I've just started my first kivy app. The app is intended to start with button "Start Scan" and then show up the QR scanner built with ZBarCam.
I'm using Screens with the ScreenManager to change from the button view to the camera view (with zbarcam), the problem is that I realized that the camera is initialized from the beginning , so before clicking on the button the camera is already on (I know it because the led from the camera is on).
I don't know if Screen should not be used in this case, or if is there a way to tell the app to do not initialize all screens.
The code I'm using is the following:
QrApp.py:
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
class QrReader(Screen):
pass
class ScanButton(Screen):
pass
class QrApp(App):
pass
if __name__ == '__main__':
QrApp().run()
qrapp.kv:
ScreenManager:
id: screen_manager
ScanButton:
id: scan_btn
name: 'scan_btn'
manager: 'screen_manager'
QrReader:
id: qr_reader
name: 'qr_reader'
manager: 'screen_manager'
<ScanButton>:
BoxLayout:
orientation: 'vertical'
Button:
text:'Start Scan'
font_size:"50sp"
color: [0, 255, 255, .67]
on_press: app.root.current = 'qr_reader'
<QrReader>:
#:import ZBarCam kivy_garden.zbarcam.ZBarCam
BoxLayout:
orientation: 'vertical'
ZBarCam:
id:qrcodecam
Label:
size_hint: None, None
size: self.texture_size[0], 50
text: ' '.join([str(symbol.data) for symbol in qrcodecam.symbols])
Thanks!
==== ALTERNATIVE BASED IN A COMMENT (still fails) ====
Based on the comment from n4321d I tried to add the ZBarCam as widget in the QrReader Screen. While I can now initiate the camera when the widget is added, I don't see how I can get the symbols that is, the text read from the QR.
This alternative code is the following:
QrApp.py:
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.widget import Widget
from kivy.core.window import Window
from kivy.uix.label import Label
from kivy.uix.screenmanager import ScreenManager, Screen
class QrReader(Screen):
def on_enter(self):
from kivy_garden.zbarcam import ZBarCam
zbarcam = ZBarCam()
self.add_widget(zbarcam)
self.add_widget(Label(
text='PRINT SYMBOLS', #' '.join([str(symbol.data) for symbol in zbarcam.symbols] does not work
size_hint=(None,None),
size=(Window.width*0.1, Window.height*0.1),
center=(Window.width*0.3, Window.height*0.5)))
class ScanButton(Screen):
pass
class QrApp(App):
pass
if __name__ == '__main__':
QrApp().run()
qrapp.kv
ScreenManager:
id: screen_manager
ScanButton:
id: scan_btn
name: 'scan_btn'
manager: 'screen_manager'
QrReader:
id: qr_reader
name: 'qr_reader'
manager: 'screen_manager'
<ScanButton>:
BoxLayout:
orientation: 'vertical'
Button:
text:'Start Scan'
font_size:"50sp"
color: [0, 255, 255, .67]
on_press:
app.root.current = 'qr_reader'
<QrReader>:
BoxLayout:
orientation: 'vertical'
====== SOLUTION ========
My workaround solution is posted as an answer to this question here
First:
I would also add an on_leave function where you remove your cam widget otherwise you will keep adding new widgets every time you load it.
I dont have a working cam now , so i cannot test your code. Looking at your code I think you have to bind the text in your Label to the text in zbarcam.symbols with a function: self.label = Label(....); zbarcam.bind(symbols=lambda *x: setattr(self.label, "text", str(x[1]))) or somethign like that.
Here is an example using a random text generator instead of ZBarCam (since i cannot run that).
