Class PropertyObject

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;Description
 
;Description

Revision as of 18:23, 6 July 2018


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.

Contents

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:
  • 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:
    • For "string", "int" and "float" properties:
    • For "list" properties:
    • For "map-object" and "asset-list" properties:
  • 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.


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

public string GetDescriptionHTML(void)
Parameters

/None/

Return Value;

HTML formatted string to be loaded into the Property Browser.

Example Implementation

public string GetDescriptionHTML(void) { StringTable strTable = GetAsset().GetStringTable(); HTMLBuffer buffer = HTMLBufferStatic.Construct(); buffer.Print("<html><body>"); buffer.Escape(strTable.GetString("property_name_forename")); buffer.Print(": <a href=live://property/forename>"); buffer.Escape(m_foreName); buffer.Print("</a><br>"); buffer.Escape(strTable.GetString("property_name_surname")); buffer.Print(": <a href=live://property/forename>"); buffer.Escape(m_surName); buffer.Print("</a><br>"); buffer.Print("</body></html>"); return buffer.AsString(); }

Description

This method is called by Trainz to retrieve HTML which a player can use to configure the objects properties. Any embedded properties should use the live://property/propertyID format, all player readable strings should be sourced from the asset string-table, and all player configurable values should be appropriately escaped to avoid HTML corruption.

GetProperties

public Soup GetProperties(void)
Parameters
  • None
Returned Value
  • Soup object containing session file data assigned to the current object.
Example Implementation 
public Soup GetProperties(void)
{
  Soup soup = inherited();
  soup.SetNamedTag("forename", m_foreName);
  soup.SetNamedTag("surname", m_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

public void SetProperties(Soup soup)
Parameters
  • soup = reference to soup to be saved to session.
Returned Value
  • None
Example Implementation 
public void SetProperties(Soup soup)
{
  inherited(soup);
  m_foreName = soup.GetNamedTag("forename");
  m_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

string GetPropertyType(string propertyID)


Parameters
  • propertyID = Name of property.
Returned Value
  • The type of the current property.
Example Implementation 
string GetPropertyType(string propertyID)
{
  if (propertyID == "forename" or propertyID == "surname")
    return "string";
  
  return inherited(propertyID);
}
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

string GetPropertyName(string propertyID)
Parameters
  • propertyID = Name of property.
Returned Value
  • The name of the current property.
Example Implementation 
string GetPropertyName(string propertyID)
{
  if (propertyID == "forename")
    return GetAsset().GetStringTable().GetString("property_name_forename");
  if (propertyID == "surname")
    return GetAsset().GetStringTable().GetString("property_name_surname");

  return inherited(propertyID);
}


GetPropertyDescription

string GetPropertyDescription(string propertyID)
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.
Example Implementation 
string GetPropertyDescription(string propertyID)
{
  if (propertyID == "forename")
    return GetAsset().GetStringTable().GetString("property_description_forename");
  if (propertyID == "surname")
    return GetAsset().GetStringTable().GetString("property_description_surname");

  return inherited(propertyID);
}


GetPropertyValue

public string GetPropertyValue(string propertyID)
Parameters
  • propertyID = Name of property.
Returned Value
  • A string representation of the value of the current property.


Example Implementation 
public string GetPropertyValue(string propertyID)
{
  if (propertyID == "forename")
    return m_foreName;
  if (propertyID == "surname")
    return m_foreName;

  return inherited(propertyID);
}
Description
  • Returns a string representation of the current value of the selected property.


LinkPropertyValue

void LinkPropertyValue(string propertyID)
Parameters
  • propertyID = Name of property.
Returned Value
  • None


Example Implementation 
void LinkPropertyValue(string propertyID)
{
  if (propertyID == "doors")
  {
    m_doorsOpen = !m_doorsOpen;
    SetMeshAnimationState("doors", m_doorsOpen);
    return;
  }

  inherited(propertyID);
}
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

public string[ ] GetPropertyElementList(string propertyID)
Parameters
  • propertyID = Name of property.
Returned Value
  • String array to be presented to the user for a new selection to be made.
Example Implementation 
public string[] GetPropertyElementList(string propertyID)
{
  if (propertyID == "mode")
  {
    StringTable strTable = GetAsset().GetStringTable();
    
    string[] result = new string[10];
    int i;
    for (i = 1; i < 10; ++i)
      result[i] = strTable.GetString("property_list_mode_" + i);
    
    return result;
  }
  
  return inherited(propertyID);
}
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)
void SetPropertyValue(string propertyID, int value)
void SetPropertyValue(string propertyID, float value)
void SetPropertyValue(string propertyID, string value, int index)
void SetPropertyValue(string propertyID, GSObject value, string readableName)


Parameters
  • propertyID = Name of property.
  • value = string, int, float or object value to assign to the property.
  • index = list types only, specifies the index of the selected item in the list.
  • readableName = map-object and asset-list types only, specifies the localised name of the object/asset selected.
Returned Value
  • None
Example Implementations 
void SetPropertyValue(string propertyID, string value)
{
  if (propertyID == "forename")
  {
    m_foreName = value;
    return;
  }
  if (propertyID == "surname")
  {
    m_surName = value;
    return;
  }
  
  inherited(propertyID, value);
}

void SetPropertyValue(string propertyID, GSObject value, string readableName)
{
  if (propertyID == "junction")
  {
    m_junctionID = cast<GameObjectID>(value);
    m_junctionName = readableName;
    return;
  }
  if (propertyID == "sound-asset")
  {
    m_sound = cast<Asset>(value);
    m_soundName = readableName;
    return;
  }
  
  inherited(propertyID, value, readableName);
}
Description

Sets a new value for the named property. The variant called depends on the property type, as returned by GetPropertyType().

PropertyBrowserRefresh

public void PropertyBrowserRefresh(Browser browser)
Parameters
  • browser = Reference to browser object displaying properties.
Returned Value
  • None
Description

A callback method which the script writer can override to specify tasks to be carried out whenever the Browser is refreshed.

SetPropertyHandler

public void SetPropertyHandler(HTMLPropertyHandler handler)
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

public HTMLPropertyHandler GetPropertyHandler(void)
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.



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