I am writing a small application using PyGI which will interactively draw a line on a Gtk.DrawingArea between mouse clicks. But I am unable to figure out how to draw using the cairo context at the coordinates returned by the mouse click event.
How should the drawing be handled from 'button-press-event' to draw a pattern similar to that produced by the 'draw' callback in the attached code?
class MyApp(Gtk.Window): def __init__(self): Gtk.Window.__init__(self, title="Draw on button press") self.set_size_request(800, 500) self.connect('delete-event', Gtk.main_quit) self.drawing_area = Gtk.DrawingArea() self.drawing_area.add_events(Gdk.EventMask.BUTTON_PRESS_MASK) self.drawing_area.connect('draw', self.on_drawing_area_draw) self.drawing_area.connect('button-press-event', self.on_drawing_area_button_press) self.drawing_area.show() self.add(self.drawing_area) self.show_all() def on_drawing_area_button_press(self, widget, event): print "Mouse clicked... at ", event.x, ", ", event.y # How to draw a line starting at this point on the drawing area? return True def on_drawing_area_draw(self, drawing_area, cairo_context): cairo_context.move_to(50, 50) cairo_context.rel_line_to(0, 200) cairo_context.rel_line_to(200, 0) cairo_context.rel_line_to(0, -200) cairo_context.set_source_rgb(0, 0, 0) cairo_context.stroke() return False
app = MyApp()
Gtk.main()1 Answer
What you should do is set variables that are drawn in the draw callback. If you want it to redraw itself you can use this to force it to:
drawing_area.queue_draw()Edit: Here is an example of code you may use:
clicks = [];
def on_drawing_area_button_press(self, widget, event): print "Mouse clicked... at ", event.x, ", ", event.y clicks.append([event.x, event.y]) drawing_area.queue_draw() return True
def on_drawing_area_draw(self, drawing_area, cairo_context): cairo_context.move_to(50, 50) for point in clicks cairo_context.line_to(point[0], point[1]) cairo_context.stroke() return False
