Drawpile 2.0 stable release

March 18, 2017 by callaa

The 2.0.0 stable release is finally here! Version 2.0 has finally reached the level of quality where I feel it is ready to replace version 1.0.6 as the official stable release.

Version 2.0 is unfortunately incompatible with 1.x versions. For this reason, version 1.0.6 is still available on the download page as a ZIP package (Windows) that does not require installation, so that it can be used in parallel with the new version.

The public server will be switched over to version 2.0 later today. Privately run 1.x servers will of course continue to function, and the public listing server will continue to accept announcements from the old version.

Compatibility notice: If you get an error saying "this is not a drawpile server" when you connect to a server, that means you're running version 1.0.6 and the server requires 2.0. If you try to connect to a 1.0 server with the 2.0 client, the client will just sit there until the connection times out. (It's waiting for a message in the new format that will not arrive.)

When upgrading from 1.0.6, I recommend first uninstalling the previous version to make sure no old libraries are left over. The Windows version now comes in 64 and 32 bit varieties. If the 64 bit version does not work for you, try the 32 bit one.

So, what's new in version 2.0? Read on to find out. (TL;DR at the end.)

New client features

While most of the changes in version 2.0 are behind the scenes architectural improvements, there are quite a few new features as well.

Perhaps the most visible change is that the tool slot buttons are now gone. In their place is a tool preset pie menu that pops up with the Z key. (Mouse/stylus button configuration is coming in the next version)

The IRC style commands for changing session options are also gone. They've been (finally) replaced by a settings dialog where you can easily change and see all session properties. Only commands directly related to chat, such as /!, /me and /pin remain.

Session event log entries have been moved away from the chat box into a window of their own. More events are also logged than before, including all operator actions (op, kick, ban, etc.)

Users can now be banned from the session. This is a session specific ban and does not prevent the user from joining other sessions. The autoban script has been updated to take advantage of the server's improved logging. It now adds a serverwide ban when a user has been banned from multiple different sessions in a short time period. Kicks no longer count toward bans.

There is now a GUI for session resetting. This replaces the old /force_snapshot command. This is useful for cutting down session history size so that new users can join faster, but it also makes it possible to revert the session to an earlier state, making it easy to recover the damage if a griefer comes in and defaces the canvas. (A more fine grained "region revert" feature is on the TODO list as well.)

The recording playback dialog has been overhauled too. Instead of the rather technical looking sequence diagram, it now shows a filmstrip preview of the session, which makes finding specific moments a snap.

One big final feature is integrated support for parental controls. All sessions can now be tagged as "not safe for minors". Previously, only session listings could be tagged, and the tagging was based on the session title. Now, setting (or removing) the tag is done just by clicking on a checkbox. Title based autotagging is still available too, and the tag trigger words can be configured in the client.

The client can be configured to hide NSFM sessions or even block access to them. On Windows, if parental controls are enabled for the user account, Drawpile will lock the out the configuration and always block access.

Other new features include:

  • Selections can now be moved when cut&paste is blocked
  • Shape tool (line, rectangle, ellipse) previews are now drawn with real brushes
  • New laser pointer trail style
  • The session announcement list now includes a Server column
  • A layer can be marked as default for new users
  • Faster login time
  • Annotations can be aligned vertically
  • Annotations can be locked like layers
  • Users can be blocked from sending chat messages
  • Many more small fixes and improvements

New protocol and almost completely rewritten server

Drawpile 2.0 introduces a radical change to the network protocol and recording file format. This unfortunately breaks compatibilty with the current 1.x versions, but the upside is that in the future, breakages will be more limited as the new protocol has been designed with forward compatibility in mind.

The protocol has now been divided into two parts: the part the server must understand and the part that is only relevant to clients. The server part is fairly small and simple. This means all Drawpile 2.x versions will be able to use the same server. This is in contrast to the 1.x versions where changes, such as adding a new brush type, would require changes to the server as well, and different client versions (like 0.9.9 and 1.0.0) could not share the same server. (Versions 1.0.0 to 1.0.6 could use the same one due to a policy decision: no compatibility breaking features could be added.)

