Blink does not respect input.selectionStart and input.selectionEnd for some cases

Source/core/html/HTMLTextFormControlElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 145 matching lines @@
     if (!placeholderElement() || placeholderValueChanged)
         updatePlaceholderText();
     HTMLElement* placeholder = placeholderElement();
     if (!placeholder)
         return;
     placeholder->setInlineStyleProperty(CSSPropertyVisibility, placeholderShouldBeVisible() ? CSSValueVisible : CSSValueHidden);
 }
 
 void HTMLTextFormControlElement::setSelectionStart(int start)
 {
-    setSelectionRange(start, std::max(start, selectionEnd()), selectionDirection());
+    if (!innerEditorValue().isEmpty())

[yosin_UTC9, 2014/07/03 01:58:36]

It is better to call setSelectionRange(start, selectionEnd(),
selectionDirection()) then adjust start and end in setSelectionRange.

[harpreet.sk, 2014/07/04 13:50:26]

Adjusting values in setSelectionRange

+        setSelectionRange(start, std::max(start, selectionEnd()), selectionDirection());
+    else
+        setSelectionRange(start, std::max(start, m_cachedSelectionEnd), selectionDirection());

[yosin_UTC9, 2014/07/03 01:58:35]

Since, control has empty string, we can set 0, 0 to selection.

[harpreet.sk, 2014/07/04 13:50:27]

This condition is removed from here and adjusting values in setSelectionRange

 }
 
 void HTMLTextFormControlElement::setSelectionEnd(int end)
 {
-    setSelectionRange(std::min(end, selectionStart()), end, selectionDirection());
+    if (!innerEditorValue().isEmpty())
+        setSelectionRange(std::min(end, selectionStart()), end, selectionDirection());
+    else
+        setSelectionRange(std::min(end, m_cachedSelectionStart), end, selectionDirection());

[yosin_UTC9, 2014/07/03 01:58:36]

Since, control has empty string, we can set 0, 0 to selection.

[harpreet.sk, 2014/07/04 13:50:26]

ditto

 }
 
 void HTMLTextFormControlElement::setSelectionDirection(const String& direction)
 {
     setSelectionRange(selectionStart(), selectionEnd(), direction);
 }
 
 void HTMLTextFormControlElement::select()
 {
     setSelectionRange(0, std::numeric_limits<int>::max(), SelectionHasNoDirection);
@@ skipping 93 matching lines @@
     return setSelectionRange(start, end, direction);
 }
 
 void HTMLTextFormControlElement::setSelectionRange(int start, int end, TextFieldSelectionDirection direction)
 {
     document().updateLayoutIgnorePendingStylesheets();
 
     if (!renderer() || !renderer()->isTextControl())
         return;
 
     end = std::max(end, 0);

[yosin_UTC9, 2014/07/03 01:58:35]

How about
int textLength = innerEditorValue.length();
end = std::max(std::min(end, length), 0);
start = std::max(std::min(start, end), 0);

[harpreet.sk, 2014/07/04 13:50:27]

thanks for the suggestion... incorporated in new patch.

     start = std::min(std::max(start, 0), end);
+    int textLength = innerEditorValue().length();
+    if (textLength) {
+        if (textLength < start) {
+            start = textLength;
+            end = textLength;
+        } else if (textLength < end) {
+            end = textLength;
+        }
+    }
+    cacheSelection(start, end, direction);
+    bool isCaretSelection = (start == end);

[yosin_UTC9, 2014/07/03 01:58:35]

nit: we don't need to have surrounding parenthesis.

[harpreet.sk, 2014/07/04 13:50:27]

Done.

+    bool shouldSetSelection = (document().focusedElement() == this) || (!isCaretSelection && start < textLength);
 
-    if (!hasVisibleTextArea(renderer(), innerEditorElement())) {
-        cacheSelection(start, end, direction);
+    if (!hasVisibleTextArea(renderer(), innerEditorElement()))

[yosin_UTC9, 2014/07/03 01:58:35]

It seems we should set |FrameSelection| if text area has focus. But this isn't
related to this patch.

[harpreet.sk, 2014/07/04 13:50:26]

this check was already there ... i just moved the calling of cacheSelection from
the inside of the check.. this check is not part of this bug

         return;
-    }
     VisiblePosition startPosition = visiblePositionForIndex(start);
     VisiblePosition endPosition;
     if (start == end)
         endPosition = startPosition;
     else
         endPosition = visiblePositionForIndex(end);
 
     // startPosition and endPosition can be null position for example when
     // "-webkit-user-select: none" style attribute is specified.
     if (startPosition.isNotNull() && endPosition.isNotNull()) {
         ASSERT(startPosition.deepEquivalent().deprecatedNode()->shadowHost() == this
             && endPosition.deepEquivalent().deprecatedNode()->shadowHost() == this);
     }
     VisibleSelection newSelection;
     if (direction == SelectionHasBackwardDirection)
         newSelection = VisibleSelection(endPosition, startPosition);
     else
         newSelection = VisibleSelection(startPosition, endPosition);
     newSelection.setIsDirectional(direction != SelectionHasNoDirection);
 
-    if (LocalFrame* frame = document().frame())
+    LocalFrame* frame = document().frame();
+    if (frame && shouldSetSelection)

[yosin_UTC9, 2014/07/03 01:58:35]

Please move this if-statement just after L306 if (!hasVisibleTextArea(...).
When we don't have |LocalFrame| and |!shouldSelection| we don't need to
construct |VisibleSelection|.

