tor-browser

commit 52e752321ecc315ca070141c51ec567de2f9d882
parent 433945a2c7e55e2e361b18c76e8d1844838e174f
Author: Botond Ballo <botond@mozilla.com>
Date:   Wed,  3 Dec 2025 20:04:36 +0000

Bug 1999440 - Introduce ScrollContainerFrame::ScrollModeForScrollBehavior(). r=hiro,layout-reviewers

This helper function encapsulates checks in various places which
were of a form similar to:

  sf->IsSmoothScroll(behavior) ? ScrollMode::SmoothMsd
                               : ScrollMode::Instant

Differential Revision: https://phabricator.services.mozilla.com/D272346

Diffstat:
M
docshell/base/nsDocShell.cpp
 | 
3
+--
M
dom/base/Element.cpp
 | 
8
++------
M
dom/base/nsGlobalWindowInner.cpp
 | 
16
++++------------
M
layout/base/PresShell.cpp
 | 
9
++-------
M
layout/generic/ScrollContainerFrame.cpp
 | 
6
++++++
M
layout/generic/ScrollContainerFrame.h
 | 
8
++++++++

6 files changed, 23 insertions(+), 27 deletions(-)
diff --git a/docshell/base/nsDocShell.cpp b/docshell/base/nsDocShell.cpp
@@ -5037,8 +5037,7 @@ nsresult nsDocShell::SetCurScrollPosEx(int32_t aCurHorizontalPos,
   ScrollContainerFrame* sf = GetRootScrollContainerFrame();
   NS_ENSURE_TRUE(sf, NS_ERROR_FAILURE);
 
-  ScrollMode scrollMode =
-      sf->IsSmoothScroll() ? ScrollMode::SmoothMsd : ScrollMode::Instant;
+  ScrollMode scrollMode = sf->ScrollModeForScrollBehavior();
 
   nsPoint targetPos(aCurHorizontalPos, aCurVerticalPos);
   sf->ScrollTo(targetPos, scrollMode);
diff --git a/dom/base/Element.cpp b/dom/base/Element.cpp
@@ -899,9 +899,7 @@ void Element::ScrollTo(const ScrollToOptions& aOptions) {
     scrollPos.y = ToZeroIfNonfinite(
         frame->Style()->EffectiveZoom().Zoom(aOptions.mTop.Value()));
   }
-  ScrollMode scrollMode = sf->IsSmoothScroll(aOptions.mBehavior)
-                              ? ScrollMode::SmoothMsd
-                              : ScrollMode::Instant;
+  ScrollMode scrollMode = sf->ScrollModeForScrollBehavior(aOptions.mBehavior);
   sf->ScrollToCSSPixels(scrollPos, scrollMode);
 }
 
@@ -930,9 +928,7 @@ void Element::ScrollBy(const ScrollToOptions& aOptions) {
         frame->Style()->EffectiveZoom().Zoom(aOptions.mTop.Value()));
   }
 
-  auto scrollMode = sf->IsSmoothScroll(aOptions.mBehavior)
-                        ? ScrollMode::SmoothMsd
-                        : ScrollMode::Instant;
+  auto scrollMode = sf->ScrollModeForScrollBehavior(aOptions.mBehavior);
   sf->ScrollByCSSPixels(scrollDelta, scrollMode);
 }
 
diff --git a/dom/base/nsGlobalWindowInner.cpp b/dom/base/nsGlobalWindowInner.cpp
@@ -3947,9 +3947,7 @@ void nsGlobalWindowInner::ScrollTo(const ScrollToOptions& aOptions) {
   if (scrollPos.y > maxpx) {
     scrollPos.y = maxpx;
   }
-  auto scrollMode = sf->IsSmoothScroll(aOptions.mBehavior)
-                        ? ScrollMode::SmoothMsd
-                        : ScrollMode::Instant;
+  auto scrollMode = sf->ScrollModeForScrollBehavior(aOptions.mBehavior);
   sf->ScrollToCSSPixels(scrollPos, scrollMode);
 }
 
@@ -3982,9 +3980,7 @@ void nsGlobalWindowInner::ScrollBy(const ScrollToOptions& aOptions) {
     return;
   }
 
-  auto scrollMode = sf->IsSmoothScroll(aOptions.mBehavior)
-                        ? ScrollMode::SmoothMsd
-                        : ScrollMode::Instant;
+  auto scrollMode = sf->ScrollModeForScrollBehavior(aOptions.mBehavior);
   sf->ScrollByCSSPixels(scrollDelta, scrollMode);
 }
 
