【问题标题】：How to use an if statement in a .kv file如何在 .kv 文件中使用 if 语句
【发布时间】：2019-03-28 21:29:55
【问题描述】：

我想加载一个特定的图像，在这种情况下，我希望我的游戏显示一个钢铁侠的图像，但只有当变量 'char' 设置为钢铁侠时，玩家将在他们选择玩时设置和他一样。

<Game2>:
    name: "Avengers Tower"
    FloatLayout:
        Image:
            source: "avengerstower.png"

下面这个图像代码是我想在char是钢铁侠时运行的代码

        Image:
            source: "ironmanhover.png" 
            pos_hint: {"x": .6, "y": .05}
            size_hint: .4, .7

        Label:
            text: "You are in the Avengers Tower!"
            pos_hint: {"x": .45, "y": .6}
            font_size: "20dp"
            color: (0,0,0,1)
            size_hint: None, None

        Button:
            text: "North"
            pos_hint: {"x": .45, "y": .85}
            size_hint: None, None
            height: 50
            on_press:
                root.manager.current = "AvengersCourtyard"

下面这段代码是设置 char 值的地方。

<Game>:
    name: "main"
    FloatLayout:
        Image:
            source: "choosecharacter.png"

        Image:
            source: "choosechar.png" 
            pos_hint: {"x": .3, "y": .25}
            size_hint: .4, .8

        Button:
            text: "<- Back"
            font_size: "15dp"
            pos: 40, 510
            size_hint: None, None
            height: 50
            on_press:
                root.manager.current = "Title"

        ToggleButton:
            text: "Iron Man"
            font_size: "15dp"
            pos: 200, 150
            size_hint: None, None
            height: 80
            group: "character"
            on_press:
                char = "Iron Man"

        ToggleButton:
            text: "Thor"
            font_size: "15dp"
            pos: 350, 150
            size_hint: None, None
            height: 80
            group: "character"
            on_press:
                char = "Thor"

        ToggleButton:
            text: "Scarlett Witch"
            font_size: "15dp"
            pos: 500, 150
            size_hint: None, None
            height: 80
            group: "character"
            on_press:
                char = "Scarlett Witch"

        Button:
            text: "Play!"
            height: 50
            font_size: "15dp"
            pos: 650, 60
            size_hint: None, None
            on_press:
                root.manager.current = "Avengers Tower"

这些是上面的切换按钮^^

【问题讨论】：

标签： python python-3.x kivy kivy-language

【解决方案1】：

ToggleButton 没有on_press 事件。它有on_state 事件。

Kivy » ToggleButton

ToggleButton 小部件就像一个复选框。当您触摸或单击时它，状态在“正常”和“关闭”之间切换（而不是按钮，只要按下它就会“向下”）。

切换按钮也可以组合成单选按钮 - 只有一个组中的按钮可以处于“关闭”状态。

片段

    ToggleButton:
        text: "Iron Man"
        font_size: "15dp"
        pos: 200, 150
        size_hint: None, None
        height: 80
        group: "character"
        #on_press:
        on_state:
            if self.state == "down": \
            print(self.text); \
            root.manager.current = "Avengers Tower"

    ToggleButton:
        text: "Thor"
        font_size: "15dp"
        pos: 350, 150
        size_hint: None, None
        height: 80
        group: "character"
        #on_press:
        on_state:
            if self.state == "down": \
            print(self.text); \
            root.manager.current = "Thor"

    ToggleButton:
        text: "Scarlett Witch"
        font_size: "15dp"
        pos: 500, 150
        size_hint: None, None
        height: 80
        group: "character"
        #on_press:
        on_state:
            if self.state == "down": \
            print(self.text); \
            root.manager.current = "Scarlett Witch"

【讨论】：

谢谢！我会看看这个并回复你！