自定义 Kivy 小部件仅产生黑屏

Question

我正在尝试创建一个自定义 kivy 小部件，但是当我在我的测试应用程序中渲染它时，会出现一个空白屏幕。我试过跟踪代码调用，看起来所有的初始化和绘图方法都被调用了（我在小部件代码下面包含了打印语句的终端输出。我还包括我的测试应用程序，但这很简单并且是我用于我已经创建的几个工作应用程序的相同外壳）。我的应用程序主循环开始，但没有显示任何内容。为什么我没有看到我的小部件？

[编辑]所以我已经让 NodeEnd 对象进行渲染，并进行了一些重大的结构更改，将大量代码带入了 .kv 语言。我正在用较新的版本替换帖子上的代码。不幸的是，它们之间的标签仍然没有渲染

nodewidget.kv

#: kivy 1.9.0

<NodeEnd>
    canvas:
        Color:
            rgba: self.color[0], self.color[1], self.color[2], self.color[3]
        Ellipse:
            pos: self.center
            size: self.width / 2, self.height / 2
            angle_start: self.degree_range[0]
            angle_end: self.degree_range[1]

<NodeWidget>
    left: left
    body: body
    right: right
    GridLayout:
        cols: 3
        NodeEnd:
            id: left
            degree_range: 180, 360
            on_pressed: self.PressedLeft(self, args[0])
            on_moved: self.MovedLeft(self, args[0])
            on_released: self.ReleasedLeft(self, args[0])
            on_color: self.LeftSwitch(self, args[0])
        NodeBody:
            id: body
            text: self.title
            on_pressed: self.PressedBody(self, args[0])
            on_moved: self.MovedBody(self, args[0])
            on_released: self.ReleasedBody(self, args[0])
            on_pressed_flag: self.BodySwitch(self, args[0])
        NodeEnd:
            id: right
            degree_range: 0, 180
            on_pressed: self.PressedRight(self, args[0])
            on_moved: self.MovedRight(self, args[0])
            on_released: self.ReleasedRight(self, args[0])
            on_color: self.RightSwitch(self, args[0])

NodeWidget3.py

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.properties import ListProperty, StringProperty, BooleanProperty, ObjectProperty
from kivy.uix.gridlayout import GridLayout
from kivy.uix.label import Label
from kivy.graphics import *
from kivy.lang import Builder

Builder.load_file('nodewidget.kv')

class NodeWidget(GridLayout):

    title = StringProperty('')
    pressed_body = ListProperty([0, 0])
    released_body = ListProperty([0, 0])
    moved_body = ListProperty([0, 0])
    switch_body = BooleanProperty(False)
    pressed_left = ListProperty([0, 0])
    released_left = ListProperty([0, 0])
    moved_left = ListProperty([0, 0])
    switch_left = BooleanProperty(False)
    pressed_right = ListProperty([0, 0])
    released_right = ListProperty([0, 0])
    moved_right = ListProperty([0, 0])
    switch_right = BooleanProperty(False)

    left = ObjectProperty(None)
    body = ObjectProperty(None)
    right = ObjectProperty(None)

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

    def PressedBody(self, *args):
        self.pressed_body = args
    def MovedBody(self, *args):
        self.moved_body = args
    def ReleasedBody(self, *args):
        self.released_body = args
    def BodySwitch(self, *args):
        pass
    def PressedLeft(self, *args):
        self.pressed_left = args
    def MovedLeft(self, *args):
        self.moved_left = args
    def ReleasedLeft(self, *args):
        self.released_left = args
    def LeftSwitch(self, *args):
        pass
    def PressedRight(self, *args):
        self.pressed_right = args
    def MovedRight(self, *args):
        self.moved_right = args
    def ReleasedRight(self, *args):
        self.released_right = args
    def RightSwitch(self, *args):
        pass

class NodeBody(Label):

#on_color is triggered on down or up on the button and move off or on the button
#it will return the initial values when the button is not pressed
#when the button is pressed, this will return True
    pressed_flag = BooleanProperty(False)

#on_pressed is triggered when the button is initially hit
    pressed = ListProperty([0, 0])

#on_released is triggered when the button is released
    released = ListProperty([0, 0])

#on_moved is triggered when the touch is moved and the touch is not taken outside the button
    moved = ListProperty([0, 0])

    title = StringProperty('')

