Bug 373839

Summary: Continuously face thumbnails flicker/update
Product: [Applications] digikam Reporter: Kristian Karl <kristian.hermann.karl>
Component: Thumbs-ImageAssignee: Digikam Developers <digikam-bugs-null>
Status: RESOLVED FIXED    
Severity: normal CC: caulier.gilles, graeme.rubble, metzpinguin
Priority: NOR    
Version First Reported In: 4.12.0   
Target Milestone: ---   
Platform: Appimage   
OS: Linux   
Latest Commit: https://invent.kde.org/graphics/digikam/commit/ea71d3e0a2f1e527300d729bed8dc3f47fc819d7 Version Fixed/Implemented In: 7.2.0
Sentry Crash Report:

Description Kristian Karl 2016-12-18 15:44:51 UTC 
When opening the people view in a large window allowing for many faces, the thumbnails will flicker continuously.

Steps to reproduce
==================
1) Use the faces images from http://cswww.essex.ac.uk/mv/allfaces/faces94.html
   http://cswww.essex.ac.uk/mv/allfaces/faces94.zip
2) Create test folder and put the images there.
3) Create a new test database, and use the images above
5) Open the People view, and scan all images for faces using the default options.
5) Look for Unknown, and set the size of the face thumbnails to smallest (124px)
6) Make the window size for Digikam large enough until the flicker starts. I usually get it with > ~210 faces (thumbnails).

Expected result
================
People view displays the thumbnails without flicker.

Actual result
===============
People view displays the thumbnails constant flickering

Additional info
===============
See video of flickering at https://youtu.be/AwmapnWNDBw
I get this on my laptop and desktop.

I was using digikam built from sources (d72b486b7109fd80f6071fd78af2b9509de56044)

Observation
===========
It seems that applying following patch makes the flicker go away. But I'm not sure  what the downside of the patch is...

krikar@krikar-desktop:~/dev/kde/digikam/core$ git diff
diff --git a/app/items/imagecategorizedview.cpp b/app/items/imagecategorizedview.cpp
index d5847c7..ba6dd47 100644
--- a/app/items/imagecategorizedview.cpp
+++ b/app/items/imagecategorizedview.cpp
@@ -737,14 +737,14 @@ ImageInfoList ImageCategorizedView::resolveGrouping(const QModelIndexList indexe
 void ImageCategorizedView::paintEvent(QPaintEvent* e)
 {
     // We want the thumbnails to be loaded in order.
-    ImageThumbnailModel* const thumbModel = imageThumbnailModel();
+/*    ImageThumbnailModel* const thumbModel = imageThumbnailModel();
 
     if (thumbModel)
     {
         QModelIndexList indexesToThumbnail = imageFilterModel()->mapListToSource(categorizedIndexesIn(viewport()->rect()));
         d->delegate->prepareThumbnails(thumbModel, indexesToThumbnail);
     }
-
+*/
     ItemViewCategorized::paintEvent(e);
 }
Comment 1 Kristian Karl 2016-12-18 15:54:03 UTC 
I noticed this first, when using a maximized Digikam window on a 4K monitor, where enough faces/thumbnails were rendered to cause the flickering.

Reducing the size of the Digikam window will make the flickering go away.
Comment 2 caulier.gilles 2016-12-24 18:11:14 UTC 
Can you reproduce the problem with pre-release 5.4.0 AppImage univerdal bundle for Linux available here :

