I'm trying to make a horizontal scroll view in Kivy (Python) which would display an image (buttons for now) that you can scroll through. I've been able to figure out how to do the horizontal scroll view, but I just can't seem to figure out what I'm doing wrong to center on the screen. Here is what I have so far:
import kivy
kivy.require('1.8.0')
from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.scrollview import ScrollView
from kivy.uix.gridlayout import GridLayout
class MyGrid(GridLayout):
def __init__(self, **kwargs):
super(MyGrid, self).__init__(**kwargs)
self.rows = 1
self.spacing=50
self.size_hint=(None, .5)
self.bind(minimum_width=self.setter('width'))
class ScrollViewApp(App):
def build(self):
scroll = ScrollView( size_hint=(1,1), do_scroll_x=True, do_scroll_y=False )
grid = MyGrid()
for i in range(60):
grid.add_widget(Button(text='#00' + str(i),size=(100,100), size_hint=(1,1)))
scroll.add_widget(grid)
return scroll
if __name__ == '__main__':
ScrollViewApp().run()
I looked through the documentation and I think it has something to do with pos_hint: https://kivy.org/doc/stable/api-kivy.uix.widget.html?highlight=pos_hint#kivy.uix.widget.Widget.pos_hint
I tried adding:
self.pos={'center_y':1}
in my MyGrid() class, but nothing is being changed. No matter what value is I put after center_y, my the ScrollView contained in the grid still appears at the top of the screen, rather than centered halfway down. I've also tried adjusting things in the ScrollViewApp() class too, using
scroll.pos={'center_y':1}
as well. I can't seem to figure out what I'm doing wrong. Does anyone have any ideas on what I'm not understanding here? I feel like I'm so close!!!
Edit:
I'm trying to have the buttons centered, but also be able to scroll by dragging the black space around the buttons. In the picture below, you can see there is a bunch of black space beneath the buttons. I can click a button or this black space and scroll horizontally. I just need this to happen with the buttons centered!
The layout is behaving as you told it to.
You have a ScrollView as a root widget, and inside it you put your Grid that has size_hint_y = 0.5.
It takes half of the parent widget height, that takes the full window height.
One way to center your Grid is to put some spacers over and under it, but this is not possible, since ScrollView accepts onle one widget as content.
So, one solution is to..
let the Grid have the full height of the ScrollView
add the ScrollView inside another Layout (e.g. a BoxLayout)
and finally, add two widgets to force the ScrollView in the center.
class MyGrid(GridLayout):
def __init__(self, **kwargs):
super(MyGrid, self).__init__(**kwargs)
self.rows = 1
self.spacing = 50
self.size_hint = (None, 1)
self.bind(minimum_width=self.setter('width'))
class ScrollViewApp(App):
def build(self):
base = BoxLayout(orientation="vertical", size_hint=(1, 1))
base.add_widget(Widget(size_hint_y=.3))
scroll = ScrollView(size_hint=(1, .4), do_scroll_x=True, do_scroll_y=False)
grid = MyGrid()
for i in range(60):
grid.add_widget(
Button(text='#00' + str(i), size=(100, 100), size_hint=(1, 1)))
scroll.add_widget(grid)
base.add_widget(scroll)
base.add_widget(Widget(size_hint_y=.3))
return base
if __name__ == '__main__':
ScrollViewApp().run()
Another approach would be to..
put the ScrollView inside a FloatLayout
and position it using pos_hint
class MyGrid(GridLayout):
def __init__(self, **kwargs):
super(MyGrid, self).__init__(**kwargs)
self.rows = 1
# self.spacing = 50
self.size_hint = (None, 1)
self.bind(minimum_width=self.setter('width'))
class ScrollViewApp(App):
def build(self):
base = FloatLayout(size_hint=(1, 1))
scroll = ScrollView(size_hint=(1, .4), do_scroll_x=True, do_scroll_y=False,
pos_hint={"center_y": .5})
grid = MyGrid()
for i in range(60):
grid.add_widget(
Button(text='#00' + str(i), width=100, size_hint=(None, 1)))
scroll.add_widget(grid)
base.add_widget(scroll)
return base
if __name__ == '__main__':
ScrollViewApp().run()
Edit:
OK. After the update of the question, this is a way to to center and use the black bars to scroll:
Builder.load_string("""
<BaseWidget>:
ScrollView:
do_scroll_y: False
BoxLayout:
orientation: "vertical"
size_hint_x: None
width: self.minimum_width
Widget:
size_hint_y: .3
GridLayout:
id: grid
rows: 1
size_hint_y: .4
size_hint_x: None
width: self.minimum_width
Widget:
size_hint_y: .3
""")
class BaseWidget(FloatLayout):
pass
class ScrollViewApp(App):
def build(self):
base = BaseWidget()
for i in range(60):
base.ids.grid.add_widget(Button(text='#00' + str(i),
width=100, size_hint_x=None))
return base
if __name__ == '__main__':
ScrollViewApp().run()
It uses kv_lng to create the layout because I find it easier to the eye.
