= Review UI

Reviewing changes is an important task and the Gerrit Web UI provides
many functionalities to make the review process comfortable and
efficient. This is a guide through the review UI that explains the
different functions and UI elements.

[[change-screen]]
== Change Screen

The change screen shows the details of a single change and provides
various actions on it.

image::images/user-review-ui-change-screen.png[width=800, link="images/user-review-ui-change-screen.png"]

[[commit-message]]
=== Commit Message Block

The focus of the change screen is on the commit message since this is
the most important information about a change. The numeric change ID
and the change status are displayed right above the commit message.

image::images/user-review-ui-change-screen-commit-message.png[width=800, link="images/user-review-ui-change-screen-commit-message.png"]

[[permalink]]
The numeric change ID is a link to the change and clicking on it
refreshes the change screen. By copying the link location you can get
the permalink of the change.

image::images/user-review-ui-change-screen-permalink.png[width=800, link="images/user-review-ui-change-screen-permalink.png"]

[[change-status]]
The change status shows the state of the change:

- [[needs]]`Needs <label>`:
+
The change is in review and an approval on the shown label is still
required to make the change submittable.

- [[not]]`Not <label>`:
+
The change is in review and a veto vote on the shown label is
preventing the submit.

- [[not-current]]`Not Current`:
+
The currently viewed patch set is outdated.
+
Please note that some operations, like voting, are not available on
outdated patch sets, but only on the current patch set.

- [[ready-to-submit]]`Ready to Submit`:
+
The change has all necessary approvals and may be submitted.

- [[merged]]`Merged`:
+
The change was successfully merged into the destination branch.

- [[abandoned]]`Abandoned`:
+
The change was abandoned.

- [[draft]]`Draft`:
+
The change is a draft that is only visible to the change owner, the
reviewers that were explicitly added to the change, and users who have
the link:access-control.html#category_view_drafts[View Drafts] global
capability assigned.

[[commit-info]]
=== Commit Info Block

The commit info block shows information about the commit of the
currently viewed patch set.

It displays the author and the committer as links to a list of this
person's changes that have the same status as the currently viewed
change.

The commit ID, the parent commit(s) and the link:user-changeid.html[Change-Id] are
displayed with a copy-to-clipboard icon that allows the ID to be copied
into the clipboard.

If a Git web browser, such as gitweb or Gitiles, is configured, there
is also a link to the commit in the Git web browser.

image::images/user-review-ui-change-screen-commit-info.png[width=800, link="images/user-review-ui-change-screen-commit-info.png"]

If a merge commit is viewed this is highlighted by an icon.

image::images/user-review-ui-change-screen-commit-info-merge-commit.png[width=800, link="images/user-review-ui-change-screen-commit-info-merge-commit.png"]

[[change-info]]
=== Change Info Block

The change info block contains detailed information about the change
and offers actions on the change.

image::images/user-review-ui-change-screen-change-info.png[width=800, link="images/user-review-ui-change-screen-change-info.png"]

- [[change-owner]]Change Owner:
+
The owner of the change is displayed as a link to a list of the owner's
changes that have the same status as the currently viewed change.
+
image::images/user-review-ui-change-screen-change-info-owner.png[width=800, link="images/user-review-ui-change-screen-change-info-owner.png"]

- [[reviewers]]Reviewers:
+
The reviewers of the change are displayed as chip tokens.
+
For each reviewer there is a tooltip that shows on which labels the
reviewer is allowed to vote.
+
New reviewers can be added by clicking on the `Add...` button. Typing
into the pop-up text field activates auto completion of user and group
names.
+
[[remove-reviewer]]
Reviewers can be removed from the change by clicking on the `x` icon
in the reviewer's chip token. Removing a reviewer also removes the
current votes of the reviewer. The removal of votes is recorded as a
message on the change.
+
Removing reviewers is protected by permissions:

** Users can always remove themselves.
** The change owner may remove any zero or positive score.
** Users with the link:access-control.html#category_remove_reviewer[
   Remove Reviewer] access right, the branch owner, the project owner
   and Gerrit administrators may remove anyone.

+
image::images/user-review-ui-change-screen-change-info-reviewers.png[width=800, link="images/user-review-ui-change-screen-change-info-reviewers.png"]

- [[project-branch-topic]]Project / Branch / Topic:
+
The name of the project for which the change was done is displayed as a
link to the link:user-dashboards.html#project-default-dashboard[default
dashboard] of the project. If no default dashboard is defined, the link
opens a list of open changes on the project.
+
Clicking on the settings icon on the right side navigates to the
project administration screen.
+
The name of the destination branch is displayed as a link to a list
with all changes on this branch that have the same status as the
currently viewed change.
+
If a topic was assigned to the change it is displayed below the branch.
By clicking on the edit icon the topic can be set. This requires the
link:access-control.html#category_edit_topic_name[Edit Topic Name]
access right. To be able to set a topic on a closed change, the
`Edit Topic Name` must be assigned with the `force` flag.
+
image::images/user-review-ui-change-screen-change-info-project-branch-topic.png[width=800, link="images/user-review-ui-change-screen-change-info-project-branch-topic.png"]

