kivy shaderlabel

shader_label.py

from kivy.app import App
from kivy.properties import DictProperty
from kivy.uix.effectwidget import AdvancedEffectBase, EffectWidget
from kivy.properties import NumericProperty, ListProperty
from kivy.lang import Builder
from kivy.uix.label import Label


KV = """
BoxLayout:
    ShaderLabel:
        shader_color: 1.0,0.0,1.0
        text: "1"
    Label:
    ShaderLabel:
        shader_color: 1.0,0.0,0.0
        text: "2"
"""


class ShaderLabel(Label):
    shader_color = ListProperty([0.0,0.0,0.0])

    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.shader = Shader()
        self.ew = EffectWidget(effects=[self.shader])
        self.add_widget(self.ew)

    def on_shader_color(self, *args):
        self.shader.color = self.shader_color

    def on_pos(self, *args):
        self.ew.pos = self.pos
        self.shader.x, self.shader.y = self.pos

    def on_size(self, *args):
        self.ew.size = self.size
        self.shader.width = self.width
        self.shader.height = self.height

class Shader(AdvancedEffectBase):
    uniforms = DictProperty(
        {'x': 0.0, 'y': 0.0, 'width': 10.0, 'height': 10.0, 'r':0.0, 'g':0.0, 'b':0.0})
    x = NumericProperty(0.0)
    y = NumericProperty(0.0)
    width = NumericProperty(10.0)
    height = NumericProperty(10.0)
    color = ListProperty([0.0,0.0,0.0])

    def on_color(self, _, color):
        self.uniforms.r = color[0]
        self.uniforms.g = color[1]
        self.uniforms.b = color[2]

    def on_x(self, _, x):
        self.uniforms['x'] = x

    def on_y(self, _, y):
        self.uniforms['y'] = y

    def on_width(self, _, width):
        self.uniforms['width'] = float(width)

    def on_height(self, _, height):
        self.uniforms['height'] = float(height)

    glsl = '''
uniform float x;
uniform float y;
uniform float width;
uniform float height;
uniform float r;
uniform float g;
uniform float b;

vec4 effect(vec4 color, sampler2D texture, vec2 tex_coords, vec2 coords) {
    
    if (coords.x > x && coords.x < x+width && coords.y > y && coords.y < x+height) {
        return vec4(r, g, b, 1.0);
    }
}
'''

class MyApp(App):
    def build(self):
        return Builder.load_string(KV)

MyApp().run()