how do i make a full text area scroll up when i add more text?

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steve draving
steve draving 2017 年 8 月 1 日
コメント済み: Matthew Pelmear 2021 年 6 月 17 日
i designed a gui for running automated tests using App Designer. it writes messages to a text area. after the text area fills up, it continues add the text to the bottom of the text array and adds a scroll bar on the right of the text area. all new text is added off-screen, below the bottom of the displayed text area and you have manually scroll to see any new messages. how do I make it automatically scroll, so that you always see the new messages without have to keep scrolling it manually?
  2 件のコメント
steve draving
steve draving 2021 年 1 月 3 日
Whoo Hoo! Thanks.



Sven Kneer
Sven Kneer 2019 年 4 月 3 日
編集済み: Sven Kneer 2019 年 4 月 3 日
Scrolling to the latest Line is a basic feature for a "TextArea" Component. I dont want to use workarounds with Listboxes. Please Mathworks, fix this little important Issue!
  1 件のコメント
steve draving
steve draving 2019 年 4 月 3 日
I agree. Fixing the problem would save other people grief in the future. It's the right thing to do.


その他の回答 (4 件)

Eric Sargent
Eric Sargent 2020 年 12 月 9 日
編集済み: Eric Sargent 2020 年 12 月 9 日
As of R2020b uitextarea now supports scroll.
In this case you could use:
scroll(textArea, 'bottom')
  1 件のコメント
Matthew Pelmear
Matthew Pelmear 2021 年 6 月 17 日
This is nice in theory, but I had to add an extra newline to my textarea every time it's updated in order to ensure that the text will always be shown after calling scroll(). (It doesn't acually scroll all the way to the bottom for me, at least in linux.) R2021a.


Ted Shultz
Ted Shultz 2018 年 6 月 4 日
I had the exact same issue. My crude work around was to add the new text to the start rather than the end of the text block. As new lines are added (now to the top) they remain visible as the scroll bar stays at the top and the older entries go down. I maintained two separate text objects, one (added to the bottom) for saving a text file, and one added to the top for displaying in the app designer window. Because all my events include a timestamp, it is not as bad as you may think. BUT yes, I completely agree with the implied premise of this question, of "can I set scroll = 100". I also would have liked this feature.
  3 件のコメント


Walter Roberson
Walter Roberson 2017 年 8 月 1 日
I have not looked at this using app designer. If you were doing it outside of app designer you would have two choices:
1) go in at the Java level to adjust the properties of the Java swing object; or
2) put the text area inside a uipanel that is inside a second uipanel, and as you add text, keep making the text area larger so that it does not create scroll bars, and set the position of the inner uipanel so that the bottom of it is visible inside the outer uipanel. The outer uipanel works like a frame allowing only a fixed size of the inner panel to be visible.
  2 件のコメント
Walter Roberson
Walter Roberson 2017 年 8 月 4 日
The design I outlined still allows for a scroll bar: the scroll bar would be put into the outer uipanel and it would control the position of the inner uipanel compared to the outer uipanel.
The reason I mentioned "so that it does not create scroll bars" is that unless you go into the java level, there is no external control over what portion of the uicontrol style text that is visible, so to be able to keep the bottom of the text area visible you have to keep the text area large enough to not create scroll bars -- but you can put a window frame on top of that large text area and move the text area relative to the window frame.
A couple of us have implemented this design; it is not the most pleasant of designs but it it is not horrible either.
However, I see that as yet app designer has no support for uicontrol, so you cannot do the above directly in app designer.
On the other hand, app designer does support uipanel(), and uitextarea(), and uislider(), so you might be able to achieve the same effect.


Mark Myong-Sik Otero
Mark Myong-Sik Otero 2019 年 9 月 9 日
Hi there's an easy workaround that I implemented:
% Append to Text Area
msg = 'Hello World';
% Where app.taLog is a TextArea component
app.taLog.Value = [msg;app.taLog.Value];
  2 件のコメント
Mark Myong-Sik Otero
Mark Myong-Sik Otero 2019 年 10 月 8 日
yes, that's correct. we're using the text area like a log so for our use case it works. but, i can see how the inversion could be unconventional when not used the way we use it.



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