- [[submit-strategy]]Submit Strategy:
+
The link:project-setup.html#submit_type[submit strategy] that will be
used to submit the change. The submit strategy is only displayed for
open changes.
+
image::images/user-review-ui-change-screen-change-info-submit-strategy.png[width=800, link="images/user-review-ui-change-screen-change-info-submit-strategy.png"]
+
If a change cannot be merged due to path conflicts this is highlighted
by a bold red `Cannot Merge` label.
+
image::images/user-review-ui-change-screen-change-info-cannot-merge.png[width=800, link="images/user-review-ui-change-screen-change-info-cannot-merge.png"]

- [[update-time]]Time of Last Update:
+
image::images/user-review-ui-change-screen-change-info-last-update.png[width=800, link="images/user-review-ui-change-screen-change-info-last-update.png"]

- [[actions]]Actions:
+
Depending on the change state and the permissions of the user, different
actions are available on the change:

** [[submit]]`Submit`:
+
Submits the change and adds it to the merge queue. If possible the
change is merged into the destination branch.
+
The `Submit` button is available if the change is submittable and
the link:access-control.html#category_submit[Submit] access right is
assigned.
+
It is also possible to submit changes that have merge conflicts. This
allows to do the conflict resolution for a change series in a single
merge commit and submit the changes in reverse order.

** [[abandon]]`Abandon`:
+
Abandons the change.
+
The `Abandon` button is only available if the change is open and the
link:access-control.html#category_abandon[Abandon] access right is
assigned.
+
When a change is abandoned, a panel appears that allows one to type a
comment message to explain why the change is being abandoned.

** [[restore]]`Restore`:
+
Restores the change.
+
The `Restore` button is only available if the change is abandoned and
the link:access-control.html#category_abandon[Abandon] and the
link:access-control.html#category_push[Push] access right is
assigned.
+
When a change is restored, a panel appears that allows one to type a
comment message to explain why the change is being restored.

** [[rebase]]`Rebase`:
+
Rebases the change. The rebase is always done with content merge
enabled. If the rebase is successful a new patch set with the rebased
commit is created. If the rebase fails, there are conflicts that have
to be resolved manually.
+
If the change does not depend on another open change, it is rebased
onto the tip of the destination branch.
+
If the change depends on another open change, it is rebased onto the
current patch set of that other change.
+
It is possible to change parent revision of a change. The new parent
revision can be another change towards the same target branch, or
the tip of the target branch.
+
The `Rebase` button is only available if
the link:access-control.html#category_rebase[Rebase] access right is
assigned. Rebasing merge commits is not supported.

** [[cherry-pick]]`Cherry-Pick`:
+
Allows to cherry-pick the change to another branch. The destination
branch can be selected from a dialog. Cherry-picking a change creates a
new open change on the selected destination branch.
+
It is also possible to cherry-pick a change to the same branch. This is
effectively the same as rebasing it to the current tip of the
destination branch. This can be used to remove dependencies on other
open changes.
+
Users can only cherry-pick changes to branches for which they are
allowed to upload changes for review.

** [[publish]]`Publish`:
+
Publishes the currently viewed draft patch set. If this is the first
patch set of a change that is published, the change will be published
as well.
+
The `Publish` button is only available if a draft patch set is viewed
and the user is the change owner or has the
link:access-control.html#category_publish_drafts[Publish Drafts] access
right assigned.

** [[delete]]`Delete Change` / `Delete Revision`:
+
Deletes the draft change / the currently viewed draft patch set.
+
The `Delete Change` / `Delete Revision` buttons are only available if a
draft patch set is viewed and the user is the change owner or has the
link:access-control.html#category_delete_drafts[Delete Drafts] access
right assigned.

** [[plugin-actions]]Further actions may be available if plugins are installed.

+
image::images/user-review-ui-change-screen-change-info-actions.png[width=800, link="images/user-review-ui-change-screen-change-info-actions.png"]

- [[labels]]Labels & Votes:
+
Approving votes are colored green; veto votes are colored red.
+
image::images/user-review-ui-change-screen-change-info-labels.png[width=800, link="images/user-review-ui-change-screen-change-info-labels.png"]

[[files]]
=== File List

The file list shows the files that are modified in the currently viewed
patch set.

image::images/user-review-ui-change-screen-file-list.png[width=800, link="images/user-review-ui-change-screen-file-list.png"]

[[change-screen-mark-reviewed]]
The checkboxes in front of the file names allow files to be marked as reviewed.

image::images/user-review-ui-change-screen-file-list-mark-as-reviewed.png[width=800, link="images/user-review-ui-change-screen-file-list-mark-as-reviewed.png"]

[[modification-type]]
The type of a file modification is indicated by the character in front
of the file name:

- 'no character' (Modified):
+
The file existed before this change and is modified.

