Canisters [ Continuation of clement-or #2544 ] (#2628)

* Added atmos sprites from CEV-Eris

* Moved canister sprites to appropriate dir

* Removed unnecessary sprites, edited canisters prototype

* Created Gas Canister UI and release pressure buttons

* Changed GasMixture's pressure calculation (convert liters to cube meters)

* Added relabeling Canisters

* Reverted changes on GasMixture

* Changed my name in the credits

* Added valve opening on canisters

* Change canister visual state when connected to a port

* Added nullable to SharedGasCanisterComponent

* Replaced nullable contexts

* Changed again nullable annotation context

* Moved name in the credits to correct alphabetical order

* Canisters: Fix the most blatant issues with this PR (the added project interdependencies for no reason whatsoever)

* Canisters: Stop crashes when canisters leave atmosphere

* Canisters: Gas released into no atmosphere gets transferred "into space" (deleted)

* Atmos: Nullability annotations on TileAtmosphere, explaination of the states of TileAtmosphere.Air

* Canisters: If in an airblocked tile, do NOT release gas

* Scrubbers: Fix typo leading to them not connecting properly.

* Revert manual changes to credits file (sorry!) (1/2)

This reverts commit 94f3b0e5df8d9c2fa189866a17a231920f99bdaf.

* Revert manual changes to credits file (sorry!) (2/2)

This reverts commit 1986fb094dfaa44060f08d280f36b755258d17a6.

* Canisters: Apply @Zumorica 's reviews

* Canisters: Add missing localization as suggested by PJB

Co-authored-by: Pieter-Jan Briers <pieterjan.briers@gmail.com>

* Canisters: Pressure lights!

* Canisters: Light is now unshaded.

* Canisters: Now using IActivate

* Gas canisters (& air canister), now with their numbers properly calibrated (hopefully)

* Canisters: Refactor how their layers are added to be more like ApcVisualizer

* Canisters: Clean up of the tile invalidation/air release logic

* Canisters: Some gas canister window improvements

* Canisters: Clean up release pressure change button label code

Co-authored-by: Clement-O <topy72.mine@gmail.com>
Co-authored-by: Clément <clement.orlandini@gmail.com>
Co-authored-by: Pieter-Jan Briers <pieterjan.briers@gmail.com>

Content.Client/GameObjects/Components/Atmos/GasCanisterBoundUserInterface.cs

@@ -0,0 +1,115 @@
+#nullable enable
+using System;
+using System.Diagnostics;
+using JetBrains.Annotations;
+using Robust.Client.GameObjects.Components.UserInterface;
+using Robust.Shared.GameObjects.Components.UserInterface;
+using Content.Client.GameObjects.Components.Atmos;
+using Content.Shared.GameObjects.Components.Atmos;
+using Robust.Shared.Localization;
+
+namespace Content.Client.GameObjects.Components.Atmos
+{
+    /// <summary>
+    /// Initializes a <see cref="GasCanisterWindow"/> and updates it when new server messages are received.
+    /// </summary>
+    [UsedImplicitly]
+    public class GasCanisterBoundUserInterface : BoundUserInterface
+    {
+
+        private GasCanisterWindow? _window;
+
+        public GasCanisterBoundUserInterface(ClientUserInterfaceComponent owner, object uiKey) : base(owner, uiKey)
+        {
+
+        }
+
+
+        /// <summary>
+        /// When a button is pressed, send a network message to the server
+        /// </summary>
+        /// <param name="button">Which button has been pressed, as an enum item</param>
+        private void ButtonPressed(UiButton button)
+        {
+            SendMessage(new UiButtonPressedMessage(button));
+        }
+
+
+        /// <summary>
+        /// When the release pressure is changed
+        /// </summary>
+        /// <param name="value">The pressure value</param>
+        private void ReleasePressureButtonPressed(float value)
+        {
+            SendMessage(new ReleasePressureButtonPressedMessage(value));
+        }
+
+
+        protected override void Open()
+        {
+            base.Open();
+
+            _window = new GasCanisterWindow();
+            _window.Title = Loc.GetString("Gas Canister");
+
+            _window.OpenCentered();
+            _window.OnClose += Close;
+
+            // Bind buttons OnPressed event
+            foreach (ReleasePressureButton btn in _window.ReleasePressureButtons)
+            {
+                btn.OnPressed += _ => ReleasePressureButtonPressed(btn.PressureChange);
+            }
+
+            // Bind events
+            _window.EditLabelBtn.OnPressed += _ => EditLabel();
+            _window.ToggleValve.OnPressed += _ => ToggleValve();
+        }
+
+
+        /// <summary>
+        /// Called when the edit label button is pressed
+        /// </summary>
+        private void EditLabel()
+        {
+            // Obligatory check because bool isn't nullable
+            if (_window == null) return;
+
+            if (_window.LabelInputEditable)
+            {
+                if (_window.LabelInput.Text != _window.OldLabel)
+                    SendMessage(new CanisterLabelChangedMessage(_window.LabelInput.Text));
+
+                _window.LabelInputEditable = false;
+            }
+            else
+            {
+                _window.LabelInputEditable = true;
+                _window.LabelInput.HasKeyboardFocus();
+            }
+        }
+
+
+        private void ToggleValve()
+        {
+            SendMessage(new UiButtonPressedMessage(UiButton.ValveToggle));
+        }
+
+
+        /// <summary>
+        /// Update the UI state based on server-sent info
+        /// </summary>
+        /// <param name="state"></param>
+        protected override void UpdateState(BoundUserInterfaceState state)
+        {
+            base.UpdateState(state);
+
+            if (!(state is GasCanisterBoundUserInterfaceState cast))
+            {
+                return;
+            }
+
+            _window?.UpdateState(cast);
+        }
+    }
+}

