XO ImageQuiz/Plugins

This page is all about how to write Plugins for the XO ImageQuiz. You can get the latest source code here:

git clone git://dev.laptop.org/projects/xo-quiz

Services

Overview

Here's an overview of all services:

/*** Styles and Layout: Use with Layout. ***\

- Have a look at layout.py. Very self-explanatory. Any wishes?

/*** DB Services: Use with db. ***\

- query(q) ................................................... Returns result of db-query in a list
- commit(q) .................................................. Executes query and following commit()

/*** Frontend Services: Use with frontend. ***\

/* Menu */

- add_menu_dir (path, caption, part = 3) ..................... Add menu directory
- add_menu_item(path, caption, onclick, part = 3) ............ Add menu item
- change_dir(dir) ............................................ Change menu directory and update menu

/* Interaction */

- add_event_hook(event, onclick) ............................. Hook a Plugin's function to an event (here def onclick())
- add_react(x, y, width, height, onclick, display = False) ... Create a React and hook in Plugin's function. Returns react's id
- del_react(id) .............................................. Remove React

/* Question Frame */

- question_display() ......................................... Display last Question
- question_frame_clear() ..................................... Clear Question Frame
- question_frame_show_image(imgfn, x, y) ..................... Show Image in Question-Frame
- question_frame_show_surface(surface, x, y).................. Show Surface in Question-Frame
- question_frame_show_text(text, x, y) ....................... Show Text in Question-Frame

/* PyGame & Other Tools */

- image_load(img_fn) ......................................... Load and convert() image. Return image, image_rect
- sound_load(snd_fn) ......................................... Loads a sound, return sound object
- point_inside_polygon(x, y, poly) ........................... True if x and y inside the polygon

Events

A Plugin can attach functions to some events. Currently supported events (list is growing):

* onclick

How to use services

Services can be accessed via the object __SERVICES__

print __SERVICES__.db.query('SELECT * FROM xoquiz WHERE 1')

Easier-to-use Trick

In load() is's possible to assign a short name to any __SERVICES__-subclass. In the examples we're using this:

def load():
	global sf
	sf = __SERVICES__.frontend

Reacts - Reacting Rectangles

Reacts are reacting, invisible or visible, rectangular areas on the screen. Created by the Plugins, they start a given function if clicked on. A found react (currently!) stops searching for other clickable objects below. A react can be build with this command:

react_id = __SERVICES__.frontend.add_react(x, y, width, height, start_function, display)

• start_function: a function of your plugin
• display: default is False. If you pass True, a visible rectangle will be created

Reacts can be removed like this:

__SERVICES__.frontend.del_react(react_id) 

Put together it looks like that:

def test():
	pass

react_id = __SERVICES__.frontend.add_react(100, 100, 400, 200, test)
// do stuff
__SERVICES__.frontend.del_react(react_id)

Examples

git clone git://dev.laptop.org/projects/xo-quiz

Then change to the directory xo-quiz/ImageQuiz.activity/imagequiz.

• Plugins are .py files saved in the directory 'plugins/'
• A filename beginning with '_' prevents loading.

Minimum

This is the bare minimum of code, a plugin script requires:

__PLUGIN_NAME__ = ""
def load():
	pass

Hello World

• Creates a menu-item linked to the local function click1()
• This button clears the Question Frame and prints 'Hello World' with an Image below

__PLUGIN_NAME__ = 'Demo Plugin'
def click1():
	sf.question_frame_clear()
	sf.question_frame_show_text('Hello World!', 0, 0)
	sf.question_frame_show_image('../images/europe.gif', 0, 50)

def load():
	global sf
	sf = __SERVICES__.frontend
	
 	sf.add_menu_dir('/tools', 'Tools')
	sf.add_menu_item('/tools', 'Hello', click1)

Hook to event 'onclick'

• Extends the Hello-World example, that it reacts on a mouse click

__PLUGIN_NAME__ = 'Demo Plugin'
def event1(var):
 	x, y = var
	print 'click at ', x, '-', y

def click1():
	sf.question_frame_clear()
	sf.question_frame_show_text('Hello World!', 0, 0)
	sf.question_frame_show_image('../images/europe.gif', 0, 50)

	sf.add_event_hook('onclick', event1)

def load():
	global sf
	sf = __SERVICES__.frontend
	
 	sf.add_menu_dir('/tools', 'Tools')
	sf.add_menu_item('/tools', 'Hello', click1)

Create a React and Toggle Fullscreen

• Extend the Hello-World example, that uses a React, and toggles fullscreen

import pygame
__PLUGIN_NAME__ = 'Demo Plugin'

def clickReact(): print "Clicked on my first React"
def clickReact2(): print "Clicked on my second React"

def clickToggleFS():
	pygame.display.toggle_fullscreen()

def click1():
	sf.question_frame_clear()
	sf.question_frame_show_text('Hello World!', 0, 0)
	sf.question_frame_show_image('../images/europe.gif', 0, 50)

def load():
	global sf
	sf = __SERVICES__.frontend
	
 	sf.add_menu_dir('/tools', 'Tools')
	sf.add_menu_item('/tools', 'Hello', click1)
	sf.add_menu_item('/tools', 'Toggle Fullscreen', clickToggleFS)

	sf.add_react(0, 0, 100, 100, clickReact)
	sf.add_react(100, 100, 200, 200, clickReact2, True)

The function takes this parameters:

• add_react (x, y, width, height, function, display=False)

The parameter display is set to False by default, but if you explicitly say 'True', it will draw the rectangle on the screen. Mainly for development.