I try to design a GUI to handle stepper motors via ROS, kivy and python. You can find a minimal version of the GUI below. Actually I want to use a ROS message to update a kivy text input field (read only). In the minimal example, pressing the button should transfer the data of the first input field over a local ROS node to the second input field. Actually it seems, that the Callback within the rospy.Subscriber() doesn't enter the Test class.
Thank You for any suggestions!
main.py
import kivy
kivy.require('1.7.2')
import rospy
from std_msgs.msg import String
from kivy.app import App
from kivy.core.window import Window
from kivy.uix.widget import Widget
from kivy.uix.boxlayout import BoxLayout
class Test(BoxLayout):
text_is = 'text before button press'
def Pub(self):
publish = self.ids.test_text_pub.text
try:
ROSNode.new_text_is.publish(publish)
except rospy.ROSInterruptException: pass
class ROSNode(Widget):
def Callback(publish):
print(publish.data) #check if Callback has been called
test.text_is = publish.data
new_text_is = rospy.Publisher('new_text_is', String, queue_size=10)
rospy.Subscriber('new_text_is', String, Callback)
rospy.init_node('talker', anonymous=True)
class TestApp(App):
def build(self):
return Test()
if __name__ == '__main__':
TestApp().run()
test.kv
#:kivy 1.0
<Test>:
BoxLayout:
orientation: 'vertical'
Button:
id: test_button
text: 'publish'
on_press: root.Pub()
TextInput:
id: test_text_pub
text: 'text after button press'
TextInput:
id: test_text_sub
text: root.text_is
If you want your text to automatically update, you need to use Kivy properties .
from kivy.properties import StringProperty
class Test(BoxLayout):
text_is = StringProperty('text before button press')
Kivy properties support data binding, so any updates to the property will propagate through to any bound widget. Binding happens automatically in kv, so when you do this:
text: root.text_is
..you're telling Kivy that when root.text_is
is updated, update my text
also.
So I found the solution:
I had to add an on_release event to the button.
on_release: test_text_sub.text = root.text_is
那么最终的代码是什么?
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