Simplify CullRect computation in LineBoxList::hitTest; fixing off-by-one

Simplify CullRect computation in LineBoxList::hitTest; fixing off-by-one

In the old formulation, we were essentially trying to "restore" the
margins from the HitTestLocation bounding-box and point, to compute a
"slice" to cull with. The "width" and "height" expressions for the slice
however trivially simplify to just the corresponding dimension of the
HitTestLocation bounding-box. For the "x" and "y" expressions however
the left/top margin is computed using the rounded point - which for
certain values of x/y will end up shifting the cullrect left/up by one
additional "unit" (pixel).
When the font size is small, one "unit" will be a lot, meaning that lines
can be missed entirely.

Change the computation of the cull rect to just use the bounding-box
from directly rather than restoring it from the (re)computed margin.
This gets rid of the last user of the HitTestLocation::*Padding()
methods, so remove those.

BUG=466617
Committed: https://crrev.com/cd159234dd394de40cb354fe71444b787b3b3bb7
Cr-Commit-Position: refs/heads/master@{#380194}

[fs, 2016-03-09 17:36:33]

fs@opera.com changed reviewers:
+ leviw@chromium.org, pdr@chromium.org

[fs, 2016-03-09 18:24:07]

Description was changed from

==========
Simplify CullRect computation in LineBoxList::hitTest; fixing off-by-one

In the old formulation, we were essentially trying to "restore" the
margins from the HitTestLocation bounding-box and point, to compute a
"slice" to cull with. The "width" and "height" expressions for the slice
however trivially simplify to just the corresponding dimension of the
HitTestLocation bounding-box. For the "x" and "y" expressions however
the left/top margin is computed using the rounded point - which for
certain values of x/y will end up shifting the cullrect left/up by one
additional "unit" (pixel).
When the font size is small, one "unit" will be a lot, meaning that the
lines can be missed entirely.
Change the computation of the cull rect to just use the bounding-box
from directly rather than restoring it from the (re)computed margin.
This gets rid of the last user of the HitTestLocation::*Padding()
methods, so remove those.

BUG=466617
==========

to

==========
Simplify CullRect computation in LineBoxList::hitTest; fixing off-by-one

In the old formulation, we were essentially trying to "restore" the
margins from the HitTestLocation bounding-box and point, to compute a
"slice" to cull with. The "width" and "height" expressions for the slice
however trivially simplify to just the corresponding dimension of the
HitTestLocation bounding-box. For the "x" and "y" expressions however
the left/top margin is computed using the rounded point - which for
certain values of x/y will end up shifting the cullrect left/up by one
additional "unit" (pixel).
When the font size is small, one "unit" will be a lot, meaning that lines
can be missed entirely.

Change the computation of the cull rect to just use the bounding-box
from directly rather than restoring it from the (re)computed margin.
This gets rid of the last user of the HitTestLocation::*Padding()
methods, so remove those.

BUG=466617
==========

[pdr., 2016-03-09 19:48:57]

LGTM

[fs, 2016-03-09 20:04:58]

The CQ bit was checked by fs@opera.com

[commit-bot: I haz the power, 2016-03-09 20:05:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1780673002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1780673002/1

[commit-bot: I haz the power, 2016-03-09 20:11:52]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-03-09 20:14:17]

Description was changed from

==========
Simplify CullRect computation in LineBoxList::hitTest; fixing off-by-one

In the old formulation, we were essentially trying to "restore" the
margins from the HitTestLocation bounding-box and point, to compute a
"slice" to cull with. The "width" and "height" expressions for the slice
however trivially simplify to just the corresponding dimension of the
HitTestLocation bounding-box. For the "x" and "y" expressions however
the left/top margin is computed using the rounded point - which for
certain values of x/y will end up shifting the cullrect left/up by one
additional "unit" (pixel).
When the font size is small, one "unit" will be a lot, meaning that lines
can be missed entirely.

Change the computation of the cull rect to just use the bounding-box
from directly rather than restoring it from the (re)computed margin.
This gets rid of the last user of the HitTestLocation::*Padding()
methods, so remove those.

BUG=466617
==========

to

==========
Simplify CullRect computation in LineBoxList::hitTest; fixing off-by-one

In the old formulation, we were essentially trying to "restore" the
margins from the HitTestLocation bounding-box and point, to compute a
"slice" to cull with. The "width" and "height" expressions for the slice
however trivially simplify to just the corresponding dimension of the
HitTestLocation bounding-box. For the "x" and "y" expressions however
the left/top margin is computed using the rounded point - which for
certain values of x/y will end up shifting the cullrect left/up by one
additional "unit" (pixel).
When the font size is small, one "unit" will be a lot, meaning that lines
can be missed entirely.

Change the computation of the cull rect to just use the bounding-box
from directly rather than restoring it from the (re)computed margin.
This gets rid of the last user of the HitTestLocation::*Padding()
methods, so remove those.

BUG=466617

Committed: https://crrev.com/cd159234dd394de40cb354fe71444b787b3b3bb7
Cr-Commit-Position: refs/heads/master@{#380194}
==========

[commit-bot: I haz the power, 2016-03-09 20:14:18]

Patchset 1 (id:??) landed as
https://crrev.com/cd159234dd394de40cb354fe71444b787b3b3bb7
Cr-Commit-Position: refs/heads/master@{#380194}