KIVY：如何創建一個按鈕來啟動我的Paint應用程序

Question

我有一個工作的Kivy代碼，如下所示。 我運行后能夠繪制隨機形狀。 現在，我想在單擊Hello按鈕一次后才啟用繪圖。 我應該如何修改我的代碼？

Python代碼

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen, FadeTransition
from kivy.uix.widget import Widget
from kivy.graphics import Line


class Painter(Widget):
    def on_touch_down(self, touch):
        with self.canvas:
            touch.ud["line"] = Line( points = (touch.x, touch.y))
    def on_touch_move(self, touch):
        touch.ud["line"].points += [touch.x, touch.y]

class MainScreen(Screen):
    pass
class ScreenManagement(ScreenManager):
    pass

presentation = Builder.load_file("main3.kv")

class MainApp(App):
    def build(self):
        return presentation

if __name__=="__main__":
    MainApp().run()

kv文件：

#:kivy 1.0.9
ScreenManagement:
    MainScreen:

<MainScreen>:
    name:"main"
    FloatLayout:
        Painter
        Button:
            text: "Hello"
            font_size: 50
            color: 0,1,0,1
            size_hint: 0.3,0.2
            pos_hint: {"right":1, "top":1}

Answer 1

如何制作一個新的繪畫畫面。

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen, FadeTransition
from kivy.uix.widget import Widget
from kivy.graphics import Line


KV = '''
ScreenManagement:
    MainScreen:
    PaintScreen:

<MainScreen>:
    name:"main"
    FloatLayout:
        Button:
            text: "Go paint"
            font_size: 50
            color: 0,1,0,1
            size_hint: 0.3,0.2
            pos_hint: {"right":1, "top":1}
            on_release:
                root.manager.current = 'paint'

<PaintScreen@Screen>:
    name: 'paint'
    FloatLayout:
        Button:
            text: "Exit painting"
            font_size: 40
            color: 0,1,0,1
            size_hint: 0.3,0.2
            pos_hint: {"right":1, "top":1}
            on_release:
                root.manager.current = 'main'
        Painter:
'''


class Painter(Widget):
    def on_touch_down(self, touch):
        with self.canvas:
            touch.ud["line"] = Line( points = (touch.x, touch.y))
    def on_touch_move(self, touch):
        touch.ud["line"].points += [touch.x, touch.y]


class MainScreen(Screen):
    pass


class ScreenManagement(ScreenManager):
    pass


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

if __name__=="__main__":
    MainApp().run()

Answer 2

您可以使用a切換按鈕並將其狀態鏈接到Painter：

    ...
    Painter:
        hello_active: hello_button.state == 'down'
    ToggleButton:
        id: hello_button
        text: "Hello"
        font_size: 50
        color: 0,1,0,1
        size_hint: 0.3,0.2
        pos_hint: {"right":1, "top":1}

並在python文件中...

class Painter(Widget):

    hello_active = BooleanProperty(False)

    def on_touch_down(self, touch):
        if not self.hello_active:
            return #nothing to see here ...
        with self.canvas:
            touch.ud["line"] = Line( points = (touch.x, touch.y))
    def on_touch_move(self, touch):
        if 'line' in touch.ud:
            touch.ud["line"].points += [touch.x, touch.y]