FWIW, report about the possibly related problem with SAL_USE_VCLPLUGIN=kde5 is bug 122133

Interesting phenomenon, which I can't reproduce.

It's not related to bug 122133. One eventually related bug is 121283.

The menu bar is a real QMenu, so I guess that's the reason why it's font is ok.

Currently I have no idea what might force icon and font scaling in LO. I guess it's something DPI related, but have currently no idea how to reproduce this.

Is this some small screen like a 10" notebook, which might result in a high DPI value? What's your output for xdpyinfo? The interesting part looks something like:

$ xdpyinfo
...
screen #0:
  dimensions:    1920x1200 pixels (508x317 millimeters)
  resolution:    96x96 dots per inch
...

I'm setting the bug to NEEDINFO. Please change the bug back to UNCONFIRMED when you have provided the requested information.

Please also include the following stuff:

- check the possible settings mentioned in http://doc.qt.io/qt-5/highdpi.html (paragraph: High DPI Support in Qt), especially the environment variables of the soffice.bin process via /proc.

- provide the kwin support information via "qdbus org.kde.KWin /KWin supportInformation".

This is on a 24" desktop screen.

xdpyinfo doesn't say anything too surprising.

screen #0:
  dimensions:    1920x1080 pixels (508x285 millimeters)
  resolution:    96x96 dots per inch


The only relevant bit in /proc/$(pidof soffice.bin)/environ is

QT_AUTO_SCREEN_SCALE_FACTOR=0


$ qdbus org.kde.KWin /KWin supportInformation
KWin Support Information:
The following information should be used when requesting support on e.g. http://forum.kde.org.
It provides information about the currently running instance, which options are used,
what OpenGL driver and which effects are running.
Please post the information provided underneath this introductory text to a paste bin service
like http://paste.kde.org instead of pasting into support threads.

==========================

Version
=======
KWin version: 5.14.4
Qt Version: 5.12.0
Qt compile version: 5.11.2
XCB compile version: 1.13.1

Operation Mode: X11 only

Build Options
=============
KWIN_BUILD_DECORATIONS: yes
KWIN_BUILD_TABBOX: yes
KWIN_BUILD_ACTIVITIES: yes
HAVE_DRM: yes
HAVE_GBM: yes
HAVE_X11_XCB: yes
HAVE_EPOXY_GLX: yes
HAVE_WAYLAND_EGL: yes

X11
===
Vendor: OpenMandriva
Vendor Release: 12003000
Protocol Version/Revision: 11/0
SHAPE: yes; Version: 0x11
RANDR: yes; Version: 0x14
DAMAGE: yes; Version: 0x11
Composite: yes; Version: 0x4
RENDER: yes; Version: 0xb
XFIXES: yes; Version: 0x50
SYNC: yes; Version: 0x31
GLX: yes; Version: 0x0

Decoration
==========
Plugin: org.kde.breeze
Theme: 
Blur: 0
onAllDesktopsAvailable: false
alphaChannelSupported: true
closeOnDoubleClickOnMenu: false
decorationButtonsLeft: 0, 2
decorationButtonsRight: 6, 3, 4, 5
borderSize: 3
gridUnit: 10
font: Noto Sans,10,-1,5,50,0,0,0,0,0
smallSpacing: 2
largeSpacing: 10

Platform
==========
Name: KWin::X11StandalonePlatform

Options
=======
focusPolicy: 0
nextFocusPrefersMouse: false
clickRaise: true
autoRaise: false
autoRaiseInterval: 0
delayFocusInterval: 0
shadeHover: false
shadeHoverInterval: 250
separateScreenFocus: false
placement: 4
focusPolicyIsReasonable: true
borderSnapZone: 10
windowSnapZone: 10
centerSnapZone: 0
snapOnlyWhenOverlapping: false
rollOverDesktops: true
focusStealingPreventionLevel: 1
legacyFullscreenSupport: false
operationTitlebarDblClick: 5000
operationMaxButtonLeftClick: 5000
operationMaxButtonMiddleClick: 5015
operationMaxButtonRightClick: 5014
commandActiveTitlebar1: 0
commandActiveTitlebar2: 30
commandActiveTitlebar3: 2
commandInactiveTitlebar1: 4
commandInactiveTitlebar2: 30
commandInactiveTitlebar3: 2
commandWindow1: 7
commandWindow2: 8
commandWindow3: 8
commandWindowWheel: 31
commandAll1: 10
commandAll2: 3
commandAll3: 14
keyCmdAllModKey: 16777251
showGeometryTip: false
condensedTitle: false
electricBorderMaximize: true
electricBorderTiling: true
electricBorderCornerRatio: 0.25
borderlessMaximizedWindows: false
killPingTimeout: 5000
hideUtilityWindowsForInactive: true
inactiveTabsSkipTaskbar: false
autogroupSimilarWindows: false
autogroupInForeground: true
compositingMode: 1
useCompositing: true
compositingInitialized: true
hiddenPreviews: 1
glSmoothScale: 0
xrenderSmoothScale: false
maxFpsInterval: 16666666
refreshRate: 0
vBlankTime: 6000000
glStrictBinding: true
glStrictBindingFollowsDriver: true
glCoreProfile: true
glPreferBufferSwap: 101
glPlatformInterface: 1
windowsBlockCompositing: true