@@ -4001,9 +3997,7 @@ void nsGlobalWindowInner::ScrollByLines(int32_t numLines,
   // It seems like it would make more sense for ScrollByLines to use
   // SMOOTH mode, but tests seem to depend on the synchronous behaviour.
   // Perhaps Web content does too.
-  ScrollMode scrollMode = sf->IsSmoothScroll(aOptions.mBehavior)
-                              ? ScrollMode::SmoothMsd
-                              : ScrollMode::Instant;
+  ScrollMode scrollMode = sf->ScrollModeForScrollBehavior(aOptions.mBehavior);
   sf->ScrollBy(nsIntPoint(0, numLines), ScrollUnit::LINES, scrollMode);
 }
 
@@ -4020,9 +4014,7 @@ void nsGlobalWindowInner::ScrollByPages(int32_t numPages,
   // It seems like it would make more sense for ScrollByPages to use
   // SMOOTH mode, but tests seem to depend on the synchronous behaviour.
   // Perhaps Web content does too.
-  ScrollMode scrollMode = sf->IsSmoothScroll(aOptions.mBehavior)
-                              ? ScrollMode::SmoothMsd
-                              : ScrollMode::Instant;
+  ScrollMode scrollMode = sf->ScrollModeForScrollBehavior(aOptions.mBehavior);
 
   sf->ScrollBy(nsIntPoint(0, numPages), ScrollUnit::PAGES, scrollMode);
 }
diff --git a/layout/base/PresShell.cpp b/layout/base/PresShell.cpp
@@ -3267,8 +3267,7 @@ nsresult PresShell::GoToAnchor(const nsAString& aAnchorName,
     // Check |aScroll| after setting |rv| so we set |rv| to the same
     // thing whether or not |aScroll| is true.
     if (aScroll && sf) {
-      ScrollMode scrollMode =
-          sf->IsSmoothScroll() ? ScrollMode::SmoothMsd : ScrollMode::Instant;
+      ScrollMode scrollMode = sf->ScrollModeForScrollBehavior();
       // Scroll to the top of the page
       sf->ScrollTo(nsPoint(0, 0), scrollMode);
     }
@@ -3458,7 +3457,6 @@ static WhereToScroll GetApplicableWhereToScroll(
 static ScrollMode GetScrollModeForScrollIntoView(
     const ScrollContainerFrame* aScrollContainerFrame,
     ScrollFlags aScrollFlags) {
-  ScrollMode scrollMode = ScrollMode::Instant;
   // Default to an instant scroll, but if the scroll behavior given is "auto"
   // or "smooth", use that as the specified behavior. If the user has disabled
   // smooth scrolls, a given mode of "auto" or "smooth" should not result in
@@ -3469,10 +3467,7 @@ static ScrollMode GetScrollModeForScrollIntoView(
   } else if (aScrollFlags & ScrollFlags::ScrollSmoothAuto) {
     behavior = ScrollBehavior::Auto;
   }
-  if (aScrollContainerFrame->IsSmoothScroll(behavior)) {
-    scrollMode = ScrollMode::SmoothMsd;
-  }
-  return scrollMode;
+  return aScrollContainerFrame->ScrollModeForScrollBehavior(behavior);
 }
 
 /**
diff --git a/layout/generic/ScrollContainerFrame.cpp b/layout/generic/ScrollContainerFrame.cpp
@@ -7827,6 +7827,12 @@ bool ScrollContainerFrame::IsSmoothScroll(dom::ScrollBehavior aBehavior) const {
               StyleScrollBehavior::Smooth);
 }
 
+ScrollMode ScrollContainerFrame::ScrollModeForScrollBehavior(
+    dom::ScrollBehavior aBehavior) const {
+  return IsSmoothScroll(aBehavior) ? ScrollMode::SmoothMsd
+                                   : ScrollMode::Instant;
+}
+
 nsTArray<ScrollPositionUpdate> ScrollContainerFrame::GetScrollUpdates() const {
   return mScrollUpdates.Clone();
 }
diff --git a/layout/generic/ScrollContainerFrame.h b/layout/generic/ScrollContainerFrame.h
@@ -862,6 +862,14 @@ class ScrollContainerFrame : public nsContainerFrame,
   bool IsSmoothScroll(
       dom::ScrollBehavior aBehavior = dom::ScrollBehavior::Auto) const;
 
+  /**
+   * Returns the ScrollMode that this scroll frame should use for a
+   * programmatic scroll governed by CSSOM-View `scroll-behavior`.
+   * This includes most programmatic scrolls but not scroll snapping.
+   */
+  ScrollMode ScrollModeForScrollBehavior(
+      dom::ScrollBehavior aBehavior = dom::ScrollBehavior::Auto) const;
+
   static nscoord GetNonOverlayScrollbarSize(const nsPresContext*,
                                             StyleScrollbarWidth);