For a "Python only" code you can use this:
class MyGrid(GridLayout):
def __init__(self, **kwargs):
super(MyGrid, self).__init__(**kwargs)
self.rows = 1
self.size_hint = None, .4
self.bind(minimum_width=self.setter('width'))
class MyBox(BoxLayout):
def __init__(self, **kwargs):
super(MyBox, self).__init__(**kwargs)
self.orientation = "vertical"
self.size_hint_x = None
self.bind(minimum_width=self.setter('width'))
class ScrollViewApp(App):
def build(self):
base = FloatLayout()
grid = MyGrid()
box = MyBox()
box.add_widget(Widget(size_hint_y=.3))
box.add_widget(grid)
box.add_widget(Widget(size_hint_y=.3))
for i in range(60):
grid.add_widget(Button(text='#00' + str(i), width=100, size_hint_x=None))
scroll = ScrollView(do_scroll_y=False, pos_hint={"center_y": .5})
scroll.add_widget(box)
base.add_widget(scroll)
return base
if __name__ == '__main__':
ScrollViewApp().run()
Immediately after the super() function is called, it creates a duplicate WidgetClass instance.
My understanding of the super() I've used is that it refers to the EditImageLayout class to inherit from. To this end I've tried to implement different variations of the super() but admittedly I'm only guessing at this stage.
Updated to full working, I've cut out a few hundred lines
Run as > OK > Select an Image > Open > Crop (dual instances start running here)
App_R3App.py
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.floatlayout import FloatLayout
from kivy.lang import Builder
from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.widget import Widget
from kivy.graphics import Line, Color
from kivy.properties import NumericProperty, ObjectProperty, StringProperty, ListProperty
from kivy.uix.image import Image
import io
from kivy.core.image import Image as CoreImageKivy
from kivy.uix.bubble import Bubble
from kivy.core.window import Window
__version__ = '0.1'
class FirstScreen(Screen):
pass
class SecondScreen(Screen):
def hl(self, image_address):
self.new_image_address = image_address # for the sake of this
self.callback_image(self.new_image_address, image_address, "Auto-cropped image")
def callback_image(self, new_image_address_tmp, image_address_tmp, title):
if new_image_address_tmp:
third_screen = self.manager.get_screen("_third_screen_")
new_image_address_tmp = [k.replace("\\", "/") for k in new_image_address_tmp]
third_screen.callback_image(new_image_address_tmp[0], image_address_tmp[0], title)
class ThirdScreen(Screen, BoxLayout):
# class attribute references
image_size = (0, 0)
image_pos = (0, 0)
image_address = ""
new_image_address = ""
title = "Upload"
rect_box = ObjectProperty(None)
t_x = NumericProperty(0.0)
t_y = NumericProperty(0.0)
x1 = y1 = x2 = y2 = NumericProperty(0.0)
def __init__(self, **kwargs):
super(ThirdScreen, self).__init__(**kwargs)
pass
def callback_image(self, new_image_address, image_address, title):
sm.current = "_third_screen_"
self.new_image_address = new_image_address
self.image_address = image_address
self.title = title
self.ids.main_image.source = self.new_image_address
self.ids.main_title.text = self.title
def enable_cropping(self):
# overwrite class attributes
ThirdScreen.image_address = self.image_address
ThirdScreen.new_image_address = self.new_image_address
print("enable_cropping")
sm.current = "_edit_image_screen_"
return True
class EditImageScreen(Screen):
def __init__(self, **kwargs):
print("EditImageScreen")
super(EditImageScreen, self).__init__(**kwargs)
self.layout = None
def on_pre_enter(self):
print("on_pre_enter")
self.layout = EditImageLayout()
self.add_widget(self.layout)
class EditImageLayout(FloatLayout):
color_button = ListProperty([1, .3, .4, 1])
button_color = ListProperty([0, 0, 0, 1])
rectangle_selector = ObjectProperty()
text_size_rectangle = ObjectProperty()
image_layout = ObjectProperty()
bubble_buttons = ObjectProperty()
bubble_buttons_undo_confirm = ObjectProperty()
def __init__(self, **kwargs):
print("EditImageLayout")
self.sm = kwargs.pop('sm', None)
self.crop_image_screen = kwargs.pop('crop_image_screen', None)