https://drive.google.com/drive/folders/0BzeiVr-byqt5Y0tIRWVWelRJenM
Comment 3 Kristian Karl 2016-12-25 11:38:38 UTC 
Yes, I could reproduce the problem on the pre-release 5.4.0 AppImage.
Comment 4 Kristian Karl 2017-06-26 08:41:19 UTC 
The flickering still exists digikam 5.7.0, installed from neon CI repository:
aptitude show digikam                                                          
Package: digikam                                                                                              
State: installed                                                                                              
Automatically installed: no                                                                                   
Version: 4:5.5.0+p16.04+git20170621.0646-0                                                                    
Priority: optional                                                                                            
Section: graphics                                                                                             
Maintainer: Neon CI <neon@kde.org>                                                                            
Architecture: amd64                                                                                           
Uncompressed Size: 26,6 M                                                                                     
Depends: digikam-data (= 4:5.5.0+p16.04+git20170621.0646-0), libqt5sql5-sqlite, perl, libc6 (>= 2.14),        
         libexiv2-14 (>= 0.25), libexpat1 (>= 2.0.1), libgcc1 (>= 1:3.0), libgl1-mesa-glx | libgl1, libgomp1  
         (>= 4.9), libgphoto2-6 (>= 2.5.9), libgphoto2-port12 (>= 2.5.9), libjasper1, libjpeg8 (>= 8c),       
         libkf5akonadicontact5, libkf5calendarcore5, libkf5configcore5, libkf5configgui5,                     
         libkf5configwidgets5, libkf5contacts5, libkf5coreaddons5, libkf5filemetadata3, libkf5i18n5,          
         libkf5iconthemes5, libkf5kdelibs4support5, libkf5kiowidgets5, libkf5kipi32.0.0, libkf5notifications5,
         libkf5notifyconfig5, libkf5sane5, libkf5service5, libkf5solid5, libkf5threadweaver5,                 
         libkf5widgetsaddons5, libkf5windowsystem5, libkf5xmlgui5, liblcms2-2 (>= 2.2+git20110628),           
         liblensfun0 (>= 0.2.8), liblqr-1-0 (>= 0.4.0), libmarblewidget-qt5-28, libopencv-contrib2.4v5,       
         libopencv-core2.4v5, libopencv-imgproc2.4v5, libopencv-objdetect2.4v5, libpng12-0 (>= 1.2.13-4),     
         libqt5concurrent5 (>= 5.9.0), libqt5core5a (>= 5.9.0), libqt5dbus5 (>= 5.9.0), libqt5gui5 (>= 5.9.0),
         libqt5network5 (>= 5.9.0), libqt5opengl5 (>= 5.9.0), libqt5printsupport5 (>= 5.9.0), libqt5sql5 (>=  
         5.9.0), libqt5webkit5, libqt5widgets5 (>= 5.9.0), libqt5x11extras5, libqt5xml5 (>= 5.9.0), libstdc++6
         (>= 5.2), libtiff5 (>= 4.0.3), libx11-6
Comment 5 caulier.gilles 2017-06-26 08:44:45 UTC 
Here, i tried with digiKam 5.7.0 + Qt 5.9. + KF5 5.35, and OpenCV 3.1.0 with a 4K monitor under Mageia6. I cannot reproduce the problem.

Which screen resolution do you use exactly ?

Gilles Caulier
Comment 6 Kristian Karl 2017-06-26 08:56:21 UTC 
I have seen this problem on 2 different 4K screens. One connected to my midtower machine. 
And last, my laptop Lenovo Thinkpad X240 connected using Display Port to a BenQ BL3201PT 32-inch Ultra HD, running 3840x2160 30 FPS

It does not matter what size I have on the thumbnails, 128 or 256 px.
Comment 7 caulier.gilles 2018-08-29 07:48:56 UTC 
The AppImage Linux Bundle have been recompiled with last changes from source code and is available here for testing :

https://files.kde.org/digikam/

Take a care : 6.0.0 is a beta release for the moment. Make a database backup before to test.

Problem still here ?

Gilles Caulier
Comment 8 Maik Qualmann 2018-09-03 11:59:02 UTC 
I had looked at this a while ago. I suspect after the video here is some display composer used (Compiz?). This probably sends a paint event constantly. Normally, the paint event occurs only when e.g. a window is moved in front over the thumbnails. At the moment I do not see a solution to not break other display managers.

Maik
Comment 9 Kristian Karl 2018-09-06 11:59:01 UTC 
I tested this on a different 4k screen, and I get the same problem.
Using the latest from git: 0890e2005cae874dd1fcf71c2d3642152c00eff0, digikam produces the following on the terminal during this flickering
:
:
digikam.general: Request to get thumbnail for ""
digikam.general: Could not open input file:  ""
digikam.general: Failed to extract video thumbnail for ""
QFSFileEngine::open: No file name specified
digikam.general: Request to get thumbnail for ""
digikam.general: Could not open input file:  ""
digikam.general: Failed to extract video thumbnail for ""
QFSFileEngine::open: No file name specified
digikam.general: Request to get thumbnail for ""
digikam.general: Could not open input file:  ""
digikam.general: Failed to extract video thumbnail for ""
QFSFileEngine::open: No file name specified
digikam.general: Request to get thumbnail for ""
digikam.general: Could not open input file:  ""
digikam.general: Failed to extract video thumbnail for ""
digikam.general: Request to get thumbnail for ""
QFSFileEngine::open: No file name specified
digikam.general: Could not open input file:  ""
digikam.general: Failed to extract video thumbnail for ""
QFSFileEngine::open: No file name specified
digikam.general: Request to get thumbnail for ""
digikam.general: Could not open input file:  ""
digikam.general: Failed to extract video thumbnail for ""
QFSFileEngine::open: No file name specified
digikam.general: Request to get thumbnail for ""
digikam.general: Could not open input file:  ""
digikam.general: Failed to extract video thumbnail for ""
QFSFileEngine::open: No file name specified
digikam.general: Request to get thumbnail for ""
digikam.general: Could not open input file:  ""
digikam.general: Failed to extract video thumbnail for ""
QFSFileEngine::open: No file name specified
:
:
Comment 10 Maik Qualmann 2018-09-07 06:03:33 UTC 
The first thing that is strange is that you constantly have a paint event. As I said, usually only when the mouse pointer or a window moves in front of it or the view is scrolled. The second question is where the empty ImageInfo::filePath() come from to preload thumbnails. If I create a patch with more debug output, can you apply it for testing?

