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Bug 591363 - (in)visible state is not always correct? r=tbsaunde, marcoz

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Here we depart from relying on layout because we don't want to walk
up the ancestor chain all the way past the property page parent since
this messes with screen readers virtual buffer updates (see bug).
This commit is contained in:
David Bolter 2012-01-05 22:45:11 -05:00
parent d58fe9d9c1
commit 00bbb552fa
4 changed files with 123 additions and 69 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

117
accessible/src/base/nsAccessible.cpp
View File

@ -590,75 +590,63 @@ nsresult nsAccessible::GetTranslatedString(const nsAString& aKey, nsAString& aSt
return NS_OK;
}
bool
nsAccessible::IsVisible(bool* aIsOffscreen)
PRUint64
nsAccessible::VisibilityState()
{
PRUint64 vstates = states::INVISIBLE | states::OFFSCREEN;
// We need to check the parent chain for visibility.
nsAccessible* accessible = this;
do {
// We don't want background tab page content to be aggressively invisible.
// Otherwise this foils screen reader virtual buffer caches.
PRUint32 role = accessible->Role();
if (role == nsIAccessibleRole::ROLE_PROPERTYPAGE ||
role == nsIAccessibleRole::ROLE_PANE) {
break;
}
nsIFrame* frame = accessible->GetFrame();
if (!frame)
return vstates;
const nsIView* view = frame->GetView();
if (view && view->GetVisibility() == nsViewVisibility_kHide)
return vstates;
} while (accessible = accessible->Parent());
nsIFrame* frame = GetFrame();
const nsCOMPtr<nsIPresShell> shell(GetPresShell());
// We need to know if at least a kMinPixels around the object is visible,
// otherwise it will be marked states::OFFSCREEN. The states::INVISIBLE flag
// is for elements which are programmatically hidden.
*aIsOffscreen = true;
if (IsDefunct())
return false;
// otherwise it will be marked states::OFFSCREEN.
const PRUint16 kMinPixels = 12;
// Set up the variables we need, return false if we can't get at them all
nsCOMPtr<nsIPresShell> shell(GetPresShell());
if (!shell)
return false;
nsIFrame *frame = GetFrame();
if (!frame) {
return false;
}
// If visibility:hidden or visibility:collapsed then mark with STATE_INVISIBLE
if (!frame->GetStyleVisibility()->IsVisible())
{
return false;
}
// We don't use the more accurate GetBoundsRect, because that is more expensive
// and the STATE_OFFSCREEN flag that this is used for only needs to be a rough
// indicator
nsSize frameSize = frame->GetSize();
nsRectVisibility rectVisibility =
const nsSize frameSize = frame->GetSize();
const nsRectVisibility rectVisibility =
shell->GetRectVisibility(frame, nsRect(nsPoint(0,0), frameSize),
nsPresContext::CSSPixelsToAppUnits(kMinPixels));
if (frame->GetRect().IsEmpty()) {
bool isEmpty = true;
if (rectVisibility == nsRectVisibility_kVisible)
vstates &= ~states::OFFSCREEN;
nsIAtom *frameType = frame->GetType();
if (frameType == nsGkAtoms::textFrame) {
// Zero area rects can occur in the first frame of a multi-frame text flow,
// in which case the rendered text is not empty and the frame should not be marked invisible
nsAutoString renderedText;
frame->GetRenderedText (&renderedText, nsnull, nsnull, 0, 1);
isEmpty = renderedText.IsEmpty();
}
else if (frameType == nsGkAtoms::inlineFrame) {
// Yuck. Unfortunately inline frames can contain larger frames inside of them,
// so we can't really believe this is a zero area rect without checking more deeply.
// GetBounds() will do that for us.
PRInt32 x, y, width, height;
GetBounds(&x, &y, &width, &height);
isEmpty = width == 0 || height == 0;
}
// Zero area rects can occur in the first frame of a multi-frame text flow,
// in which case the rendered text is not empty and the frame should not be
// marked invisible.
// XXX Can we just remove this check? Why do we need to mark empty
// text invisible?
if (frame->GetType() == nsGkAtoms::textFrame &&
!(frame->GetStateBits() & NS_FRAME_OUT_OF_FLOW) &&
frame->GetRect().IsEmpty()) {
nsAutoString renderedText;
frame->GetRenderedText(&renderedText, nsnull, nsnull, 0, 1);
if (renderedText.IsEmpty())
return vstates;
if (isEmpty && !(frame->GetStateBits() & NS_FRAME_OUT_OF_FLOW)) {
// Consider zero area objects hidden unless they are absolutely positioned
// or floating and may have descendants that have a non-zero size
return false;
}
}
// The frame intersects the viewport, but we need to check the parent view chain :(
bool isVisible = frame->IsVisibleConsideringAncestors(nsIFrame::VISIBILITY_CROSS_CHROME_CONTENT_BOUNDARY);
if (isVisible && rectVisibility == nsRectVisibility_kVisible) {
*aIsOffscreen = false;
}
return isVisible;
// Assume we are visible enough.
return vstates &= ~states::INVISIBLE;
}
PRUint64
@ -701,15 +689,8 @@ nsAccessible::NativeState()
state |= states::FOCUSED;
}
// Check if states::INVISIBLE and
// states::OFFSCREEN flags should be turned on for this object.
bool isOffscreen;
if (!IsVisible(&isOffscreen)) {
state |= states::INVISIBLE;
}
if (isOffscreen) {
state |= states::OFFSCREEN;
}
// Gather states::INVISIBLE and states::OFFSCREEN flags for this object.
state |= VisibilityState();
nsIFrame *frame = GetFrame();
if (frame && (frame->GetStateBits() & NS_FRAME_OUT_OF_FLOW))