- `A` (Added):
+
The file is newly added.

- `D` (Deleted):
+
The file is deleted.

- `R` (Renamed):
+
The file is renamed.

- `C` (Copied):
+
The file is new and is copied from an existing file.

image::images/user-review-ui-change-screen-file-list-modification-type.png[width=800, link="images/user-review-ui-change-screen-file-list-modification-type.png"]

[[rename-or-copy]]
If a file is renamed or copied, the name of the original file is
displayed in gray below the file name.

image::images/user-review-ui-change-screen-file-list-rename.png[width=800, link="images/user-review-ui-change-screen-file-list-rename.png"]

[[repeating-path-segments]]
Repeating path segments are grayed out.

image::images/user-review-ui-change-screen-file-list-repeating-paths.png[width=800, link="images/user-review-ui-change-screen-file-list-repeating-paths.png"]

[[inline-comments-column]]
Inline comments on a file are shown in the `Comments` column.

Draft comments, i.e. comments that have been written by the current
user but not yet published, are highlighted in red.

New comments from other users, that were published after the current
user last reviewed this change, are highlighted in bold.

image::images/user-review-ui-change-screen-file-list-comments.png[width=800, link="images/user-review-ui-change-screen-file-list-comments.png"]

[[size]]
The size of the modifications in the files can be seen in the `Size` column. The
footer row shows the total size of the change.

The size information is useful to easily spot the files that contain
the most modifications; these files are likely to be the most relevant
files for this change. The total change size gives an estimate of how
long a review of this change may take.

When the "Show Change Sizes As Colored Bars" user preference is enabled, the
`Size` column shows the sum of inserted and deleted lines as one number.  In
addition, the change size is shown as a bar. The size of the bar indicates the
amount of changed lines, and its coloring shows the proportion of insertions
(green) to deletions (red).

When the "Show Change Sizes As Colored Bars" user preference is disabled, the
colored bar is not shown.  For added and renamed files, the `Size` column
shows the number of inserted and deleted lines. For new files, the column only
shows the total number of lines in the new file. No size is shown for binary
files and deleted files.

image::images/user-review-ui-change-screen-file-list-size.png[width=800, link="images/user-review-ui-change-screen-file-list-size.png"]

[[diff-against]]
In the header of the file list, the `Diff Against` selection can be
changed. This selection allows one to choose if the currently viewed
patch set should be compared against its base or against another patch
set of this change. The file list is updated accordingly.

[[open-all]]
The file list header also provides an `Open All` button that opens the
diff views for all files in the file list.

image::images/user-review-ui-change-screen-file-list-header.png[width=800, link="images/user-review-ui-change-screen-file-list-header.png"]

[[patch-sets]]
=== Patch Sets

The change screen only presents one patch set at a time. Which patch
set is currently viewed can be seen from the `Patch Sets` drop-down
panel in the change header. It shows the number of the currently viewed
patch set and the total number of patch sets, in the form: "current
patch set/number of patch sets".

If a non-current patch set is viewed this is indicated by the
link:#not-current[Not Current] change state. Please note that some
operations are only available on the current patch set.

image::images/user-review-ui-change-screen-patch-sets.png[width=800, link="images/user-review-ui-change-screen-patch-sets.png"]

[[patch-set-drop-down]]
The patch set drop-down list shows the list of patch sets and allows to
switch between them. The patch sets are sorted in descending order so
that the current patch set is always on top.

Draft patch sets are marked with `DRAFT`.

image::images/user-review-ui-change-screen-patch-set-list.png[width=800, link="images/user-review-ui-change-screen-patch-set-list.png"]

[[download]]
=== Download

The `Download` drop-down panel in the change header offers commands and
links for downloading the currently viewed patch set.

image::images/user-review-ui-change-screen-download-commands.png[width=800, link="images/user-review-ui-change-screen-download-commands.png"]

The available download commands depend on the installed Gerrit plugins.
The most popular plugin for download commands, the
link:https://gerrit-review.googlesource.com/#/admin/projects/plugins/download-commands[
download-commands] plugin, provides commands to checkout, pull and
cherry-pick a patch set.

Each command has a copy-to-clipboard icon that allows the command to be
copied into the clipboard. This makes it easy to paste and execute the
command on a Git command line.

If several download schemes are configured on the server (e.g. SSH and
HTTP) there is a drop-down list to switch between the download schemes.
Gerrit automatically remembers the download scheme that was last chosen
and selects this download scheme the next time the download commands
drop-down panel is opened.

The `Patch-File` links provide the Git patch file for the currently
viewed patch set for download. The patch file can be base64 encoded or
zipped.