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.widget import Widget
from kivy.core.window import Window
from kivy.uix.label import Label
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.properties import ListProperty
import random
from kivy.clock import Clock
kv_str = """
ScreenManager:
id: screen_manager
ScanButton:
id: scan_btn
name: 'scan_btn'
manager: 'screen_manager'
QrReader:
id: qr_reader
name: 'qr_reader'
manager: 'screen_manager'
<ScanButton>:
BoxLayout:
orientation: 'vertical'
Button:
text:'Start Scan'
font_size:"50sp"
color: [0, 255, 255, .67]
on_press:
app.root.current = 'qr_reader'
<QrReader>:
BoxLayout:
orientation: 'vertical'
"""
class ZBarCam(Label):
symbols = ListProperty([])
def __init__(self, **kwargs):
super().__init__(**kwargs)
Clock.schedule_interval(self.gen_rand_text, 1)
def gen_rand_text(self, *args):
self.text = random.choice(['aaaaa', 'bbbbb', 'ccccc'])
self.symbols.append(self.text)
if len(self.symbols) > 3:
del self.symbols[0]
class QrReader(Screen):
def on_enter(self):
self.zbarcam = ZBarCam()
self.add_widget(self.zbarcam)
self.label = Label(
text='PRINT SYMBOLS', #' '.join([str(symbol.data) for symbol in zbarcam.symbols] does not work
size_hint=(None,None),
size=(Window.width*0.1, Window.height*0.1),
center=(Window.width*0.3, Window.height*0.5))
self.add_widget(self.label)
self.zbarcam.bind(symbols = lambda *x: setattr(self.label, "text", str(x[1])))
def on_leave(self, *args):
self.remove_widget(self.zbarcam)
self.remove_widget(self.label)
class ScanButton(Screen):
pass
class QrApp(App):
def build(self):
return Builder.load_string(kv_str)
if __name__ == '__main__':
QrApp().run()
if it still does not work you might have to call self.zbarcam.start() too in the on_enter method after adding it
hope this helps
Thanks to answer from n4321d I finally found a solution.
I also struggled releasing the camera, as zbarcam.stop() stops zbarcam but camera was apparently still open (led was on). After digging a lot, I found this workaround which seems to work well to release the camera.
I also merged the button and qr reader in the same Class and I no longer use kv file, in this example. The final code is the following:
QrApp.py:
from kivy.app import App
from kivy.uix.widget import Widget
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.clock import Clock
from kivy_garden.zbarcam import ZBarCam
class QrScanner(BoxLayout):
def __init__(self, **kwargs):
super(QrScanner, self).__init__(**kwargs)
btn1 = Button(text='Scan Me', font_size="50sp")
btn1.bind(on_press=self.callback)
self.add_widget(btn1)
def callback(self, instance):
"""On click button, initiate zbarcam and schedule text reader"""
self.remove_widget(instance) # remove button
self.zbarcam = ZBarCam()
self.add_widget(self.zbarcam)
Clock.schedule_interval(self.read_qr_text, 1)
def read_qr_text(self, *args):
"""Check if zbarcam.symbols is filled and stop scanning in such case"""
if(len(self.zbarcam.symbols) > 0): # when something is detected
self.qr_text = self.zbarcam.symbols[0].data # text from QR
Clock.unschedule(self.read_qr_text, 1)
self.zbarcam.stop() # stop zbarcam
self.zbarcam.ids['xcamera']._camera._device.release() # release camera
class QrApp(App):
def build(self):
return QrScanner()
if __name__ == '__main__':
QrApp().run()
There is no way to lazy-load kivy Screens. Try this as a workaround: Do not let ScreenManager know about all Screens. Use switch_to to remove the current screen and load the desired one instead. Check Kivy docs to learn how to use it.
Maybe so?
from kivy_garden.zbarcam import ZBarCam
from kivymd.uix.textfield import MDTextField
class MenuScreen(MDScreen):
zbarcam: ZBarCam = ObjectProperty()
qrfield: MDTextField = ObjectProperty()
def __init__(self, **kwargs):
super().__init__(**kwargs)
self.__cam_release()
def scan(self, instance):
self.__cam_release()
def on_touch_down(self, touch):
if self.zbarcam.collide_point(*touch.pos):
self.__cam_open()
return super().on_touch_down(touch)
def __cam_release(self):
if self.zbarcam.xcamera._camera._device.isOpened():
self.zbarcam.stop()
self.zbarcam.xcamera._camera._device.release()
def __cam_open(self):
if not self.zbarcam.xcamera._camera._device.isOpened():
self.zbarcam.xcamera._camera._device.open(0)
self.zbarcam.start()
Related
I am writing a program that requires a label, a text_input, and a checkbox to be aligned on screen in that order. They should span the width of the screen and be at the same y level.
