Re: Bug with large line width near edge of window?

Matt Peterson <[email protected]> Tue, 15 Oct 2013 08:11:51 -0600

Newsgroups	gmane.comp.lib.cairo
Message-ID	<CACEDMXL2N4-s92=C1miymeR_AOT4sz-FxkEd=fk09K03zmA8wg@mail.gmail.com>

I wrote a quick test case in Python. The bug seems very easy to reproduce
here.

--
Matt Peterson


On Tue, Oct 15, 2013 at 2:54 AM, Chris Wilson <[email protected]>wrote:

>
> Sorry, I can see it matches your description, but I don't have enough
> context to see that it is the wrong behaviour. Would it be possible to
> generate a small series of snapshots that show the sudden snapping to
> the corners? If you can automate and produce a test case... :)
> -Chris
>
> --
> Chris Wilson, Intel Open Source Technology Centre
>

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bug.py (application/octet-stream, 1.4 KB)

#! /usr/bin/env python
import pygtk
from gi.repository import GObject, Gtk, Gdk, cairo, Pango, PangoCairo

# Create a GTK+ widget on which we will draw using Cairo
class Screen(Gtk.DrawingArea):
    def __init__(self):
        Gtk.DrawingArea.__init__(self)
        self.timeout_id = GObject.timeout_add(100, self.on_timeout, None)

        self.x = 0
        self.dx = 0.01

    def on_timeout(self, a):
        self.x += self.dx

        if self.x > 0.4:
            self.dx *= -1

        if self.x < 0:
            self.dx *= -1

        self.queue_draw()

        return True

    def do_draw(self, cr):
        a = self.get_allocation()
        width = a.width
        height = a.height

        cr.save()
        cr.set_source_rgba(1, 1, 1, 1)   # clear background
        cr.paint()
        cr.restore()

        cr.translate(-self.x * width, 0)
        cr.set_line_width(20)

        cr.save()


        cr.set_source_rgba(0, 0, 0, 1)   # black line

        cr.move_to(width / 5, -5)

        cr.line_to(width / 3, height / 2)
        cr.line_to(width / 5, height + 5)

        cr.stroke()

        cr.restore()

# 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.connect('draw', widget.do_draw)
    widget.show()
    window.add(widget)
    window.present()
    Gtk.main()

if __name__ == "__main__":
    run(Screen)