Kivy自定义按钮按下时更改画布颜色

Question

Kivy自定义按钮按下时更改画布颜色

3

回答您之前的问题后，我已经查看了相关文档和示例，尝试修改自定义按钮在按下时的画布颜色。以下是我的代码，但是无论点击多少次都没有任何变化：

class CircularButton(ButtonBehavior, Label):

    # code inspired from:
        # https://github.com/kivy/kivy/issues/4263#issuecomment-217430358
        # https://stackoverflow.com/a/42886979/6924364
        # https://blog.kivy.org/2014/10/updating-canvas-instructions-declared-in-python/

    def __init__(self, **kwargs):
        super(CircularButton,self).__init__(**kwargs)

        with self.canvas.before:
            Color(rgba=(.5,.5,.5,.5))
            self.shape = Ellipse(pos=self.pos,size=self.size)

        self.bind(pos=self.update_shape, size=self.update_shape)

    def update_shape(self, *args):
        self.shape.pos = self.pos
        self.shape.size = self.size

    def on_press(self, *args): #<--- what am I doing wrong here?
        with self.canvas:
            Color(rgba=(0,0,0,0))

    def collide_point(self, x, y):
        return Vector(x, y).distance(self.center) <= self.width / 2

- Justapigeon

2个回答

2

也许这个解决方案可以帮助某些人：

.py

（注：.py是Python代码文件的扩展名）

class PositionButton(Button):
    b_color = ListProperty()

.kv

<PositionButton>:
    background_color: [0,0,0,0]
    b_color: [0, 0, 1, .3] if self.state == 'normal' else [0, 0, 1, .5]
    canvas.before:
        Color:
            rgba: self.b_color

- Vitaliy Chudikov

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- eyllanesc · Accepted Answer

您需要存储和重复使用颜色指令，并在Canvas添加指令时更改颜色。在您的情况下，您正在添加一个新的颜色指令，但它不适用于其他元素（如矩形或椭圆），因此您看不到效果。

from kivy.base import runTouchApp
from kivy.uix.behaviors import ButtonBehavior
from kivy.uix.label import Label
from kivy.vector import Vector
from kivy.graphics import Color, Ellipse
from kivy.properties import ListProperty


class CircularButton(ButtonBehavior, Label):
    background_color = ListProperty((0.5,.5,.5,.5))

    def __init__(self, **kwargs):
        super(CircularButton,self).__init__(**kwargs)
        self.draw()
        self.text='test'

    def update_shape(self, *args):
        self.shape.pos = self.pos
        self.shape.size = self.size

    def on_background_color(self, *args):
        self.shape_color.rgba = self.background_color

    def draw(self, *args):
        with self.canvas.before:
            self.shape_color = Color(rgba=(0.5,.5,.5,.5))
            self.shape = Ellipse(pos=self.pos,size=self.size)
            self.bind(pos=self.update_shape, size=self.update_shape)

    def on_press(self, *args):
        self.background_color= (1, 0, 0, 1)

    def on_release(self, *arg):
        self.background_color = (0.5,.5,.5,.5)

    def collide_point(self, x, y):
        return Vector(x, y).distance(self.center) <= self.width / 2

if __name__ == '__main__':
    runTouchApp(CircularButton())

虽然我更喜欢将.kv和.py文件组合在一起，但利用kv语言是声明性的，使连接变得简单：

from kivy.base import runTouchApp
from kivy.uix.behaviors import ButtonBehavior
from kivy.uix.label import Label
from kivy.vector import Vector
from kivy.lang import Builder


Builder.load_string('''
<CircularButton>
    background_color: 0.5,.5,.5,.5
    canvas.before:
        Color:
            rgba: self.background_color
        Ellipse:
            pos: self.pos
            size: self.size
    ''')


class CircularButton(ButtonBehavior, Label):
    def __init__(self, **kwargs):
        super(CircularButton, self).__init__(**kwargs)
        self.text = "test"

    def on_press(self, *args):
        self.background_color = (1, 0, 0, 1)

    def collide_point(self, x, y):
        return Vector(x, y).distance(self.center) <= self.width / 2

if __name__ == '__main__':
    runTouchApp(CircularButton())