The `Archive` links allow one to download an archive with the contents
of the currently viewed patch set. The archive is offered in several
formats (e.g. tar and tbz2); which formats are available depends on the
configuration of the server.

image::images/user-review-ui-change-screen-download-commands-list.png[width=800, link="images/user-review-ui-change-screen-download-commands-list.png"]

[[included-in]]
=== Included In

For merged changes the `Included In` drop-down panel is available in
the change header.

image::images/user-review-ui-change-screen-included-in.png[width=800, link="images/user-review-ui-change-screen-included-in.png"]

The `Included In` drop-down panel shows the branches and tags in which
the change is included. E.g. if a change fixes a bug, this allows to
quickly see in which released versions the bug-fix is contained
(assuming that every release is tagged).

image::images/user-review-ui-change-screen-included-in-list.png[width=800, link="images/user-review-ui-change-screen-included-in-list.png"]

[[star]]
=== Star Change

The star icon in the change header allows to mark the change as a
favorite. Clicking on the star icon again, unstars the change.

image::images/user-review-ui-change-screen-star.png[width=800, link="images/user-review-ui-change-screen-star.png"]

Starring a change turns on email notifications for this change.

Starred changed are listed under `My` > `Starred Changes`.
and can be queried by the link:user-search.html#is[is:starred] search
operator.

[[related-changes]]
=== Related Changes

If there are changes that are related to the currently viewed change
they are displayed in the third column of the change screen.

There are several lists of related changes and a tab control is used to
display each list of related changes in its own tab.

The following tabs may be displayed:

- [[related-changes-tab]]`Related Changes`:
+
This tab page shows changes on which the current change depends
(ancestors) and open changes that depend on the current change
(descendants). For merge commits it also shows the closed changes that
will be merged into the destination branch by submitting the merge
commit.
+
The changes are sorted in the same way as the output of 'git log'. This
means the relationship between the changes can be inferred from the
position of the changes in the list. Changes listed above the current
change are descendants; changes below the current change are ancestors.
+
For merged changes this tab is only shown if there are open
descendants.
+
image::images/user-review-ui-change-screen-related-changes.png[width=800, link="images/user-review-ui-change-screen-related-changes.png"]
+
Related changes may be decorated with an icon to signify dependencies
on outdated patch sets, or commits that are not associated to changes
under review:
+
** [[outdated]]Orange Dot:
+
The selected patch set of the change is outdated; it is not the current
patch set of the change.
+
If an ancestor change is marked with an orange dot it means that the
currently viewed patch set depends on a outdated patch set of the
ancestor change. This is because a new patch set for the ancestor
change was uploaded in the meantime and as result the currently viewed
patch set now needs to be rebased.
+
If a descendant change is marked with an orange dot it means that an
old patch set of the descendant change depends on the currently viewed
patch set. It may be that the descendant was rebased in the meantime
and with the new patch set this dependency was removed.

** [[indirect-descendant]]Green Tilde:
+
The selected patch set of the change is an indirect descendant of the
currently viewed patch set; it has a dependency to another patch set of
this change. E.g. this could mean that a new patch set was uploaded for
this change and the descendant change now needs to be rebased. Please
note that following the link to an indirect descendant change may
result in a completely different related changes listing.

** [[closed-ancestor]]Black Dot:
+
Indicates a closed ancestor, e.g. the commit was directly pushed into
the repository bypassing code review, or the ancestor change was
reviewed and submitted on another branch. The latter may indicate that
the user has accidentally pushed the commit to the wrong branch, e.g.
the commit was done on `branch-a`, but was then pushed to
`refs/for/branch-b`.
A black dot is also present if the change was abandoned.

** [[closed-ancestor-abandoned]]Strikethrough Subject:
+
When the commit is abandoned, its subject line will be striked
through.

+
image::images/user-review-ui-change-screen-related-changes-indicators.png[width=800, link="images/user-review-ui-change-screen-related-changes-indicators.png"]

- [[conflicts-with]]`Conflicts With`:
+
This tab page shows changes that conflict with the current change.
Non-mergeable changes are filtered out; only conflicting changes that
are mergeable are shown.
+
If this change is merged, its conflicting changes will have merge
conflicts and must be rebased. The rebase of the other changes with the
conflict resolution must then be done manually.
+
image::images/user-review-ui-change-screen-conflicts-with.png[width=800, link="images/user-review-ui-change-screen-conflicts-with.png"]

- [[same-topic]]`Same Topic`:
+
This tab page shows changes that have the same topic as the current
change. Only open changes are included in the list.
+
image::images/user-review-ui-change-screen-same-topic.png[width=800, link="images/user-review-ui-change-screen-same-topic.png"]

- [[submitted-together]]`Submitted Together`:
+
This tab page shows changes that will be submitted together with the
currently viewed change, when clicking the submit button. It includes
ancestors of the current patch set.
+
This may include changes and its ancestors with the same topic if
`change.submitWholeTopic` is enabled. Only open changes with the
same topic are included in the list.
+

- [[cherry-picks]]`Cherry-Picks`:
+
This tab page shows changes with the same link:user-changeid.html[
Change-Id] for the current project.
+
Abandoned changes are filtered out.
+
For each change in this list the destination branch is shown as a
prefix in front of the change subject.
+
image::images/user-review-ui-change-screen-cherry-picks.png[width=800, link="images/user-review-ui-change-screen-cherry-picks.png"]

If there are no related changes for a tab, the tab is not displayed.

