[Webkit-unassigned] [Bug 196339] [WinCairo][WK2] WebView should call WebPageProxy::setIntrinsicDeviceScaleFactor for high DPI

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=196339

--- Comment #13 from Fujii Hironori <Hironori.Fujii at sony.com> ---
Windows supports fractional device scale factors. Actually, I'm
using 1.5x device scale factor display.

It seems that WebKit has architectural problem for fractional
device scale factors.

In 1.5x DPI, 2x2 CSS pixels are rendered onto 3x3 device pixels.
If WebKit is going to render some text in (1,1) CSS pixel position,
it will be placed in (1.5, 1.5) device pixel position.

Here is test case to demonstrate the problem:
https://jsfiddle.net/fujihiro/2wa4zbhy/1/embedded/result/

At first rendering, all text are shown clear:
https://ibb.co/dthYf8X

But, after repaint texts by hovering all texts, only odd-y-axis positioned texts are blurred and have noisy horizontal lines:
https://ibb.co/ZWncf6z

Brent, do you have a fractional device scale factor display?

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