Scrolling to the end of a textview

[kami]

Hi,

i am trying to append some text to my textview field.
The text is really long but then i try to scroll to bottom in the textview. This i not working.

I used this code:

def appendtextview(text):
    v['viewtop']['textview1'].text = v['viewtop']['textview1'].text + str(text)
    v['viewtop']['textview1'].content_offset = (0, v['viewtop']['textview1'].content_size[1] - v['viewtop']['textview1'].height) 

Can someon help me with this?

Thanks a lot.

Cu kami

[JonB]

Try:

1. wrapping that method in an on_main_thread. That might ensure that when you set the text, the content size is also updated. I believe the content_size is probably old.
2. one thing we did in stash, was to add a slight ui.delay after setting text, to scroll to the desired location. I think we determined that content_size might not be immediately updated by the OS, so you have to wait.

[JonB]

@kami one other thing to try would be objc_util. This may be related to a long-standing iOS bug. The workaround suggested on SO is

-(void) scrollToBottom {
  [textView scrollRangeToVisible:NSMakeRange([textView.text length], 0)];
  [textView setScrollEnabled:NO];
  [textView setScrollEnabled:YES];
}

I haven't tried to convert this to python equivalent.

[kami]

Hi,

this was a good idea. The short delay with 0.5 sec is enough to get down to the last row.

Thanks a lot for the help.

Cu kami

[mikael]

@kami, good to hear. If that makes app feel sluggish in use, 0.1 sec works just as well.

[kami]

After testing a little bit, it is no running smoothly. When i scroll in the textview it is not going down to the end?

Can anyone maybe post a better version or an objc_util example?

Thanks a lot.

Cu kami

[cvp]

@kami try this

import ui
from objc_util import *

tv = ui.TextView()
tv.frame = (0,0,500,500)
tv.text = 'a'*12000

b = ui.ButtonItem()
b.title = 'bottom'
def b_action(sender):
	tvo = ObjCInstance(tv)
	tvo.scrollRangeToVisible_(NSRange(len(tv.text),0))
	tvo.setScrollingEnabled_(False)
	tvo.setScrollingEnabled_(True)
	pass
b.action = b_action
tv.right_button_items = (b,)

tv.present('sheet')

[kami]

Works much better, but only every second time. First time it scrolls to the end. The second time it scrolls to much down, so the textview is empty????

Cu kami

[cvp]

@kami With exactly this little script? For me, it is ok

[kami]

Hi,

after some testing it only works for me at everytime with a short delay of 0.4 sec.

Otherwise it comes to some errors. Is it possible to check first if the textview is reloaded and then scroll down?

Thanks a lot.

Cu kami

[mikael]

@kami, here’s an alternative approach. You can add a guard variable in update if you do not want to have it constantly ”running”.

import ui

class ScrollToBottomTextView(ui.View):
  
  def __init__(self, **kwargs):
    super().__init__(**kwargs)
    self.tv = ui.TextView(
      frame=self.bounds,
      flex='WH'
    )
    self.add_subview(self.tv)
    self.update_interval = 1/60
    
  def update(self):
    self.tv.content_offset = (
      0, self.tv.content_size[1]-self.height)
      
if __name__ == '__main__':
  
  v = ScrollToBottomTextView()
  v.present()
  
  import requests
  text = requests.get('https://forum.omz-software.com/topic/5744/scrolling-to-the-end-of-a-textview').text
  lines = text.splitlines()
  i = 0

  def add_line():
    global lines, i
    v.tv.text += lines[i] + '\n'
    i += 1
    ui.delay(add_line, 0.5)
    
  ui.delay(add_line, 0.5)

[kami]

Hi,

i am trying this function under ios 16.3 and it is not working anymore.

def scroll() :

    tvo = ObjCInstance(main['textview1'])
    tvo.scrollRangeToVisible_(NSRange(len(main['textview1'].text),0))
    tvo.setScrollingEnabled_(False)
    tvo.setScrollingEnabled_(True)

Can someone help me with this?

BR kami

[cvp]

@kami For me, my little script here-under still works under iOS 16.3 and Pythonista beta

import ui
from objc_util import *

tv = ui.TextView()
tv.frame = (0,0,500,500)
tv.text = 'a'*12000

b = ui.ButtonItem()
b.title = 'bottom'
def b_action(sender):
	tvo = ObjCInstance(tv)
	tvo.scrollRangeToVisible_(NSRange(len(tv.text),0))
	tvo.setScrollingEnabled_(False)
	tvo.setScrollingEnabled_(True)
	pass
b.action = b_action
tv.right_button_items = (b,)

tv.present('sheet')