[[reply]]
=== Reply

The `Reply...` button in the change header allows to reply to the
currently viewed patch set; one can add a summary comment, publish
inline draft comments, and vote on the labels.

image::images/user-review-ui-change-screen-reply.png[width=800, link="images/user-review-ui-change-screen-reply.png"]

Clicking on the `Reply...` button opens a popup panel.

[[summary-comment]]
A text box allows to type a summary comment for the currently viewed
patch set. Some basic markdown-like syntax is supported which renders
indented lines preformatted, lines starting with "- " or "* " as list
items, and lines starting with "> " as block quotes (also see replying to
link:#reply-to-message[messages] and link:#reply-inline-comment[inline comments]).

Note that you can set the text and tooltip of the button in
link:config-gerrit.html#change.replyLabel[gerrit.config].

[[vote]]
If the current patch set is viewed, radio buttons are displayed for
each label on which the user is allowed to vote. Voting on non-current
patch sets is not possible.

The inline draft comments that will be published are displayed in a
separate section so that they can be reviewed before publishing. There
are links to navigate to the inline comments which can be used if a
comment needs to be edited.

The `Post` button publishes the comments and the votes.

image::images/user-review-ui-change-screen-replying.png[width=800, link="images/user-review-ui-change-screen-replying.png"]

[[quick-approve]]
If a user can approve a label that is still required, a quick approve
button appears in the change header that allows to add this missing
approval by a single click. The quick approve button only appears if
there is a single label that is still required and can be approved by
the user.

E.g. if a change requires approvals on the 'Code-Review' and the
'Verified' labels, and there is already a '+1 Verified' vote, then
if the user is allowed to vote the max score on 'Code-Review', a
`Code-Review+2` quick approve button appears that approves the
'Code-Review' label if clicked.

Using the quick approve button also publishes all inline draft
comments; a summary comment is only added if the reply popup panel is
open when the quick approve button is clicked.

image::images/user-review-ui-change-screen-quick-approve.png[width=800, link="images/user-review-ui-change-screen-quick-approve.png"]

[[history]]
=== History

The history of the change can be seen in the lower part of the screen.

The history contains messages for all kinds of change updates, e.g. a
message is added when a new patch set is uploaded or when a review was
done.

Messages with new comments from other users, that were published after
the current user last reviewed this change, are automatically expanded.

image::images/user-review-ui-change-screen-history.png[width=800, link="images/user-review-ui-change-screen-history.png"]

[[reply-to-message]]
It is possible to directly reply to a change message by clicking on the
reply icon in the right upper corner of a change message. This opens
the reply popup panel and prefills the text box with the quoted comment.
Then the reply can be written below the quoted comment or inserted
inline. Lines starting with "> " will be rendered as a block quote.
Please note that for a correct rendering it is important to leave a blank
line between a quoted block and the reply to it.

image::images/user-review-ui-change-screen-reply-to-comment.png[width=800, link="images/user-review-ui-change-screen-reply-to-comment.png"]

[[inline-comments-in-history]]
Inline comments are directly displayed in the change history and there
are links to navigate to the inline comments.

image::images/user-review-ui-change-screen-inline-comments.png[width=800, link="images/user-review-ui-change-screen-inline-comments.png"]

[[expand-all]]
The `Expand All` button expands all messages; the `Collapse All` button
collapses all messages.

[[update-notification]]
=== Update Notification

The change screen automatically polls for updates to the currently
viewed change. If there is an update the user is informed by a popup
panel in the bottom right corner.

The polling frequency depends on the server configuration; by default
it is 30 seconds. Polling may also be completely disabled by the
administrator.

image::images/user-review-ui-change-screen-change-update.png[width=800, link="images/user-review-ui-change-screen-change-update.png"]

[[plugin-extensions]]
=== Plugin Extensions

Gerrit plugins may extend the change screen; they can add buttons for
additional actions to the change info block and display arbitrary UI
controls below the change info block.

image::images/user-review-ui-change-screen-plugin-extensions.png[width=800, link="images/user-review-ui-change-screen-plugin-extensions.png"]

[[side-by-side]]
== Side-by-Side Diff Screen

The side-by-side diff screen shows a single patch; the old file version
is displayed on the left side of the screen; the new file version is
displayed on the right side of the screen.

This screen allows to review a patch and to comment on it.

image::images/user-review-ui-side-by-side-diff-screen.png[width=800, link="images/user-review-ui-side-by-side-diff-screen.png"]

[[side-by-side-header]]
In the screen header the project name and the name of the viewed patch
file are shown.