Content.Client/GameObjects/Components/Atmos/GasCanisterVisualizer.cs

@@ -0,0 +1,72 @@
+using Content.Shared.GameObjects.Components.Atmos;
+using Robust.Client.GameObjects;
+using Robust.Client.Graphics;
+using Robust.Client.Interfaces.GameObjects.Components;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Interfaces.GameObjects;
+using Robust.Shared.Maths;
+using Robust.Shared.Utility;
+using YamlDotNet.RepresentationModel;
+
+namespace Content.Client.GameObjects.Components.Atmos
+{
+    public class GasCanisterVisualizer : AppearanceVisualizer
+    {
+        private string _stateConnected;
+        private string[] _statePressure = new string[] {"", "", "", ""};
+
+        public override void LoadData(YamlMappingNode node)
+        {
+            base.LoadData(node);
+
+            _stateConnected = node.GetNode("stateConnected").AsString();
+            for (int i = 0; i < _statePressure.Length; i++)
+                _statePressure[i] = node.GetNode("stateO" + i).AsString();
+        }
+
+        public override void InitializeEntity(IEntity entity)
+        {
+            base.InitializeEntity(entity);
+
+            var sprite = entity.GetComponent<ISpriteComponent>();
+
+            sprite.LayerMapSet(Layers.ConnectedToPort, sprite.AddLayerState(_stateConnected));
+            sprite.LayerSetVisible(Layers.ConnectedToPort, false);
+
+            sprite.LayerMapSet(Layers.PressureLight, sprite.AddLayerState(_stateConnected));
+            sprite.LayerSetShader(Layers.PressureLight, "unshaded");
+        }
+
+        public override void OnChangeData(AppearanceComponent component)
+        {
+            base.OnChangeData(component);
+
+            if (component.Deleted)
+            {
+                return;
+            }
+
+            if (!component.Owner.TryGetComponent(out ISpriteComponent sprite))
+            {
+                return;
+            }
+
+            // Update the visuals : Is the canister connected to a port or not
+            if (component.TryGetData(GasCanisterVisuals.ConnectedState, out bool isConnected))
+            {
+                sprite.LayerSetVisible(Layers.ConnectedToPort, isConnected);
+            }
+
+            // Update the visuals : Canister lights
+            if (component.TryGetData(GasCanisterVisuals.PressureState, out int pressureState))
+                if ((pressureState >= 0) && (pressureState < _statePressure.Length))
+                    sprite.LayerSetState(Layers.PressureLight, _statePressure[pressureState]);
+        }
+
+        enum Layers
+        {
+            ConnectedToPort,
+            PressureLight
+        }
+    }
+}

