如何在PyGTK和PyCairo的窗口中获得透明背景？ [英] How to get transparent background in window with PyGTK and PyCairo?

问题描述

我一直在努力用PyGTK创建一个没有装饰和透明背景的窗口。然后我会和开罗一起绘制窗口的内容。但我无法完成它。

I've been trying really hard to create a window with no decoration and a transparent background using PyGTK. I would then draw the content of the window with Cairo. But I can't get it to work.

我尝试了很多不同的方法，都失败了，这是其中之一。

I've tried a lot of different ways, they all failed, this is one of them

#!/usr/bin/env python

import pygtk
pygtk.require('2.0')
import gtk, sys, cairo

win = None

def expose (widget, event):
    cr = widget.window.cairo_create()

    #Start drawing
    cr.set_operator(cairo.OPERATOR_CLEAR)
    cr.set_source_rgba(0.5,1.0,0.0,0.5)
    cr.rectangle(0, 0, 0.9, 0.8)
    cr.fill()

def main (argc):
    global win

    win = gtk.Window()

    win.set_decorated(False)

    win.connect('delete_event', gtk.main_quit)
    win.connect('expose-event', expose)

    win.set_app_paintable(True)

    win.show()

    gtk.main()

if __name__ == '__main__':
    sys.exit(main(sys.argv))

什么是最简单的如何做到这一点？

So, what is the simplest way to do this?

推荐答案

所以，我实际上已经明白了这一点。

So, I actually figured this out myself.

这是一个工作示例。我已经评论了相关部分，以防其他人对如何做到这一点感兴趣。

This is a working example. I've commented the relevant parts just in case somebody else is interested in how to do this.

#!/usr/bin/env python

import pygtk
pygtk.require('2.0')
import gtk, sys, cairo
from math import pi

def expose (widget, event):
    cr = widget.window.cairo_create()

    # Sets the operator to clear which deletes everything below where an object is drawn
    cr.set_operator(cairo.OPERATOR_CLEAR)
    # Makes the mask fill the entire window
    cr.rectangle(0.0, 0.0, *widget.get_size())
    # Deletes everything in the window (since the compositing operator is clear and mask fills the entire window
    cr.fill()
    # Set the compositing operator back to the default
    cr.set_operator(cairo.OPERATOR_OVER)

    # Draw a fancy little circle for demonstration purpose
    cr.set_source_rgba(0.5,1.0,0.0,1)
    cr.arc(widget.get_size()[0]/2,widget.get_size()[1]/2,
           widget.get_size()[0]/2,0,pi*2)
    cr.fill()

def main (argc):

    win = gtk.Window()

    win.set_decorated(False)

    # Makes the window paintable, so we can draw directly on it
    win.set_app_paintable(True)
    win.set_size_request(100, 100)

    # This sets the windows colormap, so it supports transparency.
    # This will only work if the wm support alpha channel
    screen = win.get_screen()
    rgba = screen.get_rgba_colormap()
    win.set_colormap(rgba)

    win.connect('expose-event', expose)

    win.show()

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