Changing color of a part of text of a Kivy widget

Question

I am trying to write a program where if I press a button, the color of a part of the text of a Label widget changes.

For example, there’s a Label widget with text "1/0". Now, if I press the button, the color of 1 changes to some assigned color. This is the program I tried:

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.lang import Builder
from kivy.utils import get_color_from_hex

Builder.load_string('''
#: import get_color_from_hex kivy.utils.get_color_from_hex
<b>:
    orientation: 'horizontal'
    Button:
        text: 'Press Me'
        on_press: num.text[0].color = get_color_from_hex('#04d3ff')

    Label:
        id: num
        text: '1/0'
''')

class b(BoxLayout):
    pass

class main(App):
    def build(self):
        return b()

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

And this is the error I get:

Traceback (most recent call last):
   File "b.py", line 28, in <module>
     main().run()
   File "/usr/lib/python2.7/dist-packages/kivy/app.py", line 828, in run
     runTouchApp()
   File "/usr/lib/python2.7/dist-packages/kivy/base.py", line 487, in runTouchApp
     EventLoop.window.mainloop()
   File "/usr/lib/python2.7/dist-packages/kivy/core/window/window_sdl2.py", line 619, in mainloop
     self._mainloop()
   File "/usr/lib/python2.7/dist-packages/kivy/core/window/window_sdl2.py", line 362, in _mainloop
     EventLoop.idle()
   File "/usr/lib/python2.7/dist-packages/kivy/base.py", line 330, in idle
     self.dispatch_input()
   File "/usr/lib/python2.7/dist-packages/kivy/base.py", line 315, in dispatch_input
     post_dispatch_input(*pop(0))
   File "/usr/lib/python2.7/dist-packages/kivy/base.py", line 221, in post_dispatch_input
     listener.dispatch('on_motion', etype, me)
   File "kivy/_event.pyx", line 718, in kivy._event.EventDispatcher.dispatch (kivy/_event.c:7699)
   File "/usr/lib/python2.7/dist-packages/kivy/core/window/__init__.py", line 1030, in on_motion
     self.dispatch('on_touch_down', me)
   File "kivy/_event.pyx", line 718, in kivy._event.EventDispatcher.dispatch (kivy/_event.c:7699)
   File "/usr/lib/python2.7/dist-packages/kivy/core/window/__init__.py", line 1046, in on_touch_down
     if w.dispatch('on_touch_down', touch):
   File "kivy/_event.pyx", line 718, in kivy._event.EventDispatcher.dispatch (kivy/_event.c:7699)
   File "/usr/lib/python2.7/dist-packages/kivy/uix/widget.py", line 432, in on_touch_down
     if child.dispatch('on_touch_down', touch):
   File "kivy/_event.pyx", line 718, in kivy._event.EventDispatcher.dispatch (kivy/_event.c:7699)
   File "/usr/lib/python2.7/dist-packages/kivy/uix/behaviors/button.py", line 110, in on_touch_down
     self.dispatch('on_press')
   File "kivy/_event.pyx", line 714, in kivy._event.EventDispatcher.dispatch (kivy/_event.c:7654)
   File "kivy/_event.pyx", line 1224, in kivy._event.EventObservers.dispatch (kivy/_event.c:13497)
   File "kivy/_event.pyx", line 1108, in kivy._event.EventObservers._dispatch (kivy/_event.c:12329)
   File "/usr/lib/python2.7/dist-packages/kivy/lang.py", line 1557, in custom_callback
     exec(__kvlang__.co_value, idmap)
   File "<string>", line 7, in <module>
 AttributeError: 'str' object has no attribute 'color'

Asked By: Parthib Biswas

||

Source

Answer 1

Use Kivy’s basic markup syntax to set the colour, along with markup: True in the label.

Answered By: inclement

Answer 2

For the second question in your comment where you ask “I ran into another problem now. : What if there is more than one Label? What if I want to change the first character of multiple Labels together?” You should open a new question and provide us with some code.

However, at first glance it appears that you could simply loop through the labels and do the following:

Obtain the current text of the label (label.text)
Update the label color by using markup for the first character. for example, if label.text = “my_text”, I could highlight the “m” of the label text via updating the following inside the label:
```
text = '[color=FFFF00]'+label.text[0]+'[/color]'+label.text[1:]
```

This answer assumes that you have a set of existing labels and you’d like to modify the first character of each. Without code, it is difficult to give a more specific answer but this general approach would work.

Answered By: MV22

Answer 3

Inclement’s solution worked perfectly. This is the solution code for the kv language:

<b>:
    orientation: 'horizontal'
    Button:
        text: 'Press Me'
        on_press: num.text = "[color=#04d3ff]1[/color]/0"
        on_release: num.text = "[color=#ffffff]1[/color]/0"

    Label:
        id: num
        markup: True
        text: '1/0'

_{This answer was posted as an edit to the question Changing color of a part of text of a Kivy widget by the OP Parthib Biswas under CC BY-SA 3.0.}

Answered By: vvvvv

Changing color of a part of text of a Kivy widget

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