I have been having issues with using the ScrollToAsync function of a ScrollView when running on Android, not tested on iOS yet.
I'm using Xamarin.Forms version 188.8.131.524934 using .Net Standard
Testing on the Android Emulator (8.0, API26) and a Google Pixel (8.1 API27), both have the same issue.
I use NavigationPage and Navigation.PushAsync to move between pages (therefore have navigation bars on every page).
I want to create an auto populate field control, the user types in the first few letters and I look up the results in a database / static list of string and display the results below for the user to click/tap.
I have this working using a composite control (the contents of the frame marked interesting below).
The problem I have is scrolling the view to show the results.
My page has this layout hierarchy:-
ContentPage StackLayout ScrollView StackLayout Frame (some label and entry fields inside a stack layout) Frame (some label and entry fields inside a stack layout) Frame (some label and entry fields inside a stack layout) Frame (the interesting one that deals with scrolling) StackLayout Heading Label StackLayout Label x:Name="ScrollToLabel" Entry x:Name="ScrollToEntry" Grid x:Name="ScrollToGrid" Entry x:Name="Hidden" Text="I should stay visible as you type" /StackLayout /StackLayout /Frame Frame (some label and entry fields inside a stack layout) Frame (some label and entry fields inside a stack layout) /StackLayout /ScrollView StackLayout Button Text = Done /StackLayout /StackLayout /ContentPage
When the user clicks/taps in to ScrollToEntry, the keyboard opens and pans the control to above the keyboard (ok so far).
When the user starts typing in ScrollToEntry, the code populates ScrollToGrid with up to 5 results.
At this point I want to make sure that the grid results are visible for the user to tap on.
I have tried 2 different options, ScrollToAsync(ScrollToLabel, Start) and ScrollToAsync(Hidden, MakeVisible).
Neither work as I would like 100% of the time.
If the ScrollToEntry is at the bottom of the screen, the navigation bar is hidden and the view pans up too far.
The ScrollToLabel is now off the top of the screen.
When the second letter is clicked/tapped, the Navigation bar is restored and the scroll scrolls correctly, ScrollToLabel at the top of the screen.
If the ScrollToEntry is near the top of the screen, the navigation bar is not hidden and it scrolls correctly.
This is my preferred option because it would only scroll as far as needed to display all the results (not all the way to the top).
This works even worse than the first one.
In most cases, it does not scroll at all, I assume it thinks it already visible but is actually behind the keyboard?
If it does scroll, the label Hidden is still not displayed (I tested with both a HeightRequest="0" version and a visible version, both the same result).
I tried using the below code to change the adjust to resize.
1. Because it resizes, the Done button now is above the keyboard, taking up space.
2. When clicking the hardware back button (not the done or navigation back button) the previous view now has a white space where the keyboard was.
If using the done or navigation back, the screen initially appears with the white space but then refreshes to full screen.
I have created a sample app that highlights the issues (by default using pan, not resize) attached.
Its the most simple version of the layout I'm using.
Am I doing something wrong or is this just how it works?
If its how it works, this must be a bug?
If I'm doing it wrong, can someone tell me what or suggest a different way of doing it?