Class PropertyObject
- API Hierarchy
- PropertyObject
This class provides an interface that allows an object to implement properties that can be saved or loaded to a session and edited by the user through a browser window in Surveyor. To enable this for an asset, it must inherit from PropertyObject (or from a derived child class such as ScenarioBehavior or MeshObject).
PropertyObject operates by way of a series of predefined callback methods which are designed to be overridden by the script writer to allow Trainz to access an object's properties. Properties are referred to in the class methods by their propertyID. Trainz determines this by reference to links in the object browser in the form live://property/propertyID.
When Trainz is saving a session, it asks each object to save its respective state into a Soup database. Trainz doesn't know what your object needs to save, but it does know that it can request an object's state via callbacks. Trainz relies on the script programmer to give careful thought to what data is needed to save and restore an objects state.
Depending on circumstances, not all callback methods have to be implemented. For example, you don't need to override GetPropertyElementList() if there are no list-selection properties.
Callback Sequences
The precise sequence of callback method calls will vary with the content of the browser and the user's input but the following gives a general idea:
- When the Property Browser is opened Trainz calls:
- GetProperties() to read the current session data.
- GetDescriptionHTML() to read the HTML code for the browser configuration window.
- When the user clicks on a URL, the propertyID is extracted from the link and these calls are made:
- GetPropertyType() to establish the 'type' of the property is to be edited.
- For "link" properties Trainz will call:
- LinkPropertyValue(), which should respond and set the desired value
- For "string", "int" and "float" properties:
- GetPropertyValue() to establish the property's current value.
- GetPropertyName() and/or GetPropertyDescription() to obtain display info for the UI.
- Trainz then provides a pop-up edit box with a caption and current value filled in and waits for the user to edit the property, if desired.
- For "list" properties:
- GetPropertyName() and/or GetPropertyDescription() to obtain display info for the UI.
- GetPropertyElementList() to obtain the list options to display to the player.
- Trainz then provides a pop-up edit box with a caption and the list of options and waits for the user to edit the property, if desired.
- For "map-object" and "asset-list" properties:
- GetPropertyName() and/or GetPropertyDescription() to obtain display info for the UI.
- Trainz displays a filterable list dialog to the player, showing a spinner while the search runs.
- When a search completes, Trainz calls FilterPropertyElementList(), to allow the script to add/remove any custom entries.
- Once the user has carried out any edits:
- The appropriate variant of SetPropertyValue() is called to update the value of the property.
- GetDescriptionHTML() is called again to refresh the contents of the Browser window for any new configuration.
- When all edits are complete:
- If the user confirms their changes and closes the dialog:
- SetProperties() is called with the modified Soup to update the session database.
- If the user cancels the changes:
- SetProperties() is called with the original unaltered Soup to restore the script to it's original pre-edit state.
- If the user confirms their changes and closes the dialog:
Throughout the above sequences Trainz is only concerned with the loading and saving of properties. Wherever a change in a property requires an update to the appearance of the object or to the contents of its variables it is the responsibility of the script writer to implement these changes at the appropriate time. In general changes should be implemented in SetProperties() since this will help to ensure that changes can be reversed if they are cancelled or when the game's UNDO command is invoked.
Save/Load
Scripted objects do not have their state automatically saved and restored. It is the responsibility of the individual scripts to save and restored any necessary state across a Surveyor save session/load session, or across a Driver save game/load game. This is implemented using the PropertyObject GetProperties() and SetProperties() functions. When saving, Trainz will ensure that GetProperties() has been called for every PropertyObject that is being saved. The Soup returned by this function is stored along with any native state for the object in question. When reloading, Trainz will first create the object and load the native state, then will call the SetProperties() function with the saved Soup which instructs the script to restore its state.
GetDescriptionHTML
- Parameters
- None
- Returned Value;
- HTML formatted string to be loaded into the Property Browser.
- Syntax
- This is a callback method which should be overridden to suit the calling asset.