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

    def on_touch_down(self, touch):
        if self.collide_point(*touch.pos):
            self.pressed = touch.pos
            self.pressed_flag = True
            return touch
        return super(NodeBody, self).on_touch_down(touch)

    def on_touch_move(self, touch):
        if self.collide_point(*touch.pos):
            self.moved = touch.pos
            self.pressed_flag = True
            return touch
        self.pressed_flag = False
        return super(NodeBody, self).on_touch_move(touch)

    def on_touch_up(self, touch):
        if self.collide_point(*touch.pos):
            self.released = touch.pos
            self.pressed_flag = False
            return touch
        return super(NodeBody, self).on_touch_up(touch)

class NodeEnd(Widget):

#on_color is triggered on down or up on the button and move off the button
#it will return the initial values when the button is not pressed
#when the button is pressed, this will return [0.8, 0.2, 0.2, 1]
#Not meant to be updated via code, only generate events
    color = ListProperty([0.7, 0.1, 0.1, 0.8])

#[90, 270] for left
#[270, 90] for right
    degree_range = ListProperty([0, 0])

#on_pressed is triggered when the button is initially hit
    pressed = ListProperty([0, 0])

#on_released is triggered when the button is released
    released = ListProperty([0, 0])

#on_moved is triggered when the button is moved and the touch is not taken outside the button
    moved = ListProperty([0, 0])

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

    def on_touch_down(self, touch):
        if self.collide_point(*touch.pos):
            self.pressed = touch.pos
            self.color = [0.8, 0.2, 0.2, 1]
            return touch
        return super(NodeEnd, self).on_touch_down(touch)

    def on_touch_move(self, touch):
        if self.collide_point(*touch.pos):
            self.moved = touch.pos
            self.color = [0.8, 0.2, 0.2, 1]
            return touch
        self.color = [0.7, 0.1, 0.1, 0.8]
        self.released = touch.pos
        return super(NodeEnd, self).on_touch_move(touch)

    def on_touch_up(self, touch):
        if self.collide_point(*touch.pos):
            self.released = touch.pos
            self.color = [0.7, 0.1, 0.1, 0.8]
            return touch
        return super(NodeEnd, self).on_touch_up(touch)

测试应用：

nodeeditor.kv

#kivy 1.9.0

<NodeEditorWidget>:
    GridLayout:
        size: root.size
        cols: 3
        NodeWidget:
            title: 'Test 1'
            on_pressed_body: app.SelectNode(self, args[0])
            on_moved_body: app.MoveNode(self, args[0])
            on_released_body: app.DeselectNode(self, args[0])
            on_pressed_left: app.SelectLeft(self, args[0])
            on_moved_left: app.MoveLeft(self, args[0])
            on_released_left: app.DeselectLeft(self, args[0])
            on_pressed_right: app.SelectRight(self, args[0])
            on_moved_right: app.MoveRight(self, args[0])
            on_released_right: app.DeselectRight(self, args[0])

NodeTest.py

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.uix.textinput import TextInput
from kivy.properties import ObjectProperty, StringProperty
from kivy.lang import Builder
from NodeWidget3 import NodeWidget

Builder.load_file('nodeeditor.kv')

class NodeEditorWidget(Widget):
    pass

class NodeEditorApp(App):
    def build(self):
        return NodeEditorWidget()
        print('Node Editor initialized')

    def SelectNode(self, *args):
        pass

    def MoveNode(self, *args):
        pass

    def DeselectNode(self, *args):
        pass

    def SelectLeft(self, *args):
        pass

    def MoveLeft(self, *args):
        pass

    def DeselectLeft(self, *args):
        pass

    def SelectRight(self, *args):
        pass

    def MoveRight(self, *args):
        pass

    def DeselectRight(self, *args):
        pass

if __name__ == '__main__':
    NodeEditorApp().run()

Answer 1

我是 Kivy 和 Python 的新手，所以我希望这会有所帮助。当声明小部件并将其添加到您的布局时，请尝试在开头添加“self”。同样在您的原始应用程序中，我注意到您导入了 App 但我没有看到 App 类。 在您的测试中，我将 self 添加到所有内容中，并且还添加了一个按钮。按钮出现在窗口中，但其余部分是黑色的。所以我不得不问，当你添加你的小部件时，你为它们选择了颜色吗？可能它们默认显示为黑色或/并且可能是自我的东西。希望这会有所帮助。