The server has also seen many improvements that make hosting large or public sessions easier. Perhaps the most visible change is the new session reset feature. This feature replaces the old snapshot system. In version 1.0.6, session snapshotting was a way of replacing the session history with a more compact one, so new clients could join faster. Unfortunately, it was a source of many difficult to diagnose bugs and complexity.

The new session reset feature is similar, but more explicit. When a session is reset, it's history is replaced with a new one. All connected users must also download the new history. While this may be slightly inconvenient compared to the old system, it is what makes session revert possible. Luckily, joining a session is much faster in the new version and no longer locks up the application like before, so the session does not need to be reset/snapshotted as often.

Another important feature is file backed sessions. This is superficially similar to the old session hibernation feature. When a session was hibernated, it was written out to disk so it could survive server restarts. The hibernated session was then automatically reloaded when needed. However, this had one major flaw: if the server crashed, all non-hibernated sessions would be lost.

The new system writes the session to file continuously. This means sessions will survive server crashes, even if someone yanks the power cable! (Due to buffering, some data at the end of the session may be lost.) It also allows the server to keep just the most recent parts of the session in memory, thus allowing more sessions to be hosted simultaneously with less RAM.

User management is also improved in the new server: If user accounts are enabled, it will remember the Op status of authenticated users. When the user log back in, the op status is automatically restored. If the opword has been set, or the session has had authenticated operators, the server will not auto-op random users when the last operator leaves.

Since user accounts are not available on all servers, I have included a placeholder in the protocol for anonymous user authentication. I have not yet decided how that feature will work, but having the the placeholder makes it possible to implement it later in a backward compatible manner.

The new server now also has an optional graphical user interface. While the headless mode is still ideal for running on a VPS, the graphical mode makes server management easy when running it on a desktop computer. Not only that, but it also doubles as a remote admin tool for headless servers!

The server's REST admin API has been greatly expanded. Everything that can be changed via the GUI can also be changed via the API. (The GUI even uses the REST API internally.) Any webdevs out there interested in writing a web admin tool?

Other server improvements include:

  • Session templates can now be written in text format
  • Changes made via the admin API are now persisted in a database
  • The server event log is now viewable via the admin API
  • In-session bans are now supported
  • Better autoban script: kicks no longer count towards serverwide ban. Instead, the number of bans from different sessions is used.
  • New settings file format (alternative to the settings database): all settings (including user accounts and IP bans) are now set in a single configuration file

Session recording format changes

Version 2.0 cannot read recordings made with older versions. I recommend keeping 1.0.6 around if you need to access old recordings. If there is enough demand for it, I could also write a tool for upgrading recordings from the old format to the new one.

The text mode recording format has also changed in the new version. The new format is now a fully supported alternative encoding of the binary format. All message attributes are now named, making the format fairly future-proof. The text format is designed for easy parsing, while still being as human readable as possible. A sample Python script for reading and writing text mode recordings is provided.

The original text format was written as a testing tool and, as such, had some convenience features like stateful brush property changing and the ability to load images from files. Since the new format is just an alternative encoding of the protocol, these feature have been lost.

The dprec2txt and txt2dprec tools have been merged into a single dprectool utility. Currently, it can convert between the text mode and binary encodings, but in the future it will probably gain additional features, such as various filtering modes.


  • Not compatible with version 1.0.6
  • Public server requires 2.0 from now on
  • Cannot open old recordings. Keep 1.0.6 around if you need to.
  • Version 1.0.6 now available in a ZIP package, just unpack anywhere to use.
  • /force_snapshot replaced with session resetting
  • IRC style admin commands replaced with session settings dialog
  • Sessions can now be op-less if the Opword is set
  • Sessions can now survive server crashes
  • In-session bans now supported. Kicks no longer cause autobans.
  • Many other new features added