# This is where the problem occurs
super(EditImageLayout, self).__init__(**kwargs)
self.rectangle_selector.bind(size_selected=self.on_change_size_rectangle_selector)
self.rectangle_selector.bind(size_selected_temp=self.update_text_size_rectangle)
self.bind(on_touch_down=self.bubble_buttons.hide)
self.bubble_buttons.resize_button.bind(on_press=self.on_press_resize_button)
self.bubble_buttons_undo_confirm.undo_button.bind(on_press=self.on_press_undo_button)
self.bubble_buttons_undo_confirm.confirm_button.bind(on_press=self.on_press_confirm_button)
def on_change_size_rectangle_selector(self, instance, size_selected):
print("on_change_size_rectangle_selector")
if not self.rectangle_selector.tap_not_draw_a_line():
self.bubble_buttons.show()
else:
self.text_size_rectangle.text = ''
def on_press_resize_button(self, instance):
print("on_press_resize_button")
self.image_layout.resize_image(width=self.rectangle_selector.size_selected[0],
height=self.rectangle_selector.size_selected[1])
self.rectangle_selector.delete_line()
self.text_size_rectangle.text = ''
self.bubble_buttons_undo_confirm.show()
def on_press_undo_button(self, instance):
print("on_press_undo_button")
size = self.image_layout.old_size
self.image_layout.resize_image(width=size[0], height=size[1])
self.bubble_buttons_undo_confirm.hide()
def on_press_confirm_button(self, instance):
print("on_press_confirm_button")
self.bubble_buttons_undo_confirm.hide()
def update_text_size_rectangle(self, instance, size):
print("update_text_size_rectangle")
self.text_size_rectangle.text = str('({0}, {1})'.format(int(size[0]), int(size[1])))
class ImageLayout(Image):
image = ObjectProperty()
path_image = StringProperty('image_tmp.jpg')
path_image_tmp = StringProperty('image_tmp.jpg')
old_size = ListProperty([0, 0])
def __init__(self, **kwargs):
print("ImageLayout")
super(ImageLayout, self).__init__(**kwargs)
self.path_image = ThirdScreen.image_address
self.image = CoreImage(self.path_image,
data=io.BytesIO(open(self.path_image, "rb").read()),
ext=self.path_image[self.path_image.rfind('.') + 1::])
self.source = self.path_image
def resize_image(self, width, height, pos_x=None, pos_y=None):
pos_x, pos_y = abs(Window.width - width)/2 , abs(Window.height - height)/2
self.image.resize(self.path_image,
self.path_image_tmp,
int(width),
int(height))
self.source = self.path_image_tmp
self.pos = pos_x, pos_y
self.old_size = self.size
self.size = width, height
self.reload()
class CoreImage(CoreImageKivy):
def __init__(self, arg, **kwargs):
print("CoreImage")
super(CoreImage, self).__init__(arg, **kwargs)
def resize(self, fname, fname_scaled, width, height):
try:
img = Image.open(fname)
except Exception as e:
print('Exception: ', e)
return
img = img.resize((width, height), Image.ANTIALIAS)
try:
img.save(fname_scaled)
except Exception as e:
print('Exception: ', e)
return
class TouchSelector(Widget):
# Points of Line object
Ax = NumericProperty(0)
Ay = NumericProperty(0)
Bx = NumericProperty(0)
By = NumericProperty(0)
Cx = NumericProperty(0)
Cy = NumericProperty(0)
Dx = NumericProperty(0)
Dy = NumericProperty(0)
# Object line
line = ObjectProperty()
# List of line objects drawn
list_lines_in_image = ListProperty([])
# Size of the selected rectangle
size_selected = ListProperty([0, 0])
# Size previous of the selected rectangle
size_selected_previous = ListProperty([0, 0])
# Size temporary of the selected rectangle
size_selected_temp = ListProperty([0, 0])
# Line Color and width
line_color = ListProperty([0.2, 1, 1, 1])
line_width = NumericProperty(1)
# First tap in TouchSelector
first_tap = True
def __init__(self, *args, **kwargs):
super(TouchSelector, self).__init__(*args, **kwargs)
self.bind(list_lines_in_image=self.remove_old_line)
def on_touch_up(self, touch): # on button up
self.size_selected = abs(self.Cx - self.Dx), abs(self.Cy - self.By)
self.size_selected_previous = self.size_selected
print(self.Dx, self.Dy, self.Cx, self.Cy)
def on_touch_down(self, touch):
with self.canvas:
Color(self.line_color)
