Bug 391780

Summary:	Qt text rendering is always being used, leading to text looking a little lighter than necessary
Product:	[Frameworks and Libraries] frameworks-qqc2-desktop-style	Reporter:	Nate Graham <nate>
Component:	general	Assignee:	Marco Martin <notmart>
Status:	RESOLVED FIXED
Severity:	normal	CC:	kde, simonandric5
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:	https://commits.kde.org/qqc2-desktop-style/9a5f7d834f86f57e88c3993fbcf4c17d09a01e10	Version Fixed/Implemented In:	5.45
Sentry Crash Report:
Attachments:	top Qt rendering; bottom Native rendering

Description Nate Graham 2018-03-12 20:27:43 UTC

Created attachment 111351 [details]
top Qt rendering; bottom Native rendering

https://cgit.kde.org/qqc2-desktop-style.git/tree/org.kde.desktop/Label.qml#n36

renderType: Window.devicePixelRatio % 1 !== 0 ? Text.QtRendering : Text.NativeRendering

However, Window.devicePixelRatio doesn't exist (it would be in the Screen import, not Window), so the conditional always evaluates to true, so we always get QtRendering, even at integer scale factors and non-HiDPI. This is what we want for a non-integer scale factor since the alternative is even worse (see https://bugreports.qt.io/browse/QTBUG-67007), but for non-hi-dpi and integer scale factors, we should not use QtRendering, since it results in text that is ever-so-slightly lighter and wispier, which some very sensitive people can pick up on. See the attached comparison: the string on the top was rendered with QtRendering, and the one on the bottom with NativeRendering. Note how the QtRendering version is slightly lighter.

I plan to submit a patch later today if nobody else beats me to it first.

Comment 1 Nate Graham 2018-03-13 02:44:59 UTC

Submitted the patch: https://phabricator.kde.org/D11244

Comment 2 Nate Graham 2018-03-13 02:46:28 UTC

Oops, wrong patch. That one is for Plasma. The QQC2 patch is https://phabricator.kde.org/D11274

Comment 3 Nate Graham 2018-03-13 13:39:17 UTC

Git commit 9a5f7d834f86f57e88c3993fbcf4c17d09a01e10 by Nathaniel Graham.
Committed on 13/03/2018 at 13:39.
Pushed by ngraham into branch 'master'.

Fix font rendering for non-HiDPI and integer scale factors

Summary:
QQC2-desktop-style was attempting to force the use of `Text.QtRendering` for non-integer scale factors. However, it was accidentally using it everywhere. This patch resolves the issue, and makes it use `Text.QtRendering` only for non-integer scale factors.
FIXED-IN: 5.45

Test Plan:
No visual changes when there is a non-integer scale factor.

System Settings before, no scale factor:
{F5751414}

System Settings after, no scale factor:
{F5751415}

Discover before, no scale factor:
{F5751416}

Discover after, no scale factor:
{F5751418}

To notice the differences, you will probably have to open them in different tabs, zoom in with {key Meta +}, and switch between the tabs.

Reviewers: mart, davidedmundson, broulik

Reviewed By: mart, davidedmundson

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D11274

M  +4    -1    org.kde.desktop/ComboBox.qml
M  +4    -2    org.kde.desktop/Label.qml
M  +4    -2    org.kde.desktop/TextArea.qml
M  +4    -2    org.kde.desktop/TextField.qml

https://commits.kde.org/qqc2-desktop-style/9a5f7d834f86f57e88c3993fbcf4c17d09a01e10