How do I flip a (custom) kivy Widget from Python code? I've tried setting its height or width to negative value, but it actually rotates widget, ie flips both axes. The Rotate instruction obviously does the same. I'm aware there is a flip_horizontal() method of the Texture, but I don't have a slightest idea how to actually cause it to affect an existing widget rather than in-memory texture from eg Atlas.
If it helps, I use kivy 1.9.2 with Python 3.4.3.
UPD I tried Scale() to no effect.
event.actor.widget.img.canvas.before.add(PushMatrix())
event.actor.widget.canvas.before.add(Scale(x=2.0, origin=event.actor.widget.center))
event.actor.widget.img.canvas.after.add(PopMatrix())
event.actor.widget.canvas.ask_update()
It doesn't work either with or without PushMatrix/PopMatrix. The widget in question is a simple Widget subclass with stretchable image and a couple callbacks for size and position.
An easy way to achieve your goal is using a Scatter. Here is a full working example
from kivy.lang import Builder
from kivy.app import App
from kivy.clock import Clock
from kivy.uix.boxlayout import BoxLayout
import random
from kivy.graphics.transformation import Matrix
class MyBox(BoxLayout):
def later_(self, dt=None):
self.t.apply_transform(Matrix().scale(-1, 1.0, 1.0),
post_multiply=True,
anchor=self.to_local(*self.center))
Clock.schedule_once(self.later_, 1.0)
class TestApp(App):
def build(self):
Builder.load_string("""\
<MyBox>:
t: s
orientation: 'vertical'
Scatter:
id: s
do_scale: 0
do_rotate: 0
do_translation: 0,0
Label:
pos: s.pos
size: s.size
text: "The text below will keep changing using a delayed function..."
"""
)
mybox = MyBox()
Clock.schedule_once(mybox.later_, 1.0)
return mybox
if __name__ == '__main__':
TestApp().run()
How about a Scale instruction with a negative scaling?
If the widget also needs to take touch events, you'll need to modify its on_touch_down to transform them appropriately.
Related
I'm making a game in kivy and when I close the screen (android) or try to resize the window (linux) some widgets that I've moved away from the screen return to their starting position.
I created a minimal reproducible example for that:
example.py
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
class GameCanvas(BoxLayout):
def __init__(self, **kwargs):
super().__init__(**kwargs)
def start(self):
# move the label widget far away
self.children[0].pos = 10000, 10000
class Example(App):
pass
if __name__ == '__main__':
Example().run()
example.kv
GameCanvas:
<GameCanvas>:
Button:
text: 'Start Game'
size: root.width, root.height / 2
on_release: root.start()
Label:
text: 'Game Title'
size: root.width, root.height / 2
Before pressing the button:
After pressing the button:
After resizing:
As the attached images show after I press the button the label 'disappears' (moves position) but when I try to resize the Window it comes back.
Why does this happen? Also why does it happen on android as well? Does it have to do with some sort of events in kivy?
Thanks in advance!
The behavior you see is the intended behavior of the BoxLayout. The BoxLayout positions its children. So, you can move the Label, but as soon as the BoxLayout gets a chance (as in a size change event), it positions its children as intended. If you want to control the position of the children widgets, then you should use a Layout that does not position its children, perhaps a FloatLayout or RelativeLayout
I need some help with kivy,i am pretty new to kivy and I made a class to to draw a rectangle as a background.
I am pretty sure I did everything correctly but there is an error,so here is my code
The .py file
import kivy
from kivy.app import App
from kivy.uix.widget import Widget
from kivy.uix.textinput import TextInput
class Background(Widget):
pass
class MY_browser(App):
def build(self):
return Background
MY_browser().run()
The .kv file
Floatlayout:
Background:
canvas.before:
Rectangle:
pos: self.pos
size: self.size
I have tried a lot of things but no difference so if anyone can help I would really appreciate it
A couple problems:
In your build() method, the return Background is returning a class, but the build() method is expected to return a Widget instance. Perhaps this should be return Background().
In your kv, the indentation is incorrect. All indentations should be a multiple of the same number of spaces (typically 4). The indentation of Background is too large.
Your kv does not provide a rule for Background, so when Background() is returned, it will simply be an empty Widget. If you want to return Background(), you should have a <Background>: rule in the kv.
If your kv file is named my_browser.kv, then you do not need a build() method for your App class at all.
If your kv file is not named as above, then your build method can be return Builder.load_file("kv file name"), where kv file name is replaced by the correct name of your kv file.
The Floatlayout in your kv is misspelled. It should be FloatLayout.
The goal is a screen which uses one of several images (randomly chosen upon each screen load) as a background.
The app contains the following:
class AnswerScreen(Screen):
bkgd = ""
def choose_bkgd(self):
self.bkgd = "{}.jpg".format(random.randint(0,8))
My kv file contains the following:
<AnswerScreen>
on_pre_enter: root.choose_bkgd()
canvas.before:
Rectangle:
pos: self.pos
size: self.size
source: root.bkgd
Unfortunately the background is always just a solid white.
I've added a print call to choose_bkgd(), and it always prints an acceptable file name, and I've also tried using on_enter: but there is no change. If I replace source: with a file name instead of root.bkgd the image displays correctly. This leads me to believe that the background is being generated before the function is being called to set the bkgd variable, but this confuses me as I thought the whole point of on_pre_enter was to execute code prior to the loading of the screen. The kivy docs haven't cleared this up for me. Any help is greatly appreciated.
Make bkgd a kivy property. This is essential to be able to bind to it and have things automatically update when it changes.
from kivy.properties import StringProperty
class AnswerScreen(Screen):
bkgd = StringProperty("")
...
