Table Of Contents
FBO Canvas¶
This demonstrates a layout using an FBO (Frame Buffer Off-screen) instead of a plain canvas. You should see a black canvas with a button labelled ‘FBO’ in the bottom left corner. Clicking it animates the button moving right to left.
File canvas/fbo_canvas.py¶
'''
FBO Canvas
==========
This demonstrates a layout using an FBO (Frame Buffer Off-screen)
instead of a plain canvas. You should see a black canvas with a
button labelled 'FBO' in the bottom left corner. Clicking it
animates the button moving right to left.
'''
__all__ = ('FboFloatLayout', )
from kivy.graphics import Color, Rectangle, Canvas, ClearBuffers, ClearColor
from kivy.graphics.fbo import Fbo
from kivy.uix.floatlayout import FloatLayout
from kivy.properties import ObjectProperty, NumericProperty
from kivy.app import App
from kivy.core.window import Window
from kivy.animation import Animation
from kivy.factory import Factory
class FboFloatLayout(FloatLayout):
texture = ObjectProperty(None, allownone=True)
alpha = NumericProperty(1)
def __init__(self, **kwargs):
self.canvas = Canvas()
with self.canvas:
self.fbo = Fbo(size=self.size)
self.fbo_color = Color(1, 1, 1, 1)
self.fbo_rect = Rectangle()
with self.fbo:
ClearColor(0, 0, 0, 0)
ClearBuffers()
# wait that all the instructions are in the canvas to set texture
self.texture = self.fbo.texture
super(FboFloatLayout, self).__init__(**kwargs)
def add_widget(self, *largs):
# trick to attach graphics instruction to fbo instead of canvas
canvas = self.canvas
self.canvas = self.fbo
ret = super(FboFloatLayout, self).add_widget(*largs)
self.canvas = canvas
return ret
def remove_widget(self, *largs):
canvas = self.canvas
self.canvas = self.fbo
super(FboFloatLayout, self).remove_widget(*largs)
self.canvas = canvas
def on_size(self, instance, value):
self.fbo.size = value
self.texture = self.fbo.texture
self.fbo_rect.size = value
def on_pos(self, instance, value):
self.fbo_rect.pos = value
def on_texture(self, instance, value):
self.fbo_rect.texture = value
def on_alpha(self, instance, value):
self.fbo_color.rgba = (1, 1, 1, value)
class ScreenLayerApp(App):
def build(self):
f = FboFloatLayout()
b = Factory.Button(text="FBO", size_hint=(None, None))
f.add_widget(b)
def anim_btn(*args):
if b.pos[0] == 0:
Animation(x=f.width - b.width).start(b)
else:
Animation(x=0).start(b)
b.bind(on_press=anim_btn)
return f
if __name__ == "__main__":
ScreenLayerApp().run()