为什么GridView中的左上角单元格不滚动？

Question

Problem : I'm using a scrollview INSIDE a gridview. The problem is that the top-left cell never scrolls.

I've tried all the other cells in many different combinations and it is only the top left which is unscrollable.

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:DigitalMenu"
             x:Class="DigitalMenu.MainPage">

    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="*"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>

        <!-- TOP LEFT : This will NOT SCROLL :(-->
        <ScrollView Grid.Row="0" Grid.Column="0">
            <StackLayout>
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
            </StackLayout>
        </ScrollView>

        <!-- TOP RIGHT This will scroll-->
        <ScrollView Grid.Row="0" Grid.Column="1">
            <StackLayout>
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
            </StackLayout>
        </ScrollView>

        <!-- BOTTOM LEFT This will scroll-->
        <ScrollView Grid.Row="1" Grid.Column="0">
            <StackLayout>
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
            </StackLayout>
        </ScrollView>

        <!-- BOTTOM RIGHT This will scroll-->
        <ScrollView Grid.Row="1" Grid.Column="1">
            <StackLayout>
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
                <Button Text="Something" />
            </StackLayout>
        </ScrollView>

        <ListView>

        </ListView>
    </Grid>

</ContentPage>

Answer 1

Your left top cell can't be scrolled because you placed an empty list view in that space. It will overlap your original scroll view content so that you feel like it was stuck. At the bottom of your code you wrote like:

<Grid>
    ...
    <ListView>
    </ListView>
</Grid>

If you didn't explicitly set its row and column it will be 0. Grid will stretch all of its children to the whole space due to Grid's feature. And the control you set later will be in the topper hierarchy.

At last, an empty list view prevents you from touching the scroll view. Your first cell can be scrolled if you remove that list view.

Answer 2

After opening a beer I had the brilliant idea of creating a new GridView and just moving the ScrollView elements from the former GridView to the latter GridView and for some reason that just fixed the problem by itself. I still don't know why this happened in the first place