kivy lang中的条件表达式
conditional expression in kivy lang
我正在尝试通过 "on-press" 函数确定按钮的不透明度。例如，在下面的 kv 文件代码中，我想通过按下按钮 A 来改变按钮 (bt1) 的不透明度。
因此，通过按下按钮 A，它应该检查 (bt1) 的不透明度是否等于 0，如果为真，则将其更改为 1，如果为假，则应将 (bt2) 的不透明度从 0 更改为 1。任何想法怎么做？提前致谢。
FloatLayout:
size_hint: None, None
Button:
id: bt1
pos: 200, 300
opacity: 0
on_press: self.opacity = 0
Button:
id: bt2
pos: 300, 300
opacity: 0
on_press: self.opacity = 0
Button:
id: bt3
pos: 400, 300
opacity: 0
on_press: self.opacity = 0
Button:
pos: 0, 0
text: 'A'
on_press:
bt3.opacity = 1 if bt2.opacity == 1 else 0
bt2.opacity = 1 if bt1.opacity == 1 else 0
bt1.opacity = 1 if bt1.opacity == 0 else 1
Button:
pos: 100, 0
text: 'B'
on_press:
bt3.opacity = 1 if bt2.opacity == 1 else 0
bt2.opacity = 1 if bt1.opacity == 1 else 0
bt1.opacity = 1 if bt1.opacity == 0 else 1
Button:
pos: 200, 0
text: 'C'
on_press:
bt3.opacity = 1 if bt2.opacity == 1 else 0
bt2.opacity = 1 if bt1.opacity == 1 else 0
bt1.opacity = 1 if bt1.opacity == 0 else 1
解决方法是使用if...elif....
解决方案 - 更改按钮的文本
按下按钮A时，检查bt1的文本是否为空字符串。如果是，则将 bt1 的文本更改为 'A'。按下按钮 B 时，检查 bt2 的文本是否为空字符串。如果是，则将 bt2 的文本更改为 'B'.
片段
Button:
pos: 0, 0
text: 'A'
on_press:
print("Button {} pressed".format(self.text))
print("\tlen(bt1.text)={}".format(len(bt1.text)))
# Assign Text
if len(bt1.text) == 0: bt1.text = self.text
elif len(bt2.text) == 0: bt2.text = self.text
# Assign Opacity
if bt2.opacity == 1: bt3.opacity = 1
elif bt1.opacity == 1: bt2.opacity = 1
elif bt1.opacity == 0: bt1.opacity = 1
Button:
pos: 100, 0
text: 'B'
on_press:
print("Button {} pressed".format(self.text))
print("\tlen(bt1.text)={}".format(len(bt1.text)))
# Assign Text
if len(bt1.text) == 0: bt1.text = self.text
elif len(bt2.text) == 0: bt2.text = self.text
# Assign Opacity
if bt2.opacity == 1: bt3.opacity = 1
elif bt1.opacity == 1: bt2.opacity = 1
elif bt1.opacity == 0: bt1.opacity = 1
示例 - 更改按钮的文本
main.py
from kivy.lang import Builder
from kivy.base import runTouchApp
runTouchApp(Builder.load_string('''
FloatLayout:
size_hint: None, None
size: 100, 100
Button:
id: bt1
pos: 200, 300
opacity: 0
on_press: self.opacity = 0
Button:
id: bt2
pos: 300, 300
opacity: 0
on_press: self.opacity = 0
Button:
id: bt3
pos: 400, 300
opacity: 0
on_press: self.opacity = 0
Button:
pos: 0, 0
text: 'A'
on_press:
print("Button {} pressed".format(self.text))
print("\tlen(bt1.text)={}".format(len(bt1.text)))
# Assign Text
if len(bt1.text) == 0: bt1.text = self.text
elif len(bt2.text) == 0: bt2.text = self.text
