Command Plugins

A command plugin will add a new menu command to the application’s Plugins menu, and call a specified function when the menu command is selected. This is the simplest and most straightforward type of plugin, and is the most similar to MCEdit 1.0’s “filter” plugins.

To define a command plugin, create a class that inherits from CommandPlugin. Implement the __init__ function to call self.addMenuItem for each user-selectable command, and also implement the functions that correspond to each menu item.

A basic command plugin:

from mcedit2.plugins import registerPluginCommand, CommandPlugin
from PySide import QtGui

class ExampleCommand(CommandPlugin):
    def __init__(self, editorSession):
        super(ExampleCommand, self).__init__(editorSession)
        self.addMenuItem("Example Command", self.perform)

    def perform():
        dimension = self.editorSession.currentDimension
        chunkCount = dimension.chunkCount()

        QtGui.QMessageBox.information(None,         # messagebox parent (None for app-modal)
            "Example Command",                      # messagebox title
            "The Example Command was successful. "  # messagebox text
            "The current dimension contains "
            "%d chunks") % chunkCount)

You can do nearly anything you want in the perform() function. The currently edited dimension can be accessed as self.editorSession.currentDimension. See plugin_tasks for an overview of the dimension object. If you need to modify the world, be sure to read undo-history first.

Simple Commands

MCEdit 1.0’s “filter” plugins all follow the same pattern: They prompt the user for some inputs, and then call a perform() function which is given the current world, the current selection, and the inputs provided by the user. SimpleCommandPlugin fills the same role in MCEdit 2.0.

This class automatically adds a menu item to the Plugins menu. When the item is chosen, it opens a dialog box with a list of options defined by the class; when the user presses “OK”, it calls a perform() function with those same arguments. The options to present are defined by a Python data structure, making it possible to create a simple UI for your plugin without having to learn any of Qt’s UI widgets.

SimpleCommandPlugin also manages the undo history automatically. There is no need to call beginCommand() here, and to do so is an error.

A minimal SimpleCommandPlugin:

from mcedit2.plugins import registerPluginCommand, SimpleCommandPlugin

class SimpleOptionsDemo(SimpleCommandPlugin):
    displayName = "Simple Options Demo"

    options = [
            'type': 'int',
            'value': 0,
            'min': 0,
            'max': 100,
            'name': 'myIntOption',
            'text': 'Integer Option: ',

    def perform(self, dimension, selection, options):
        print("Option value: %d" % options['myIntOption'])
        print("Selection volume: %s" % selection.volume)
        print("Chunks in dimension: %d" % dimension.chunkCount())

This plugin will display a dialog with a single integer input, and print the value from that input to the console along with info about the current selection and dimension.

Simple Command Inputs

Each element in the plugin’s options list is a dict that defines a single input. All
option elements must have at least these keys:
  • type: Defines which kind of input to create.
  • name: The internal name for this input. You will use this to access the input’s value,
    and MCEdit will use it to automatically save the last used value.
  • text: The caption to display alongside this input. Should describe what the input does.
  • value: An initial value to show in the input. Optional.

Further keys are available depending on the type of input.

Input Types

  • type="int": A numeric input for integer values, within the range +/- two billion or so. If

    both the min and max keys are given, also creates a slider for selecting a value from within this range

    • min: Minimum allowed value. Optional.
    • max: Maximum allowed value. Optional.
  • type="float": Identical to the int input, but provides a floating point value (within the

    range allowed by double-precision floating point). If both the min and max keys are given, also creates a slider for selecting a value from within this range

    • min: Minimum allowed value. Optional.
    • max: Maximum allowed value. Optional.
  • type="bool": A checkbox that can be either on or off.

  • type="text": A text field that can input a single line of text.

    • placeholder: Displays this text in a light grey color if the text field is empty. Optional.
  • type="choice": A pop-up menu that offers multiple choices for the user to select from.

    Each choice is associated with a value that you define in the element’s choices list. This is the value you will receive as this option’s value in the perform() function.

    • choices: A list of tuples of the form (text, value).
  • type="blocktype": A button that allows the user to select a Minecraft block type.

    The option’s value will be a single BlockType instance that can be used with dimension.setBlock.

    • value: The block type that will initially be selected. This should be a block’s
      internal name, such as minecraft:grass.

For examples of all possible simple command inputs, see the file in the plugins folder included with MCEdit.