[webkit-changes] [WebKit/WebKit] d4fa89: visualViewport.scale() should be 1 at the default ...

[Wenson Hsieh]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: d4fa89ab44bce81fa25269d46b955777dd1804fb
      https://github.com/WebKit/WebKit/commit/d4fa89ab44bce81fa25269d46b955777dd1804fb
  Author: Wenson Hsieh <wenson_hsieh at apple.com>
  Date:   2024-06-07 (Fri, 07 Jun 2024)

  Changed paths:
    M Source/WebCore/page/ChromeClient.h
    M Source/WebCore/page/VisualViewport.cpp
    M Source/WebKit/WebProcess/WebCoreSupport/WebChromeClient.cpp
    M Source/WebKit/WebProcess/WebCoreSupport/WebChromeClient.h
    M Source/WebKit/WebProcess/WebPage/WebPage.h
    M Source/WebKit/WebProcess/WebPage/ios/WebPageIOS.mm

  Log Message:
  -----------
  visualViewport.scale() should be 1 at the default scale when using automatic view scale adjustment
https://bugs.webkit.org/show_bug.cgi?id=275260

Reviewed by Aditya Keerthi.

Report a `visualViewport.scale()` of 1 at the default scale (i.e. without any explicit user scaling)
when automatic view scale adjustments are enabled.

For context, the idea of applying a layout size scale factor is that WebKit can take the normal
minimum layout size it would've used, scale those dimensions by an arbitrary amount, perform layout
using those scaled dimensions, and finally scale down (or up) to fit the real view dimensions when
computing initial scale.

Without this change, `scale()` reports the actual page scale factor, which may not be equal to 1 (by
default) when `automaticallyAdjustsViewScaleUsingMinimumEffectiveDeviceWidth` is enabled. This
causes the entire page to be clipped on certain websites, where the result of
`(visualViewport.width * visualViewport.scale)` is used to compute an "effective layout width which
is used to size the rest of the webpage.

Mitigate this by pretending to be `scale=1` in this case, such that the result of `width * scale`
can no longer be used to infer the real size of the web view, and we can properly scale up to fit
the webpage to the view without clipping the page.

* Source/WebCore/page/ChromeClient.h:
(WebCore::ChromeClient::baseViewportLayoutSizeScaleFactor const):

Add a chrome client hook to ask for the current base layout size scale factor, so that we can adjust
the scale factor reported by `visualViewport.scale()` by this amount. See above.

* Source/WebCore/page/VisualViewport.cpp:
(WebCore::VisualViewport::update):
* Source/WebKit/WebProcess/WebCoreSupport/WebChromeClient.cpp:
(WebKit::WebChromeClient::baseViewportLayoutSizeScaleFactor const):
* Source/WebKit/WebProcess/WebCoreSupport/WebChromeClient.h:
* Source/WebKit/WebProcess/WebPage/WebPage.h:
(WebKit::WebPage::baseViewportLayoutSizeScaleFactor const):
* Source/WebKit/WebProcess/WebPage/ios/WebPageIOS.mm:
(WebKit::WebPage::setViewportConfigurationViewLayoutSize):

Canonical link: https://commits.webkit.org/279829@main



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