I have written this code in my .kv file which uses identical pos_hint values, but only the text_input box moves
Below is my .kv code:
<Union>:
BoxLayout:
orientation: "vertical"
BoxLayout:
orientation: "horizontal"
pos_hint_y: {"top":.85}
Label:
text: 'Session Length'
pos_hint: {"x":.3, "top":.85}
TextInput:
id: input
text: "test"
pos_hint: {"x":.5, "top":.85}
size_hint: 0.3, 0.05
background_disabled_normal: ""
disabled: not checkbox.active
on_text: app.return_text()
CheckBox:
id: checkbox
pos_hint: {"x":.7, "top":.85}
and here is my main.py
from kivy.core.window import Window
from kivy.lang import Builder
from kivy.uix.button import Button
from kivy.uix.dropdown import DropDown
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.gridlayout import GridLayout
from kivy.uix.screenmanager import Screen, ScreenManager
Window.size = (309, 555)
class MenuScreen(Screen):
pass
class SetupScreen(Screen):
pass
class drop_content(DropDown):
pass
class UnionScreen(Screen):
class Checkbox_Setup(FloatLayout):
pass
class TheApp(App):
def build(self):
# Create the screen manager
sm = ScreenManager()
sm.add_widget(MenuScreen(name='menu'))
sm.add_widget(SetupScreen(name='setup'))
sm.add_widget(UnionScreen(name='union'))
return sm
def return_text(self):
text = self.root.get_screen('union').ids.input.text
print(text)
def main():
Builder.load_file('menu.kv')
app = TheApp()
app.run()
if __name__ == '__main__':
main()
Finally, here is the output I am currently getting, with the label and checkbox in line but underneath the text_input which is in the right place.
I am relatively new to kivy so any help would be greatly appreciated. Thanks in advance!
Im trying to create GUI with kivy but can't figure this.Created Popup screen and trying to pick value from dropbox and add this value to my TextInput.
test.py:
from kivy.app import App
from kivy.uix.textinput import TextInput
from kivy.uix.dropdown import DropDown
from kivy.uix.spinner import Spinner
from kivy.uix.screenmanager import ScreenManager,Screen
from kivy.uix.popup import Popup
from kivy.properties import ObjectProperty
class MyDropDown(DropDown):
def on_select(self, data):
print('Selected value:',data)
#Lets add this data to TextInput ?
MyTextInput.text = data
#Lets check is that actual text ?
print('MyTextInput.text is:',MyTextInput.text)
#HOW CAN I ADD THIS TEXT TEXTINPUT AFTER THAT?
class MySpinner(Spinner):
dropdown_cls = ObjectProperty(MyDropDown)
class MyTextInput(TextInput):
pass
class MyTestPopup(Popup):
my_popup_spinner = ObjectProperty()
my_textinput_id = ObjectProperty()
class TestPage(Screen):
MypagePopup = ObjectProperty()
def open_my_popup(self, *args):
#Lets create my popup
self.MypagePopup = MyTestPopup()
self.MypagePopup.my_popup_spinner.values = ['Test1','Test2','Test3','Test4','Test']
self.MypagePopup.open()
class TestPageManager(ScreenManager):
pass
class test(App):
def build(self):
return TestPageManager()
if __name__=='__main__':
test().run()
test.kv:
<TestPageManager>:
TestPage:
name: 'mainpagename'
<MySpinner>:
text: 'Pick Value'
<MyDropDown>:
values: ['Test1','Test2','Test3','Test4','Test5']
<MyTextInput>:
<MyTestPopup>:
my_popup_spinner : my_popup_spinner
my_textinput_id : my_textinput_id
BoxLayout:
orientation: 'vertical'
Label:
text: 'Testing Label Area..'
pos: self.pos
size: self.size
MyTextInput:
id: my_textinput_id
MySpinner:
id: my_popup_spinner
Button:
text: 'Done'
on_release:
print('MyTextInput id is :',my_textinput_id.text)
<TestPage>:
Button:
text: 'Open Popup'
on_release: root.open_my_popup()
As you can see I created like that GUI.