If a Git web browser is configured on the server, the project name and
the file path are displayed as links to the project and the folder in
the Git web browser.

image::images/user-review-ui-side-by-side-diff-screen-project-and-file.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-project-and-file.png"]

[[side-by-side-mark-reviewed]]
The checkbox in front of the project name and the file name allows the
patch to be marked as reviewed. The link:#mark-reviewed[Mark Reviewed]
diff preference allows to control whether the files should be
automatically marked as reviewed when they are viewed.

image::images/user-review-ui-side-by-side-diff-screen-reviewed.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-reviewed.png"]

[[scrollbar]]
The scrollbar shows patch diffs and inline comments as annotations.
This provides a good overview of the lines in the patch that are
relevant for reviewing. By clicking on an annotation one can quickly
navigate to the corresponding line in the patch.

image::images/user-review-ui-side-by-side-diff-screen-scrollbar.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-scrollbar.png"]

[[gaps]]
A gap between lines in the file content that is caused by aligning the
left and right side or by displaying inline comments is shown as a
vertical red bar in the line number column. This prevents a gap from
being mistaken for blank lines in the file

image::images/user-review-ui-side-by-side-diff-screen-red-bar.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-red-bar.png"]

[[patch-set-selection]]
In the header, on each side, the list of patch sets is shown. Clicking
on a patch set changes the selection for the patch set comparison and
the screen is refreshed to show the diff between the selected patch
sets. The currently selected patch set is highlighted by a light blue
background.

On the left side `Base` can be selected to compare a patch set against
its base. For merge commits `Auto Merge` is available instead which
allows to compare the patch against the result of the auto merge. The
auto merge version may contain Git conflict markers and is useful for
reviewing how conflicts are resolved by a patch.

Reviewers that are reviewing a patch for the first time look at its
diff against its base; reviewers that have reviewed an old patch
version before, may see what has changed since that version by
comparing the old patch against the current patch.

image::images/user-review-ui-side-by-side-diff-screen-patch-sets.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-patch-sets.png"]

[[download-file]]
The download icon next to the patch set list allows to download the
patch. Unless the mime type of the file is configured as safe, the
download file is a zip archive that contains the patch file.

[[no-differences]]
If the compared patches are identical, this is highlighted by a red
`No Differences` label in the screen header.

image::images/user-review-ui-side-by-side-diff-screen-no-differences.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-no-differences.png"]

[[side-by-side-rename]]
If a file was renamed, the old and new file paths are shown in the
header together with a similarity index that shows how much of the file
content is unmodified.

image::images/user-review-ui-side-by-side-diff-screen-rename.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-rename.png"]

[[navigation]]
For navigating between the patches in a patch set there are navigation
buttons on the right side of the screen header. The left arrow button
navigates to the previous patch; the right arrow button navigates to
the next patch. The arrow up button leads back to the change screen. In
all cases the selection for the patch set comparison is kept.

image::images/user-review-ui-side-by-side-diff-screen-navigation.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-navigation.png"]

[[inline-comments]]
=== Inline Comments

Inline comments are displayed directly in the patch file under the code
that is commented. Inline comments can be placed on lines or on code
blocks.

If an inline comment relates to a code block, this code block is
highlighted by a yellow background.

Code blocks with comments may overlap. This means it is possible to
attach several comments to the same code.

[[line-links]]
The lines of the patch file are linkable. To link to a certain line in
the patch file, '@<line-number>' must be appended to the patch link,
e.g. `http://host:8080/#/c/56857/2/Documentation/user-review-ui.txt@665`.
To link to a line in the old file version, '@a<line-number>' must be
appended to the patch link. These links can be used to directly link to
certain inline comments.

If the diff preference link:#expand-all-comments[Expand All Comments]
is set to `Expand`, all inline comments will be automatically expanded.

image::images/user-review-ui-side-by-side-diff-screen-inline-comments.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-inline-comments.png"]

[[comment]]
In the header of the comment box, the name of the comment author and
the timestamp of the comment are shown. If avatars are configured on
the server, the avatar image of the comment author is displayed in the
top left corner. Below the actual comment there are buttons to reply to
the comment.

image::images/user-review-ui-side-by-side-diff-screen-comment-box.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-comment-box.png"]

[[reply-inline-comment]]
Clicking on the `Reply` button opens an editor to type the reply.

Quoting is supported, but only by manually copying & pasting the old
comment that should be quoted and prefixing every line by "> ". Please
note that for a correct rendering it is important to leave a blank line
between a quoted block and the reply to it.

Clicking on the `Save` button saves the comment as a draft. To make it
visible to other users it must be published from the change screen by
link:#reply[replying] to the change.

The `Cancel` button cancels the editing and discards any changes to the
draft comment.

Clicking on the `Discard` button deletes the inline draft comment.

image::images/user-review-ui-side-by-side-diff-screen-comment-reply.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-comment-reply.png"]

[[draft-inline-comment]]
Draft comments are marked by the text "Draft" in the header in the
place of the comment author.

