Bug 1644366 - Restore behavior of selection into view to keep scrolling ancestors on focus. r=smaug

... yet keep respecting the preventScroll flag.

Differential Revision: https://phabricator.services.mozilla.com/D78900

dom/base/nsFocusManager.cpp

@@ -24,6 +24,7 @@
 #include "nsCaret.h"
 #include "nsIBaseWindow.h"
 #include "nsIAppWindow.h"
+#include "nsTextControlFrame.h"
 #include "nsViewManager.h"
 #include "nsFrameSelection.h"
 #include "mozilla/dom/Document.h"
@@ -2675,6 +2676,15 @@ void nsFocusManager::ScrollIntoView(PresShell* aPresShell, nsIContent* aContent,
       aContent, ScrollAxis(kScrollMinimum, WhenToScroll::IfNotVisible),
       ScrollAxis(kScrollMinimum, WhenToScroll::IfNotVisible),
       ScrollFlags::ScrollOverflowHidden);
+  // Scroll the input / textarea selection into view, unless focused with the
+  // mouse, see bug 572649.
+  if (aFlags & FLAG_BYMOUSE) {
+    return;
+  }
+  // ScrollContentIntoView flushes layout, so no need to flush again here.
+  if (nsTextControlFrame* tf = do_QueryFrame(aContent->GetPrimaryFrame())) {
+    tf->ScrollSelectionIntoViewAsync(nsTextControlFrame::ScrollAncestors::Yes);
+  }
 }
 
 void nsFocusManager::RaiseWindow(nsPIDOMWindowOuter* aWindow,

layout/forms/nsTextControlFrame.cpp

@@ -57,6 +57,7 @@ nsIFrame* NS_NewTextControlFrame(PresShell* aPresShell, ComputedStyle* aStyle) {
 NS_IMPL_FRAMEARENA_HELPERS(nsTextControlFrame)
 
 NS_QUERYFRAME_HEAD(nsTextControlFrame)
+  NS_QUERYFRAME_ENTRY(nsTextControlFrame)
   NS_QUERYFRAME_ENTRY(nsIFormControlFrame)
   NS_QUERYFRAME_ENTRY(nsIAnonymousContentCreator)
   NS_QUERYFRAME_ENTRY(nsITextControlFrame)
@@ -714,26 +715,7 @@ void nsTextControlFrame::SetFocus(bool aOn, bool aRepaint) {
     return;
   }
 
-  // Scroll the current selection into view
-  Selection* caretSelection = caret->GetSelection();
-  const bool isFocusedRightNow = ourSel == caretSelection;
-  if (!isFocusedRightNow) {
-    // Don't scroll the current selection if we've been focused using the mouse.
-    uint32_t lastFocusMethod = 0;
-    Document* doc = GetContent()->GetComposedDoc();
-    if (doc) {
-      nsIFocusManager* fm = nsFocusManager::GetFocusManager();
-      if (fm) {
-        fm->GetLastFocusMethod(doc->GetWindow(), &lastFocusMethod);
-      }
-    }
-    if (!(lastFocusMethod & nsIFocusManager::FLAG_BYMOUSE)) {
-      // NOTE(emilio): This is asynchronous, so it can't cause havoc.
-      ScrollSelectionIntoViewAsync();
-    }
-  }
-
-  // tell the caret to use our selection
+  // Tell the caret to use our selection
   caret->SetSelection(ourSel);
 
   // mutual-exclusion: the selection is either controlled by the
@@ -843,18 +825,23 @@ nsresult nsTextControlFrame::SetSelectionInternal(
   return NS_OK;
 }
 
-void nsTextControlFrame::ScrollSelectionIntoViewAsync() {
+void nsTextControlFrame::ScrollSelectionIntoViewAsync(
+    ScrollAncestors aScrollAncestors) {
   auto* textControlElement = TextControlElement::FromNode(GetContent());
   MOZ_ASSERT(textControlElement);
   nsISelectionController* selCon = textControlElement->GetSelectionController();
   if (!selCon) {
     return;
   }
+
+  int16_t flags = aScrollAncestors == ScrollAncestors::Yes
+                   ? 0
+                   : nsISelectionController::SCROLL_FIRST_ANCESTOR_ONLY;
+
   // Scroll the selection into view (see bug 231389).
   selCon->ScrollSelectionIntoView(
       nsISelectionController::SELECTION_NORMAL,
-      nsISelectionController::SELECTION_FOCUS_REGION,
-      nsISelectionController::SCROLL_FIRST_ANCESTOR_ONLY);
+      nsISelectionController::SELECTION_FOCUS_REGION, flags);
 }
 
 nsresult nsTextControlFrame::SelectAllOrCollapseToEndOfText(bool aSelect) {

layout/forms/nsTextControlFrame.h

@@ -188,6 +188,11 @@ class nsTextControlFrame : public nsContainerFrame,
 
   NS_DECL_QUERYFRAME
 
+  // Whether we should scroll only the current selection into view in the inner
+  // scroller, or also ancestors as needed.
+  enum class ScrollAncestors { No, Yes };
+  void ScrollSelectionIntoViewAsync(ScrollAncestors = ScrollAncestors::No);
+
  protected:
   /**
    * Launch the reflow on the child frames - see nsTextControlFrame::Reflow()
@@ -290,8 +295,6 @@ class nsTextControlFrame : public nsContainerFrame,
                                          mozilla::WritingMode aWM,
                                          float aFontSizeInflation) const;
 
-  void ScrollSelectionIntoViewAsync();
-
  private:
   // helper methods
   MOZ_CAN_RUN_SCRIPT nsresult SetSelectionInternal(

testing/web-platform/tests/html/interaction/focus/processing-model/textarea-scroll-selection.html

@@ -0,0 +1,46 @@
+<!doctype html>
+<title>programatic focus() scrolls selection into view including ancestors</title>
+<link rel="author" href="https://mozilla.org" title="Mozilla">
+<link rel="author" href="mailto:emilio@crisal.io" title="Emilio Cobos Álvarez">
+<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1644366">
+<script src=/resources/testharness.js></script>
+<script src=/resources/testharnessreport.js></script>
+<div style="overflow: auto; height: 100px">
+  <textarea style="overflow: hidden; height: 200px">
+    Some text
+    That is surely more
+    Than 100px tall
+    For sure.
+    For sure.
+    For sure.
+    For sure.
+    For sure.
+    For sure.
+    For sure.
+    For sure.
+    For sure.
+    For sure.
+    For sure.
+    For sure.
+    For sure.
+    For sure.
+    For sure.
+    For sure.
+    For sure.
+    For sure.
+  </textarea>
+</div>
+<script>
+promise_test(async function(t) {
+  await new Promise(resolve => window.addEventListener("load", resolve));
+  let textarea = document.querySelector("textarea");
+  textarea.setSelectionRange(textarea.value.length, textarea.value.length);
+  textarea.focus();
+
+  await new Promise(resolve => {
+    requestAnimationFrame(() => requestAnimationFrame(resolve));
+  });
+
+  assert_not_equals(textarea.parentNode.scrollTop, 0, "Should've scrolled ancestor to show the selection");
+});
+</script>