Kivy ScrollView for paragraphs of text - scrollview

Question

I am unable to get ScrollView in Kivy to scroll through paragraphs of text. I have attached a code example below. Can anyone state what is wrong? Thank you.
import kivy
import string
from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.gridlayout import GridLayout
from kivy.uix.scrollview import ScrollView
class longTextLabelApp(App):
def build(self):
scrollViewLayout = ScrollView(do_scroll_x=False)
childLayout = GridLayout(cols = 1, size_hint_x = 1, size_hint_y = None)
childLayout.bind(minimum_height=childLayout.setter('height'))
def longTextLabel():
_long_text = """
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus odio nisi, pellentesque molestie adipiscing vitae, aliquam at tellus. Fusce quis est ornare erat pulvinar elementum ut sed felis. Donec vel neque mauris. In sit amet nunc sit amet diam dapibus lacinia. In sodales placerat mauris, ut euismod augue laoreet at. Integer in neque non odio fermentum volutpat nec nec nulla. Donec et risus non mi viverra posuere. Phasellus cursus augue purus, eget volutpat leo. Phasellus sed dui vitae ipsum mattis facilisis vehicula eu justo.
Quisque neque dolor, egestas sed venenatis eget, porta id ipsum. Ut faucibus, massa vitae imperdiet rutrum, sem dolor rhoncus magna, non lacinia nulla risus non dui. Nulla sit amet risus orci. Nunc libero justo, interdum eu pulvinar vel, pulvinar et lectus. Phasellus sed luctus diam. Pellentesque non feugiat dolor. Cras at dolor velit, gravida congue velit. Aliquam erat volutpat. Nullam eu nunc dui, quis sagittis dolor. Ut nec dui eget odio pulvinar placerat. Pellentesque mi metus, tristique et placerat ac, pulvinar vel quam. Nam blandit magna a urna imperdiet molestie. Nullam ut nisi eget enim laoreet sodales sit amet a felis.
"""
reallyLongText = _long_text + _long_text + _long_text + _long_text +_long_text
myLabel = Label(text = reallyLongText, text_size = (700,None), line_height=1.5)
return myLabel
childLayout.add_widget(longTextLabel())
scrollViewLayout.add_widget(childLayout)
return scrollViewLayout
if __name__ == '__main__':
longTextLabelApp().run()

Answer 1

The default size of a Label (and Widget) is (100,100). It doesn't matter if you are seeing all the text on the screen. If you print myLabel.size you will realize of this. You need to be sure to set the height of the Label (myLabel.height: 2200) but first set the size_hint_y to None first (myLabel.size_hint_y=None). The following code should work:
import kivy
import string
from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.gridlayout import GridLayout
from kivy.uix.scrollview import ScrollView
from kivy.graphics import Rectangle, Color
class longTextLabelApp(App):
def build(self):
scrollViewLayout = ScrollView(do_scroll_x=False)
childLayout = GridLayout(cols = 1, size_hint_x = 1, size_hint_y = None)
childLayout.bind(minimum_height=childLayout.setter('height'))
def longTextLabel():
_long_text = """
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus odio nisi, pellentesque molestie adipiscing vitae, aliquam at tellus. Fusce quis est ornare erat pulvinar elementum ut sed felis. Donec vel neque mauris. In sit amet nunc sit amet diam dapibus lacinia. In sodales placerat mauris, ut euismod augue laoreet at. Integer in neque non odio fermentum volutpat nec nec nulla. Donec et risus non mi viverra posuere. Phasellus cursus augue purus, eget volutpat leo. Phasellus sed dui vitae ipsum mattis facilisis vehicula eu justo.
Quisque neque dolor, egestas sed venenatis eget, porta id ipsum. Ut faucibus, massa vitae imperdiet rutrum, sem dolor rhoncus magna, non lacinia nulla risus non dui. Nulla sit amet risus orci. Nunc libero justo, interdum eu pulvinar vel, pulvinar et lectus. Phasellus sed luctus diam. Pellentesque non feugiat dolor. Cras at dolor velit, gravida congue velit. Aliquam erat volutpat. Nullam eu nunc dui, quis sagittis dolor. Ut nec dui eget odio pulvinar placerat. Pellentesque mi metus, tristique et placerat ac, pulvinar vel quam. Nam blandit magna a urna imperdiet molestie. Nullam ut nisi eget enim laoreet sodales sit amet a felis.
"""
reallyLongText = _long_text + _long_text + _long_text + _long_text +_long_text
myLabel = Label(text = reallyLongText, text_size = (700,None), line_height=1.5)
print "The label size is ", myLabel.size
myLabel.size_hint_y = None
myLabel.height = 2200
return myLabel
childLayout.add_widget(longTextLabel())
scrollViewLayout.add_widget(childLayout)
return scrollViewLayout
if __name__ == '__main__':
longTextLabelApp().run()
EDIT - RST Document
Depending on your objectives it might be better to use a RSTDocument. Label are just that, labels. They don't adjust to content or text. Think of them as stickers. The (RSTDocment)[http://kivy.org/docs/api-kivy.uix.rst.html], still indicated as highly experimental though is more suitable for long texts, specially if they are dynamic. They actually includes the Scroll.
from kivy.app import App
from kivy.uix.rst import RstDocument
class RstDocumentApp(App):
def build(self):
_long_text = """
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus odio nisi, pellentesque molestie adipiscing vitae, aliquam at tellus. Fusce quis est ornare erat pulvinar elementum ut sed felis. Donec vel neque mauris. In sit amet nunc sit amet diam dapibus lacinia. In sodales placerat mauris, ut euismod augue laoreet at. Integer in neque non odio fermentum volutpat nec nec nulla. Donec et risus non mi viverra posuere. Phasellus cursus augue purus, eget volutpat leo. Phasellus sed dui vitae ipsum mattis facilisis vehicula eu justo.
Quisque neque dolor, egestas sed venenatis eget, porta id ipsum. Ut faucibus, massa vitae imperdiet rutrum, sem dolor rhoncus magna, non lacinia nulla risus non dui. Nulla sit amet risus orci. Nunc libero justo, interdum eu pulvinar vel, pulvinar et lectus. Phasellus sed luctus diam. Pellentesque non feugiat dolor. Cras at dolor velit, gravida congue velit. Aliquam erat volutpat. Nullam eu nunc dui, quis sagittis dolor. Ut nec dui eget odio pulvinar placerat. Pellentesque mi metus, tristique et placerat ac, pulvinar vel quam. Nam blandit magna a urna imperdiet molestie. Nullam ut nisi eget enim laoreet sodales sit amet a felis.
"""
reallyLongText = _long_text + _long_text + _long_text + _long_text +_long_text
return RstDocument(text = reallyLongText)
if __name__ == '__main__':
RstDocumentApp().run()