Screen Edges
============
desktopSwitching: false
desktopSwitchingMovingClients: true
cursorPushBackDistance: 1x1
timeThreshold: 150
reActivateThreshold: 350
actionTopLeft: 0
actionTop: 0
actionTopRight: 0
actionRight: 0
actionBottomRight: 0
actionBottom: 0
actionBottomLeft: 0
actionLeft: 0

Screens
=======
Multi-Head: no
Active screen follows mouse:  no
Number of Screens: 1

Screen 0:
---------
Name: HDMI-2
Geometry: 0,0,1920x1080
Scale: 1
Refresh Rate: 60


Compositing
===========
Compositing is active
Compositing Type: OpenGL
OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) Haswell Desktop 
OpenGL version string: 4.5 (Core Profile) Mesa 18.3.1
OpenGL platform interface: GLX
OpenGL shading language version string: 4.50
Driver: Intel
GPU class: Haswell
OpenGL version: 4.5
GLSL version: 4.50
Mesa version: 18.3.1
Linux kernel version: 4.20
Direct rendering: Requires strict binding: yes
GLSL shaders:  yes
Texture NPOT support:  yes
Virtual Machine:  no
OpenGL 2 Shaders are used
Painting blocks for vertical retrace:  no

Loaded Effects:
---------------
zoom
kwin4_effect_fade
kwin4_effect_frozenapp
kwin4_effect_login
kwin4_effect_maximize
kwin4_effect_logout
kwin4_effect_translucency
kwin4_effect_morphingpopups
kwin4_effect_windowaperture
kwin4_effect_dialogparent
slidingpopups
slide
screenshot
minimizeanimation
desktopgrid
cube
colorpicker
presentwindows
highlightwindow
blur
contrast
startupfeedback
screenedge
kscreen

Currently Active Effects:
-------------------------
blur
contrast

Effect Settings:
----------------
zoom:
zoomFactor: 1.2
mousePointer: 0
mouseTracking: 0
enableFocusTracking: false
followFocus: true
focusDelay: 350
moveFactor: 20
targetZoom: 1

kwin4_effect_fade:

kwin4_effect_frozenapp:

kwin4_effect_login:

kwin4_effect_maximize:

kwin4_effect_logout:

kwin4_effect_translucency:

kwin4_effect_morphingpopups:

kwin4_effect_windowaperture:

kwin4_effect_dialogparent:

slidingpopups:
slideInDuration: 150
slideOutDuration: 250

slide:
duration: 500
horizontalGap: 45
verticalGap: 20
slideDocks: false
slideBackground: true

screenshot:

minimizeanimation:

desktopgrid:
zoomDuration: 300
border: 10
desktopNameAlignment: 0
layoutMode: 0
customLayoutRows: 2
usePresentWindows: true

cube:
cubeOpacity: 0.800000011920929
opacityDesktopOnly: false
displayDesktopName: true
reflection: true
rotationDuration: 500
backgroundColor: #000000
capColor: #eff0f1
paintCaps: true
closeOnMouseRelease: false
zPosition: 100
useForTabBox: false
invertKeys: false
invertMouse: false
capDeformationFactor: 0
useZOrdering: false
texturedCaps: true

colorpicker:

presentwindows:
layoutMode: 0
showCaptions: true
showIcons: true
doNotCloseWindows: false
ignoreMinimized: false
accuracy: 20
fillGaps: true
fadeDuration: 150
showPanel: false
leftButtonWindow: 1
rightButtonWindow: 2
middleButtonWindow: 0
leftButtonDesktop: 2
middleButtonDesktop: 0
rightButtonDesktop: 0

highlightwindow:

blur:

contrast:

startupfeedback:
type: 1

screenedge:

kscreen:

Created attachment 147880 [details]
Minimal Qt5 program to dump QScreen information

Nothing in this output shows any problem I can identify :-(

I've added a minimal program to dump all QScreen information. It's just a 64bit binary, but I included the source if you need to build a 32bit version. This can be done simply by calling
$ qmake && make