Content.Client/GameObjects/Components/Atmos/GasCanisterWindow.cs

@@ -0,0 +1,166 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Content.Shared.GameObjects.Components.Disposal;
+using Robust.Client.Graphics.Drawing;
+using Robust.Client.UserInterface;
+using Robust.Client.UserInterface.Controls;
+using Robust.Client.UserInterface.CustomControls;
+using Robust.Shared.Localization;
+using Robust.Shared.Maths;
+using Content.Client.GameObjects.Components.Atmos;
+using Content.Shared.GameObjects.Components.Atmos;
+
+namespace Content.Client.GameObjects.Components.Atmos
+{
+    /// <summary>
+    /// Client-side UI used to control a <see cref="SharedGasCanisterComponent"/>
+    /// </summary>
+    public class GasCanisterWindow : SS14Window
+    {
+        private readonly Label _pressure;
+        private readonly Label _releasePressure;
+
+        public readonly CheckButton ToggleValve;
+        public readonly LineEdit LabelInput;
+        public readonly Button EditLabelBtn;
+        public string OldLabel { get; set; } = "";
+
+        public bool LabelInputEditable {
+            get => LabelInput.Editable;
+            set {
+                LabelInput.Editable = value;
+                EditLabelBtn.Text = value ? Loc.GetString("OK") : Loc.GetString("Edit");
+            }
+        }
+
+        public List<ReleasePressureButton> ReleasePressureButtons { get; private set; }
+
+        protected override Vector2? CustomSize => (300, 200);
+
+        public GasCanisterWindow()
+        {
+            HBoxContainer releasePressureButtons;
+
+            Contents.AddChild(new VBoxContainer
+            {
+                Children =
+                {
+                    new VBoxContainer
+                        {
+                            Children =
+                            {
+                                new HBoxContainer()
+                                    {
+                                        Children =
+                                        {
+                                            new Label(){ Text = Loc.GetString("Label") },
+                                            (LabelInput = new LineEdit() { Text = Name, Editable = false,
+                                                CustomMinimumSize = new Vector2(200, 30)}),
+                                            (EditLabelBtn = new Button()),
+                                        }
+                                    },
+                                new HBoxContainer
+                                    {
+                                        Children =
+                                        {
+                                            new Label {Text = Loc.GetString("Pressure:")},
+                                            (_pressure = new Label())
+                                        }
+                                    },
+                                new VBoxContainer()
+                                {
+                                    Children =
+                                    {
+                                        new HBoxContainer()
+                                        {
+                                            Children =
+                                            {
+                                                new Label() {Text = Loc.GetString("Release pressure:")},
+                                                (_releasePressure = new Label())
+                                            }
+                                        },
+                                        (releasePressureButtons = new HBoxContainer()
+                                        {
+                                            Children =
+                                            {
+                                                new ReleasePressureButton() {PressureChange = -50},
+                                                new ReleasePressureButton() {PressureChange = -10},
+                                                new ReleasePressureButton() {PressureChange = -1},
+                                                new ReleasePressureButton() {PressureChange = -0.1f},
+                                                new ReleasePressureButton() {PressureChange = 0.1f},
+                                                new ReleasePressureButton() {PressureChange = 1},
+                                                new ReleasePressureButton() {PressureChange = 10},
+                                                new ReleasePressureButton() {PressureChange = 50}
+                                            }
+                                        })
+                                    }
+                                },
+                                new HBoxContainer()
+                                {
+                                    Children =
+                                    {
+                                        new Label { Text = Loc.GetString("Valve") },
+                                        (ToggleValve = new CheckButton() { Text = Loc.GetString("Open") })
+                                    }
+                                }
+                            },
+                        }
+                }
+            });
+
+            // Create the release pressure buttons list
+            ReleasePressureButtons = new List<ReleasePressureButton>();
+            foreach (var control in releasePressureButtons.Children.ToList())
+            {
+                var btn = (ReleasePressureButton) control;
+                ReleasePressureButtons.Add(btn);
+            }
+
+            // Reset the editable label
+            LabelInputEditable = false;
+        }
+
+
+        /// <summary>
+        /// Update the UI based on <see cref="GasCanisterBoundUserInterfaceState"/>
+        /// </summary>
+        /// <param name="state">The state the UI should reflect</param>
+        public void UpdateState(GasCanisterBoundUserInterfaceState state)
+        {
+            _pressure.Text = Loc.GetString("{0}kPa", state.Volume);
+            _releasePressure.Text = Loc.GetString("{0}kPa", state.ReleasePressure);
+
+            // Update the canister label
+            OldLabel = LabelInput.Text;
+            LabelInput.Text = state.Label;
+            Title = state.Label;
+
+            // Reset the editable label
+            LabelInputEditable = false;
+
+            ToggleValve.Pressed = state.ValveOpened;
+        }
+    }
+
+
+    /// <summary>
+    /// Special button class which stores a numerical value and has it as a label
+    /// </summary>
+    public class ReleasePressureButton : Button
+    {
+        public float PressureChange
+        {
+            get { return _pressureChange; }
+            set
+            {
+                _pressureChange = value;
+                Text = (value >= 0) ? ("+" + value) : value.ToString();
+            }
+        }
+
+        private float _pressureChange;
+
+        public ReleasePressureButton() : base() {}
+    }
+}

Content.Server/Atmos/GasMixture.cs

@@ -452,15 +452,16 @@ namespace Content.Server.Atmos
 
         /// <summary>
         ///     Releases gas from this mixture to the output mixture.
+        ///     If the output mixture is null, then this is being released into space.
         ///     It can't transfer air to a mixture with higher pressure.
         /// </summary>
         /// <param name="outputAir"></param>
         /// <param name="targetPressure"></param>
         /// <returns></returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public bool ReleaseGasTo(GasMixture outputAir, float targetPressure)
+        public bool ReleaseGasTo(GasMixture? outputAir, float targetPressure)
         {
-            var outputStartingPressure = outputAir.Pressure;
+            var outputStartingPressure = outputAir?.Pressure ?? 0;
             var inputStartingPressure = Pressure;
 
             if (outputStartingPressure >= MathF.Min(targetPressure, inputStartingPressure - 10))
@@ -472,11 +473,11 @@ namespace Content.Server.Atmos
 