A draft comment can be edited by clicking on the `Edit` button, or
deleted by clicking on the `Discard` button.

image::images/user-review-ui-side-by-side-diff-screen-comment-edit.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-comment-edit.png"]

[[done]]
Clicking on the `Done` button is a quick way to reply with "Done" to a
comment. This is used to mark a comment as addressed by a follow-up
patch set.

image::images/user-review-ui-side-by-side-diff-screen-replied-done.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-replied-done.png"]

[[add-inline-comment]]
To add a new inline comment there are several possibilities:

- select a code block and press 'c'
- select a code block and click on the popup comment icon
- go to a line, by clicking on it or by link:#key-navigation[key
  navigation], and press 'c'
- click on a line number

There are many ways to select code for commenting on it. The most
frequently used methods are:

- by mouse:
** click and drag with the mouse to select a block
** double-click on a word to select it
** double-click and drag with the mouse to select a code block word-wise
** triple-click on a line to select it
** triple-click and drag with the mouse to select a code block line-wise

- by keys (the same keys that are used for visual selection in Vim):
** press 'v' + arrow keys (or 'h', 'j', 'k', 'l') to select a block
** press 'V' + arrow keys (or 'j', 'k') to select a code block line-wise
** type 'bvw' to select a word

image::images/user-review-ui-side-by-side-diff-screen-comment.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-comment.png"]

For typing the new comment, a new comment box is shown under the code
that is commented.

Clicking on the `Save` button saves the new comment as a draft. To make
it visible to other users it must be published from the change screen
by link:#reply[replying] to the change.

Clicking on the `Discard` button deletes the new comment.

image::images/user-review-ui-side-by-side-diff-screen-commented.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-commented.png"]

[[file-level-comments]]
=== File Level Comments

Comments that apply to a whole file can be added on file level.

File level comments are added by clicking on the comment icon in the
header above the file.

image::images/user-review-ui-side-by-side-diff-screen-file-level-comment.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-file-level-comment.png"]

Clicking on the comment icon opens a comment box for typing the file
level comment.

image::images/user-review-ui-side-by-side-diff-screen-file-level-commented.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-file-level-commented.png"]

[[search]]
=== Search

For searching within a patch file, a Vim-like search is supported.
Typing `/` opens the search box. Typing in the search box immediately
highlights matches in the patch file with a yellow background. Using
JavaScript regular expressions in the search term is supported. The
search is case insensitive. After confirming the search by `ENTER` one
can navigate between the matches by `n` / `N` to go to the next /
previous match. Skipped lines are automatically expanded if they
contain a match and one navigates to it.

For additional possibilities to search please check the
link:http://www.vim.org/docs.php[Vim documentation]. There are other
useful ways to search, e.g. while the cursor is on a word, pressing `*`
or `#` searches for the next or previous occurrence of the word.

Searching by `Ctrl-F` finds matches only in the visible area of the
screen unless the link:#render[Render] diff preference is set to `Slow`.

image::images/user-review-ui-side-by-side-diff-screen-search.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-search.png"]

[[key-navigation]]
=== Key Navigation

Vim-like commands can be used to navigate within a patch file:

- `h` / `j` / `k` / `l` moves the cursor left / down / up / right
- `0` / `$` moves the cursor to the start / end of the line
- `gg` / `G` moves to cursor to the start / end of the file
- `Ctrl-D` / `Ctrl-U` scolls downwards / upwards

Please check the link:http://www.vim.org/docs.php[Vim documentation]
for further information.

[[diff-preferences]]
=== Diff Preferences

There are several options to control how patch diffs should be
rendered. Users can configure their preferences in the diff
preferences. The diff preferences can be accessed by clicking on the
settings icon in the screen header.

image::images/user-review-ui-side-by-side-diff-screen-preferences.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-preferences.png"]

The diff preferences popup allows to change the diff preferences.
By clicking on the `Save` button changes to the diff preferences are
saved permanently. Clicking on the `Apply` button applies the new
diff preferences to the current screen, but they are discarded when the
screen is refreshed. The `Save` button is only available if the user is
signed in.

image::images/user-review-ui-side-by-side-diff-screen-preferences-popup.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-preferences-popup.png"]

The following diff preferences can be configured:

- [[theme]]`Theme`:
+
Controls the theme that is used to render the file content.
+
E.g. users could choose to work with a dark theme.
+
image::images/user-review-ui-side-by-side-diff-screen-dark-theme.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-dark-theme.png"]

- [[ignore-whitespace]]`Ignore Whitespace`:
+
Controls whether differences in whitespace should be ignored or not.
+
** `None`:
+
All differences in whitespace are highlighted.
+
** `At Line End`:
+
Whitespace differences at the end of lines are ignored.
+
** `Leading, At Line End`:
+
Whitespace differences at the beginning and end of lines are ignored.
+
** `All`:
+
All differences in whitespace are ignored.