Maik
Comment 11 Kristian Karl 2018-09-07 06:52:21 UTC 
Absolutely!
I'll try some debugging of my own in the meantime. I got a dual screen setup to hel me debug now.
Comment 12 Kristian Karl 2018-09-07 08:31:48 UTC 
When debugging this morning, I paused during flicker, and paused execution. Every time I paused , the stack trace for Digikam code started at:
https://github.com/KDE/digikam/blob/c013f88088bf08e321e4da8be71a61b02b67af2c/core/libs/widgets/itemview/itemviewcategorized.cpp#L997

I added before the return statement:
    qCDebug(DIGIKAM_GENERAL_LOG) << "Event: " << event;
    return DCategorizedView::viewportEvent(event);

Which now gave the following output during flicker:

digikam.general: Event:  QPaintEvent(QRegion(929,888 144x212))
digikam.general: Event:  QPaintEvent(QRegion(1083,888 144x212))
digikam.general: Event:  QPaintEvent(QRegion(1237,888 144x212))
digikam.general: Event:  QPaintEvent(QRegion(1545,888 144x212))
digikam.general: Event:  QPaintEvent(QRegion(1699,888 144x212))
digikam.general: Event:  QPaintEvent(QRegion(1853,888 144x212))
digikam.general: Event:  QPaintEvent(QRegion(2007,888 144x212))
digikam.general: Event:  QPaintEvent(QRegion(2161,888 144x212))
digikam.general: Event:  QPaintEvent(QRegion(1391,888 144x212))
digikam.general: Event:  QPaintEvent(QRegion(2315,888 144x212))
digikam.general: Event:  QPaintEvent(QRegion(2469,888 144x212))
digikam.general: Event:  QPaintEvent(QRegion(size=2, bounds=(2623,888 298x212) - [(2623,888 144x212), (2777,888 144x212)]))
digikam.general: Event:  QPaintEvent(QRegion(2931,888 144x212))
digikam.general: Event:  QPaintEvent(QRegion(3085,888 144x212))
digikam.general: Event:  QPaintEvent(QRegion(3239,888 144x212))
digikam.general: Event:  QPaintEvent(QRegion(3393,888 144x212))
digikam.general: Event:  QPaintEvent(QRegion(3547,888 144x212))
digikam.general: Event:  QPaintEvent(QRegion(5,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(159,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(313,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(467,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(621,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(775,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(929,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(1083,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(1237,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(1391,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(1545,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(1699,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(1853,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(2007,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(size=2, bounds=(2161,1110 298x212) - [(2161,1110 144x212), (2315,1110 144x212)]))
digikam.general: Event:  QPaintEvent(QRegion(size=2, bounds=(2469,1110 298x212) - [(2469,1110 144x212), (2623,1110 144x212)]))
digikam.general: Event:  QPaintEvent(QRegion(2777,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(2931,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(3085,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(3239,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(3393,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(3547,1110 144x212))
digikam.general: Event:  QPaintEvent(QRegion(5,1332 144x212))
digikam.general: Event:  QPaintEvent(QRegion(159,1332 144x212))
digikam.general: Event:  QPaintEvent(QRegion(313,1332 144x212))
digikam.general: Event:  QPaintEvent(QRegion(467,1332 144x212))
digikam.general: Event:  QPaintEvent(QRegion(621,1332 144x212))
digikam.general: Event:  QPaintEvent(QRegion(775,1332 144x212))
digikam.general: Event:  QPaintEvent(QRegion(929,1332 144x212))
digikam.general: Event:  QPaintEvent(QRegion(1083,1332 144x212))
digikam.general: Event:  QPaintEvent(QRegion(1237,1332 144x212))
Comment 13 Kristian Karl 2018-09-07 10:29:23 UTC 
Some more details observed while debugging.
It seems like ThumbnailLoadingTask is getting called repeatably during flicker:

libdigikamcore.so.6.0.0!Digikam::ThumbnailCreator::loadDetail(const Digikam::ThumbnailCreator * const this, const Digikam::ThumbnailIdentifier & identifier, const QRect & rect) (/home/krikar/dev/kde/digikam/core/libs/threadimageio/thumbnailcreator.cpp:187)
libdigikamcore.so.6.0.0!Digikam::ThumbnailLoadingTask::execute(Digikam::ThumbnailLoadingTask * const this) (/home/krikar/dev/kde/digikam/core/libs/threadimageio/thumbnailtask.cpp:169)
libdigikamcore.so.6.0.0!Digikam::LoadSaveThread::run(Digikam::LoadSaveThread * const this) (/home/krikar/dev/kde/digikam/core/libs/threadimageio/loadsavethread.cpp:133)
libdigikamcore.so.6.0.0!Digikam::DynamicThread::Private::run(Digikam::DynamicThread::Private * const this) (/home/krikar/dev/kde/digikam/core/libs/threads/dynamicthread.cpp:183)
libQt5Core.so.5![Unknown/Just-In-Time compiled code] (Unknown Source:0)
libpthread.so.0!start_thread(void * arg) (/build/glibc-OTsEL5/glibc-2.27/nptl/pthread_create.c:463)
libc.so.6!clone() (/build/glibc-OTsEL5/glibc-2.27/sysdeps/unix/sysv/linux/x86_64/clone.S:95)
Comment 14 Maik Qualmann 2018-09-10 19:53:54 UTC 
That's right, the thumbnails are "preloaded" by the Paint Event. The thumbnail task will send a signal to the image model that the thumbnail is available and it will be drawn. By you over and over again.  The advantage of this thumbnail preload only with the fast scrolling, the thumbnails appear faster. The problem is the Paint Event, which is constantly triggered by you. So again my question: which desktop? which display manager and extension? Graphics card and driver?

Maik
Comment 15 Kristian Karl 2018-09-11 08:19:59 UTC 
Oh sorry!

Desktop: KDE Neon (Plasma 5.13.4,KDE frameworks 5.49.0, Qt 5.11.1 ) on Ubuntu 18.04

Display manager and extension: 
cat /etc/X11/default-display-manager 
/usr/bin/sddm

Graphics card and driver?
glxinfo | grep OpenGL
OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) HD Graphics 620 (Kaby Lake GT2) 
OpenGL core profile version string: 4.5 (Core Profile) Mesa 18.0.5
OpenGL core profile shading language version string: 4.50
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL core profile extensions:
OpenGL version string: 3.0 Mesa 18.0.5
OpenGL shading language version string: 1.30
OpenGL context flags: (none)
OpenGL extensions:
OpenGL ES profile version string: OpenGL ES 3.2 Mesa 18.0.5
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20
OpenGL ES profile extensions:

Resolution on the screen: 3840x2160
Comment 16 caulier.gilles 2018-09-11 08:33:29 UTC 
Do you use X11 or Wayland ?

I never tested AppImage with Wayland, and think it must miss some piece of Qt plugins in the bundle.

Gilles Caulier
Comment 17 Kristian Karl 2018-09-11 11:31:42 UTC 
I use x11

echo $XDG_SESSION_TYPE
x11
Comment 18 Kristian Karl 2018-09-11 11:34:03 UTC 
I think that maybe the resolution might be involved somehow.
If I use may 2560x1440, I don't get any flickering.
When I use 3840x2160, I do get flickering.

Please note, that the digikam window is maximized in both cases.
Comment 19 Kristian Karl 2018-09-11 11:44:37 UTC 
Maybe a long shot, but could maybe this method be involved somehow?

https://github.com/KDE/digikam/blob/c013f88088bf08e321e4da8be71a61b02b67af2c/core/libs/widgets/itemview/dcategorizedview.cpp#L70-L132

I'll add some debug logging and see what I can find
Comment 20 caulier.gilles 2018-09-11 13:55:06 UTC 
Another way to experiment :

In appimage, we use Qt 5.9.6 LTS. Perhaps a major update to Qt 5.11.x can solve this problem.