             // We calculate the necessary moles to transfer with the ideal gas law.
             var pressureDelta = MathF.Min(targetPressure - outputStartingPressure, (inputStartingPressure - outputStartingPressure) / 2f);
-            var transferMoles = pressureDelta * outputAir.Volume / (Temperature * Atmospherics.R);
+            var transferMoles = pressureDelta * (outputAir?.Volume ?? Atmospherics.CellVolume) / (Temperature * Atmospherics.R);
 
             // And now we transfer the gas.
             var removed = Remove(transferMoles);
-            outputAir.Merge(removed);
+            outputAir?.Merge(removed);
 
             return true;
 

Content.Server/Atmos/TileAtmosphere.cs

@@ -1,4 +1,5 @@
-using System;
+#nullable enable annotations
+using System;
 using System.Buffers;
 using System.Collections.Generic;
 using System.Runtime.CompilerServices;
@@ -49,7 +50,7 @@ namespace Content.Server.Atmos
         private static int _soundCooldown;
 
         [ViewVariables]
-        public TileAtmosphere PressureSpecificTarget { get; set; }
+        public TileAtmosphere? PressureSpecificTarget { get; set; }
 
         [ViewVariables]
         public float PressureDifference { get; set; }
@@ -103,8 +104,12 @@ namespace Content.Server.Atmos
         [ViewVariables]
         public ExcitedGroup ExcitedGroup { get; set; }
 
+        /// <summary>
+        /// The air in this tile. If null, this tile is completely airblocked.
+        /// This can be immutable if the tile is spaced.
+        /// </summary>
         [ViewVariables]
-        public GasMixture Air { get; set; }
+        public GasMixture? Air { get; set; }
 
         [ViewVariables, UsedImplicitly]
         private int _blockedAirflow => (int)BlockedAirflow;

Content.Server/GameObjects/Components/Atmos/GasCanisterComponent.cs

@@ -1,4 +1,6 @@
-using Content.Server.Atmos;
+#nullable enable
+using System;
+using Content.Server.Atmos;
 using Content.Server.GameObjects.Components.Atmos.Piping;
 using Content.Server.Interfaces;
 using Robust.Shared.GameObjects;
@@ -6,36 +8,83 @@ using Robust.Shared.GameObjects.Components;
 using Robust.Shared.GameObjects.Components.Transform;
 using Robust.Shared.Serialization;
 using Robust.Shared.ViewVariables;
-using System;
 using System.Linq;
+using Content.Server.GameObjects.EntitySystems;
+using Content.Server.Interfaces.GameObjects.Components.Items;
+using Content.Server.Utility;
+using Content.Shared.GameObjects.Components.Atmos;
+using Content.Shared.GameObjects.EntitySystems;
+using Content.Shared.Interfaces;
+using Content.Shared.Interfaces.GameObjects.Components;
+using Content.Shared.Atmos;
+using Robust.Server.GameObjects;
+using Robust.Server.GameObjects.Components.UserInterface;
+using Robust.Server.Interfaces.GameObjects;
+using Robust.Shared.Containers;
+using Robust.Shared.GameObjects.Systems;
+using Robust.Shared.Interfaces.GameObjects;
+using Robust.Shared.Localization;
 
 namespace Content.Server.GameObjects.Components.Atmos
 {
+    /// <summary>
+    /// Component that manages gas mixtures temperature, pressure and output.
+    /// </summary>
     [RegisterComponent]
-    public class GasCanisterComponent : Component, IGasMixtureHolder
+    [ComponentReference(typeof(IActivate))]
+    public class GasCanisterComponent : Component, IGasMixtureHolder, IActivate
     {
         public override string Name => "GasCanister";
 
-        [ViewVariables]
+        private const int MaxLabelLength = 32;
-        public GasMixture Air { get; set; }
+
+        [ViewVariables(VVAccess.ReadWrite)]
+        public string Label { get; set; } = "Gas Canister";
+
+        [ViewVariables(VVAccess.ReadWrite)]
+        public bool ValveOpened { get; set; } = false;
+
+        /// <summary>
+        /// What <see cref="GasMixture"/> the canister contains.
+        /// </summary>
+        [ViewVariables(VVAccess.ReadWrite)]
+        public GasMixture Air { get; set; } = default!;
 
         [ViewVariables]
         public bool Anchored => !Owner.TryGetComponent<IPhysicsComponent>(out var physics) || physics.Anchored;
 
+        /// <summary>
+        /// The floor connector port that the canister is attached to.
+        /// </summary>
         [ViewVariables]
-        public GasCanisterPortComponent ConnectedPort { get; private set; }
+        public GasCanisterPortComponent? ConnectedPort { get; private set; }
 
