PDF Viewer pinch zoom: Compute the zoom needed for the paint offset.

PDF Viewer pinch zoom: Compute the zoom needed for the paint offset.

Currently, when pinch zooming in, starting with a document that doesn't
cover the width of the plugin, we record the last zoom before the
document does cover the width. This value is used to compute the
|paint_offset| for the rest of the pinch. However, if the pinch is done
quickly, the last zoom value we record may differ significantly from the
zoom at which the rendered document width matches the plugin width. This
leads to an incorrect |paint_offset| as the gesture continues.

We now compute the correct zoom value, rather than relying on the last
one we see to be accurate.

BUG=704160
Review-Url: https://codereview.chromium.org/2764353002
Cr-Commit-Position: refs/heads/master@{#459069}
Committed: https://chromium.googlesource.com/chromium/src/+/08f7da01c04697fb873396bdf84b4ee34175fddd

[Kevin McNee, 2017-03-22 16:52:32]

The CQ bit was checked by mcnee@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-03-22 16:52:54]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Kevin McNee, 2017-03-22 16:57:07]

Description was changed from

==========
PDF Viewer pinch zoom: Compute the zoom needed for the paint offset.

Currently, when pinch zooming in, starting with a document that doesn't
cover the width of the plugin, we record the last zoom before the
document does cover the width. This value is used to compute the
|paint_offset| for the rest of the pinch. However, if the pinch is done
quickly, the last zoom value we record may differ significantly from the
zoom at which the rendered document width matches the plugin width. This
leads to an incorrect |paint_offset| as the gesture continues.

We now compute the correct zoom value, rather than relying on the last
one we see to be accurate.

BUG=704160
==========

to

==========
PDF Viewer pinch zoom: Compute the zoom needed for the paint offset.

Currently, when pinch zooming in, starting with a document that doesn't
cover the width of the plugin, we record the last zoom before the
document does cover the width. This value is used to compute the
|paint_offset| for the rest of the pinch. However, if the pinch is done
quickly, the last zoom value we record may differ significantly from the
zoom at which the rendered document width matches the plugin width. This
leads to an incorrect |paint_offset| as the gesture continues.

We now compute the correct zoom value, rather than relying on the last
one we see to be accurate.

BUG=704160
==========

[Kevin McNee, 2017-03-22 16:57:07]

mcnee@chromium.org changed reviewers:
+ bokan@chromium.org, thestig@chromium.org

[Kevin McNee, 2017-03-22 16:59:53]

Hello, thestig. Could you take a look at this change? I've also added bokan, who
originally reviewed the pinch zooming logic.

[commit-bot: I haz the power, 2017-03-22 18:07:35]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-03-22 18:07:35]

Dry run: This issue passed the CQ dry run.

[bokan, 2017-03-22 20:30:19]

change looks good to me but are we still unable to get tests here?

[Kevin McNee, 2017-03-22 20:50:05]

On 2017/03/22 20:30:19, bokan wrote:
> change looks good to me but are we still unable to get tests here?

As discussed previously: https://codereview.chromium.org/2541903002/#msg15
I'm afraid it doesn't look like anything's changed since then.

[bokan, 2017-03-22 21:39:27]

ok then, lgtm from me

[Lei Zhang, 2017-03-22 21:45:04]

On 2017/03/22 20:50:05, Kevin McNee wrote:
> On 2017/03/22 20:30:19, bokan wrote:
> > change looks good to me but are we still unable to get tests here?
> 
> As discussed previously: https://codereview.chromium.org/2541903002/#msg15
> I'm afraid it doesn't look like anything's changed since then.

We added a pdf_unittests target, but that's probably not what you need.

[Lei Zhang, 2017-03-22 21:46:12]

lgtm

[Kevin McNee, 2017-03-23 13:54:06]

The CQ bit was checked by mcnee@chromium.org

[commit-bot: I haz the power, 2017-03-23 13:54:29]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-23 13:59:01]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1490277246250980, "parent_rev":
"ff3375389bc379a05ec1b7a75719956cb423fdd5", "commit_rev":
"08f7da01c04697fb873396bdf84b4ee34175fddd"}

[commit-bot: I haz the power, 2017-03-23 13:59:46]

Description was changed from

==========
PDF Viewer pinch zoom: Compute the zoom needed for the paint offset.

Currently, when pinch zooming in, starting with a document that doesn't
cover the width of the plugin, we record the last zoom before the
document does cover the width. This value is used to compute the
|paint_offset| for the rest of the pinch. However, if the pinch is done
quickly, the last zoom value we record may differ significantly from the
zoom at which the rendered document width matches the plugin width. This
leads to an incorrect |paint_offset| as the gesture continues.

We now compute the correct zoom value, rather than relying on the last
one we see to be accurate.

BUG=704160
==========

to

==========
PDF Viewer pinch zoom: Compute the zoom needed for the paint offset.

Currently, when pinch zooming in, starting with a document that doesn't
cover the width of the plugin, we record the last zoom before the
document does cover the width. This value is used to compute the
|paint_offset| for the rest of the pinch. However, if the pinch is done
quickly, the last zoom value we record may differ significantly from the
zoom at which the rendered document width matches the plugin width. This
leads to an incorrect |paint_offset| as the gesture continues.

We now compute the correct zoom value, rather than relying on the last
one we see to be accurate.

BUG=704160

Review-Url: https://codereview.chromium.org/2764353002
Cr-Commit-Position: refs/heads/master@{#459069}
Committed:
https://chromium.googlesource.com/chromium/src/+/08f7da01c04697fb873396bdf84b...
==========

[commit-bot: I haz the power, 2017-03-23 13:59:48]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/08f7da01c04697fb873396bdf84b...