Align Element.ScrollIntoView() with the spec.

This also removes the (unused) shadow alias from nsIDOMHTMLElement
which used the different calling convention.

This resolves #927

2 files changed, 53 insertions, 14 deletions

diff --git a/dom/base/Element.cpp b/dom/base/Element.cpp
index 67759fdb26..5c3277e841 100644
--- a/dom/base/Element.cpp
+++ b/dom/base/Element.cpp
@@ -687,19 +687,23 @@ Element::GetScrollFrame(nsIFrame **aStyledFrame, bool aFlushLayout)
 }
 
 void
-Element::ScrollIntoView()
+Element::ScrollIntoView(const BooleanOrScrollIntoViewOptions& aObject)
 {
-  ScrollIntoView(ScrollIntoViewOptions());
-}
+  if (aObject.IsScrollIntoViewOptions()) {
+    return ScrollIntoView(aObject.GetAsScrollIntoViewOptions());
+  }
+
+  MOZ_DIAGNOSTIC_ASSERT(aObject.IsBoolean());
 
-void
-Element::ScrollIntoView(bool aTop)
-{
   ScrollIntoViewOptions options;
-  if (!aTop) {
+  if (aObject.GetAsBoolean()) {
+    options.mBlock = ScrollLogicalPosition::Start;
+    options.mInline = ScrollLogicalPosition::Nearest;
+  } else {
     options.mBlock = ScrollLogicalPosition::End;
+    options.mInline = ScrollLogicalPosition::Nearest;
   }
-  ScrollIntoView(options);
+  return ScrollIntoView(options);
 }
 
 void
@@ -716,9 +720,41 @@ Element::ScrollIntoView(const ScrollIntoViewOptions &aOptions)
     return;
   }
 
-  int16_t vpercent = (aOptions.mBlock == ScrollLogicalPosition::Start)
-                       ? nsIPresShell::SCROLL_TOP
-                       : nsIPresShell::SCROLL_BOTTOM;
+  int16_t vpercent = nsIPresShell::SCROLL_CENTER;
+  switch (aOptions.mBlock) {
+    case ScrollLogicalPosition::Start:
+      vpercent = nsIPresShell::SCROLL_TOP;
+      break;
+    case ScrollLogicalPosition::Center:
+      vpercent = nsIPresShell::SCROLL_CENTER;
+      break;
+    case ScrollLogicalPosition::End:
+      vpercent = nsIPresShell::SCROLL_BOTTOM;
+      break;
+    case ScrollLogicalPosition::Nearest:
+      vpercent = nsIPresShell::SCROLL_MINIMUM;
+      break;
+    default:
+      MOZ_ASSERT_UNREACHABLE("Unexpected ScrollLogicalPosition value");
+  }
+
+  int16_t hpercent = nsIPresShell::SCROLL_CENTER;
+  switch (aOptions.mInline) {
+    case ScrollLogicalPosition::Start:
+      hpercent = nsIPresShell::SCROLL_LEFT;
+      break;
+    case ScrollLogicalPosition::Center:
+      hpercent = nsIPresShell::SCROLL_CENTER;
+      break;
+    case ScrollLogicalPosition::End:
+      hpercent = nsIPresShell::SCROLL_RIGHT;
+      break;
+    case ScrollLogicalPosition::Nearest:
+      hpercent = nsIPresShell::SCROLL_MINIMUM;
+      break;
+    default:
+      MOZ_ASSERT_UNREACHABLE("Unexpected ScrollLogicalPosition value");
+  }
 
   uint32_t flags = nsIPresShell::SCROLL_OVERFLOW_HIDDEN;
   if (aOptions.mBehavior == ScrollBehavior::Smooth) {
@@ -731,7 +767,9 @@ Element::ScrollIntoView(const ScrollIntoViewOptions &aOptions)
                                    nsIPresShell::ScrollAxis(
                                      vpercent,
                                      nsIPresShell::SCROLL_ALWAYS),
-                                   nsIPresShell::ScrollAxis(),
+                                   nsIPresShell::ScrollAxis(
+                                     hpercent,
+                                     nsIPresShell::SCROLL_ALWAYS),
                                    flags);
 }
 
diff --git a/dom/base/Element.h b/dom/base/Element.h
index ef57a64668..ce84b74fb4 100644
--- a/dom/base/Element.h
+++ b/dom/base/Element.h
@@ -818,9 +818,10 @@ public:
     return slots ? slots->mShadowRoot.get() : nullptr;
   }
 
-  void ScrollIntoView();
-  void ScrollIntoView(bool aTop);
+private:
   void ScrollIntoView(const ScrollIntoViewOptions &aOptions);
+public:
+  void ScrollIntoView(const BooleanOrScrollIntoViewOptions& aObject);
   void Scroll(double aXScroll, double aYScroll);
   void Scroll(const ScrollToOptions& aOptions);
   void ScrollTo(double aXScroll, double aYScroll);