# Assign Opacity
if bt2.opacity == 1: bt3.opacity = 1
elif bt1.opacity == 1: bt2.opacity = 1
elif bt1.opacity == 0: bt1.opacity = 1
Button:
pos: 100, 0
text: 'B'
on_press:
print("Button {} pressed".format(self.text))
print("\tlen(bt1.text)={}".format(len(bt1.text)))
# Assign Text
if len(bt1.text) == 0: bt1.text = self.text
elif len(bt2.text) == 0: bt2.text = self.text
# Assign Opacity
if bt2.opacity == 1: bt3.opacity = 1
elif bt1.opacity == 1: bt2.opacity = 1
elif bt1.opacity == 0: bt1.opacity = 1
Button:
pos: 200, 0
text: 'C'
on_press:
print("Button {} pressed".format(self.text))
# Assign Opacity
if bt2.opacity == 1: bt3.opacity = 1
elif bt1.opacity == 1: bt2.opacity = 1
elif bt1.opacity == 0: bt1.opacity = 1
'''))
输出 - 更改按钮的文本
解决方案 - 更改按钮的不透明度
按下按钮A时，检查bt1的不透明度是否等于0。如果为真则将其更改为1。如果为假则将bt2的不透明度从0更改为1。
片段
Button:
pos: 0, 0
text: 'A'
on_press:
if bt1.opacity == 0: bt1.opacity = 1
elif bt1.opacity == 1: bt2.opacity = 1
示例 - 更改按钮的不透明度
main.py
from kivy.lang import Builder
from kivy.base import runTouchApp
runTouchApp(Builder.load_string('''
FloatLayout:
size_hint: None, None
size: 100, 100
Button:
id: bt1
text: 'bt1'
pos: 200, 300
opacity: 0
on_press: self.opacity = 0
Button:
id: bt2
text: 'bt2'
pos: 300, 300
opacity: 0
on_press: self.opacity = 0
Button:
pos: 0, 0
text: 'A'
on_press:
if bt1.opacity == 0: bt1.opacity = 1
elif bt1.opacity == 1: bt2.opacity = 1
'''))
输出 - 解决方案 1
我正在尝试通过 "on-press" 函数确定按钮的不透明度。例如，在下面的 kv 文件代码中，我想通过按下按钮 A 来改变按钮 (bt1) 的不透明度。 因此，通过按下按钮 A，它应该检查 (bt1) 的不透明度是否等于 0，如果为真，则将其更改为 1，如果为假，则应将 (bt2) 的不透明度从 0 更改为 1。任何想法怎么做？提前致谢。
FloatLayout:
size_hint: None, None
Button:
id: bt1
pos: 200, 300
opacity: 0
on_press: self.opacity = 0
Button:
id: bt2
pos: 300, 300
opacity: 0
on_press: self.opacity = 0
Button:
id: bt3
pos: 400, 300
opacity: 0
on_press: self.opacity = 0
Button:
pos: 0, 0
text: 'A'
on_press:
bt3.opacity = 1 if bt2.opacity == 1 else 0
bt2.opacity = 1 if bt1.opacity == 1 else 0
bt1.opacity = 1 if bt1.opacity == 0 else 1
Button:
pos: 100, 0
text: 'B'
on_press:
bt3.opacity = 1 if bt2.opacity == 1 else 0
bt2.opacity = 1 if bt1.opacity == 1 else 0
bt1.opacity = 1 if bt1.opacity == 0 else 1
Button:
pos: 200, 0
text: 'C'
on_press:
bt3.opacity = 1 if bt2.opacity == 1 else 0
bt2.opacity = 1 if bt1.opacity == 1 else 0
bt1.opacity = 1 if bt1.opacity == 0 else 1
解决方法是使用if...elif....
解决方案 - 更改按钮的文本
按下按钮A时，检查bt1的文本是否为空字符串。如果是，则将 bt1 的文本更改为 'A'。按下按钮 B 时，检查 bt2 的文本是否为空字符串。如果是，则将 bt2 的文本更改为 'B'.