         [ViewVariables]
         public bool ConnectedToPort => ConnectedPort != null;
 
         private const float DefaultVolume = 10;
 
+        [ViewVariables(VVAccess.ReadWrite)] public float ReleasePressure { get; set; }
+
+        /// <summary>
+        /// The user interface bound to the canister.
+        /// </summary>
+        private BoundUserInterface? UserInterface => Owner.GetUIOrNull(SharedGasCanisterComponent.GasCanisterUiKey.Key);
+
+        /// <summary>
+        /// Stores the last ui state after it's been casted into <see cref="GasCanisterBoundUserInterface"/>
+        /// </summary>
+        private GasCanisterBoundUserInterfaceState? _lastUiState;
+
+        private AppearanceComponent? _appearance;
+
         public override void ExposeData(ObjectSerializer serializer)
         {
             base.ExposeData(serializer);
             serializer.DataField(this, x => Air, "gasMixture", new GasMixture(DefaultVolume));
         }
 
+
         public override void Initialize()
         {
             base.Initialize();
@@ -44,8 +93,21 @@ namespace Content.Server.GameObjects.Components.Atmos
                 AnchorUpdate();
                 physics.AnchoredChanged += AnchorUpdate;
             }
+            if (UserInterface != null)
+            {
+                UserInterface.OnReceiveMessage += OnUiReceiveMessage;
             }
 
+            // Init some variables
+            Label = Owner.Name;
+            Owner.TryGetComponent(out _appearance);
+
+            UpdateUserInterface();
+            UpdateAppearance();
+        }
+
+        #region Connector port methods
+
         public override void OnRemove()
         {
             base.OnRemove();
@@ -53,23 +115,27 @@ namespace Content.Server.GameObjects.Components.Atmos
             {
                 physics.AnchoredChanged -= AnchorUpdate;
             }
+            if (UserInterface != null)
+            {
+                UserInterface.OnReceiveMessage -= OnUiReceiveMessage;
+            }
             DisconnectFromPort();
         }
 
-
         public void TryConnectToPort()
         {
             if (!Owner.TryGetComponent<SnapGridComponent>(out var snapGrid)) return;
             var port = snapGrid.GetLocal()
                 .Select(entity => entity.TryGetComponent<GasCanisterPortComponent>(out var port) ? port : null)
                 .Where(port => port != null)
-                .Where(port => !port.ConnectedToCanister)
+                .Where(port => !port!.ConnectedToCanister)
                 .FirstOrDefault();
             if (port == null) return;
             ConnectedPort = port;
             ConnectedPort.ConnectGasCanister(this);
         }
 
