开罗和 Gdk.Window 与 Gtk.DrawingArea 使用 python gobject-introspection 和 gtk3

Question

我正在尝试遵循参考文档中的 Gtk+ v3 教程。特别是第一个绘图示例使用 cairo 将绘图处理到 Gtk.DrawingArea.

https://developer.gnome.org/gtk3/stable/ch01s03.html

作为参考，我正在使用这些资源：

https://python-gtk-3-tutorial.readthedocs.org/en/latest/

http://lazka.github.io/pgi-docs/

请看一下我将 ch01s03 程序（部分）翻译成 python。我遇到的主要问题是 configure_event_cb() 程序应该创建一个 cairo.Surface 对象连接到 Gdk.Window。我不知道如何找到这个 Gdk.Window 甚至不知道在哪里查看参考文档。

from gi.repository import Gtk, Gdk, cairo

surface = None

def clear_surface():
    global surface
    surface = cairo.Surface()
    surface.set_source_rgb(1,1,1)
    surface.paint()

def configure_event_cb(wid,evt):
    global surface

    if surface is not None:
        surface.destroy()
        surface = None

    '''
    Here, I am trying to implement the following C code:

    surface = gdk_window_create_similar_surface(
                gtk_widget_get_window(widget),
                CAIRO_CONTENT_COLOR,
                gtk_widget_get_allocated_width(widget),
                gtk_widget_get_allocated_height(widget) );
    '''

    clear_surface()
    return True

def close_window(wid):
    global surface
    if surface is not None:
        surface.destroy()
    Gtk.main_quit()

if __name__ == '__main__':
    win = Gtk.Window(Gtk.WindowType.TOPLEVEL)
    win.set_title('Drawing Area')
    win.connect('destroy',close_window)
    win.set_border_width(8)

    frame = Gtk.Frame()
    frame.set_shadow_type(Gtk.ShadowType.IN)
    win.add(frame)

    da = Gtk.DrawingArea()
    da.set_size_request(100,100)
    frame.add(da)

    da.connect('configure-event',configure_event_cb)

    win.show_all()
    Gtk.main()

Answer 1

我了解到 DrawingArea 现在使用 draw 事件而不是 configure-event 这是一个简单的代码：

from gi.repository import Gtk

def draw_cb(widget, cr):
  cr.set_source_rgba(0,0,0,0.5)
  cr.rectangle(50,75,100,100)
  cr.fill()
  return False

win = Gtk.Window()

win.set_title("test")
win.set_default_size(800,600)
win.connect('delete-event', Gtk.main_quit)
da=Gtk.DrawingArea()
da.connect('draw', draw_cb)
win.add(da)
win.show_all()
Gtk.main()

但是如果你真的想在公开事件的回调中创建一个 cairo 上下文，只需使用它来获取 gtk.gdk.window:

myGdkWindow = mywin.get_window()
cr = myGdkWindow.cairo_create()

Answer 2

在@cedlemo 的（已接受）答案的帮助下，我能够在 python 中重新创建 ch01s03 Gtk+ 示例。但是，我不得不导入 cairo actual 因为 gi.repository.cairo.Context() 构造函数不存在。起初这并不明显，但也许是有道理的。这是完整的工作版本。请参阅 original C version with comments.

from gi.repository import Gtk, Gdk
import cairo


surface = None


def clear_surface():
    global surface

    cr = cairo.Context(surface)
    cr.set_source_rgb(1,1,1)
    cr.paint()

    del cr


def configure_event_cb(wid,evt):
    global surface

    if surface is not None:
        del surface
        surface = None

    win = wid.get_window()
    width = wid.get_allocated_width()
    height = wid.get_allocated_height()

    surface = win.create_similar_surface(
        cairo.CONTENT_COLOR,
        width,
        height)

    clear_surface()
    return True


def draw_cb(wid,cr):
    global surface

    cr.set_source_surface(surface,0,0)
    cr.paint()
    return False


def draw_brush(wid,x,y):
    global surface

    cr = cairo.Context(surface)
    cr.set_source_rgb(0,0,0)
    cr.rectangle(x-3,y-3,6,6)
    cr.fill()
    del cr

    wid.queue_draw_area(x-3,y-3,6,6)


def button_press_event_cb(wid,evt):
    global surface

    if surface is None:
        return False

    if evt.button == Gdk.BUTTON_PRIMARY:
        draw_brush(wid,evt.x,evt.y)
    elif evt.button == Gdk.BUTTON_SECONDARY:
        clear_surface()
        wid.queue_draw()

    return True


def motion_notify_event_cb(wid,evt):
    global surface

    if surface is None:
        return False

    if evt.state & Gdk.EventMask.BUTTON_PRESS_MASK:
        draw_brush(wid,evt.x,evt.y)

    return True


def close_window(wid):
    global surface

    if surface is not None:
        del surface
        surface = None

    Gtk.main_quit()


if __name__ == '__main__':
    win = Gtk.Window()
    win.set_title('Drawing Area')
    win.connect('destroy',close_window)
    win.set_border_width(8)

    frame = Gtk.Frame()
    frame.set_shadow_type(Gtk.ShadowType.IN)
    win.add(frame)

    da = Gtk.DrawingArea()
    da.set_size_request(100,100)
    frame.add(da)

    da.connect('draw',draw_cb)
    da.connect('configure-event',configure_event_cb)

    da.connect('motion-notify-event',motion_notify_event_cb)
    da.connect('button-press-event',button_press_event_cb)
    da.set_events(da.get_events() | Gdk.EventMask.BUTTON_PRESS_MASK | Gdk.EventMask.POINTER_MOTION_MASK)

    win.show_all()
    Gtk.main()

开罗和 Gdk.Window 与 Gtk.DrawingArea 使用 python gobject-introspection 和 gtk3

Cairo and Gdk.Window with Gtk.DrawingArea using python gobject-introspection and gtk3

python

user-interface

cairo

gtk3

gobject-introspection