I am making a BoxLayout widget (orientation = 'horizontal') that contains three widgets inside of it, a label, a text box, and a check box.
thisRow = BoxLayout(orientation='horizontal')
l = Label(text='Enter plate 1:\n(Plate #)')
t = TextInput(text = 'this is a text box')
c = CheckBox()
thisRow.add_widget(l)
thisRow.add_widget(t)
thisRow.add_widget(c)
This produces the following widget (thisRow):
After the box is checked...
The rightmost black box is actually the checkbox, and works functionally, however there is no way for the user to know that it is in fact a checkbox. I would expect a smaller empty square in the middle, as is depicted in pictures here.
How do i get the traditional checkbox image (smaller empty square box)? Or generally, how can I make it more obvious that the box is a check box and not just an empty label?
Thank you
This is really interesting question and Malonge tried it in a good way. Right now(1.9.2-dev) there is still fixed size on CheckBox's well, call it a background. It's an image that Widget takes from atlas and changes if the state changes. Therefore until now there was no clear way how to do it. Here is an example. Soon on master there'll be CheckBox(color=[r,g,b,a]) option. Thanks ;)
from kivy.lang import Builder
from kivy.base import runTouchApp
from kivy.uix.boxlayout import BoxLayout
Builder.load_string('''
<CheckBoxBG>:
Label:
TextInput:
CheckBox:
canvas.before:
Color:
rgb: 1,0,0
Rectangle:
pos:self.center_x-8, self.center_y-8
size:[16,16]
Color:
rgb: 0,0,0
Rectangle:
pos:self.center_x-7, self.center_y-7
size:[14,14]
''')
class CheckBoxBG(BoxLayout):pass
runTouchApp(CheckBoxBG())
Looks like the smaller check box is hidden when the background color is black. Here is an example of a red background.
It's not ideal because I do like the black background, but I can run with it for now. If anyone knows how to do this with a black background that would be great. Thank you
Alternatively, to change your checkboxes background, you can use another image from the atlas or create images and then load them:
mycheckbox= CheckBox(
background_checkbox_normal ='tlas://data/images/defaulttheme/button_disabled'
background_checkbox_down = 'my_checkboxes_checked.png'
)
In Kivy 1.9.2.dev0 (and apparently since version 1.9.0) you can change the background image of checkboxes. By default, Kivy uses for these backgrounds from the atlas*.
background_checkbox_normal = StringProperty('atlas://data/images/defaulttheme/checkbox_off') #when the checkbox is not active.
background_checkbox_down = StringProperty('atlas://data/images/defaulttheme/checkbox_on') # when the checkbox is active.
background_checkbox_disabled_normal = StringProperty('atlas://data/images/defaulttheme/checkbox_disabled_off') #when the checkbox is disabled and not active.
background_checkbox_disabled_down = StringProperty('atlas://data/images/defaulttheme/checkbox_disabled_on') #when the checkbox is disabled and active.
You can have a look here at all the attributes :
*The atlas is a package of multiple textures that reduces the number of images loaded and speedup the application loading. You have see a preview of the atlas in Python Install Folder\Lib\site-packages\kivy\data\images\defaulttheme-0.png
I'm trying to use Kivy to display a background image, so I want the root widget to be the same size as the image. Currently, when I load the image from the kv file it appears as a small thumbnail in the bottom-left corner. The app window appears to be about the correct (full-scale) size, but hard to tell. Code below, any thoughts?
.kv file:
#:kivy 1.8.0
<BarBot_splash>:
BoxLayout:
size: image.size
Image:
id: image
source: 'MainMenu.png'
.py file:
import kivy
kivy.require('1.8.0')
from kivy.app import App
from kivy.uix.widget import Widget
class BarBot_splash(Widget):
def on_touch_up(self, touch):
if touch.x < self.width/3:
#we touched the menu button
pass
elif touch.x > self.width/3*2:
#we touched the custom button
pass
else:
return False
class BarBot(App):
def build(self):
return BarBot_splash()
if __name__=='__main__':
BarBot().run()
In main.py:
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
class BarBot_splash(BoxLayout): # subclass BoxLayout.. now it's inherently a Boxlayout
kv:
#:kivy 1.8.0
<BarBot_splash>: # I'm a BoxLayout...
Image:
id: image
source: 'MainMenu.png'
That should do the trick. The BoxLayout should take up the window. It's one child, the Image, should in turn take up the full size of the BoxLayout. Why? Well, someone correct me if I'm wrong, but I think it's because the size_hint property of the BoxLayout and the Image both default to (1, 1), which translates to: "Take up as much space in your parent as you can" or (100% width, 100% height). Though it may not be possible for a child to take up all of it's parents area if there are also other children in the parent, like if you had a few Images in the BoxLayout, or more than one BoxLayout in your app etc.. Setting a size_hint to (.5, .3) would mean take up (50% the width, 30% the height) of your parent/container, or available space.
BarBot_splash is just a widget, so it doesn't apply any position or size to its children, therefore the boxlayout (and thus its child image) have only the default position of (0, 0) and size of (100, 100).
Change BarBot_splash to a BoxLayout or other resizing layout and this will propagate correctly. You also don't need the size: image.size line, this does nothing.
Obviously very old question but I'm new to Kivy and just had to work through a very similar problem and there was very little help on the topic, so this is for future people like me:
I had the same problem but the image was also in a scatter widget. Solution is really simple, just frustrating to find. Hierarchy has to be as follows:
BoxLayout:
Scatter:
size: image.size
Image:
id: image
size: root.size