+
         public void DisconnectFromPort()
         {
             ConnectedPort?.DisconnectGasCanister();
@@ -86,6 +152,181 @@ namespace Content.Server.GameObjects.Components.Atmos
             {
                 DisconnectFromPort();
             }
+            UpdateAppearance();
+        }
+
+        #endregion
+
+        void IActivate.Activate(ActivateEventArgs eventArgs)
+        {
+            if (!eventArgs.User.TryGetComponent(out IActorComponent? actor))
+                return;
+
+            UserInterface?.Open(actor.playerSession);
+        }
+
+        private void OnUiReceiveMessage(ServerBoundUserInterfaceMessage obj)
+        {
+            if (obj.Session.AttachedEntity == null)
+            {
+                return;
+            }
+
+            if (!PlayerCanUse(obj.Session.AttachedEntity))
+            {
+                return;
+            }
+
+            // If the label has been changed by a client
+            if (obj.Message is CanisterLabelChangedMessage canLabelMessage)
+            {
+                var newLabel = canLabelMessage.NewLabel;
+                if (newLabel.Length > MaxLabelLength)
+                    newLabel = newLabel.Substring(0, MaxLabelLength);
+                Label = newLabel;
+                Owner.Name = Label;
+                UpdateUserInterface();
+                return;
+            }
+
+            // If the release pressure has been adjusted by the client on the gas canister
+            if (obj.Message is ReleasePressureButtonPressedMessage rPMessage)
+            {
+                ReleasePressure += rPMessage.ReleasePressure;
+                ReleasePressure = Math.Clamp(ReleasePressure, 0, 1000);
+                ReleasePressure = MathF.Round(ReleasePressure, 2);
+                UpdateUserInterface();
+                return;
+            }
+
+
+            if (obj.Message is UiButtonPressedMessage btnPressedMessage)
+            {
+                switch (btnPressedMessage.Button)
+                {
+                    case UiButton.ValveToggle:
+                        ToggleValve();
+                        break;
+                }
+            }
+        }
+
+        /// <summary>
+        /// Update the user interface if relevant
+        /// </summary>
+        private void UpdateUserInterface()
+        {
+            var state = GetUserInterfaceState();
+
+            if (_lastUiState != null && _lastUiState.Equals(state))
+            {
+                return;
+            }
+
+            _lastUiState = state;
+            UserInterface?.SetState(state);
+        }
+
+        /// <summary>
+        /// Update the canister's sprite
+        /// </summary>
+        private void UpdateAppearance()
+        {
+            _appearance?.SetData(GasCanisterVisuals.ConnectedState, ConnectedToPort);
+            // The Eris canisters are being used, so best to use the Eris light logic unless someone else has a better idea.
+            // https://github.com/discordia-space/CEV-Eris/blob/fdd6ee7012f46838a6711adb1737cd90c48ae448/code/game/machinery/atmoalter/canister.dm#L129
+            if (Air.Pressure < 10)
+            {
+	            _appearance?.SetData(GasCanisterVisuals.PressureState, 0);
+            }
+            else if (Air.Pressure < Atmospherics.OneAtmosphere)
+            {
+	            _appearance?.SetData(GasCanisterVisuals.PressureState, 1);
+            }
+            else if (Air.Pressure < (15 * Atmospherics.OneAtmosphere))
+            {
+	            _appearance?.SetData(GasCanisterVisuals.PressureState, 2);
+            }
+            else
+            {
+	            _appearance?.SetData(GasCanisterVisuals.PressureState, 3);
+            }
+        }
+
+        /// <summary>
+        /// Get the current interface state from server data
+        /// </summary>
+        /// <returns>The state</returns>
+        private GasCanisterBoundUserInterfaceState GetUserInterfaceState()
+        {
+            // We round the pressure for ease of reading
+            return new GasCanisterBoundUserInterfaceState(Label,
+                MathF.Round(Air.Pressure, 2),
+                ReleasePressure,
+                ValveOpened);
+        }
+
+        public void AirWasUpdated()
+        {
+            UpdateUserInterface();
+            UpdateAppearance();
+        }
+
+        #region Check methods
+
+        private bool PlayerCanUse(IEntity? player)
+        {
+            if (player == null)
+            {
+                return false;
+            }
+
+            if (!ActionBlockerSystem.CanInteract(player) ||
+                !ActionBlockerSystem.CanUse(player))
+            {
+                return false;
+            }
+
+            return true;
+        }
+
+        #endregion
+
+
+        /// <summary>
+        /// Called when the canister's valve is toggled
+        /// </summary>
+        private void ToggleValve()
+        {
+            ValveOpened = !ValveOpened;
+            UpdateUserInterface();
+        }
+
+        /// <summary>
+        /// Called every frame
+        /// </summary>
+        /// <param name="frameTime"></param>
+        public void Update(in float frameTime)
+        {
+            if (ValveOpened)
+            {
+                var tileAtmosphere = Owner.Transform.Coordinates.GetTileAtmosphere();
+                if (tileAtmosphere != null)
+                {
+                    // If tileAtmosphere.Air is null, then we're airblocked, so DON'T release
+                    if (tileAtmosphere.Air != null)
+                    {
+                        Air.ReleaseGasTo(tileAtmosphere.Air, ReleasePressure);
+                        tileAtmosphere.Invalidate();
+                    }
+                }
+                else
+                {
+                    Air.ReleaseGasTo(null, ReleasePressure);
+                }
+
+                AirWasUpdated();
+            }
         }
     }
 }

Content.Server/GameObjects/Components/Atmos/GridAtmosphereComponent.cs

@@ -283,6 +283,7 @@ namespace Content.Server.GameObjects.Components.Atmos
         {
             var tile = GetTile(indices);
             if (tile?.GridIndex != _gridId) return;
+            // includeAirBlocked is false, therefore all tiles in this have Air != null.
             var adjacent = GetAdjacentTiles(indices);
             tile.Air = new GasMixture(GetVolumeForCells(1), AtmosphereSystem){Temperature = Atmospherics.T20C};
             Tiles[indices] = tile;
@@ -291,7 +292,7 @@ namespace Content.Server.GameObjects.Components.Atmos
 
             foreach (var (_, adj) in adjacent)
             {
-                var mix = adj.Air.RemoveRatio(ratio);
+                var mix = adj.Air!.RemoveRatio(ratio);
                 tile.Air.Merge(mix);
                 adj.Air.Merge(mix);
             }

Content.Server/GameObjects/Components/Atmos/Piping/GasCanisterPortComponent.cs

@@ -62,6 +62,7 @@ namespace Content.Server.GameObjects.Components.Atmos.Piping
         public override void Update()
         {
             ConnectedCanister?.Air.Share(_gasPort.Air, 1);
+            ConnectedCanister?.AirWasUpdated();
         }
 
         public void ConnectGasCanister(GasCanisterComponent gasCanister)

