Drawing a rectangle around mouse drag Pyglet

Question

I'm trying to create a square that forms around the drag of a mouse (like the one that appears when dragging on the desktop, for example.) THis is the code I've tried:

import pyglet
from pyglet.window import mouse

window = pyglet.window.Window()

@window.event
def on_draw():
    window.clear()

@window.event
def on_mouse_drag(x, y, dx, dy, buttons, modifiers):
    pyglet.graphics.draw(4, pyglet.gl.GL_QUADS, ('v2f', [x, y, dx, y, dx, dy, x, dy]))

pyglet.app.run()

However, it's not working, and I can't see why. Any advice?

Answer 1

So, as there hasn't been an answer, this is how I solved the problem:

import pyglet
from pyglet.window import mouse

window = pyglet.window.Window()

@window.event
def on_draw():
    pass

@window.event
def on_mouse_drag(x, y, dx, dy, buttons, modifiers):
    pyglet.graphics.draw(4, pyglet.gl.GL_QUADS, ('v2f', [x, y, x-dx, y, x-dx, y-dy, x, y-dy]))
    print x, y, dx, y, dx, dy, x, dy
pyglet.app.run()

Now I just need to work out how to destroy the rectangles...

Answer 2

I started with your solution and improved it a bit. The rectangle artifacting problem is fixed by adding an on_draw function, and in that function you clear the window and then re-draw every object. Pyglet (OpenGL) uses double-buffering, so this works a lot faster than it sounds.

import pyglet

# rectangle class

class Rect:

  def __init__(self, x, y, w, h):
    self.set(x, y, w, h)

  def draw(self):
    pyglet.graphics.draw(4, pyglet.gl.GL_QUADS, self._quad)

  def set(self, x=None, y=None, w=None, h=None):
    self._x = self._x if x is None else x
    self._y = self._y if y is None else y
    self._w = self._w if w is None else w
    self._h = self._h if h is None else h
    self._quad = ('v2f', (self._x, self._y,
                          self._x + self._w, self._y,
                          self._x + self._w, self._y + self._h,
                          self._x, self._y + self._h))

  def __repr__(self):
    return f"Rect(x={self._x}, y={self._y}, w={self._w}, h={self._h})"

# main function

def main():
  r1 = Rect(10, 10, 100, 100)
  window = pyglet.window.Window()

  @window.event
  def on_draw():
    window.clear()
    r1.draw()

  @window.event
  def on_mouse_press(x, y, button, modifiers):
    r1.set(x=x, y=y)
    print(r1)

  @window.event
  def on_mouse_drag(x, y, dx, dy, buttons, modifiers):
    r1.set(x=x, y=y)
    print(r1)

  pyglet.app.run()

if __name__ == '__main__':
  main()