- Implementation
public string GetDescriptionHTML(void) {
return inherited()
+ "<font size=5><br>"
+ "Forename: <a href=live://property/forename>" + foreName + "</a><br>"
+ "Surname: <a href=live://property/surname>" + surName + "</a><br>"
+ "</font>";
return html;
}
- Description
- This method is called by Trainz from Surveyor to retrieve the properties of the object as HTML code for display in a Browser window.
- Refer to the MiniBrowser page for details of supported HTML tags.
- Link URLs should be included in the form live://property/propertyID, where propertyID is the name of the property.
- When the user clicks on a link Trainz will use the appropriate callback methods to establish the action that needs to be taken to enable the property to be edited.
- To allow for translation, text should be extracted from the asset's StringTable rather than being included in code as a literal string. This allows translated string table data to be substituted in foreign language installations if it is available.
GetProperties
- Parameters
- None
- Returned Value
- Soup object containing session file data assigned to the current object.
- Syntax
- This is a callback method which should be overridden to suit the calling asset.
- Implementation
public Soup GetProperties(void) {
Soup soup = inherited();
soup.SetNamedTag("forename",foreName);
soup.SetNamedTag("surname",surName);
return soup;
}
- Description
- This method is used to save current properties into the session database.
- Care must be taken to ensure it writes data in the same tag format that SetProperties() is expecting.
- When overriding this method to handle your own properties, always call through to the overridden parent by using inherited().
SetProperties
- Parameters
- soup = reference to soup to be saved to session.
- Returned Value
- None
- Syntax
- This is a callback method which should be overridden to suit the calling asset.
- Implementation
public void SetProperties(Soup soup) {
inherited(soup);
foreName = soup.GetNamedTag("forename");
surName = soup.GetNamedTag("surname");
}
- Description
- Instructs the current object to initialise its properties from data held in the session files.
- The data is passed to the method via the soup parameter.
- If the database is empty, as it will be when an object is first placed, then the object should initialise itself with sensible defaults.
- When overriding this method to handle your own properties, always call through to the overridden parent by using inherited(soup)
- This ensures that any data required by any parent class is made available.
GetPropertyType
- Parameters
- propertyID = Name of property.
- Returned Value
- The type of the current property.
- Example Implementation
string GetPropertyType(string propertyID)
{
string result = inherited(propertyID);
if (propertyID == "forename" or propertyID == "surname")
return "string";
return inherited();
}
- Description
This method is used by Trainz to determine the type of the named property. The supported types and their parameters are listed in the table below.
| Value type | Parameters | Description |
| string | minimum-length,maximum-length | A string value, with optional minimum and maximum lengths. e.g. "string,0,200". |
| int | minimum-value,maximum-value,step-value | An integer value with optional minimum, maximum and 'step' value. e.g. "int,0,100,5". |
| float | minimum-value,maximum-value,step-value | An floating point value with optional minimum, maximum and 'step' value. e.g. "float,0,10,0.5". |
| list | sorted-bool | An list, with an optional sorting flag (default off). e.g. "list,1" to sort, "list,0" for unsorted. |
| map-object | category-list | A list of map objects in the route which match a specific non-optional category list. e.g. "map-object,IND" for an industry list. |
| asset-list | category-list | A list of locally installed, compatible and available assets which match a specific non-optional category list. e.g. "asset-list,DR" for a list of installed Driver Character assets. |
| link | A link type. This would usually respond and set some specific value, or perhaps toggle a bool. |
GetPropertyName
- Parameters
- propertyID = Name of property.
- Returned Value
- The name of the current property.
- Syntax
- This is a callback method which should be overridden to suit the calling asset.
- Implementation
string GetPropertyName(string propertyID) {
string result = inherited(propertyID);
if (propertyID == "forename") result = "Forename";
else if (propertyID == "surname") result = "Surname";
return result;
}
GetPropertyDescription
- Parameters
- propertyID = Name of property.
- Returned Value
- Description to be used as a caption for the edit box presented to the user, allowing the current property to be edited.
- Syntax
- This is a callback method which should be overridden to suit the calling asset.