Gilles Caulier
Comment 21 Kristian Karl 2018-09-11 14:50:58 UTC 
I tested the latest appimage of Digikam (digikam-5.9.0-01-x86-64.appimage) on the latest KUbuntu (18-04.1) version on Virtualbox. 

1) I used images from http://cswww.essex.ac.uk/mv/allfaces/faces94.html
   http://cswww.essex.ac.uk/mv/allfaces/faces94.zip

2) I then let Digikam scan for faces on all the images

3) I open People view, and select the tag unknown

4) Select a Flat List in the View | Separate Items

4) I maximize my VirtualBox window in my 3840x2160 screen, and then maximize Digikam in VirtualBox.

5) I click on the People view tab (hide it), so I can maximize the number of thumbnails in the window.

6) Adjust thumbnail sizes to smallest possible.

I get flicker.

Using the steps above should be enough to reproduce the flicker on any 4k screen.

If an 4K screen is not available, the VirtualBox window could be made very large by just increasing the size of that window, and moving it outside, until a very large window is made, the maximize the Digikam window.

I think the problem perhaps is related to the actual size of the Digikam window, and the number of people thumbnails being displayed?
Comment 22 caulier.gilles 2018-09-11 15:13:17 UTC 
In virtualbox, did you enable 3D support (openGL)

Gilles Caulier
Comment 23 Kristian Karl 2018-09-11 15:39:29 UTC 
No. 3D Acceleration was disabled.
Comment 24 caulier.gilles 2018-09-11 15:51:04 UTC 
Well, try again with this option...

Gilles Caulier
Comment 25 Kristian Karl 2018-09-11 16:41:22 UTC 
With 3D Acceleration enabled, I still get flickering on my VirtualBox installation, I'm afraid.
Comment 26 caulier.gilles 2018-09-11 17:21:09 UTC 
ok, 

What's about the cores assigned to the VM ? Same for the system memory and the video memory.

This is important because it can influence to the rendering performances.

Gilles Caulier
Comment 27 Kristian Karl 2018-09-11 18:16:13 UTC 
System
=======
Processors: 1 CPU
Base memory: 4610 MB
Acceleration: VT-x/AMD-V, Nested Paging, KVM Paravirtualization

Display
=======
Video memory: 33 MB
Acceleration: 3D
Comment 28 Kristian Karl 2018-09-11 18:26:17 UTC 
Complete printout of information regarding the VM machine

