[BUG] `HAS_GCODE_PREVIEW` thumbnail preview not working

[classicrocker883]

Did you test the latest bugfix-2.1.x code?

Yes, and the problem still exists.

Bug Description

with HAS_GCODE_PREVIEW it doesn't popup to show the thumbnail of the model preview.

also, this is the 2nd part to the issue, when it was working, it only allowed selecting 1 or 2 previews at a time before freezing/rebooting.

this is especially prevalent with 256K memory max. so im certain it has to do with the cache being stored and not cleared properly after going back to the menu.

Bug Timeline

No response

Expected behavior

suppose to show a popup with a 3D rendering image of the gcode image.
asking to confirm to print or cancel.

Actual behavior

just goes straight to print, no popup to preview and ask to confirm or cancel

Steps to Reproduce

1. Enable DWIN_LCD_PROUI
2. make sure HAS_GCODE_PREVIEW is enabled
3. flash onto board
4. go to Print menu
5. select file with known preview image

Version of Marlin Firmware

current bugfix

Printer model

No response

Electronics

No response

Add-ons

No response

Bed Leveling

None

Your Slicer

None

Host Software

None

Don't forget to include

• A ZIP file containing your Configuration.h and Configuration_adv.h.

Additional information & file uploads

Marlin-Configs.zip

when I was able to have this working, there was also an issue when selecting the thumbnail preview file again.

basically anytime you go to select another or the same gcode file with preview, it would freeze/crash then reboot automatically.

a way around this was to after seeing the thumbnail - go to another file that did not have one or simply go back to another folder directory. once there it basically refreshes itself and you can select another file to preview.

I noticed that files which had larger thumbnail "cache" or whatever you want to call it - whatever was being written to the FLASH memory - or wherever its store (SRAM?) - you could only select these files once or twice in a row before it freezes/reboots.

files with smaller image sizes (which also load the preview faster) can be loaded several times 3 or 4 in a row before the issue happens.

if there is a way to clear the cache or memory after you "Cancel"/ not confirm the file to print, inorder to view another file, that would fix that issue.

i've tried a few things like

   { fileprop.thumbsize = 0; Preview_Invalidate(); delete[] fileprop.thumbdata; fileprop.clear(); card.closefile(); return }

ect... dont know where to go from there.

[mriscoc]

delete[] fileprop.thumbdata;

Should clear all thumbnail data. Be sure that your thumbnail does not exceed 10kB with the current implementation.

[classicrocker883]

delete[] fileprop.thumbdata;

Should clear all thumbnail data. Be sure that your thumbnail does not exceed 10kB with the current implementation.

sorry,
but where can this be used?

  void onClickConfirmToPrint() {
    dwinResetStatusLine();
    if (hmiFlag.select_flag) {     // Confirm
      gotoMainMenu();
      return card.openAndPrintFile(card.filename);
    }
    else {
      delete[] fileprop.thumbdata;  // added here
      hmiReturnScreen();
    }
  }

I tried here, yet doesn't help. i may have mentioned a quick temporary fix is to select another file without a thumbnail so it says Thumbnail not found or to another folder directory and it resets or clears the thumbnail stored memory automatically.

another note to make is should gotoMainMenu(); be part of the Confirm button? because in my testing, I omitted that and there was no difference.

[classicrocker883]

unrelated:
I hope you see the other comment and understand I wasnt trying to copy something that was yours, I respect you and any one else to not do that. so sorry if it came off that way.

[classicrocker883]

I also tried

return delete[] fileprop.thumbdata, 
      hmiReturnScreen(); 

maybe I have it in the wrong spot?

I would assume this is correct, it is where it selects to print or to cancel on the display.

I will say removing gotoMainMenu(); did not make a difference. I am just wondering why is this function here when return is to go ahead and print file.
maybe it was supposed to be something like redrawDash?

HAS_GCODE_PREVIEW enabled still doesn't work within this Marlin fork. I have to test using the Ender3V2S1 fork. the files and code is the same mostly except for PROUI_EX.

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