Please run it on the same screen from a terminal, where you start LO.
For my single NEC monitor the output is:

availableGeometry: QRect(0,0 1920x1170)
availableSize: QSize(1920, 1170)
availableVirtualGeometry: QRect(0,0 1920x1170)
availableVirtualSize: QSize(1920, 1170)
depth: 24
devicePixelRatio: 1
geometry: QRect(0,0 1920x1200)
logicalDotsPerInch: 96.0757
logicalDotsPerInchX: 96
logicalDotsPerInchY: 96.1514
nativeOrientation: Qt::ScreenOrientation(PrimaryOrientation)
orientation: Qt::ScreenOrientation(LandscapeOrientation)
orientationUpdateMask: QFlags<Qt::ScreenOrientation>(PrimaryOrientation)
physicalDotsPerInch: 94.1104
physicalDotsPerInchX: 94.1467
physicalDotsPerInchY: 94.0741
physicalSize: QSizeF(518, 324)
primaryOrientation: Qt::ScreenOrientation(LandscapeOrientation)
refreshRate: 59
size: QSize(1920, 1200)
virtualGeometry: QRect(0,0 1920x1200)
virtualSiblings: (QScreen(0x563f582e6780, name="DVI-0"))
virtualSize: QSize(1920, 1200)

Thanks.

The interesting part is probably physicalSize (and the resulting physicalDotsPerInch). Those numbers look off... (but KDE and other Qt applications look perfect).



manufacturer: "Samsung Electric Company"
model: "SyncMaster-"
name: "HDMI-2"
serialNumber: "1162228275"

availableGeometry: QRect(0,0 1920x1026)
availableSize: QSize(1920, 1026)
availableVirtualGeometry: QRect(0,0 1920x1026)
availableVirtualSize: QSize(1920, 1026)
depth: 24
devicePixelRatio: 1
geometry: QRect(0,0 1920x1080)
logicalDotsPerInch: 96
logicalDotsPerInchX: 96
logicalDotsPerInchY: 96
nativeOrientation: Qt::PrimaryOrientation
orientation: Qt::LandscapeOrientation
orientationUpdateMask: QFlags<Qt::ScreenOrientation>(PrimaryOrientation)
physicalDotsPerInch: 304.8
physicalDotsPerInchX: 304.8
physicalDotsPerInchY: 304.8
physicalSize: QSizeF(160, 90)
primaryOrientation: Qt::LandscapeOrientation
refreshRate: 60
size: QSize(1920, 1080)
virtualGeometry: QRect(0,0 1920x1080)
virtualSiblings: (QScreen(0x55aff8c7a610, name="HDMI-2"))
virtualSize: QSize(1920, 1080)

(In reply to Bernhard Rosenkraenzer from comment #6)
> The interesting part is probably physicalSize (and the resulting
> physicalDotsPerInch). Those numbers look off... (but KDE and other Qt
> applications look perfect).
> 
> logicalDotsPerInch: 96
> physicalDotsPerInch: 304.8
> physicalSize: QSizeF(160, 90)

Yup - that would be a tiny screen, as it's in mm...
xdpyinfo seems more correct with "508x317 millimeters"; not sure if this is a guess based on the 96 DPI or on real data.

The icons are roughly scaled 3x when I tried to measure their rectangle using gimp, so that would correspond to logicalDotsPerInch : physicalDotsPerInch.

Currently Qt5Font uses QFont::setPixelSize to set the font size. Quoting the docs: "Using this function makes the font device dependent. Use setPointSize() or setPointSizeF() to set the size of the font in a device independent manner."

So in theory
-    setPixelSize(rFSP.mnHeight);
+    setPointSizeF(rFSP.mfExactHeight * 72.0 / QGuiApplication::primaryScreen()->logicalDotsPerInch());

should fix your problem. Docs for QScreen::logicalDotsPerInch claim "this value can be used to convert font point sizes to pixel sizes".

My final patch is a bit different. LO still looks ok for me, but I have no idea, if this would work for you.
Maybe this needs adaption of Qt5Font::ImplGetGlyphBoundRect too

Can you test the patch at https://gerrit.libreoffice.org/#/c/65696/ ?

Still looks the same after applying the patch (and updating to 6.2.0.1)

New patch, which might be related: https://gerrit.libreoffice.org/#/c/66525/

(In reply to Jan-Marek Glogowski from comment #9)
> New patch, which might be related: https://gerrit.libreoffice.org/#/c/66525/

@Bernhard: The patch was merged to master now. Any chance you could do a quick test whether this fixes the issue for you?

Setting to NEEDINFO until the question from comment:10 has been answered.

(In reply to Michael Weghorn from comment #10)
> (In reply to Jan-Marek Glogowski from comment #9)
> > New patch, which might be related: https://gerrit.libreoffice.org/#/c/66525/
> 
> @Bernhard: The patch was merged to master now. Any chance you could do a
> quick test whether this fixes the issue for you?

Since a potential fix has been merged and there has been no reply in the meantime, let's set this to WORKSFORME.

@Bernhard: Please just reopen this bug if the problem is still there for you with a current master build.