Content.Server/GameObjects/Components/Disposal/DisposalUnitComponent.cs

@@ -414,7 +414,6 @@ namespace Content.Server.GameObjects.Components.Disposal
                 case UiButton.Power:
                     TogglePower();
                     EntitySystem.Get<AudioSystem>().PlayFromEntity("/Audio/Machines/machine_switch.ogg", Owner, AudioParams.Default.WithVolume(-2f));
-
                     break;
                 default:
                     throw new ArgumentOutOfRangeException();

Content.Server/GameObjects/Components/Doors/ServerDoorComponent.cs

@@ -351,7 +351,8 @@ namespace Content.Server.GameObjects.Components.Doors
 
             foreach (var (_, adjacent) in gridAtmosphere.GetAdjacentTiles(tileAtmos.GridIndices))
             {
-                var moles = adjacent.Air.TotalMoles;
+                // includeAirBlocked remains false, and therefore Air must be present
+                var moles = adjacent.Air!.TotalMoles;
                 if (moles < minMoles)
                     minMoles = moles;
                 if (moles > maxMoles)

Content.Server/GameObjects/EntitySystems/GasCanisterSystem.cs

@@ -0,0 +1,19 @@
+using Content.Server.GameObjects.Components.Atmos;
+using Content.Server.GameObjects.Components.Recycling;
+using JetBrains.Annotations;
+using Robust.Shared.GameObjects.Systems;
+
+namespace Content.Server.GameObjects.EntitySystems
+{
+    [UsedImplicitly]
+    internal sealed class GasCanisterSystem : EntitySystem
+    {
+        public override void Update(float frameTime)
+        {
+            foreach (var component in ComponentManager.EntityQuery<GasCanisterComponent>())
+            {
+                component.Update(frameTime);
+            }
+        }
+    }
+}

Content.Shared/GameObjects/Components/Atmos/SharedGasCanisterComponent.cs

@@ -0,0 +1,123 @@
+#nullable enable annotations
+using System;
+using Robust.Shared.GameObjects;
+using Robust.Shared.GameObjects.Components.UserInterface;
+using Robust.Shared.Serialization;
+using Robust.Shared.ViewVariables;
+
+namespace Content.Shared.GameObjects.Components.Atmos
+{
+    public class SharedGasCanisterComponent : Component
+    {
+        public override string Name => "GasCanister";
+
+        /// <summary>
+        /// Key representing which <see cref="BoundUserInterface"/> is currently open.
+        /// Useful when there are multiple UI for an object. Here it's future-proofing only.
+        /// </summary>
+        [Serializable, NetSerializable]
+        public enum GasCanisterUiKey
+        {
+            Key,
+        }
+    }
+
+    #region Enums
+
+    /// <summary>
+    /// Enum representing a UI button.
+    /// </summary>
+    [Serializable, NetSerializable]
+    public enum UiButton
+    {
+        ValveToggle
+    }
+
+    /// <summary>
+    /// Used in <see cref="GasCanisterVisualizer"/> to determine which visuals to update.
+    /// </summary>
+    [Serializable, NetSerializable]
+    public enum GasCanisterVisuals
+    {
+        ConnectedState,
+        PressureState
+    }
+
+    #endregion
+
+    /// <summary>
+    /// Represents a <see cref="GasCanisterComponent"/> state that can be sent to the client
+    /// </summary>
+    [Serializable, NetSerializable]
+    public class GasCanisterBoundUserInterfaceState : BoundUserInterfaceState
+    {
+        public readonly string Label;
+        public readonly float Volume;
+        public readonly float ReleasePressure;
+        public readonly bool ValveOpened;
+
+        public GasCanisterBoundUserInterfaceState(string newLabel, float volume, float releasePressure, bool valveOpened)
+        {
+            Label = newLabel;
+            Volume = volume;
+            ReleasePressure = releasePressure;
+            ValveOpened = valveOpened;
+        }
+
+        public bool Equals(GasCanisterBoundUserInterfaceState? other)
+        {
+            if (ReferenceEquals(null, other)) return false;
+            if (ReferenceEquals(this, other)) return true;
+            return Label == other.Label &&
+                   Volume.Equals(other.Volume) &&
+                   ReleasePressure.Equals(other.ReleasePressure) &&
+                   ValveOpened == other.ValveOpened;
+        }
+    }
+
+    #region NetMessages
+
+    /// <summary>
+    /// Message sent from the client to the server when a gas canister button is pressed
+    /// </summary>
+    [Serializable, NetSerializable]
+    public class UiButtonPressedMessage : BoundUserInterfaceMessage
+    {
+        public readonly UiButton Button;
+
+        public UiButtonPressedMessage(UiButton button)
+        {
+            Button = button;
+        }
+    }
+
+    /// <summary>
+    /// Message sent when the release pressure is changed client side
+    /// </summary>
+    [Serializable, NetSerializable]
+    public class ReleasePressureButtonPressedMessage : BoundUserInterfaceMessage
+    {
+        public readonly float ReleasePressure;
+
+        public ReleasePressureButtonPressedMessage(float val) : base()
+        {
+            ReleasePressure = val;
+        }
+    }
+
+    /// <summary>
+    /// Message sent when the canister label has been changed
+    /// </summary>
+    [Serializable, NetSerializable]
+    public class CanisterLabelChangedMessage : BoundUserInterfaceMessage
+    {
+        public readonly string NewLabel;
+
+        public CanisterLabelChangedMessage(string newLabel) : base()
+        {
+            NewLabel = newLabel;
+        }
+    }
+
+    #endregion
+}

