TALMemo effect in TALVertScrollBox

[Elinulok32]

Hello @Zeus64, I have a TALMemo in a TALVertScrollBox which is also in one of the pages of a TALPageController. On Android when I move the scrollbox, I get this effect as in the .gif image below. This doesn't happen when I run in windows. I checked the TALMemo in ALFMXControlsDemo and its fine, when I run in Android. Don't know why mine does this in Android.

[Zeus64]

hmm, can you try to put the memo just on the TALVertScrollBox to know if the bug is because of TALVertScrollBox + TALPageController ?

it's look like the position of the native windows that represent the TextEdit is didn't updated.

[Elinulok32]

I placed the memo on just the TALVertScrollBox without TALPageCcontroller and it still behaved same way. It's works fine on iOS though. Sometimes it also becomes unresponsive to touch, even with HitTest := True and Enabled := True; I'm testing on Android 10. Don't know if that might be the problem.

[Zeus64]

is it possible for you to make a small demo so i can reproduce the bug and work on it ?

[Elinulok32]

Interestingly, I created the small demo and mimic the structure of the app with the issue, and it worked just fine (without that strange effect), but I still have that issue with the main app. I'll have to critically look into my code, but if there's anything you think I can do to resolve this, I gladly welcome it. Thank you.

[Zeus64]

for what i know, only another native control can hide the content of the EditText, do you have another native control in your form ?

[Elinulok32]

Yes, I do have another TALEdit that is aligned to None inside a different Control. They don't share the same parent and they're far from each other. A similar thing is happening with TALEdit inside a TALDialog. Take a look at the .gif image below. Even with the Virtual Keyboard in view, the text in the field refuses to show. As soon as the virtual Keyboard shows up, the caret vanishes.

[Elinulok32]

I noticed that this happens when the TALEdit or TALMemo moves from the position where its first displayed, either due to the appearance of the Virtual Keyboard or the user scrolls the ScrollBox in which the Native control is. Is there any procedure call to repaint, realign, refresh or update the position of the Native control to get it to appear? I tried the available refresh, repaint procedures. The fact that this happens only on my android devices (and not my iOS device) makes me believe that it has to do with painting in Android or something in Android that I can't comprehend.

[Zeus64]

Yes, but this is puzzling—I can’t reproduce the issue (e.g., with ALFmxControlDemo). There’s definitely something specific to your app. In your last video, the TEdit is positioned correctly and responds to interaction, but the text isn’t visible. Remember, TEdit is a native Android window layered above the FMX form—so nothing in FMX can hide it. The only explanation I can think of from that video is a color clash (text color = background color).

To help effectively, I really need a minimal, reproducible demo. Also note: the function that refreshes the position of the native view hosting the edit is UpdateFrame, and it’s bound to the native view, not the edit itself:
Edit.NativeView.UpdateFrame.

[Zeus64]

@Elinulok32 I will also check in the android style, maybe you use a special style for your app?

[Elinulok32]

I tested on Android 11, and I did not face that issue. I guess it's a problem with android 10 and below (I'm facing the same issue on Android 8.1)

[Zeus64]

hmm, so i need to find a device with android 10 to reproduce the problem

[Elinulok32]

hmm, so i need to find a device with android 10 to reproduce the problem

Yes please, I think so.

[Zeus64]

with device do you have ? i will try to buy the same

[Elinulok32]

I'm so sorry to put you in the situation of an impromptu purchase. I use a Huawei Y9s having Android 10, but I don't think it's about the specific phone but the version of Android, because the issue also occurs on a ZTE Blade A32 (Android 8.1). So any phone with Android 10 and below can help reproduce the problem. Thank you also for you feedback and rapid response. Really appreciate that. You're the best.

[Elinulok32]

Hello @Zeus64, I found a hack. It's not ideal but it worked. I set the TALEdit or TALMemo NativeView.Control.Parent to Nil and then back to its original parent and the text and caret showed up. I tested on other phones using Android 10 and below and it worked as expected. I'll still be in wait for a better workaround from you. Thank you.