- [[tab-width]]`Tab Width`:
+
Controls how many spaces should be displayed for a tab.

- [[columns]]`Columns`:
+
Sets the preferred line length. At this position a vertical dashed line
is displayed so that one can easily detect lines the exceed the
preferred line length.
+
image::images/user-review-ui-side-by-side-diff-screen-column.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-column.png"]

- [[lines-of-context]]`Lines Of Context`:
+
The number of context lines that should be displayed before and after
any diff. If the `entire file` checkbox is selected, the full file is
rendered.
+
Skipped common lines can be expanded by clicking on the placeholder for
the skipped lines.
+
Clicking on "... skipped <n> common lines ..." expands the complete
block of skipped lines.
+
If many lines are skipped there are additional links to expand the
context by ten lines before and after the skipped block.
+
image::images/user-review-ui-side-by-side-diff-screen-expand-skipped-lines.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-expand-skipped-lines.png"]

- [[intraline-difference]]`Intraline Difference`:
+
Controls whether intraline differences should be highlighted.
+
image::images/user-review-ui-side-by-side-diff-screen-intraline-difference.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-intraline-difference.png"]

- [[syntax-highlighting]]`Syntax Highlighting`:
+
Controls whether syntax highlighting should be enabled.
+
The language for the syntax highlighting is automatically detected from
the file extension. The language can also be set manually by selecting
it from the `Language` drop-down list.
+
image::images/user-review-ui-side-by-side-diff-screen-syntax-coloring.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-syntax-coloring.png"]

- [[whitespace-errors]]`Whitespace Errors`:
+
Controls whether whitespace errors are highlighted.

- [[show-tabs]]`Show Tabs`:
+
Controls whether tabs are highlighted.

- [[line-numbers]]`Line Numbers`:
+
Controls whether line numbers are shown.

- [[empty-pane]]`Empty Pane`:
+
Controls whether empty panes are shown or not. The Left pane is empty when a
file was added; the right pane is empty when a file was deleted.

- [[left-side]]`Left Side`:
+
Controls whether the left side is shown. This preference is not
persistent and is ignored by the `Save` button. Every time a
patch diff is opened, this preference is reset to `Show`.

- [[top-menu]]`Top Menu`:
+
Controls whether the top menu is shown.

- [[auto-hide-diff-table-header]]`Auto Hide Diff Table Header`:
+
Controls whether the diff table header should be automatically hidden
when scrolling down more than half of a page.

- [[mark-reviewed]]`Mark Reviewed`:
+
Controls whether the files of the patch set should be automatically
marked as reviewed when they are viewed.

- [[expand-all-comments]]`Expand All Comments`:
+
Controls whether all comments should be automatically expanded.

- [[render]]`Render`:
+
Controls how patch files that exceed the screen size are rendered.
+
If `Fast` is selected file contents which are outside of the visible
area are not attached to the browser's DOM tree. This makes the
rendering fast, but searching by `Ctrl+F` only finds content which is
in the visible area.
+
If `Slow` is selected all file contents are attached to the browser's
DOM tree, which makes the rendering slow for large files. The advantage
of this setting is that `Ctrl+F` can be used to search in the complete
file.
+
Large files that exceed 4000 lines will not be fully rendered.

[[keyboard-shortcuts]]
== Keyboard Shortcuts

Navigation within the review UI can be completely done by keys, and
most actions can be controlled by keyboard shortcuts. Typing `?` opens
a popup that shows a list of available keyboard shortcuts:

- Change Screen
+
image::images/user-review-ui-change-screen-keyboard-shortcuts.png[width=800, link="images/user-review-ui-change-screen-keyboard-shortcuts.png"]

- Side-by-Side Diff Screen
+
image::images/user-review-ui-side-by-side-diff-screen-keyboard-shortcuts.png[width=800, link="images/user-review-ui-side-by-side-diff-screen-keyboard-shortcuts.png"]
+
In addition, Vim-like commands can be used to link:#key-navigation[
navigate] and link:#search[search] within a patch file.

[[new-vs-old]]
== New Review UI vs. Old Review UI

There are some important conceptual differences between the old and
new review UIs:

- The old change screen directly shows all patch sets of the change.
  With the new change screen only a single patch set is displayed;
  users can switch between the patch sets by choosing another patch
  set from the link:#patch-sets[Patch Sets] drop down panel in the
  screen header.
- On the old side-by-side diff screen, new comments are inserted by
  double-clicking on a line. With the new side-by-side diff screen
  double-click is used to select a word for commenting on it; there
  are link:#add-inline-comment[several ways to insert new comments],
  e.g. by selecting a code block and clicking on the popup comment
  icon.

[[limitations]]
Limitations of the new review UI:

- The new side-by-side diff screen cannot render images.

- The new side-by-side diff screen isn't able to highlight line
  endings.

GERRIT
------
Part of link:index.html[Gerrit Code Review]

SEARCHBOX
---------