# Save initial tap position
self.Ax, self.Ay = self.first_touch_x, self.first_touch_y = touch.x, touch.y
# Initilize positions to save
self.Bx, self.By = 0, 0
self.Cx, self.Cy = 0, 0
self.Dx, self.Dy = 0, 0
# Create initial point with touch x and y postions.
self.line = Line(points=([self.Ax, self.Ay]), width=self.line_width, joint='miter', joint_precision=30)
# Save the created line
self.list_lines_in_image.append(self.line)
print("on_touch_down")
def remove_old_line(self, instance=None, list_lines=None):
if len(self.list_lines_in_image) > 1:
self.delete_line()
def delete_line(self, pos=0):
try:
self.list_lines_in_image.pop(pos).points = []
except:
pass
def on_touch_move(self, touch):
# Assign the position of the touch at the point C
self.Cx, self.Cy = touch.x, touch.y
# There are two known points A (starting point) and C (endpoint)
# Assign the positions x and y known of the points
self.Bx, self.By = self.Cx, self.Ay
self.Dx, self.Dy = self.Ax, self.Cy
# Assign points positions to the last line created
self.line.points = [self.Ax, self.Ay,
self.Bx, self.By,
self.Cx, self.Cy,
self.Dx, self.Dy,
self.Ax, self.Ay]
self.size_selected_temp = abs(self.Cx - self.Dx), abs(self.Cy - self.By)
def tap_not_draw_a_line(self):
return (self.size_selected[0] == 0 and self.size_selected[1] == 0)
class BaseBubbleButtons(Bubble):
def __init__(self, **kwargs):
super(BaseBubbleButtons, self).__init__(**kwargs)
def hide(self, instance=None, value=None):
self.opacity = 0
def show(self, instance=None, value=None):
self.opacity = 1
class BubbleButtons(BaseBubbleButtons):
resize_button = ObjectProperty()
cut_button = ObjectProperty()
rotate_button = ObjectProperty()
class BubbleButtonsUndoConfirm(BaseBubbleButtons):
undo_button = ObjectProperty()
confirm_button = ObjectProperty()
class App_R3App(App):
Builder.load_file('App_R3.kv')
def build(self):
return sm
def on_start(self):
return True
def on_pause(self):
return True
def on_resume(self):
return True
def on_stop(self):
return True
if __name__ == '__main__':
# Create the screen manager
sm = ScreenManager()
sm.add_widget(FirstScreen(name='_first_screen_'))
sm.add_widget(SecondScreen(name='_second_screen_'))
sm.add_widget(ThirdScreen(name='_third_screen_'))
sm.add_widget(EditImageScreen(name='_edit_image_screen_'))
App_R3App().run()
App_R3.kv
#:import Window kivy.core.window.Window
<MyScreenManager>:
FirstScreen:
id: first_screen
SecondScreen:
id: second_screen
ThirdScreen:
id: third_screen
EditImageScreen:
id: edit_image_screen
<FirstScreen>:
name: '_first_screen_'
BoxLayout:
orientation: "horizontal"
Label:
id: first_screen_label
text: "Hi, I'm the home page"
BoxLayout:
orientation: "vertical"
Button:
text: "Okay!"
on_press: root.manager.current = '_second_screen_'
Button:
text: "Cancel!"
