CODEWITHSUNDEEP
colorsgtkalpha
user2327814
user2327814

Reputation: 543

python gtk.gdk.Color change alpha

I am using a GTK drawing area to display circles. I am creating the circles by drawing 2 pi arcs and filling them with a color. I want to give the color of the circles an alpha. This way when a circle is drawn on top of another circle I will be able to see the circle underneath.

Does anyone have an ideas to achieve what I want?

Maybe I missed something that would be useful in the gtk.gdk.GC.

Thanks, Ian

Upvotes: 0

Views: 571

Answers (1)

LiuLang
LiuLang

Reputation: 773

Try Cairo, please. Here is a deom:

#!/usr/bin/env python3

import cairo
from gi.repository import Gtk
import math

class Demo(Gtk.Window):

    def __init__(self):
        super(Demo, self).__init__()

        self.init_ui()

    def init_ui(self):
        darea = Gtk.DrawingArea()
        darea.connect('draw', self.on_draw)
        self.add(darea)

        self.set_title('Fill & stroke')
        self.resize(300, 150)
        self.set_position(Gtk.WindowPosition.CENTER)
        self.connect('delete-event', Gtk.main_quit)
        self.show_all()

    def on_draw(self, window, cr):
        cr.set_source_rgba(0.3, 0.4, 0.5, 0.5)
        cr.arc(60, 60, 40, 0, 2*math.pi)
        cr.fill()

        cr.set_source_rgba(0.5, 0.2, 0.7, 0.5)
        cr.arc(70, 60, 30, 0, 2*math.pi)
        cr.fill()


def main():
    app = Demo()
    Gtk.main()

if __name__ == '__main__':
    main()

And here is the screenshot:

screenshot

Visit here to learn more about Cairo.

Upvotes: 1

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