Agregamos las imagenes de primer plano y de fondo. Empezamos a probar las mascaras para la imagen de primer plano.

1 files changed, 73 insertions, 6 deletions

diff --git a/cake.py b/cake.py
index 0c18288..b68db41 100755
--- a/cake.py
+++ b/cake.py
@@ -1,14 +1,47 @@
 #!/usr/bin/env python
 # -*- encoding: utf8 -*-
+"""
+La torta es una imagen redonda en un archivo de 500x500 pixeles.
+Tiene un borde de 30 pixeles.
+
+Pasado a coordenadas mundiales el radio es: (500-2*30)/(2*500) = 0.44
+
+"""
 import math
 import gtk
 import cairo
 
 
+WRADIUS = 0.44
+
+
+def draw_grid(context, N):
+    context.set_source_rgb(0, 0, 0)
+    context.arc(250, 250, 500*WRADIUS, 0, 2 * math.pi)
+    context.stroke()
+    for i in xrange(N):
+        angle = 2 * math.pi * i / N
+        context.move_to(250, 250)
+        context.line_to(
+            250 + 500*WRADIUS*math.cos(angle),
+            250 + 500*WRADIUS*math.sin(angle)
+            )
+        context.stroke()
+
+
+def mask_image(context, selected, image):
+    context.set_source_surface(image, 0, 0)
+    context.paint()
+
+
 class Cake(gtk.DrawingArea):
-    def __init__(self):
+    def __init__(self, N):
         gtk.DrawingArea.__init__(self)
         self.connect("expose_event", self.expose)
+        #self.N = N
+        #self.selected = N * [0]
+        self.N = 5
+        self.selected = [0, 0, 1, 1, 1]
 
 
     def expose(self, widget, event):
@@ -33,21 +66,55 @@ class Cake(gtk.DrawingArea):
 
 
     def draw_image(self, context):
+        # Load images
+        image_bg = cairo.ImageSurface.create_from_png("bg.png")
+        image_fg = cairo.ImageSurface.create_from_png("fg.png")
+
+        # Scale the surface
         rect = self.get_allocation()
-        image = cairo.ImageSurface.create_from_png("fg.png")
         context.save()
         context.scale(
-            float(rect.width) / image.get_width(),
-            float(rect.height) / image.get_height()
+            #float(rect.width) / float(image.get_width()),
+            #float(rect.height) / float(image.get_height())
+            rect.width / 500.0,
+            rect.height / 500.0,
             )
-        context.set_source_surface(image, 0, 0)
+
+        # Draw the background
+        context.set_source_surface(image_bg, 0, 0)
         context.paint()
+
+        # Draw the foreground
+        mask_image(context, self.selected, image_fg)
+
+        # Draw the grid
+        draw_grid(context, self.N)
         context.restore()
 
 
+    def select(self, ux, uy):
+        """
+        Si x, y esta dentro de la torta cambiamos el sector.
+
+        """
+        # Transformamos las coordenadas del usuario al rango 0.0, 1.0.
+        rect = self.get_allocation()
+        wx = float(ux - rect.x) / float(rect.width)
+        wy = float(uy - rect.y) / float(rect.height)
+        if math.pow(wx, 2) + math.pow(wy, 2) > math.pow(WRADIUS, 2):
+            return False
+        angle = math.atan2(wy, wx)
+        if angle < 0:
+            angle += 2 * math.pi
+        sector = angle * self.N / (2 * math.pi)
+        index = int(math.floor(sector))
+        self.selected[index] = 1 - self.selected[index]
+        return True
+
+
 def main():
     window = gtk.Window()
-    cake = Cake()
+    cake = Cake(6)
 
     window.add(cake)
     window.connect("destroy", gtk.main_quit)