on_press: app.stop()
<SecondScreen>:
name: '_second_screen_'
id: file_chooser
BoxLayout:
id: file_chooser_box_layout
orientation: "horizontal"
Button
text: "Open"
on_press: root.hl(file_chooser_list_view.selection)
FileChooserListView:
id: file_chooser_list_view
<ThirdScreen>:
name: '_third_screen_'
id: third_screen
xx1: root.x1
yy1: root.y1
tt_x: root.t_x
tt_y: root.t_y
BoxLayout:
orientation: "vertical"
id: third_screen_boxlayout
Label:
id: main_title
text: root.title
size_hint: (1, 0.1)
BoxLayout:
id: image_box_layout
# limits the box layout to the position of the image
Image:
id: main_image
source: root.image_address
pos_hint: {'center_x': 0.5, 'center_y': 0.5}
BoxLayout:
id: button_boxlayout
orientation: "horizontal"
padding: 10
size_hint: (1, 0.15)
Button:
id: accept_button
text: "Okay"
size_hint: (0.33, 1)
on_press: root.image_accepted_by_user(root.image_address)
Button:
id: crop_button
text: "Crop"
size_hint: (0.33, 1)
on_press: root.enable_cropping()
Button:
id: cancel_button
text: "Cancel"
size_hint: (0.33, 1)
on_press: root.manager.current = '_first_screen_'
<EditImageLayout>:
rectangle_selector: rectangle_selector
text_size_rectangle: text_size_rectangle
image_layout: image_layout
bubble_buttons: bubble_buttons
bubble_buttons_undo_confirm: bubble_buttons_undo_confirm
canvas.before:
Color:
rgba: (1, 1, 1, 0.2)
Rectangle:
pos: self.pos
size: Window.width, Window.height
Label:
id: text_size_rectangle
pos_hint_x: None
pos_hint_y: None
pos: Window.width*.45, Window.height*.45
color: (1, 1, 1, 1)
ImageLayout:
id: image_layout
size: Window.width*.8, Window.height*.8
pos: Window.width*.1, Window.height*.1
size_hint: None, None
pos_hint_x: None
pos_hint_y: None
TouchSelector:
id: rectangle_selector
BubbleButtons:
id: bubble_buttons
size_hint: (None, None)
size: (200, 40)
pos_hint_x: None
pos_hint_y: None
pos: Window.width*.4, Window.height*.1
opacity: 0
arrow_pos: 'top_mid'
BubbleButtonsUndoConfirm:
id: bubble_buttons_undo_confirm
size_hint: (None, None)
size: (200, 40)
pos_hint_x: None
pos_hint_y: None
pos: Window.width*.4, Window.height*.9
opacity: 0
arrow_pos: 'top_mid'
<BubbleButtons>:
resize_button: resize_button
cut_button: cut_button
rotate_button: rotate_button
BubbleButton:
id: resize_button
text: 'Resize'
BubbleButton:
id: cut_button
text: 'Cut'
BubbleButton:
id: rotate_button
text: 'Rotate'
<BubbleButtonsUndoConfirm>:
undo_button: undo_button
confirm_button: confirm_button
BubbleButton:
id: undo_button
text: 'Undo'
BubbleButton:
id: confirm_button
text: 'Confirm'
Console output, aka what the code prints (you can see that ImageLayout and CoreImage run twice)
EditImageScreen
enable_cropping
on_pre_enter
EditImageLayout
ImageLayout
CoreImage
ImageLayout
CoreImage
What I suspect is happening is that the super() is calling the base class EditImageLayout, the static elements of that base class are calling the .kv file and initating the ImageLayout and CoreImage classes from there. At the same time, "self" goes into action and does the exact same thing. This causes trouble later on when I implement on_touch_down over it (on_touch_down then appears twice, etc. )
Problem
ImageLayout and CoreImage were called twice.
[INFO ] [GL ] Unpack subimage support is available
enable_cropping
on_pre_enter
EditImageLayout
ImageLayout
CoreImage
ImageLayout
CoreImage
[INFO ] [Base ] Leaving application in progress...
Process finished with exit code 0
Root Cause
The double calls to ImageLayout and CoreImage were due to two kv files, App_R3.kv and app_r3.kv present as shown in the screen shots below. In the application, the app class is App_R3App(App): and it is using Builder.load_file('App_R3.kv') to load kv code into application.
Solution
Remove kv file, app_r3.kv. In the example, we renamed it to app_r3-off.kv
Kv language » How to load KV
There are two ways to load Kv code into your application:
By name convention:
Kivy looks for a Kv file with the same name as your App class in
lowercase, minus “App” if it ends with ‘App’ e.g:
MyApp -> my.kv
If this file defines a Root Widget it will be attached to the App’s
root attribute and used as the base of the application widget tree.