[harpreet.sk, 2014/07/04 13:50:27]

Done.

         frame->selection().setSelection(newSelection);
 }
 
 VisiblePosition HTMLTextFormControlElement::visiblePositionForIndex(int index) const
 {
     if (index <= 0)
         return VisiblePosition(firstPositionInNode(innerEditorElement()), DOWNSTREAM);
     RefPtrWillBeRawPtr<Range> range = Range::create(document());
     range->selectNodeContents(innerEditorElement(), ASSERT_NO_EXCEPTION);
     CharacterIterator it(range.get());
     it.advance(index - 1);
     return VisiblePosition(it.range()->endPosition(), UPSTREAM);
 }
 
 int HTMLTextFormControlElement::indexForVisiblePosition(const VisiblePosition& pos) const
 {
     Position indexPosition = pos.deepEquivalent().parentAnchoredEquivalent();
     if (enclosingTextFormControl(indexPosition) != this)
         return 0;
     ASSERT(indexPosition.document());
     RefPtrWillBeRawPtr<Range> range = Range::create(*indexPosition.document());
     range->setStart(innerEditorElement(), 0, ASSERT_NO_EXCEPTION);
     range->setEnd(indexPosition.containerNode(), indexPosition.offsetInContainerNode(), ASSERT_NO_EXCEPTION);
     return TextIterator::rangeLength(range.get());
 }
 
 int HTMLTextFormControlElement::selectionStart() const
 {
-    if (!isTextFormControl())
+    if (!isTextFormControl() || innerEditorValue().isEmpty())

[yosin_UTC9, 2014/07/03 01:58:35]

We should reset |m_cachedSelectionStart| when value is changed. Rather than
check whether value is empty or not.

[harpreet.sk, 2014/07/04 13:50:27]

Done.

         return 0;
     if (document().focusedElement() != this)
         return m_cachedSelectionStart;
-
     return computeSelectionStart();
 }
 
 int HTMLTextFormControlElement::computeSelectionStart() const
 {
     ASSERT(isTextFormControl());
     LocalFrame* frame = document().frame();
     if (!frame)
         return 0;
 
     return indexForVisiblePosition(VisiblePosition(frame->selection().start()));
 }
 
 int HTMLTextFormControlElement::selectionEnd() const
 {
-    if (!isTextFormControl())
+    if (!isTextFormControl() || innerEditorValue().isEmpty())

[yosin_UTC9, 2014/07/03 01:58:35]

We should reset |m_cachedSelectionEnd| when value is changed. Rather than check
whether value is empty or not.

[harpreet.sk, 2014/07/04 13:50:27]

Done.

         return 0;
     if (document().focusedElement() != this)
         return m_cachedSelectionEnd;
     return computeSelectionEnd();
 }
 
 int HTMLTextFormControlElement::computeSelectionEnd() const
 {
     ASSERT(isTextFormControl());
     LocalFrame* frame = document().frame();
@@ skipping 98 matching lines @@
 void HTMLTextFormControlElement::restoreCachedSelection()
 {
     setSelectionRange(m_cachedSelectionStart, m_cachedSelectionEnd, m_cachedSelectionDirection);
 }
 
 void HTMLTextFormControlElement::selectionChanged(bool userTriggered)
 {
     if (!renderer() || !isTextFormControl())
         return;
 
-    // selectionStart() or selectionEnd() will return cached selection when this node doesn't have focus
-    cacheSelection(computeSelectionStart(), computeSelectionEnd(), computeSelectionDirection());
+    if (document().focusedElement() == this)

[yosin_UTC9, 2014/07/03 01:58:36]

We should keep cached selection up-to date.

[harpreet.sk, 2014/07/04 13:50:26]

The cached selection is getting up-to-date in setSelectionRange.

+        cacheSelection(computeSelectionStart(), computeSelectionEnd(), computeSelectionDirection());
 
     if (LocalFrame* frame = document().frame()) {
         if (frame->selection().isRange() && userTriggered)
             dispatchEvent(Event::createBubble(EventTypeNames::select));
     }
 }
 
 void HTMLTextFormControlElement::parseAttribute(const QualifiedName& name, const AtomicString& value)
 {
     if (name == placeholderAttr) {
@@ skipping 161 matching lines @@
 
     return "ltr";
 }
 
 HTMLElement* HTMLTextFormControlElement::innerEditorElement() const
 {
     return toHTMLElement(userAgentShadowRoot()->getElementById(ShadowElementNames::innerEditor()));
 }
 
 } // namespace Webcore