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Bug 1816601: HyperTextAccessibleBase::OffsetAtPoint: Return 0 if the point is within the container but before the rect at offset 0. r=nlapre

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This perpetuates a bug in (local) HyperTextAccessible that some users have unfortunately come to rely on.

Differential Revision: https://phabricator.services.mozilla.com/D169802
This commit is contained in:
James Teh 2023-02-16 11:57:14 +00:00
parent 21d3624930
commit e425f02438
2 changed files with 44 additions and 4 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

17
accessible/basetypes/HyperTextAccessibleBase.cpp
View file

@ -279,7 +279,7 @@ int32_t HyperTextAccessibleBase::OffsetAtPoint(int32_t aX, int32_t aY,
return -1;
}
TextLeafPoint point = ToTextLeafPoint(0, false);
TextLeafPoint startPoint = ToTextLeafPoint(0, false);
// As with TextBounds, we walk to the very end of the text contained in this
// hypertext and then step backwards to make our endPoint inclusive.
TextLeafPoint endPoint =
@ -287,18 +287,27 @@ int32_t HyperTextAccessibleBase::OffsetAtPoint(int32_t aX, int32_t aY,
endPoint =
endPoint.FindBoundary(nsIAccessibleText::BOUNDARY_CHAR, eDirPrevious,
/* aIncludeOrigin */ false);
TextLeafPoint point = startPoint;
// XXX: We should create a TextLeafRange object for this hypertext and move
// this search inside the TextLeafRange class.
// If there are no characters in this container, we might have moved endPoint
// before point. In that case, we shouldn't try to move further forward, as
// that might result in an infinite loop.
if (point <= endPoint) {
// before startPoint. In that case, we shouldn't try to move further forward,
// as that might result in an infinite loop.
if (startPoint <= endPoint) {
for (; !point.ContainsPoint(coords.x, coords.y) && point != endPoint;
point = point.FindBoundary(nsIAccessibleText::BOUNDARY_CHAR, eDirNext,
/* aIncludeOrigin */ false)) {
}
}
if (!point.ContainsPoint(coords.x, coords.y)) {
LayoutDeviceIntRect startRect = startPoint.CharBounds();
if (coords.x < startRect.x || coords.y < startRect.y) {
// Bug 1816601: The point is within the container but above or to the left
// of the rectangle at offset 0. We should really return -1, but we've
// returned 0 for many years due to a bug. Some users have unfortunately
// come to rely on this, so perpetuate this here.
return 0;
}
return -1;
}
DebugOnly<bool> ok = false;

31
accessible/tests/browser/hittest/browser_test_text.js
View file

@ -13,6 +13,13 @@ a
a
<iframe width="1" height="1"></iframe>
</div>
<button id="pointBeforeText">
<div style="display: flex;">
<div style="width: 100px; background-color: red;" role="none"></div>
test
<div style="width: 100px; background-color: blue;" role="none"></div>
</div>
</button>
`,
async function(browser, docAcc) {
const dpr = await getContentDPR(browser);
@ -43,6 +50,30 @@ a
x += width - 1;
y += height - 1;
await testOffsetAtPoint(iframeAtEnd, x, y, COORDTYPE_SCREEN_RELATIVE, -1);
// Test that 0 is returned if the point is within the container but before
// the rectangle at offset 0. This is buggy behavior that some users have
// unfortunately come to rely on (bug 1816601).
const pointBeforeText = findAccessibleChildByID(docAcc, "pointBeforeText", [
Ci.nsIAccessibleText,
]);
[x, y, width, height] = Layout.getBounds(pointBeforeText, dpr);
await testOffsetAtPoint(
pointBeforeText,
x + 1,
y + 1,
COORDTYPE_SCREEN_RELATIVE,
0
);
// But this buggy behavior only applies for a point before offset 0, not
// a point after the last offset. So it's asymmetrically buggy. :(
await testOffsetAtPoint(
pointBeforeText,
x + width - 1,
y + height - 1,
COORDTYPE_SCREEN_RELATIVE,
-1
);
},
{
topLevel: true,