drawing a pixbuf onto a drawing area using pygtk and glade

问题

i'm trying to make a GTK application in python where I can just draw a loaded image onto the screen where I click on it. The way I am trying to do this is by loading the image into a pixbuf file, and then drawing that pixbuf onto a drawing area.

the main line of code is here:

def drawing_refresh(self, widget, event):
    #clear the screen
    widget.window.draw_rectangle(widget.get_style().white_gc, True, 0, 0, 400, 400) 
    for n in self.nodes:
         widget.window.draw_pixbuf(widget.get_style().fg_gc[gtk.STATE_NORMAL],
                                   self.node_image, 0, 0, 0, 0)

This should just draw the pixbuf onto the image in the top left corner, but nothing shows but the white image. I have tested that the pixbuf loads by putting it into a gtk image. What am I doing wrong here?

回答1:

You can make use of cairo to do this. First, create a gtk.DrawingArea based class, and connect the expose-event to your expose func.

class draw(gtk.gdk.DrawingArea):
    def __init__(self):
        self.connect('expose-event', self._do_expose)
        self.pixbuf = self.gen_pixbuf_from_file(PATH_TO_THE_FILE)

    def _do_expose(self, widget, event):
        cr = self.window.cairo_create()
        cr.set_operator(cairo.OPERATOR_SOURCE)
        cr.set_source_rgb(1,1,1)
        cr.paint()
        cr.set_source_pixbuf(self.pixbuf, 0, 0)
        cr.paint()

This will draw the image every time the expose-event is emited.

回答2:

I found out I just need to get the function to call another expose event with widget.queue_draw() at the end of the function. The function was only being called once at the start, and there were no nodes available at this point so nothing was being drawn.

来源：https://stackoverflow.com/questions/775528/drawing-a-pixbuf-onto-a-drawing-area-using-pygtk-and-glade