$ VBoxManage showvminfo "Kubuntu 18.04"
Name:            Kubuntu 18.04
Groups:          /
Guest OS:        Ubuntu (64-bit)
UUID:            73aa30f4-e0f1-4359-96ba-b1e860f8038f
Config file:     /home/krikar/VirtualBox VMs/Kubuntu 18.04/Kubuntu 18.04.vbox
Snapshot folder: /home/krikar/VirtualBox VMs/Kubuntu 18.04/Snapshots
Log folder:      /home/krikar/VirtualBox VMs/Kubuntu 18.04/Logs
Hardware UUID:   73aa30f4-e0f1-4359-96ba-b1e860f8038f
Memory size:     4610MB
Page Fusion:     off
VRAM size:       33MB
CPU exec cap:    100%
HPET:            off
Chipset:         piix3
Firmware:        BIOS
Number of CPUs:  1
PAE:             off
Long Mode:       on
Triple Fault Reset: off
APIC:            on
X2APIC:          on
CPUID Portability Level: 0
CPUID overrides: None
Boot menu mode:  message and menu
Boot Device (1): Floppy
Boot Device (2): DVD
Boot Device (3): HardDisk
Boot Device (4): Not Assigned
ACPI:            on
IOAPIC:          on
BIOS APIC mode:  APIC
Time offset:     0ms
RTC:             UTC
Hardw. virt.ext: on
Nested Paging:   on
Large Pages:     off
VT-x VPID:       on
VT-x unr. exec.: on
Paravirt. Provider: Default
Effective Paravirt. Provider: KVM
State:           powered off (since 2018-09-11T16:41:47.676000000)
Monitor count:   1
3D Acceleration: on
2D Video Acceleration: off
Teleporter Enabled: off
Teleporter Port: 0
Teleporter Address: 
Teleporter Password: 
Tracing Enabled: off
Allow Tracing to Access VM: off
Tracing Configuration: 
Autostart Enabled: off
Autostart Delay: 0
Default Frontend: 
Storage Controller Name (0):            IDE
Storage Controller Type (0):            PIIX4
Storage Controller Instance Number (0): 0
Storage Controller Max Port Count (0):  2
Storage Controller Port Count (0):      2
Storage Controller Bootable (0):        on
Storage Controller Name (1):            SATA
Storage Controller Type (1):            IntelAhci
Storage Controller Instance Number (1): 0
Storage Controller Max Port Count (1):  30
Storage Controller Port Count (1):      1
Storage Controller Bootable (1):        on
IDE (1, 0): Empty
SATA (0, 0): /home/krikar/VirtualBox VMs/Kubuntu 18.04/Snapshots/{d346dd72-695a-4b30-a07f-9e743849bb7a}.vdi (UUID: d346dd72-695a-4b30-a07f-9e743849bb7a)
NIC 1:           MAC: 0800272205A2, Attachment: NAT, Cable connected: on, Trace: off (file: none), Type: 82540EM, Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny, Bandwidth group: none
NIC 1 Settings:  MTU: 0, Socket (send: 64, receive: 64), TCP Window (send:64, receive: 64)
NIC 2:           disabled
NIC 3:           disabled
NIC 4:           disabled
NIC 5:           disabled
NIC 6:           disabled
NIC 7:           disabled
NIC 8:           disabled
Pointing Device: USB Tablet
Keyboard Device: PS/2 Keyboard
UART 1:          disabled
UART 2:          disabled
UART 3:          disabled
UART 4:          disabled
LPT 1:           disabled
LPT 2:           disabled
Audio:           enabled (Driver: PulseAudio, Controller: AC97, Codec: AD1980)
Audio playback:  disabled
Audio capture: enabled
Clipboard Mode:  disabled
Drag and drop Mode: disabled
VRDE:            disabled
USB:             enabled
EHCI:            enabled
XHCI:            disabled

USB Device Filters:

<none>

Bandwidth groups:  <none>

Shared folders:  <none>

Capturing:          not active
Capture audio:      not active
Capture screens:    0
Capture file:       /home/krikar/VirtualBox VMs/Kubuntu 18.04/Kubuntu 18.04.webm
Capture dimensions: 1024x768
Capture rate:       512 kbps
Capture FPS:        25
Capture options:    ac_enabled=false

Guest:

Configured memory balloon size:      0 MB

Snapshots:

   Name: Prestine (UUID: 43f8bf90-35c4-440e-b854-23041d709ac4) *
Comment 29 caulier.gilles 2019-03-20 15:16:07 UTC 
After 3 weeks of work, i finally completed the compilation of AppImage using Qt
5.11.3 + QWebkit 5.212.

New 6.1.0 pre-release AppImage bundle can be found here (64 bits only for the
moment) :

https://files.kde.org/digikam/

Please check if this bugzilla entry still valid.

Thanks in advance

Gilles Caulier
Comment 30 Kristian Karl 2019-03-21 12:04:03 UTC 
I can confirm, that the issue still exists.

I tried using digikam-6.1.0-git-20190321T102236-x86-64.appimage

If there's anything I can do, to try to pin-point the problem, I'm happy to help out.
Comment 31 Maik Qualmann 2020-11-08 06:40:10 UTC 
Git commit ea71d3e0a2f1e527300d729bed8dc3f47fc819d7 by Maik Qualmann.
Committed on 08/11/2020 at 06:39.
Pushed by mqualmann into branch 'master'.

remove dead code to update thumbnails when a paint event occurs
Related: bug 426208
FIXED-IN: 7.2.0

M  +5    -3    NEWS
M  +0    -5    core/app/items/delegate/itemdelegate.cpp
M  +0    -5    core/app/items/delegate/itemdelegate.h
M  +1    -6    core/app/items/delegate/itemfacedelegate.cpp
M  +0    -2    core/app/items/delegate/itemfacedelegate.h
M  +0    -15   core/app/items/views/itemcategorizedview.cpp
M  +0    -1    core/app/items/views/itemcategorizedview.h
M  +0    -5    core/libs/models/itemalbumfiltermodel.cpp
M  +0    -3    core/libs/models/itemalbumfiltermodel.h
M  +0    -5    core/showfoto/thumbbar/showfotodelegate.h

https://invent.kde.org/graphics/digikam/commit/ea71d3e0a2f1e527300d729bed8dc3f47fc819d7