By Builder:
You can tell Kivy to directly load a string or a file. If this string
or file defines a root widget, it will be returned by the method:
Builder.load_file('path/to/file.kv')
or:
Builder.load_string(kv_string)
Recommendations
Since class rule, <MyScreenManager>: is defined in your kv file, you should use it rather than define sm = ScreenManager() in your Python code. On top of that, keep the view/design separate.
kv file
Add missing class rule for EditImageScreen.
<EditImageScreen>:
name: '_edit_image_screen_'
<EditImageLayout>:
Python code
Add class definition for MyScreenManager
In build() method, replace return sm with return MyScreenManager()
Before App_R3().run(), remove all references to sm
Since each screen has by default a property manager that gives you the instance of the ScreenManager used. In callback_image() and enable_cropping() methods, replace sm.current with self.manager.current
In __init__() method of EditImageLayout() class, remove self.sm = kwargs.pop('sm', None). If you need to access the root/ScreenManager, use sm = App.get_running_app().root
Snippet
class MyScreenManager(ScreenManager):
pass
...
def callback_image(self, new_image_address, image_address, title):
self.manager.current = "_third_screen_"
self.new_image_address = new_image_address
...
def enable_cropping(self):
...
print("enable_cropping")
self.manager.current = "_edit_image_screen_"
...
def __init__(self, **kwargs):
print("EditImageLayout")
self.crop_image_screen = kwargs.pop('crop_image_screen', None)
...
class App_R3App(App):
def build(self):
return MyScreenManager()
if __name__ == '__main__':
App_R3App().run()
ScreenManager » Basic Usage
Each screen has by default a property manager that gives you the
instance of the ScreenManager used.
I need to set up dynamically list in Drop-Down. For setting I want to use constructor of class DiscDropDown, which is decendant of class DropDown. (It means, that want to set up value for variable li_disc in class DiscDropDown). Instance of this class is not part of python code, because I use Builder.
How do I realize it in next code?
Builder.load_string('''
<Save_As>:
drop_down: drop_down
orientation:'vertical'
DiscDropDown:
id: drop_down
size_hint: None,None
height: 50
Button:
id: bt_delete_file
disabled: False
size_hint: 1,None
height: 250
text: 'Fictive'
''')
class DiscDropDown(DropDown):
def __init__(self, **kwarg):
super(DiscDropDown, self).__init__(**kwarg)
self.dropdown = DropDown()
# I wanted to set up value Button.text during creation Buttons
for name in li_disc:
btn = Button(text = name, size_hint_y=None, height=44)
btn.bind(on_release=lambda btn: self.dropdown.select(btn.text))
self.dropdown.add_widget(btn)
mainbutton = Button(text='Disc', size_hint=(None, None),size = (50,50))
mainbutton.bind(on_release = self.dropdown.open)
self.dropdown.bind(on_select=lambda instance, x: setattr(mainbutton, 'text', x))
self.add_widget(mainbutton)
class Save_As(BoxLayout):
# drop_down = ObjectProperty()
def __init__(self, **kwargs):
super(Save_As, self).__init__( **kwargs)
return
class ExplorerApp(App):
def build(self):
self.save_as = Save_As()
return self.save_as
if __name__ == '__main__':
ExplorerApp().run()
For solving my problem I used next process for setting value variable Button.text:
class Save_As(BoxLayout):
drop_down = ObjectProperty()
def __init__(self, **kwargs):
li_disc = ['aa','bb','cc']
super(Save_As, self).__init__( **kwargs)
# I set up Button.text here
for i in range(0,3):
self.children[1].dropdown.children[0].children[i].text = li_disc[i]
return
I think that my solution isn't ideal, cann you recommend me better process?
I'm trying to convert this kv code into my own class
<BaseScreen>: # This is GridLayout
cols: 4
rows: 4
padding: 25
Button:
size_hint_x: None
size_hint_y: None
Image:
source: "business_bookcover.png"
x: self.parent.x
y: self.parent.y
width: self.parent.width
height: self.parent.height
keep_ratio: False
The problem is that I'm trying to make "clickable image", but when I append widget to the button, image is on the default position (0,0), totally out of the button position. Is there any workaround how to do it?