- Implementation
string GetPropertyDescription(string propertyID) {
string result = inherited(propertyID);
if (propertyID == "forename") result = "Enter Forename";
else if (propertyID == "surname") result = "Enter Surname";
return result;
}
GetPropertyValue
- Parameters
- propertyID = Name of property.
- Returned Value
- A string representation of the value of the current property.
- Syntax
- This is a callback method which should be overridden to suit the calling asset.
- Implementation
public string GetPropertyValue(string propertyID) {
string result = inherited(propertyID);
if (propertyID == "forename") result = foreName;
else if (propertyID == "surname") result = surName;
return result;
}
- Description
- Returns a string representation of the current value of the selected property.
LinkPropertyValue
- Parameters
- propertyID = Name of property.
- Returned Value
- None
- Syntax
- This is a callback method which should be overridden to suit the calling asset.
- Implementation
void LinkPropertyValue(string propertyID) {
string result = inherited(propertyID);
if (propertyID == "doors") {
doorsOpen = !doorsOpen;
SetMeshAnimationState("doors",doorsOpen);
}
}
- Description
- Trainz calls this method when the user has clicked on a property URL which is defined as a "link"
- No further information will be available to the game.
- Link properties are most frequently used to toggle boolean values.
GetPropertyElementList
- Parameters
- propertyID = Name of property.
- Returned Value
- String array to be presented to the user for a new selection to be made.
- Syntax
- This is a callback method which should be overridden to suit the calling asset.
- Implementation
public string[] GetPropertyElementList(string propertyID) {
string[] result = inherited(propertyID);
if (propertyID == "junctions") {
Junction[] junctions = World.GetJunctionList();
int n;
for (n = 1; n < junctions.size(); n++) {
result[result.size()] = junctions[n].GetName();
}
}
return result;
}
- Description
- Retrieves a list of elements the user can select from for the named property.
- If a property is of type "list", as returned by GetPropertyType(), Trainz will display these items in a pop-up window for user selection.
- The script programmer is free to fill the returned elements array from the current game environment and can create this dynamically if necessary (eg a list of industries in the current route).
FilterPropertyElementList
TBD
SetPropertyValue
void SetPropertyValue(string propertyID, string value, int index)
void SetPropertyValue(string propertyID, string value)
void SetPropertyValue(string propertyID, float value)
void SetPropertyValue(string propertyID, int value)
- Parameters
- propertyID = Name of property.
- value = int, float or string value to assign to the property.
- index = list index value to assign to the property.
- Returned Value
- None
- Syntax
- These are callback methods which should be overridden to suit the calling asset.
- Implementation
void SetPropertyValue(string propertyID, string value) {
if (propertyID == "forename") foreName = value;
else if (propertyID == "surname") surName = value;
else inherited(propertyID);
}
- Description
- Sets a new value for the named property.
PropertyBrowserRefresh
- Parameters
- browser = Reference to browser object displaying properties.
- Returned Value
- None
- Syntax
- This is a callback method which should be overridden to suit the calling asset.
- Implementation
public void PropertyBrowserRefresh(Browser browser) {
inherited(browser);
refreshed++;
Interface.Print("Browser has been refreshed " + refreshed + " times");
}
- Description
- A callback method which the script writer can override to specify tasks to be carried out whenever the Browser is refreshed.
SetPropertyHandler
- Parameters
- handler = Handler to assign to this property object.
- Returned Value
- None
- Description
- A PropertyObject can be overridden by assigning an HTMLPropertyHandler which allows more sophisticated processing.
- This method allows PropertyObject methods to be processed by such an object.
- Once SetPropertyHandler() has been used to assign a Property Handler the default methods in this class will be replaced by the corresponding methods defined in the handler.
GetPropertyHandler
- Parameters
- None
- Returned Value
- A reference to the current Property Handler for this object, or null if none has been set.
- Description
- A PropertyObject can be overridden by assigning an HTMLPropertyHandler which allows more sophisticated processing.
- This method returns a reference to such an object if it has been assigned.
- If this method returns null then no HTMLPropertyHandler is assigned and the default PropertyObject methods described on this page will apply.