But can't update TextInput after pick from spinner.How can i update this textinput after pick value from dropbox.I can't figure it out.I think i correctly describe my problem. Thanks for reading and answering.
kv = "Spinner:
on_text:
my_textinput_id.text = my_popup_spinner.text"
did this in my kv string for Builder.load_string(kv)and it works for me
you can try and implement it in you code example and see if it works.
set the id.text of the textinput = to my spinner id.text in the on_text: event of the Spinner
I want to switch screens to screen 2 from screen 1 after 3 seconds of being on screen 1.
The program compiles but it just stays on Screen1 and I want it to change to screen2 after 3 seconds of being on screen1.
from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang import Builder
from kivy.uix.image import Image
from kivy.clock import Clock
class Screen1(Screen):
def callNext(self, dt):
self.manager.current = 'screen2'
class Screen2(Screen):
pass
kv = Builder.load_file('my.kv')
class MyApp(App):
def build(self):
return Screen1()
return kv
if __name__ == '__main__':
MyApp().run()
kv file:
#:import Clock kivy.clock.Clock
<Screen1>:
name: 'screen1'
on_enter:
Clock.schedule_once(self.callNext, 3)
canvas.before:
Rectangle:
pos: self.pos
size: self.size
source: 'logokivy.png'
<Screen2>:
name: 'screen2'
Button:
text: 'Hello'
Your code doesn't use a ScreenManager. Make the root widget a ScreenManager with the two screens as children, and it looks like everything else should be fine and it will work.
You should be able to import time and use time.sleep() to wait 3 seconds and then close it.
I am trying to make an APP with 2 screen:
First screen is a Button
Second screen shows a graph
When the Button of the first screen is pressed, the second screen appears with the graph.
I was able to plot the graph with 1 screen only, using matplotlib.
Here is my code:
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang import Builder
import matplotlib.pyplot as plt
import matplotlib
matplotlib.use("module://kivy.garden.matplotlib.backend_kivy")
from kivy.garden.matplotlib import FigureCanvasKivyAgg
from kivy.uix.widget import Widget
class Sensores(Screen):
pass
class Grafico(Screen):
def build(self):
box = BoxLayout()
box.add_widget(FigureCanvasKivyAgg(plt.gcf()))
return box
class Menu(ScreenManager):
pass
presentation = Builder.load_file('sensor.kv')
class sensor(App):
def build(self):
return presentation
if __name__ == "__main__":
sensor().run()
KIVY
Menu:
Sensores:
Grafico:
<Sensores>
name: 'sensores'
BoxLayout:
Button:
text: "Sensor 01"
on_release:
root.Grafico()
<Grafico>
name: 'grafico'
I expect to have the graph in the second screen.
I see two problems with your code. First, in your kv file the Button action is incorrect:
Button:
text: "Sensor 01"
on_release:
root.Grafico()
If the Button is intended to switch to the other screen, it should be:
Button:
text: "Sensor 01"
on_release:
root.manager.current='grafico'
Second, in your Grafico class you have a build() method that is never called. If you change that from:
class Grafico(Screen):
def build(self):
box = BoxLayout()
box.add_widget(FigureCanvasKivyAgg(plt.gcf()))
return box
to:
class Grafico(Screen):
def on_enter(self, *args):
box = BoxLayout()
box.add_widget(FigureCanvasKivyAgg(plt.gcf()))
self.add_widget(box)
I think you will get the desired result. The key is that the on_enter() method is called when the Grafico Screen is displayed. The method is your code, but with a self.add_widget(box) added in order to add the box to the screen. See the Screen Documentation for more info.
Thank you very much!