Resources/Prototypes/Entities/Constructible/Ground/gascanisters.yml

@@ -18,12 +18,101 @@
   - type: GasCanister
   - type: Anchorable
   - type: Pullable
+  - type: UserInterface
+  - type: Appearance
+
+
 
 - type: entity
   parent: GasCanisterBase
   id: GasCanister
   name: Gas Canister
+  description: A canister that can contain any type of gas. It can be attached to connector ports using a wrench.
   components:
   - type: Sprite
-    sprite: "Constructible/Power/apc.rsi"
+    netsync: false
-    state: apc0
+    sprite: Constructible/Atmos/canister.rsi
+    state: grey
+  - type: Appearance
+    visuals:
+    - type: GasCanisterVisualizer
+      stateConnected: can-connector
+      stateO0: can-o0
+      stateO1: can-o1
+      stateO2: can-o2
+      stateO3: can-o3
+  - type: UserInterface
+    interfaces:
+      - key: enum.GasCanisterUiKey.Key
+        type: GasCanisterBoundUserInterface
+  - type: Physics
+    mass: 25
+    anchored: false
+    shapes:
+      - !type:PhysShapeAabb
+        bounds: "-0.5,-0.25,0.5,0.25"
+        mask:
+          - Impassable
+          - MobImpassable
+          - VaultImpassable
+          - SmallImpassable
+        layer:
+          - Opaque
+          - MobImpassable
+          - VaultImpassable
+          - SmallImpassable
+
+# Filled canisters, contain 1871.71051 moles each
+
+- type: entity
+  parent: GasCanister
+  id: AirCanister
+  name: Air Canister
+  components:
+  - type: Sprite
+    sprite: Constructible/Atmos/canister.rsi
+    state: grey
+  - type: GasCanister
+    gasMixture:
+      volume: 1000
+      moles:
+        - 393.0592071 # oxygen 21%
+        - 1478.6513029 # nitrogen 79%
+      temperature: 293.15
+
+
+
+- type: entity
+  parent: GasCanister
+  id: OxygenCanister
+  name: Oxygen Canister
+  components:
+  - type: Sprite
+    sprite: Constructible/Atmos/canister.rsi
+    state: blue
+  - type: GasCanister
+    gasMixture:
+      volume: 1000
+      moles:
+        - 1871.71051 # oxygen
+      temperature: 293.15
+
+
+
+- type: entity
+  parent: GasCanister
+  id: PhoronCanister
+  name: Phoron Canister
+  components:
+    - type: Sprite
+      sprite: Constructible/Atmos/canister.rsi
+      state: orange
+    - type: GasCanister
+      gasMixture:
+        volume: 1000
+        moles:
+          - 0 # oxygen
+          - 0 # nitrogen
+          - 0 # carbon dioxide
+          - 1871.71051 # phoron
+        temperature: 293.15

Resources/Prototypes/Entities/Constructible/Ground/scrubbers.yml

@@ -34,7 +34,7 @@
   - type: NodeContainer
     nodes:
     - !type:PipeNode
-      nodeGroID: Pipe
+      nodeGroupID: Pipe
       pipeDirection: East
   - type: PressureSiphon
     scrubberOutletDirection: East

Resources/Textures/Constructible/Atmos/canister.rsi/meta.json

@@ -0,0 +1,201 @@
+{
+  "version": 1,
+  "size": {
+    "x": 32,
+    "y": 32
+  },
+  "license": "CC-BY-SA-3.0",
+  "copyright": "Taken from https://github.com/discordia-space/CEV-Eris",
+  "states": [
+    {
+      "name": "black",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "black-1",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "blue",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "blue-1",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "can-connector",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "can-o0",
+      "directions": 1,
+      "delays": [
+        [
+          0.2,
+          0.2
+        ]
+      ]
+    },
+    {
+      "name": "can-o1",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "can-o2",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "can-o3",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "can-oa1",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "can-open",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "grey",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "grey-1",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "orange",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "orange-1",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "red",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "red-1",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "redws",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "redws-1",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "yellow",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    },
+    {
+      "name": "yellow-1",
+      "directions": 1,
+      "delays": [
+        [
+          1
+        ]
+      ]
+    }
+  ]
+}