quickframework

A Quick GTK+ GNU/Linux Framework

I got this from http://www.tortall.net/mu/wiki/PyGTKCairoTutorial : it's handy for running snippets of cairo code to see what's going on.

This sample shows how to use a mask (a second source to filter the first source.)

#! /usr/bin/env python
import pygtk
pygtk.require('2.0')
import gtk, gobject, cairo

# Create a GTK+ widget on which we will draw using Cairo
class Screen(gtk.DrawingArea):

    # Draw in response to an expose-event
    __gsignals__ = { "expose-event": "override" }

    # Handle the expose-event by drawing
    def do_expose_event(self, event):

        # Create the cairo context
        cr = self.window.cairo_create()

        # Restrict Cairo to the exposed area; avoid extra work
        cr.rectangle(event.area.x, event.area.y,
                event.area.width, event.area.height)
        cr.clip()

        self.draw(cr, *self.window.get_size())

    def draw(self, cr, width, height):
        # Fill the background with gray
        cr.set_source_rgb(0.5, 0.5, 0.5)
        cr.rectangle(0, 0, width, height)
        cr.fill()

# GTK mumbo-jumbo to show the widget in a window and quit when it's closed
def run(Widget):
    window = gtk.Window()
    window.connect("delete-event", gtk.main_quit)
    widget = Widget()
    widget.show()
    window.add(widget)
    window.present()
    gtk.main()



## Do all your testing in Shapes ##



class Shapes(Screen):
    def draw(self, cr, width, height):

        ## This will draw using a mask.
        cr.scale(width,height) #Without this line the mask does not seem to work!
        self.linear = cairo.LinearGradient(0, 0, 1, 1)
        self.linear.add_color_stop_rgb(0, 0, 0.3, 0.8)
        self.linear.add_color_stop_rgb(1, 0, 0.8, 0.3)

        self.radial = cairo.RadialGradient(0.5, 0.5, 0.25, 0.5, 0.5, 0.5)
        self.radial.add_color_stop_rgba(0, 0, 0, 0, 1)
        self.radial.add_color_stop_rgba(0.5, 0, 0, 0, 0)

        cr.set_source(self.linear)
        cr.mask(self.radial)

run(Shapes)