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Bug 1644638. ScrollFrameHelper::ReflowFinished should use GetVisualScrollRange instead of trying to calculate it itself. r=kats

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This avoids a bug where the scroll range can be negative.

Differential Revision: https://phabricator.services.mozilla.com/D79029
This commit is contained in:
Timothy Nikkel 2020-06-12 08:12:30 +00:00
parent aec8dd9651
commit af9202b6b8
1 changed files with 16 additions and 21 deletions
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37
layout/generic/nsGfxScrollFrame.cpp
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@ -6024,13 +6024,6 @@ bool ScrollFrameHelper::ReflowFinished() {
}
}
nsRect scrolledContentRect = GetScrolledRect();
nsSize scrollClampingScrollPort = GetVisualViewportSize();
nscoord minX = scrolledContentRect.x;
nscoord maxX = scrolledContentRect.XMost() - scrollClampingScrollPort.width;
nscoord minY = scrolledContentRect.y;
nscoord maxY = scrolledContentRect.YMost() - scrollClampingScrollPort.height;
// Suppress handling of the curpos attribute changes we make here.
NS_ASSERTION(!mFrameIsUpdatingScrollbar, "We shouldn't be reentering here");
mFrameIsUpdatingScrollbar = true;
@ -6045,6 +6038,9 @@ bool ScrollFrameHelper::ReflowFinished() {
// for scrollbars. XXXmats is this still true now that we have a script
// blocker in this scope? (if not, remove the weak frame checks below).
if (vScroll || hScroll) {
nsSize visualViewportSize = GetVisualViewportSize();
nsRect scrollRange = GetVisualScrollRange();
AutoWeakFrame weakFrame(mOuter);
nsPoint scrollPos = GetScrollPosition();
nsSize lineScrollAmount = GetLineScrollAmount();
@ -6053,20 +6049,19 @@ bool ScrollFrameHelper::ReflowFinished() {
Preferences::GetInt("toolkit.scrollbox.verticalScrollDistance",
NS_DEFAULT_VERTICAL_SCROLL_DISTANCE);
nscoord increment = lineScrollAmount.height * kScrollMultiplier;
// We normally use (scrollArea.height - increment) for height
// of page scrolling. However, it is too small when
// increment is very large. (If increment is larger than
// scrollArea.height, direction of scrolling will be opposite).
// To avoid it, we use (float(scrollArea.height) * 0.8) as
// lower bound value of height of page scrolling. (bug 383267)
// We normally use (visualViewportSize.height - increment) for height of
// page scrolling. However, it is too small when increment is very large.
// (If increment is larger than visualViewportSize.height, direction of
// scrolling will be opposite). To avoid it, we use
// (float(visualViewportSize.height) * 0.8) as lower bound value of height
// of page scrolling. (bug 383267)
// XXX shouldn't we use GetPageScrollAmount here?
nscoord pageincrement =
nscoord(scrollClampingScrollPort.height - increment);
nscoord pageincrement = nscoord(visualViewportSize.height - increment);
nscoord pageincrementMin =
nscoord(float(scrollClampingScrollPort.height) * 0.8);
FinishReflowForScrollbar(vScroll, minY, maxY, scrollPos.y,
std::max(pageincrement, pageincrementMin),
increment);
nscoord(float(visualViewportSize.height) * 0.8);
FinishReflowForScrollbar(
vScroll, scrollRange.y, scrollRange.YMost(), scrollPos.y,
std::max(pageincrement, pageincrementMin), increment);
}
if (hScroll) {
const double kScrollMultiplier =
@ -6074,8 +6069,8 @@ bool ScrollFrameHelper::ReflowFinished() {
NS_DEFAULT_HORIZONTAL_SCROLL_DISTANCE);
nscoord increment = lineScrollAmount.width * kScrollMultiplier;
FinishReflowForScrollbar(
hScroll, minX, maxX, scrollPos.x,
nscoord(float(scrollClampingScrollPort.width) * 0.8), increment);
hScroll, scrollRange.x, scrollRange.XMost(), scrollPos.x,
nscoord(float(visualViewportSize.width) * 0.8), increment);
}
NS_ENSURE_TRUE(weakFrame.IsAlive(), false);
}