a C++ project add and call the code below.

When using LDR the ensure always triggers

When screen is HDR callback is never called.

UGameViewportClient::OnScreenshotCaptured().AddLambda([](int32 InSizeX, int32 InSizeY, const TArray<FColor>& InImageData)
{
    ensureAlways(false);
});
FScreenshotRequest::RequestScreenshot(false);
3

Hi Colas,

Thank you for making the effort to create a fix for the screenshot utility. Would it be possible for you to submit this change via a pull request on GitHub? Through pull requests, we can easily review and integrate your changes. Here is a guide on how to create a pull request, in case you have not gone through the process before: https://dev.epicgames.com/documentation/en\-us/unreal\-engine/contributing\-to\-the\-unreal\-engine. Please let me know if you have any further questions.

4

Hi Tim,

thanks for the quick answer, i’m accessing sources with Perforce (and we’re 2 weeks away from certification, you can read “we’re in the panic path”) that’s why i went for a brute-force quick-fix and not a clean PR request.

I don’t think my proposed code is clean enough for integration “as-it” it’s kind of bypassing the logic for my precise issue, i mostly posted here so other UE user don’t struggle on this like i did :wink:

Cø

5

Hi Colas,

Thank you for the clarification and the effort to provide a usable workaround. I attempted to review that part of our codebase yesterday to find a more elegant solution, but I concluded that a more knowledgeable developer should examine it instead. I filed a Jira to track that effort here: https://issues.unrealengine.com/issue/UE-354875. Once the link goes live, you should be able to see the status of the ticket. Please let me know if there is anything else I can do for you.

Cheers,

Tim

6

Ok, sounds good! Have a good rest of your day.

7

Hi Tim,

thanks for forwarding this to the main dev team, you can close this ticket as it was mainly there for futur updates as it’s hotfixed in our master candidate :wink:

Regards

Cø