from kivy.app import App

from kivy.graphics import Line, Color   # 引入绘图线条，颜色

from kivy.uix.widget import Widget    # 引入控件

from kivy.lang import Builder

from kivy.utils import get_color_from_hex

Builder.load_string("""

#:import C kivy.utils.get_color_from_hex

<DrawCanvasWidget>:

    canvas.before:

        # 最下面纸的颜色

        Color:

            rgba:[1,1,1,1]

        # 形状

        Rectangle:

            # 位置

            pos:self.pos

            # 大小

            size:self.size

    Button:

        background_color:C('#FF0000')

        text:'1'

""")

# 布局类

class DrawCanvasWidget(Widget):

    def __init__(self, **kwargs):

        super().__init__(**kwargs)

        # 1.设置默认颜色,在画布中加入颜色  16进制写法    # 画笔的颜色

        new_color = get_color_from_hex('#FF0000')

        self.canvas.add(Color(*new_color))

        # 1.设置默认颜色,在画布中加入颜色  十进制写法传入0到1的浮点数

        # self.canvas.add(Color(rgb=[0,0,0]))

        self.line_width = 1   # 线宽

    # 触摸显示轨迹

    def on_touch_down(self, touch):

        if Widget.on_touch_down(self,touch):

            return

        with self.canvas:

            touch.ud['current_line'] = Line(points=(touch.x,touch.y),width=self.line_width)

    # 连线

    def on_touch_move(self, touch):

        if 'current_line' in touch.ud:

            touch.ud['current_line'].points += (touch.x,touch.y)

# 应用类

class PaintApp(App):

    def build(self):

        self.draw_canvas_widget = DrawCanvasWidget()

        return self.draw_canvas_widget

if __name__ == '__main__':

    PaintApp().run()