# Widget (Python)

Marta Maria Casetti
mmcasetti@gmail.com 2013
Un widget que usa la biblioteca Cairo para dibujar
Daniel Mustieles
daniel.mustieles@gmail.com 2011 - 2019
Nicolás Satragno
nsatragno@gmail.com 2012 - 2013
Jorge González
jorgegonz@svn.gnome.org 2011

# Widget

Introduzca un ángulo, visualícelo.

# Código usado para generar este ejemplo

from gi.repository import Gtk from gi.repository import cairo import sys import math

class MyWindow(Gtk.ApplicationWindow):

def __init__(self, app): Gtk.Window.__init__(self, title="Choose an angle", application=app) self.set_default_size(400, 400) self.set_border_width(10)

# a default angle self.angle = 360

grid = Gtk.Grid()

# a spinbutton that takes the value of an angle ad = Gtk.Adjustment(360, 0, 360, 1, 0, 0) self.spin = Gtk.SpinButton(adjustment=ad, climb_rate=1, digits=0) self.spin.connect("value-changed", self.get_angle)

# a drawing area for drawing whatever we want self.darea = Gtk.DrawingArea() # that we describe in the method draw(), connected to the signal "draw" self.darea.connect("draw", self.draw) # we have to request a minimum size of the drawing area, or it will # disappear self.darea.set_size_request(300, 300)

grid.attach(self.spin, 0, 0, 1, 1) grid.attach(self.darea, 0, 1, 1, 1)

self.add(grid)

# whenever we get a new angle in the spinbutton def get_angle(self, event): self.angle = self.spin.get_value_as_int() # redraw what is in the drawing area self.darea.queue_draw()

def draw(self, darea, cr): # a 10-pixels-wide line cr.set_line_width(10) # red cr.set_source_rgba(0.5, 0.0, 0.0, 1.0)

# get the width and height of the drawing area w = self.darea.get_allocated_width() h = self.darea.get_allocated_height()

# move to the center of the drawing area # (translate from the top left corner to w/2, h/2) cr.translate(w / 2, h / 2) # draw a line to (55, 0) cr.line_to(55, 0) # and get back to (0, 0) cr.line_to(0, 0) # draw an arc centered in the origin, 50 pixels wide, from the angle 0 # (in radians) to the angle given by the spinbutton (in degrees) cr.arc(0, 0, 50, 0, self.angle * (math.pi / 180)) # draw a line back to the origin cr.line_to(0, 0) # drawing the path, and keeping the path for future use cr.stroke_preserve()

# set a colour cr.set_source_rgba(0.0, 0.5, 0.5, 1.0) # and use it to fill the path (that we had kept) cr.fill()

class MyApplication(Gtk.Application):

def __init__(self): Gtk.Application.__init__(self)

def do_activate(self): win = MyWindow(self) win.show_all()

def do_startup(self): Gtk.Application.do_startup(self)

app = MyApplication() exit_status = app.run(sys.argv) sys.exit(exit_status)

# Referencias de la API

En este ejemplo se usa lo siguiente:

GtkWidget

GtkDrawingArea

El tutorial de Cairo para programadores en Python