Answer 2

You can set the Label to be of the size of the texture inside it like this.
FloatLayout:
Label:
# adding a background to see the amount of space the label takes
canvas.before:
Color:
rgba: .5, .5, .5, .5
Rectangle:
size: self.size
pos: self.pos
text: "How can the only thing constant in the universe be `change` when\nchange itself is by it's very nature `not constant`?"
pos_hint: {'center_x': .5, 'center_y': .5}
size_hint: None, None
size: self.texture_size
However with this you would only get a label that just expands how much text is in it and would require you to add \n yourself to make it wrap. A better approach would be to let the text inside the label auto wrap at a certain width by setting text_size something like the following::
FloatLayout:
ScrollView:
# take half of parents size
size_hint: .5, .5
pos_hint: {'center_x': .5, 'center_y': .5}
Label:
canvas.before:
Color:
rgba: .5, .5, .5, .5
Rectangle:
size: self.size
pos: self.pos
text: "\n1. Two hunters are out in the woods when one of them collapses. He doesn't seem to be breathing and his eyes are glazed. The other guy whips out his phone and calls the emergency services. He gasps, `My friend is dead! What can I do?`\n\n The operator says `Calm down. I can help. First, let's make sure he's dead.`\n\n There is a silence, then a gun shot is heard. Back on the phone, the guy says `OK, now what?`\n\n\n2. Sherlock Holmes and Dr Watson were going camping. They pitched their tent under the stars and went to sleep. Sometime in the middle of the night Holmes woke Watson up and said:\n\n `Watson, look up at the sky, and tell me what you see.`\n\n Watson replied: `I see millions and millions of stars.`\n\n Holmes said: `And what do you deduce from that?`\n\n Watson replied: `Well, if there are millions of stars, and if even a few of those have planets, it’s quite likely there are some planets like Earth out there. And if there are a few planets like Earth out there, there might also be life.`\n\n And Holmes said: `Watson, you idiot, it means that somebody stole our tent.`\n\n\n3. Three women talk about their husband is performance as lovers.\n\nThe first woman says, `My husband is a marriage counselor, so he always buys me flowers and candy before we make love.`\n\nThe second woman says, `My husband is a motorcycle mechanic. He likes to play rough and use leather sometimes.`\n\nThe third woman shakes her head and says, `My husband works for an Internet company. He just sits on the edge of the bed and tells me how great it's going to be when I get it.` \n\n\n4. As within, so outside. Fractals equations show the possibility of having infinity within minutia. Each and every cell can be a image of the whole; merging the micro and the macro into one.\n"
pos_hint: {'center_x': .5, 'center_y': .5}
size_hint: 1, None
text_size: self.width, None
height: self.texture_size[1]