片段
Button:
pos: 0, 0
text: 'A'
on_press:
print("Button {} pressed".format(self.text))
print("\tlen(bt1.text)={}".format(len(bt1.text)))
# Assign Text
if len(bt1.text) == 0: bt1.text = self.text
elif len(bt2.text) == 0: bt2.text = self.text
# Assign Opacity
if bt2.opacity == 1: bt3.opacity = 1
elif bt1.opacity == 1: bt2.opacity = 1
elif bt1.opacity == 0: bt1.opacity = 1
Button:
pos: 100, 0
text: 'B'
on_press:
print("Button {} pressed".format(self.text))
print("\tlen(bt1.text)={}".format(len(bt1.text)))
# Assign Text
if len(bt1.text) == 0: bt1.text = self.text
elif len(bt2.text) == 0: bt2.text = self.text
# Assign Opacity
if bt2.opacity == 1: bt3.opacity = 1
elif bt1.opacity == 1: bt2.opacity = 1
elif bt1.opacity == 0: bt1.opacity = 1
示例 - 更改按钮的文本
main.py
from kivy.lang import Builder
from kivy.base import runTouchApp
runTouchApp(Builder.load_string('''
FloatLayout:
size_hint: None, None
size: 100, 100
Button:
id: bt1
pos: 200, 300
opacity: 0
on_press: self.opacity = 0
Button:
id: bt2
pos: 300, 300
opacity: 0
on_press: self.opacity = 0
Button:
id: bt3
pos: 400, 300
opacity: 0
on_press: self.opacity = 0
Button:
pos: 0, 0
text: 'A'
on_press:
print("Button {} pressed".format(self.text))
print("\tlen(bt1.text)={}".format(len(bt1.text)))
# Assign Text
if len(bt1.text) == 0: bt1.text = self.text
elif len(bt2.text) == 0: bt2.text = self.text
# Assign Opacity
if bt2.opacity == 1: bt3.opacity = 1
elif bt1.opacity == 1: bt2.opacity = 1
elif bt1.opacity == 0: bt1.opacity = 1
Button:
pos: 100, 0
text: 'B'
on_press:
print("Button {} pressed".format(self.text))
print("\tlen(bt1.text)={}".format(len(bt1.text)))
# Assign Text
if len(bt1.text) == 0: bt1.text = self.text
elif len(bt2.text) == 0: bt2.text = self.text
# Assign Opacity
if bt2.opacity == 1: bt3.opacity = 1
elif bt1.opacity == 1: bt2.opacity = 1
elif bt1.opacity == 0: bt1.opacity = 1
Button:
pos: 200, 0
text: 'C'
on_press:
print("Button {} pressed".format(self.text))
# Assign Opacity
if bt2.opacity == 1: bt3.opacity = 1
elif bt1.opacity == 1: bt2.opacity = 1
elif bt1.opacity == 0: bt1.opacity = 1
'''))
输出 - 更改按钮的文本
解决方案 - 更改按钮的不透明度
按下按钮A时，检查bt1的不透明度是否等于0。如果为真则将其更改为1。如果为假则将bt2的不透明度从0更改为1。
片段
Button:
pos: 0, 0
text: 'A'
on_press:
if bt1.opacity == 0: bt1.opacity = 1
elif bt1.opacity == 1: bt2.opacity = 1
示例 - 更改按钮的不透明度
main.py
from kivy.lang import Builder
from kivy.base import runTouchApp
runTouchApp(Builder.load_string('''
FloatLayout:
size_hint: None, None
size: 100, 100
Button:
id: bt1
text: 'bt1'
pos: 200, 300
opacity: 0
on_press: self.opacity = 0
Button:
id: bt2
text: 'bt2'
pos: 300, 300
opacity: 0
on_press: self.opacity = 0
Button:
pos: 0, 0
text: 'A'
on_press:
if bt1.opacity == 0: bt1.opacity = 1
elif bt1.opacity == 1: bt2.opacity = 1
'''))