3
accessible/src/base/nsAccessible.h
View File

@ -671,7 +671,8 @@ protected:
virtual nsIFrame* GetBoundsFrame();
virtual void GetBoundsRect(nsRect& aRect, nsIFrame** aRelativeFrame);
bool IsVisible(bool *aIsOffscreen);
PRUint64 VisibilityState();
//////////////////////////////////////////////////////////////////////////////
// Name helpers

1
accessible/tests/mochitest/states/Makefile.in
View File

@ -63,6 +63,7 @@ _TEST_FILES =\
test_stale.html \
test_textbox.xul \
test_tree.xul \
test_visibility.html \
z_frames.html \
z_frames_article.html \
z_frames_checkbox.html \

71
accessible/tests/mochitest/states/test_visibility.html Normal file
View File

@ -0,0 +1,71 @@
<html>
<head>
<title>visibility state testing</title>
<link rel="stylesheet" type="text/css"
href="chrome://mochikit/content/tests/SimpleTest/test.css" />
<script type="application/javascript"
src="chrome://mochikit/content/MochiKit/packed.js"></script>
<script type="application/javascript"
src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
<script type="application/javascript"
src="../common.js"></script>
<script type="application/javascript"
src="../role.js"></script>
<script type="application/javascript"
src="../states.js"></script>
<script type="application/javascript">
function doTest()
{
testStates("div", 0, 0, STATE_INVISIBLE);
testStates("div_off", STATE_OFFSCREEN, 0, STATE_INVISIBLE);
testStates("div_abschild", 0, 0, STATE_INVISIBLE);
// Confirm destruction of accessibles.
document.getElementById("div").style.visibility = "hidden";
document.getElementById("div_off").style.visibility="hidden";
document.getElementById("div_abschild").style.visibility="hidden";
document.body.clientWidth; // flush layout
testAccessibleTree("outer_div", {children:[]});
SimpleTest.finish();
}
SimpleTest.waitForExplicitFinish();
addA11yLoadEvent(doTest);
</script>
</head>
<body>
<a target="_blank"
href="https://bugzilla.mozilla.org/show_bug.cgi?id=591363"
title="(in)visible state is not always correct?">
Mozilla Bug 591363
</a>
<p id="display"></p>
<div id="content" style="display: none"></div>
<pre id="test">
</pre>
<div id="outer_div">
<!-- trivial cases -->
<div id="div">div</div>
<div id="div_off" style="position: absolute; left:-999px; top:-999px">
offscreen!
</div>
<!-- edge case: no rect but has out of flow child -->
<div id="div_abschild">
<p style="position: absolute; left: 120px; top:120px;">absolute</p>
</div>
</div>
</body>
</html>