This is my try
class Book(Button):
def __init__(self, **kwargs):
super().__init__(**kwargs)
self.size_hint = (None, None)
book_cover_image_source = kwargs.get('cover') or BLANK_BOOK_COVER
book_cover = Image(source=book_cover_image_source)
book_cover.pos = self.pos
book_cover.width = self.width
book_cover.height = self.height
book_cover.allow_stretch = True
book_cover.keep_ratio = False
self.add_widget(book_cover)
In kv languaje properties used in the expression (x:, y:, width:) will be observed. When the parent's size/pos change, child widget change accordingly. You must suply this event bindings in the Python class:
class Book(Button):
def __init__(self, cover=BLANK_BOOK_COVER, **kwargs):
super(Book, self).__init__(**kwargs)
self.size_hint = (None, None)
self.book_cover = Image(source=cover)
self.book_cover.allow_stretch = True
self.book_cover.keep_ratio = False
self.add_widget(self.book_cover)
def on_size(self, *args):
self.book_cover.size = self.size
def on_pos(self, *args):
self.book_cover.pos = self.pos
A simpler option to get a clickable image is to have your class Book inherit from ButtonBehabior and Image classes:
from kivy.uix.behaviors import ButtonBehavior
from kivy.uix.image import Image
class Book(ButtonBehavior, Image):
def __init__(self, cover=BLANK_BOOK_COVER, **kwargs):
super(Book, self).__init__(**kwargs)
self.source = cover
self.size_hint = (None, None)
self.allow_stretch = True
self.keep_ratio = False
Related: Kivy: understanding widget instances in apps
I am initializing my app with 2 widget instances, the (.kv) file is as follows:
#:kivy 1.0.9
<GraphInterface>:
node: graph_node
edge: graph_edge
GraphNode:
id: graph_node
center: self.parent.center
GraphEdge:
id: graph_edge
center: 150,200
<GraphNode>:
size: 50, 50
canvas:
Color:
rgba: (root.r,1,1,1)
Ellipse:
pos: self.pos
size: self.size
<GraphEdge>:
size: self.size
canvas:
Color:
rgba: (root.r,1,1,1)
Line:
width: 2.0
close: True
The node and edge objects are defined as follows:
class GraphNode(Widget):
r = NumericProperty(1.0)
def __init__(self, **kwargs):
self.size= [50,50]
self.pos = [175,125]
self.r = 1.0
super(GraphNode, self).__init__(**kwargs)
def on_touch_down(self, touch):
if self.collide_point(*touch.pos):
if touch.grab_current == None:
self.r = 0.6
touch.grab(self)
return True
return super(GraphNode, self).on_touch_down(touch)
def on_touch_move(self, touch):
if touch.grab_current is self:
self.pos=[touch.x-25,touch.y-25]
for widget in self.parent.children:
if isinstance(widget, GraphEdge) and widget.collide_widget(self):
print "collision detected"
widget.snap_to_node(self)
return True
return super(GraphNode, self).on_touch_move(touch)
def on_touch_up(self, touch):
if touch.grab_current is self:
touch.ungrab(self)
self.r = 1.0
# and finish up here
pass
class GraphEdge(Widget):
r = NumericProperty(1.0)
def __init__(self, **kwargs):
super(GraphEdge, self).__init__(**kwargs)
with self.canvas:
self.line = Line(points=[100, 200, 200, 200], width = 2.0, close = True)
def snap_to_node(self, node):
if self.collide_widget(node):
print "collision detected"
del self.line.points[-2:]
self.line.points+=node.center
self.size = [math.sqrt(((self.line.points[0]-self.line.points[2])**2 + (self.line.points[1]-self.line.points[3])**2))]*2
self.center = ((self.line.points[0]+self.line.points[2])/2,(self.line.points[1]+self.line.points[3])/2)
return True
pass
Sorry that there is so much code here, I don't know which part is causing the issue though I suspect it is simply the way I am initializing in the (.kv) file.
Key Problem:
When I click on the node the edge changes colour as well, despite the fact they do not share the same colour property. (I also tried renaming the GraphEdge colour property, but the issue still arises).
Below I show the issue, and the expected result (respectively).
You were actually trying to create two edges - one in with self.canvas: in your GraphEdge class (where you did not specified color) and second in your *.kv file (where you did not specified points). So you can remove whole <GraphEdge> in your *.kv file and then expand with self.canvas: like this:
with self.canvas:
Color(self.r, 1, 1, 1)
self.line = Line(points=[100, 200, 200, 200], width = 2.0, close = True)