It works now! Follow the code:
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang import Builder
import matplotlib.pyplot as plt
import matplotlib
matplotlib.use("module://kivy.garden.matplotlib.backend_kivy")
from kivy.garden.matplotlib import FigureCanvasKivyAgg
from kivy.uix.widget import Widget
plt.plot([1,23,2,4])
plt.ylabel("alguns numeros legais")
class Sensores(Screen):
pass
class Grafico(Screen):
def on_enter(self, *args):
box = BoxLayout()
box.add_widget(FigureCanvasKivyAgg(plt.gcf()))
self.add_widget(box)
class Menu(ScreenManager):
pass
presentation = Builder.load_file('sensor.kv')
class sensor(App):
def build(self):
return presentation
if __name__ == "__main__":
sensor().run()
KV LANG
#:kivy 1.9.1
Menu:
Sensores:
Grafico:
name: 'grafico'
<Sensores>
name: 'sensores'
BoxLayout:
Button:
text: "Sensor 01"
on_release:
root.manager.current = 'grafico'
<Grafico>
name: 'grafico'
I asked a question regarding updating label text (Kivy change label text with python) - it was answered and was working but I've been trying for hours trying to adapt my running code to ScreenManager so I can have multiple screens. I've cut down the code to the basic stuff I can't get working.
ScreenManager code breaks the solution, I know what the issue is I just can't resolve it. The code is working, text and time updating in the shell but not the labels, I couldn't add return self.first_screen to the Kivy def build so its not binding to the_time: _id_lbl_time - Any help/pointers would be really appreciated.
from kivy.app import App
from kivy.base import runTouchApp
from kivy.lang import Builder
from kivy.properties import ListProperty, StringProperty, ObjectProperty
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import ScreenManager, Screen, WipeTransition, FadeTransition
from kivy.uix.anchorlayout import AnchorLayout
from kivy.clock import Clock
import time
from datetime import datetime, timedelta
class FirstScreen(Screen):
def update_time(self, sec):
MyTime = time.strftime("%H:%M:%S")
print MyTime # to test update_time is called etc
self.the_time.text = MyTime #<---- self.the_time isn't working
class SecondScreen(Screen):
def update_text(self, sec):
MyText = 'New Text'
print MyText # to test update_text is called etc
self.the_set.text = MyText #<---- self.the_set isn't working
class MyScreenManager(ScreenManager):
pass
Builder.load_string('''
<FirstScreen>:
name: 'first'
the_time: _id_lbl_time
BoxLayout:
orientation: 'vertical'
Label
id: _id_lbl_time
text: 'Clock'
font_size: 30
BoxLayout:
Button:
text: 'New Here'
font_size: 20
size: 200, 50
size_hint: None, None
on_release: app.root.current = 'second'
<SecondScreen>:
name: 'second'
the_set: _id_lbl_set
BoxLayout:
orientation: 'vertical'
Label:
id: _id_lbl_set
text: 'New Here'
font_size: 30
BoxLayout:
Button:
text: 'Main'
font_size: 20
size: 200, 50
size_hint: None, None
on_release: app.root.current = 'first'
''')
class ScreenManagerApp(App):
def build(self):
sm = ScreenManager()
sm.add_widget(FirstScreen(name='first'))
sm.add_widget(SecondScreen(name='second'))
self.first_screen = FirstScreen()
self.sec_screen = SecondScreen()
return sm #<---- I can't return self.first_screen etc here?
def on_start(self):
Clock.schedule_interval(self.first_screen.update_time, 1) # 1 second
Clock.schedule_interval(self.sec_screen.update_text, 2)
ScreenManagerApp().run()
I can't return self.first_screen etc here?
No. There has to be a ScreenManager on top of the Screen widgets, otherwise it's just a RelativeLayout as is its definition in the source code.
You experienced a really common mistake by beginners. You used one instance FirstScreen() and SecondScreen() for ScreenManager(those are visible) and then you created another instances with:
self.first_screen = FirstScreen()
self.sec_screen = SecondScreen()
which you then used for Clock:
Clock.schedule_interval(self.first_screen.update_time, 1)
Clock.schedule_interval(self.sec_screen.update_text, 2)
and that means text properties in instances that actually aren't added anywhere as widgets were used for updating. The instances exist, so no error to trigger except the visual one → you don't see the values, because you used wrong instance.
Correct build():
def build(self):
sm = ScreenManager()
self.first_screen = FirstScreen(name='first')
self.sec_screen = SecondScreen(name='second')
sm.add_widget(self.first_screen)
sm.add_widget(self.sec_screen)
return sm