[UnifiedPDF] [visionOS] PDF opening as thumbnail and pushed to the co…

…rner of Safari

https://bugs.webkit.org/show_bug.cgi?id=284479
rdar://140186673

Reviewed by Wenson Hsieh.

Safari on visionOS applies a minimum effective device width (mEDW) on
the web view. This makes for a very odd layout size, which results in
the PDF plugin being displayed in a tiny rect.

Unlike regular web content, PDF content does not reflow, and hence does
not require laying out a page at a given minimum width. As such, this
patch chooses to disregard the mEDW when the viewport is configured for
a plugin document.

We do so by adding `shouldHonorMinimumEffectiveDeviceWidthFromClient` to
ViewportConfigration::Parameters, and only setting that to false for
plugin document parameters. This option is consulted when we consider
the new effective width when the view layout size is updated (as part of
mEDW application), and is also consulted during regular viewport
configuration updates where we reset mEDW to 0 if the option is set.

* Source/WebCore/page/ViewportConfiguration.cpp:
(WebCore::ViewportConfiguration::setViewLayoutSize):
(WebCore::ViewportConfiguration::pluginDocumentParameters):
(WebCore::ViewportConfiguration::updateConfiguration):
(WebCore::operator<<):

Add a couple of missing flags in text stream dumping output.

* Source/WebCore/page/ViewportConfiguration.h:

Canonical link: https://commits.webkit.org/287797@main

Source/WebCore/page/ViewportConfiguration.cpp

@@ -148,7 +148,17 @@ bool ViewportConfiguration::setContentsSize(const IntSize& contentSize)
 bool ViewportConfiguration::setViewLayoutSize(const FloatSize& viewLayoutSize, std::optional<double>&& scaleFactor, std::optional<double>&& minimumEffectiveDeviceWidthFromClient)
 {
     double newScaleFactor = scaleFactor.value_or(m_layoutSizeScaleFactor);
-    double newEffectiveWidth = minimumEffectiveDeviceWidthFromClient.value_or(m_minimumEffectiveDeviceWidthForView);
+    double newEffectiveWidth = [&] {
+        if (!m_configuration.shouldHonorMinimumEffectiveDeviceWidthFromClient)
+            return m_minimumEffectiveDeviceWidthForView;
+
+        if (!minimumEffectiveDeviceWidthFromClient)
+            return m_minimumEffectiveDeviceWidthForView;
+
+        m_minimumEffectiveDeviceWidthWasSetByClient = true;
+        return *minimumEffectiveDeviceWidthFromClient;
+    }();
+
     if (m_viewLayoutSize == viewLayoutSize && m_layoutSizeScaleFactor == newScaleFactor && newEffectiveWidth == m_minimumEffectiveDeviceWidthForView)
         return false;
 
@@ -427,6 +437,7 @@ ViewportConfiguration::Parameters ViewportConfiguration::pluginDocumentParameter
     parameters.initialScale = 1;
     parameters.initialScaleIgnoringLayoutScaleFactor = 1;
     parameters.initialScaleIsSet = true;
+    parameters.shouldHonorMinimumEffectiveDeviceWidthFromClient = false;
     return parameters;
 }
 #endif
@@ -537,6 +548,9 @@ void ViewportConfiguration::updateConfiguration()
         m_configuration.heightIsSet = viewportArgumentsOverridesHeight;
     }
 
+    if (!m_configuration.shouldHonorMinimumEffectiveDeviceWidthFromClient && std::exchange(m_minimumEffectiveDeviceWidthWasSetByClient, false))
+        m_minimumEffectiveDeviceWidthForView = 0;
+
     if (m_configuration.initialScaleIsSet && m_minimumEffectiveDeviceWidthForView > m_viewLayoutSize.width())
         m_configuration.ignoreInitialScaleForLayoutWidth = true;
 
@@ -717,6 +731,8 @@ TextStream& operator<<(TextStream& ts, const ViewportConfiguration::Parameters&
     ts.dumpProperty("allowsUserScaling", parameters.allowsUserScaling);
     ts.dumpProperty("allowsShrinkToFit", parameters.allowsShrinkToFit);
     ts.dumpProperty("avoidsUnsafeArea", parameters.avoidsUnsafeArea);
+    ts.dumpProperty("ignoreInitialScaleForLayoutWidth", parameters.ignoreInitialScaleForLayoutWidth);
+    ts.dumpProperty("shouldHonorMinimumEffectiveDeviceWidthFromClient", parameters.shouldHonorMinimumEffectiveDeviceWidthFromClient);
 
     return ts;
 }

Source/WebCore/page/ViewportConfiguration.h

@@ -61,6 +61,8 @@ class ViewportConfiguration {
 
         bool ignoreInitialScaleForLayoutWidth { false };
 
+        bool shouldHonorMinimumEffectiveDeviceWidthFromClient { true };
+
         friend bool operator==(const Parameters&, const Parameters&) = default;
     };
 
@@ -215,6 +217,7 @@ class ViewportConfiguration {
     bool m_isKnownToLayOutWiderThanViewport { false };
     bool m_prefersHorizontalScrollingBelowDesktopViewportWidths { false };
     bool m_canIgnoreViewportArgumentsToAvoidExcessiveZoom { false };
+    bool m_minimumEffectiveDeviceWidthWasSetByClient { false };
 };
 
 WTF::TextStream& operator<<(WTF::TextStream&, const ViewportConfiguration::Parameters&);